LYEL

PiNACLE pivotal clinical trial evaluating ronde-cel in 3L+ patients with LBCL on track to report additional data in second half of 2026, with pivotal data expected mid-2027 and BLA submission expected to follow in the second half of 2027 Presented updated ronde-cel data in more than 100 patients with relapsed/refractory LBCL at the EHA 2026 Congress, with Phase 1/2 safety data showing no Grade ≥ 3 CRS and low rates of Grade ≥ 3 ICANS supporting potential outpatient administration Reported updated LYL273 safety data in relapsed/refractory mCRC, with gastrointestinal prophylaxis regimen and standardized safety management plan reducing Grade ≥ 2 diarrhea or colitis from 55% to 10%; amended ongoing U.S. Phase 1 trial to a Phase 1/2 design to enable seamless expansion into a potential pivotal single-arm Phase 2 trial pending regulatory alignment Additional data from the U.S. Phase 1 trial of LYL273 in 3L+ patients with relapsed/refractory mCRC and End‑of-Phase 1 FDA meeting are expected in the second half of 2026 Approximately $228.0 million in cash, cash equivalents and marketable securities as of June 30, 2026, expected to provide runway into Q3 2027 SOUTH SAN FRANCISCO, Calif., Aug. 06, 2026 (GLOBE NEWSWIRE) -- Lyell Immunopharma, Inc. (Nasdaq: LYEL), a late-stage clinical company advancing a pipeline of next-generation chimeric antigen receptor (CAR) T-cell therapies for patients with cancer, today reported financial results and business highlights for the second quarter ended June 30, 2026. Second Quarter Updates and Recent Business Highlights Rondecabtagene Autoleucel (Ronde-cel): A next-generation dual-targeting CD19/CD20 CAR T-cell product candidate designed to increase complete response rates and prolong the duration of response as compared to approved CD19‑targeted CAR T-cell therapies for the treatment of large B-cell lymphoma (LBCL) Ronde-cel is an autologous CAR T-cell product candidate under evaluation in two pivotal trials in patients with relapsed/refractory (R/R) LBCL in the third- or later-line (3L+) setting (PiNACLE) and the second-line (2L) setting (PiNACLE‑H2H). Ronde-cel targets B cells that express either CD19 or CD20 with a true ‘OR’ logic gate to achieve full potency at either target and is manufactured with a process that enriches for CD62L-positive cells to generate more naïve and central memory CAR T cells with enhanced stemlike features and antitumor activity. The U.S. Food and Drug Administration (FDA) has granted ronde-cel Regenerative Medicine Advanced Therapy (RMAT) and Fast Track designations for the treatment of adults with R/R diffuse large B-cell lymphoma (DLBCL) in the 3L+ setting and also RMAT designation for the treatment of large B-cell lymphoma (LBCL) in the 2L setting. The FDA has also granted ronde‑cel Orphan Drug Designation for the treatment of DLBCL/HGBCL with MYC and BCL2 rearrangements. In June 2026, Lyell presented updated safety data and translational insights for ronde-cel in two presentations at the European Hematology Association (EHA) 2026 Congress in Stockholm, Sweden. The PiNACLE pivotal single-arm trial, a seamless expansion of the 3L+ cohort in the Phase 1/2 multi‑cohort trial, is ongoing. Additional data from this trial are expected in the second half of 2026, and pivotal data are expected in mid-2027 with submission of a Biologics License Application (BLA) to the FDA expected to follow in the second half of 2027. The primary endpoint of the trial is overall response rate, including an evaluation of duration of response. PiNACLE-H2H, the first-of-its-kind Phase 3 randomized controlled trial evaluating ronde-cel versus investigator’s choice of axicabtagene ciloleucel or lisocabtagene maraleucel in patients with R/R LBCL in the 2L setting, continues to enroll patients. A progress update for this trial is expected in the second half of 2026. The trial’s primary endpoint is event-free survival. LYL273: A next-generation guanylyl cyclase C (GCC)-targeted CAR T-cell product candidate for the treatment of relapsed/refractory metastatic colorectal cancer (mCRC) and other GCC-expressing cancers LYL273 is a GCC-targeted CAR T-cell product candidate enhanced with CD19 CAR expression and controlled cytokine release, designed to improve CAR T-cell expansion, immune cell infiltration and cancer cell killing in the hostile solid tumor microenvironment. In November 2025, Lyell acquired global rights (excluding mainland China, Hong Kong, Macau and Taiwan) to LYL273, which has shown promising dose-dependent clinical activity in patients with advanced R/R mCRC in a Phase 1 trial conducted in the U.S. following proof of concept in 15 patients in China. The FDA granted LYL273 Fast Track designation for the treatment of mCRC. In June 2026, Lyell reported updated safety data from patients with 3L+ R/R mCRC in the ongoing U.S. Phase 1 trial, including 19 patients, of which 10 were treated with gastrointestinal (GI) prophylaxis and a new safety management protocol and 9 were treated without GI prophylaxis across Dose Levels 1 and 2 (1 and 2 x 106 CAR+ cells/kg, respectively) as of the data cutoff date of May 5, 2026. The GI prophylaxis regimen included treatment with infliximab, vedolizumab and budesonide prior to the development of symptoms. Based on the new safety data, Lyell amended the ongoing U.S. Phase 1 trial to a Phase 1/2 design, enabling seamless expansion into a potential pivotal single-arm Phase 2 trial once the recommended Phase 2 dose is determined and subject to discussions with the FDA. The amendment adds new cohorts, including a 2L cohort and a cohort evaluating a combination strategy with radiotherapy. Additional U.S. Phase 1 clinical data in patients with R/R mCRC in the 3L+ setting and an End-of-Phase 1 meeting with the FDA are expected in the second half of 2026. Second Quarter 2026 Financial Results Lyell reported a net loss of $44.8 million for the second quarter ended June 30, 2026, compared to a net loss of $42.7 million for the same period in 2025. The $2.1 million increase in net loss was primarily due to a $4.7 million increase in research and development expenses driven by increased clinical trial activity and lower interest income, partially offset by lower property and equipment disposal losses, and a $1.4 million long-lived asset impairment charge that did not recur. Non‑GAAP net loss, which excludes non-cash stock-based compensation, non-cash expenses related to the change in the estimated fair value of the Securities Purchase Agreement put/call asset relating to the Company’s July 2025 private placement transaction and success payment liabilities, increased by $2.8 million to $40.6 million for the second quarter ended June 30, 2026, compared to $37.8 million for the same period in 2025, primarily due to increased clinical trial activity and lower interest income. GAAP and Non-GAAP Operating Expenses Research and development (R&D) expenses were $39.5 million for the second quarter ended June 30, 2026, compared to $34.9 million for the same period in 2025. The $4.7 million increase was primarily due to an $8.8 million increase in research activities, collaborations and outside services due to increased clinical trial activity, partially offset by a $4.2 million decrease in facilities and personnel expenses. Non‑GAAP R&D expenses, which exclude non-cash stock-based compensation, for the second quarter ended June 30, 2026 were $37.4 million compared to $32.6 million for the same period in 2025. General and administrative (G&A) expenses were $9.6 million for the second quarter ended June 30, 2026 compared to $9.8 million for the same period in 2025, primarily due to lower professional services expenses. Non‑GAAP G&A expenses, which exclude non-cash stock‑based compensation, for the second quarter ended June 30, 2026 were $7.2 million compared to $7.1 million for the same period in 2025. A discussion of non-GAAP financial measures, including reconciliations of the most comparable U.S. generally accepted accounting principles (GAAP) measures to non‑GAAP financial measures, is presented below under “Non-GAAP Financial Measures.” Cash, cash equivalents and marketable securities Cash, cash equivalents and marketable securities as of June 30, 2026 were $228.0 million compared to $247.2 million as of December 31, 2025. Lyell believes that its current cash, cash equivalents and marketable securities balances will be sufficient to meet working capital and capital expenditure needs into the third quarter of 2027. About Lyell Immunopharma, Inc. Lyell is a late-stage clinical company advancing a pipeline of next-generation CAR T-cell therapies for patients with hematologic malignancies and solid tumors. To realize the potential of cell therapy for cancer, Lyell utilizes a suite of technologies to arm CAR T cells with enhancements needed to drive durable tumor cytotoxicity and achieve consistent and long-lasting clinical responses, including the ability to resist exhaustion, maintain qualities of durable stemness and function in the hostile tumor microenvironment. LyFE has commercial launch capability and is expected to have the capacity to manufacture more than 1,200 CAR T-cell doses per year. To learn more, please visit www.lyell.com. Forward-Looking Statements This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements expressed or implied in this press release include, but are not limited to, statements regarding: Lyell’s plans for its existing cash, cash equivalents and marketable securities, and its expectation that its financial position and cash runway will be sufficient to meet working capital and capital expenditure needs into the third quarter of 2027; Lyell’s expectations around the progress of the PiNACLE and PiNACLE-H2H trials, including the expected timing for release of additional and pivotal data from the PiNACLE trial; the use of pivotal data from the PiNACLE trial to support a BLA submission to the FDA in 2027 and other expectations around enrollment and regulatory submissions; Lyell’s expectations around the progress of the U.S. Phase 1 trial for LYL273, including the expected timing for release of additional clinical data from this trial and an End-of-Phase 1 FDA meeting; the anticipated benefits of Orphan Drug, RMAT and Fast Track designations for ronde-cel and Fast Track designation for LYL273; the capability of LyFE to manufacture drug supply through potential commercial launch and its expected manufacturing capacity; the potential clinical benefits and therapeutic potential of Lyell’s product candidates; and other statements that are not historical fact. These statements are based on Lyell’s current plans, objectives, estimates, expectations and intentions, are not guarantees of future performance and inherently involve significant risks and uncertainties. Actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of these risks and uncertainties, which include, but are not limited to, risks and uncertainties related to: Lyell operates in a rapidly evolving industry and has a limited operating history; Lyell’s ability to successfully develop, manufacture and commercialize product candidates or its experiencing significant delays in doing so; Lyell’s dependence on the enrollment and retention of patients in its current and planned clinical trials for its product candidates; the potential for results of Lyell’s research, nonclinical studies or earlier clinical trials to not be predictive of future results; clinical development involving a lengthy and expensive process with uncertain outcomes; Lyell’s product candidates and technologies being based on novel technologies that are unproven and may not result in approvable or marketable products; Lyell facing substantial competition in a rapidly changing industry, which may result in others discovering, developing or commercializing products before or more successfully than it does; Lyell’s ability to obtain and maintain sufficient intellectual property protection for its product candidates; the complexity of manufacturing cellular therapies; Lyell’s ability to manufacture drug products for its clinical trials itself and any potential delays in further qualifying or in receiving regulatory approvals for any manufacturing facility or product candidates or in expanding its manufacturing capacity; Lyell’s reliance on third parties; implementation of Lyell’s strategic plans for its business and product candidates and Lyell’s realization of the expected benefits of such plans; the potential reduction of Lyell’s cash resources and fluctuations in Lyell’s operating results and financial condition as a result of Lyell’s milestone, royalty and success payment obligations; the sufficiency of Lyell’s capital resources and need for additional capital to achieve its goals; and other risks, including those described under the heading “Risk Factors” in Lyell’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2026, being filed with the Securities and Exchange Commission today. Forward-looking statements contained in this press release are made as of this date, and Lyell undertakes no duty to update such information except as required under applicable law. Balance Sheet Data: Non-GAAP Financial Measures To supplement our financial results and guidance presented in accordance with GAAP, we present non-GAAP net loss, non-GAAP R&D expenses and non-GAAP G&A expenses. Non‑GAAP net loss excludes non-cash stock-based compensation expense, non-cash expenses related to the change in the estimated fair value of success payment liabilities and the change in the estimated fair value of our securities purchase agreement put/call asset. Non‑GAAP R&D and G&A expenses exclude non-cash stock-based compensation expense from GAAP R&D and G&A expenses. We believe that these non‑GAAP financial measures, when considered together with our financial information prepared in accordance with GAAP, can enhance investors’ and analysts’ ability to meaningfully compare our results from period to period, and to identify operating trends in our business. We have excluded stock-based compensation expense, changes in the estimated fair value of success payment liabilities and the change in the estimated fair value of our securities purchase agreement put/call asset from our non‑GAAP financial measures because they are gains and charges that may vary significantly from period to period as a result of changes not directly or immediately related to the operational performance for the periods presented. We also regularly use these non‑GAAP financial measures internally to understand, manage and evaluate our business and to make operating decisions. These non-GAAP financial measures are in addition to, and not a substitute for or superior to, measures of financial performance prepared in accordance with GAAP. In addition, these non‑GAAP financial measures have no standardized meaning prescribed by GAAP and are not prepared under any comprehensive set of accounting rules or principles and, therefore, have limits in their usefulness to investors. We encourage investors to carefully consider our results under GAAP, as well as our supplemental non-GAAP financial information, to more fully understand our business. Contact: Pablo Fenton Associate Director, Investor Relations and Corporate Communications [email protected]

PiNACLE pivotal clinical trial evaluating ronde-cel in patients with LBCL in third- or later-line setting on track to report additional data in second half of 2026, with pivotal data expected mid-2027 and BLA submission expected to follow in 2027 PiNACLE-H2H, a first of its kind Phase 3 clinical trial evaluating ronde-cel head-to-head against standard-of-care CD19 CAR T-cell therapies in the LBCL second-line setting, commenced patient dosing Phase 1 clinical trial of LYL273 continues to enroll patients with metastatic colorectal cancer, with commencement of patient dosing at Dose Level 3 Closed second $50 million tranche of $100 million private placement at $25.61 per share, with approximately $261 million in cash as of March 31, 2026, expected to provide runway into Q3 2027 SOUTH SAN FRANCISCO, Calif., May 06, 2026 (GLOBE NEWSWIRE) -- Lyell Immunopharma, Inc. (Nasdaq: LYEL), a late-stage clinical company advancing a pipeline of next-generation chimeric antigen receptor (CAR) T-cell therapies for patients with cancer, today reported financial results and business highlights for the first quarter ended March 31, 2026. First Quarter Updates and Recent Business Highlights Ronde-cel: A next-generation dual-targeting CD19/CD20 CAR T-cell product candidate designed to increase complete response rates and prolong the duration of response as compared to approved CD19‑targeted CAR T-cell therapies for the treatment of large B-cell lymphoma (LBCL) Ronde-cel is an autologous CAR T-cell product candidate with a true ‘OR’ logic gate to target B cells that express either CD19 or CD20 with full potency and is manufactured with a process that enriches for CD62L-positive cells to generate more naïve and central memory CAR T cells with enhanced stemlike features and antitumor activity. The U.S. Food and Drug Administration (FDA) has granted ronde-cel Regenerative Medicine Advanced Therapy (RMAT) designation in the third- and later-line (3L+) and second-line (2L) settings, as well as Fast Track designation for the treatment of adults with relapsed/refractory large B-cell lymphoma (R/R LBCL). Two pivotal trials for ronde-cel in LBCL are underway. The ongoing PiNACLE pivotal single-arm trial, a seamless expansion of the 3L+ cohort in the Phase 1/2 multi‑cohort trial, is ongoing. Additional data from this trial are expected in the second half of 2026, and pivotal data are expected in mid-2027 with submission of a Biologics License Application (BLA) to the FDA expected to follow in 2027. The primary endpoint of the trial is the overall response rate, including an evaluation of duration of response. In February 2026, patient dosing commenced in PiNACLE-H2H, the first-of-its-kind Phase 3 randomized controlled trial evaluating ronde-cel versus investigator’s choice of axicabtagene ciloleucel or lisocabtagene maraleucel in patients with R/R LBCL in the 2L setting. The trial’s primary endpoint is event-free survival. LYL273: A next-generation guanylyl cyclase C (GCC)-targeted CAR T-cell product candidate for the treatment of metastatic colorectal cancer (mCRC) and other GCC-expressing cancers LYL273 is a GCC-targeted CAR T-cell product candidate enhanced with CD19 CAR expression and controlled cytokine release, designed to improve CAR T-cell expansion, immune cell infiltration and cancer cell killing in the hostile solid tumor microenvironment. In November 2025, Lyell acquired global rights (excluding mainland China, Hong Kong, Macau and Taiwan) to LYL273, which has shown promising dose-dependent clinical activity in patients with advanced mCRC in a Phase 1 trial conducted in the U.S. following proof of concept in 15 patients in China. The FDA granted LYL273 Fast Track designation for the treatment of mCRC. The U.S. Phase 1 clinical trial is continuing to enroll patients to determine the recommended Phase 2 dose. In March 2026, dosing commenced at Dose Level 3 (3 x 106 CAR T cells/kg). A data update focused on safety from this trial is expected in the first half of 2026, with a second data update including clinical outcomes expected in the second half of 2026. Additional Business Highlights In March 2026, Lyell closed the second $50 million tranche of its July 2025 equity private placement, following the successful achievement of a clinical milestone in PiNACLE. In the second tranche of the financing, which completed the total $100 million private placement, shares of common stock were sold at a purchase price of $25.61 per share. In March 2026, Smital Shah was appointed Chief Financial and Business Officer. First Quarter 2026 Financial Results Lyell reported a net loss of $24.2 million for the first quarter ended March 31, 2026, compared to a net loss of $52.2 million for the same period in 2025. The $28.0 million decrease in net loss was primarily due to a $17.6 million gain on our Securities Purchase Agreement put/call asset relating to our July 2025 equity private placement. Non‑GAAP net loss, which excludes non-cash stock-based compensation, non-cash expenses related to the change in the estimated fair value of the Securities Purchase Agreement put/call asset and success payment liabilities, decreased by $8.5 million to $37.8 million for the first quarter ended March 31, 2026, compared to $46.3 million for the same period in 2025 primarily due to the decreased headcount from the successful technology transfer of ronde-cel to the Company’s LyFE Manufacturing CenterTM (LyFE) in 2025. GAAP and Non-GAAP Operating Expenses Research and development (R&D) expenses were $36.6 million for the first quarter ended March 31, 2026, compared to $43.4 million for the same period in 2025. The $6.8 million decrease was primarily due to a $7.5 million reduction in personnel expenses, partially offset by a $3.4 million increase in clinical trials activity and outside services. Non‑GAAP R&D expenses, which exclude non-cash stock-based compensation, for the first quarter ended March 31, 2026 were $34.4 million compared to $41.1 million for the same period in 2025. General and administrative (G&A) expenses were $9.6 million for the first quarter ended March 31, 2026 compared to $14.0 million for the same period in 2025. The $4.5 million decrease was primarily due to a $4.0 million reduction in personnel‑related expenses, including a $1.5 million decrease in stock-based compensation expense. Non‑GAAP G&A expenses, which exclude non-cash stock‑based compensation, for the first quarter ended March 31, 2026 were $7.5 million compared to $10.4 million for the same period in 2025. A discussion of non-GAAP financial measures, including reconciliations of the most comparable U.S. generally accepted accounting principles (GAAP) measures to non‑GAAP financial measures, is presented below under “Non-GAAP Financial Measures.” Cash, cash equivalents and marketable securities Cash, cash equivalents and marketable securities as of March 31, 2026 were $261.0 million compared to $247.2 million as of December 31, 2025. Lyell believes that its current cash, cash equivalents and marketable securities balances will be sufficient to meet working capital and capital expenditure needs into the third quarter of 2027. About Lyell Immunopharma, Inc. Lyell is a late-stage clinical company advancing a pipeline of next-generation CAR T-cell therapies for patients with hematologic malignancies and solid tumors. To realize the potential of cell therapy for cancer, Lyell utilizes a suite of technologies to arm CAR T cells with enhancements needed to drive durable tumor cytotoxicity and achieve consistent and long-lasting clinical responses, including the ability to resist exhaustion, maintain qualities of durable stemness and function in the hostile tumor microenvironment. LyFE has commercial launch capability and is expected to have the capacity to manufacture more than 1,200 CAR T-cell doses per year. To learn more, please visit www.lyell.com. Forward-Looking Statements This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements expressed or implied in this press release include, but are not limited to, statements regarding: Lyell’s plans for its existing cash, cash equivalents and marketable securities, and its expectation that its financial position and cash runway will be sufficient to meet working capital and capital expenditure needs into the third quarter of 2027; Lyell’s expectations around the progress of the PiNACLE and PiNACLE-H2H trials, including the expected timing for release of additional and pivotal data from the PiNACLE trial; the use of pivotal data from the PiNACLE trial to support a BLA submission to the FDA in 2027 and other expectations around enrollment and regulatory submissions; Lyell’s expectations around the progress of the U.S. Phase 1 trial for LYL273, including the expected timing for release of clinical data from this trial; the anticipated benefits of RMAT and Fast Track designations for ronde-cel and Fast Track designation for LYL273; the capability of LyFE to manufacture drug supply through potential commercial launch and its expected manufacturing capacity; the potential clinical benefits and therapeutic potential of Lyell’s product candidates; and other statements that are not historical fact. These statements are based on Lyell’s current plans, objectives, estimates, expectations and intentions, are not guarantees of future performance and inherently involve significant risks and uncertainties. Actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of these risks and uncertainties, which include, but are not limited to, risks and uncertainties related to: Lyell operates in a rapidly evolving industry and has a limited operating history; Lyell’s ability to successfully develop, manufacture and commercialize product candidates or its experiencing significant delays in doing so; Lyell’s dependence on the enrollment and retention of patients in its current and planned clinical trials for its product candidates; the potential for results of Lyell’s research, nonclinical studies or earlier clinical trials to not be predictive of future results; clinical development involving a lengthy and expensive process with uncertain outcomes; Lyell’s product candidates and technologies being based on novel technologies that are unproven and may not result in approvable or marketable products; Lyell facing substantial competition in a rapidly changing industry, which may result in others discovering, developing or commercializing products before or more successfully than it does; Lyell’s ability to obtain and maintain sufficient intellectual property protection for its product candidates; the complexity of manufacturing cellular therapies; Lyell’s ability to manufacture drug products for its clinical trials itself and any potential delays in further qualifying or in receiving regulatory approvals for any manufacturing facility or product candidates or in expanding its manufacturing capacity; Lyell’s reliance on third parties; implementation of Lyell’s strategic plans for its business and product candidates and Lyell’s realization of the expected benefits of such plans; the potential reduction of Lyell’s cash resources and fluctuations in Lyell’s operating results and financial condition as a result of Lyell’s milestone, royalty and success payment obligations; the sufficiency of Lyell’s capital resources and need for additional capital to achieve its goals; and other risks, including those described under the heading “Risk Factors” in Lyell’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2026, being filed with the Securities and Exchange Commission today. Forward-looking statements contained in this press release are made as of this date, and Lyell undertakes no duty to update such information except as required under applicable law. Balance Sheet Data: Non-GAAP Financial Measures To supplement our financial results and guidance presented in accordance with GAAP, we present non-GAAP net loss, non-GAAP R&D expenses and non-GAAP G&A expenses. Non‑GAAP net loss excludes non-cash stock-based compensation expense, non-cash expenses related to the change in the estimated fair value of success payment liabilities and the change in the estimated fair value of our securities purchase agreement put/call asset. Non‑GAAP R&D and G&A expenses exclude non-cash stock-based compensation expense from GAAP R&D and G&A expenses. We believe that these non‑GAAP financial measures, when considered together with our financial information prepared in accordance with GAAP, can enhance investors’ and analysts’ ability to meaningfully compare our results from period to period, and to identify operating trends in our business. We have excluded stock-based compensation expense, changes in the estimated fair value of success payment liabilities and the change in the estimated fair value of our securities purchase agreement put/call asset from our non‑GAAP financial measures because they are gains and charges that may vary significantly from period to period as a result of changes not directly or immediately related to the operational performance for the periods presented. We also regularly use these non‑GAAP financial measures internally to understand, manage and evaluate our business and to make operating decisions. These non-GAAP financial measures are in addition to, and not a substitute for or superior to, measures of financial performance prepared in accordance with GAAP. In addition, these non‑GAAP financial measures have no standardized meaning prescribed by GAAP and are not prepared under any comprehensive set of accounting rules or principles and, therefore, have limits in their usefulness to investors. We encourage investors to carefully consider our results under GAAP, as well as our supplemental non-GAAP financial information, to more fully understand our business. Contact: Pablo Fenton Associate Director, Investor Relations and Corporate Communications [email protected]

Patient dosing has commenced in first-of-its-kind Phase 3 head-to-head CAR T-cell 2L randomized controlled clinical trial (PiNACLE-H2H) in patients with large B-cell lymphoma, and the 3L+ pivotal trial (PiNACLE) evaluating ronde-cel is ongoing Phase 1 trial is ongoing for LYL273, an enhanced GCC-targeted CAR T-cell candidate for metastatic colorectal cancer; seven new patients treated without dose-limiting toxicity and including dose escalation to Dose Level 3 Smital Shah was appointed Chief Financial and Business Officer in March 2026 Second $50 million tranche of $100 million equity private placement closed in March 2026 after achievement of clinical milestone for ronde-cel Cash of approximately $247.2 million at the end of 2025 excluding the $50 million tranche; current cash expected to advance pipeline into the second quarter of 2027, including through multiple key clinical milestones SOUTH SAN FRANCISCO, Calif., March 12, 2026 (GLOBE NEWSWIRE) -- Lyell Immunopharma, Inc. (Nasdaq: LYEL), a late-stage clinical company advancing a pipeline of next-generation chimeric antigen receptor (CAR) T-cell therapies for patients with cancer, today reported financial results and business highlights for the fourth quarter and year ended December 31, 2025. Lyell has since commenced patient dosing in the first-of-its-kind Phase 3 head-to-head CAR T-cell randomized controlled clinical trial of rondecabtagene autoleucel (ronde-cel) versus investigator’s choice of axicabtagene ciloleucel (axi-cel) or lisocabtagene maraleucel (liso-cel) in patients with relapsed/refractory (R/R) large B-cell lymphoma (LBCL) with disease progression on at least one prior line of therapy (PiNACLE-H2H). Lyell has dosed seven new patients with metastatic colorectal cancer (mCRC) with LYL273, an enhanced guanylyl cyclase C (GCC)-targeted CAR T-cell product candidate, since its November 2025 acquisition, without dose-limiting toxicity and including dose escalation to Dose Level 3. Lyell also recently announced it has closed the sale of an additional $50 million of shares of its common stock to investors from its July 2025 equity private placement of up to $100 million, following achievement of a clinical milestone within its PiNACLE pivotal trial evaluating ronde-cel in patients with R/R LBCL in the third- or later-line setting (3L+), and the appointment of Smital Shah as its Chief Financial and Business Officer. “Lyell is on track to achieve multiple clinical milestones in the next 12 to 18 months. We have now advanced ronde-cel into two pivotal clinical trials, with the pivotal data supporting BLA submission from the PiNACLE trial expected to be reported mid-next year,” said Lynn Seely, M.D., President and Chief Executive Officer of Lyell. “With the encouraging emerging safety profile and clinical activity observed with LYL273 in patients with metastatic colorectal cancer, we believe Lyell is well-positioned with two next-generation CAR T‑cell product candidates.” Fourth Quarter Updates and Recent Business Highlights Ronde-cel: A next-generation dual-targeting CD19/CD20 CAR T-cell product candidate designed to increase complete response rates and prolong the duration of response as compared to approved CD19‑targeted CAR T-cell therapies for the treatment of LBCL Ronde-cel is an autologous CAR T-cell product candidate with a true ‘OR’ logic gate to target B cells that express either CD19 or CD20 with full potency and is manufactured with a process that enriches for CD62L-positive cells to generate more naïve and central memory CAR T cells with enhanced stemlike features and antitumor activity. Ronde-cel has received from the U.S. Food and Drug Administration (FDA) Regenerative Medicine Advanced Therapy (RMAT) designation as well as Fast Track designation for the treatment of adults with R/R LBCL. The pivotal PiNACLE single-arm trial is a seamless expansion of the 3L+ cohort in the Phase 1/2 multi-cohort trial and is evaluating ronde-cel at a dose of 100 x 106 CAR T cells in patients with R/R LBCL. The trial is expected to enroll approximately 120 patients in the inpatient or outpatient setting, and there is no upper age limit for eligibility. The primary endpoint of the trial is the overall response rate, including an evaluation of duration of response. Patient dosing commenced in February 2026 in PiNACLE-H2H, the Phase 3 randomized controlled trial evaluating ronde-cel versus investigator’s choice of axi-cel or liso-cel in patients with R/R LBCL in the 2L setting. The trial is expected to enroll approximately 400 patients (200 per arm) at sites in the US, Canada and Australia. Patients may be treated in either the inpatient or outpatient setting. The trial’s primary endpoint is event-free survival. Updated data from the ongoing Phase 1/2 clinical trial were presented at the December 2025 American Society of Hematology Annual Meeting and Exposition (ASH 2025): A best overall response rate of 93% and a complete response rate of 76% in 29 efficacy-evaluable patients with R/R LBCL in the 3L+ setting. The median progression-free survival was 18 months as of the data cutoff date of September 5, 2025. Data were also presented from the 2L cohort in the Phase 1/2 multi-cohort clinical trial, including an efficacy-evaluable population of 18 patients (94% with high-risk primary refractory disease) and demonstrated an 83% best overall response rate and a 61% complete response rate. The safety profile was appropriate for outpatient administration. Data from 25 patients treated with ronde-cel who received dexamethasone prophylaxis in the 3L+ and 2L settings revealed no events of ≥ Grade 3 cytokine release syndrome and a 4% rate of ≥ Grade 3 immune cell-associated neurotoxicity syndrome. LYL273 (formerly known as GCC19CART): A next-generation GCC-targeted CAR T-cell product candidate for the treatment of mCRC and other GCC-expressing cancers LYL273 is a GCC-targeted CAR T-cell product candidate enhanced with CD19 CAR expression and controlled cytokine release, designed to improve CAR T-cell expansion, immune cell infiltration and cancer cell killing in the hostile tumor microenvironment. In November 2025, we acquired global rights (excluding mainland China, Hong Kong, Macau and Taiwan) to LYL273, which has shown promising dose-dependent clinical activity in patients with advanced mCRC in a Phase 1 trial conducted in the U.S. LYL273 received from the FDA Fast Track designation for the treatment of mCRC. The U.S. Phase 1 clinical trial is continuing to enroll patients to determine the recommended Phase 2 dose. Seven additional patients with mCRC have been treated with LYL273 since the November 2025 acquisition without dose-limiting toxicity and including dose escalation to Dose Level 3. A 67% best overall response rate, an 83% disease control rate and an 8-month median progression-free survival with a manageable safety profile have been reported at the highest dose level tested as of the data cutoff date of October 28, 2025 (Dose Level 2) in patients with refractory mCRC in the U.S. Phase 1 clinical trial. Fourth Quarter and Full Year 2025 Financial Results Lyell reported a net loss of $140.7 million and $274.4 million for the fourth quarter and year ended December 31, 2025, respectively, compared to a net loss of $191.9 million and $343.0 million for the same periods in 2024. Net loss for the fourth quarter and year ended December 31, 2025 included $66.3 million in acquired in-process research and development (IPR&D) expense as part of the acquisition of our rights to LYL273, and $19.7 million in stock-based compensation expense for an equity milestone deemed probable related to the LYL273 license acquisition. Net loss for the fourth quarter and year ended December 31, 2024 included $87.2 million in acquired IPR&D expense as part of our acquisition of ImmPACT Bio and $51.3 million of long‑lived asset impairment expense. Non‑GAAP net loss, which excludes stock-based compensation, non-cash expenses related to the change in the estimated fair value of success payment liabilities and securities purchase agreement put/call liability, long‑lived asset impairment expense and certain non-cash investment gains and charges, was $33.1 million and $144.8 million for the fourth quarter and year ended December 31, 2025, respectively, compared to $45.9 million and $159.5 million for the same periods in 2024. GAAP and Non-GAAP Operating Expenses Research and development (R&D) expenses were $52.2 million for the fourth quarter ended December 31, 2025, compared to $48.7 million for the same period in 2024. The increase in fourth quarter 2025 R&D expenses of $3.5 million was primarily due to $19.7 million in stock-based compensation expense for an equity milestone deemed probable related to the LYL273 license acquisition. The increase in fourth quarter 2025 R&D expenses was partially offset by an $8.9 million reduction in personnel costs and a $4.7 million reduction in additional facilities and technology costs primarily due to reduced headcount following the successful technology transfer of ronde-cel to our LyFE Manufacturing CenterTM (LyFE) and associated workforce reduction in the first half of 2025. Non‑GAAP R&D expenses, which exclude non-cash stock-based compensation and non-cash expenses related to the change in the estimated fair value of success payment liabilities for the fourth quarter ended December 31, 2025, were $30.1 million compared to $45.4 million for the same period in 2024 due to the workforce reduction related to the successful technology transfer of ronde-cel. General and administrative (G&A) expenses were $10.6 million for the fourth quarter ended December 31, 2025, compared to $14.5 million for the same period in 2024. The decrease in fourth quarter 2025 G&A expenses of $3.9 million was primarily due to a $4.1 million decrease in personnel costs associated with the workforce reduction related to the successful ronde-cel technology transfer, partially offset by a $0.8 million increase in collaborations and licenses expenses. A discussion of non-GAAP financial measures, including reconciliations of the most comparable U.S. generally accepted accounting principles (GAAP) measures to non‑GAAP financial measures, is presented below under “Non-GAAP Financial Measures.” Cash, cash equivalents and marketable securities Cash, cash equivalents and marketable securities as of December 31, 2025 were approximately $247.2 million (excluding the $50 million tranche received in March 2026), compared to approximately $383.5 million as of December 31, 2024. Lyell believes that its current cash, cash equivalents and marketable securities balances will be sufficient to meet working capital and capital expenditure needs into the second quarter of 2027. About Lyell Immunopharma, Inc. Lyell is a late-stage clinical company advancing a pipeline of next-generation CAR T-cell therapies for patients with hematologic malignancies and solid tumors. To realize the potential of cell therapy for cancer, Lyell utilizes a suite of technologies to arm CAR T cells with enhancements needed to drive durable tumor cytotoxicity and achieve consistent and long‑lasting clinical responses, including the ability to resist exhaustion, maintain qualities of durable stemness and function in the hostile tumor microenvironment. LyFE has commercial launch capability and can manufacture more than 1,200 CAR T-cell doses at full capacity. To learn more, please visit www.lyell.com. Forward-Looking Statements This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements expressed or implied in this press release include, but are not limited to, statements regarding: Lyell’s plans for its existing cash, cash equivalents and marketable securities, and its expectation that its financial position and cash runway will support advancement of its pipeline into the second quarter of 2027 through multiple key clinical milestones; Lyell’s expectation around the timing of the achievement of clinical milestones in the next 12 to 18 months; Lyell’s expectations around the progress of the PiNACLE trial, including expectations around enrollment, and using pivotal data from the trial to support a Biologics License Application (BLA) submission to the FDA in mid‑2027; Lyell’s belief that it is well-positioned with two next generation CAR T-cell product candidates; Lyell’s expectations around the progress of the PiNACLE-H2H trial, including its expectations around enrollment; Lyell’s expectations around the progress of the U.S. Phase 1 trial for LYL273; the anticipated benefits of RMAT and Fast Track designations for ronde-cel and Fast Track designation for LYL273; Lyell’s advancement of its pipeline and its research, development and clinical capabilities; the sufficiency of the capacity of LyFE to manufacture drug supply for Lyell’s ongoing and planned pivotal trials and through potential commercial launch; Lyell’s anticipated progress of its business plans, strategy and clinical trials; the potential clinical benefits and therapeutic potential of Lyell’s product candidates; and other statements that are not historical fact. These statements are based on Lyell’s current plans, objectives, estimates, expectations and intentions, are not guarantees of future performance and inherently involve significant risks and uncertainties. Actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of these risks and uncertainties, which include, but are not limited to, risks and uncertainties related to: Lyell’s limited experience as a company in enrolling and conducting clinical trials, and lack of experience in completing clinical trials; the nonclinical profiles of Lyell’s product candidates or technology not translating in clinical trials; the potential for results from clinical trials to differ from nonclinical, early clinical, preliminary or expected results; significant adverse events, toxicities or other undesirable side effects associated with Lyell’s product candidates; Lyell’s ability to make planned regulatory submissions or progress clinical trials on the anticipated timelines, if at all; RMAT and Fast Track designations may not actually lead to faster development, regulatory review or approval process, and do not assure ultimate FDA approval; the significant uncertainty associated with Lyell’s product candidates ever receiving any regulatory approvals; Lyell’s ability to obtain, maintain or protect intellectual property rights related to its product candidates; the complexity of manufacturing cellular therapies and Lyell’s ability to manufacture and supply its product candidates for its clinical trials; implementation of Lyell’s strategic plans for its business and product candidates and Lyell’s realization of the expected benefits of such plans; the potential reduction of Lyell’s cash resources and fluctuations in Lyell’s operating results and financial condition as a result of Lyell’s milestone, royalty and success payment obligations; the sufficiency of Lyell’s capital resources and need for additional capital to achieve its goals; and other risks, including those described under the heading “Risk Factors” in Lyell’s Annual Report on Form 10-K for the year ended December 31, 2025, being filed with the Securities and Exchange Commission today. Forward-looking statements contained in this press release are made as of this date, and Lyell undertakes no duty to update such information except as required under applicable law. (1) As of October 1, 2024, the Company’s success payment liability was recognized at fair value as Stanford had provided the requisite service obligation to earn the potential success payment consideration. The change in the estimated fair value of Stanford success payment liabilities beginning in Q4 2024 was recognized within other (expense) income, net in the Consolidated Statements of Operations and Comprehensive Loss. The change in the estimated fair value of Stanford success payment liabilities in the first nine months of 2024 were recognized within research and development expenses in the Consolidated Statements of Operations and Comprehensive Loss. The change in the estimated fair value of Fred Hutch success payment liabilities was recognized within other (expense) income, net in the Consolidated Statements of Operations and Comprehensive Loss. Balance Sheet Data: Non-GAAP Financial Measures To supplement our financial results and guidance presented in accordance with GAAP, we present non-GAAP net loss, non-GAAP R&D expenses and non-GAAP G&A expenses. Non‑GAAP net loss and non-GAAP R&D expenses exclude non-cash stock-based compensation expense and non-cash expenses related to the change in the estimated fair value of success payment liabilities. Non-GAAP net loss is further adjusted by acquired IPR&D expense, non-cash long-lived asset impairment expense, non‑cash investment gains and charges and the change in the estimated fair value of our securities purchase agreement put/call, as applicable. Non‑GAAP G&A expenses exclude non-cash stock-based compensation expense from GAAP G&A expenses. We believe that these non‑GAAP financial measures, when considered together with our financial information prepared in accordance with GAAP, can enhance investors’ and analysts’ ability to meaningfully compare our results from period to period, and to identify operating trends in our business. We have excluded stock-based compensation expense, changes in the estimated fair value of success payment liabilities, acquired IPR&D expense, long‑lived asset impairment expense, non-cash investment gains and charges and the change in the estimated fair value of our securities purchase agreement put/call from our non‑GAAP financial measures because they are gains and charges that may vary significantly from period to period as a result of changes not directly or immediately related to the operational performance for the periods presented. We also regularly use these non‑GAAP financial measures internally to understand, manage and evaluate our business and to make operating decisions. These non-GAAP financial measures are in addition to, and not a substitute for or superior to, measures of financial performance prepared in accordance with GAAP. In addition, these non‑GAAP financial measures have no standardized meaning prescribed by GAAP and are not prepared under any comprehensive set of accounting rules or principles and, therefore, have limits in their usefulness to investors. We encourage investors to carefully consider our results under GAAP, as well as our supplemental non-GAAP financial information, to more fully understand our business. (1) Stock-based compensation expense for the year ended December 31, 2025 reflects the expense associated with an ICT equity milestone deemed probable of achievement of $19.7 million. (2) There was no income tax effect related to the adjustments made to calculate non-GAAP net loss because of the full valuation allowance on our net deferred tax assets for all periods presented. (1) Research and development stock-based compensation expense for the year ended December 31, 2025 reflects the expense associated with an ICT equity milestone deemed probable of achievement of $19.7 million. (2) As of October 1, 2024, the Company’s success payment liability was recognized at fair value as Stanford had provided the requisite service obligation to earn the potential success payment consideration. The change in the estimated fair value of Stanford success payment liabilities beginning in Q4 2024 was recognized within other (expense) income, net in the Consolidated Statements of Operations and Comprehensive Loss. The change in the estimated fair value of Stanford success payment liabilities in the first nine months of 2024 were recognized within research and development expenses in the Consolidated Statements of Operations and Comprehensive Loss. The change in the estimated fair value of Fred Hutch success payment liabilities was recognized within other (expense) income, net in the Consolidated Statements of Operations and Comprehensive Loss. Contact: Peter Tran Senior Director, Finance [email protected]

Acquired exclusive global rights to LYL273, a novel GCC-targeted CAR T-cell product candidate that has demonstrated a 67% overall response rate, an 83% disease control rate and a manageable safety profile at the highest dose level studied to date in patients with refractory metastatic colorectal cancer in an ongoing U.S. Phase 1 clinical trial Received RMAT designation from the U.S. FDA for ronde-cel for the treatment of patients with relapsed or refractory LBCL receiving treatment in the second-line (2L) setting Announced that two abstracts highlighting new clinical and translational data from the Phase 1/2 clinical trial of ronde‑cel for the treatment of aggressive large B-cell lymphoma have been accepted for oral presentation at the ASH 67th Annual Meeting and Exposition in December Announced the initiation of PiNACLE - H2H, a Phase 3 head-to-head CAR T-cell therapy clinical trial in aggressive large B-cell lymphoma in the 2L setting Formed a PiNACLE – H2H Steering Committee comprised of a distinguished group of lymphoma and cell therapy experts Cash of approximately $320 million at the end of the third quarter of 2025; current cash is expected to support advancing pipeline into 2027 through key clinical milestones SOUTH SAN FRANCISCO, Calif., Nov. 12, 2025 (GLOBE NEWSWIRE) -- Lyell Immunopharma, Inc. (Nasdaq: LYEL), a late-stage clinical company advancing next-generation chimeric antigen receptor (CAR) T-cell therapies for patients with cancer, today reported financial results and business highlights for the third quarter ended September 30, 2025. Lyell’s lead clinical program, rondecabtagene autoleucel (ronde-cel, or LYL314), is an autologous dual-targeting CD19/CD20 chimeric antigen receptor (CAR) T-cell product candidate under evaluation in PiNACLE, a single-arm pivotal trial enrolling patients with relapsed and/or refractory (R/R) large B-cell lymphoma (LBCL) in the third- or later-line (3L+) setting and in a Phase 1/2 trial in the 2L setting. A second pivotal trial, PiNACLE – H2H, which is a Phase 3 head-to-head CAR T-cell therapy randomized controlled trial of ronde-cel for LBCL in the 2L, is expected to begin by early 2026. The U.S. Food and Drug Administration (FDA) granted ronde-cel Regenerative Medicine Advanced Therapy (RMAT) designation for the treatment of patients with R/R LBCL receiving treatment in the 2L setting in November 2025 to complement the RMAT designation received for ronde-cel in the 3L+ setting in April 2025. Lyell recently acquired exclusive global rights (outside of mainland China, Hong Kong, Macau and Taiwan) to LYL273, a novel autologous guanylyl cyclase-C (GCC)-targeted CAR T-cell product candidate in development for patients with refractory metastatic colorectal cancer (mCRC) and other GCC-expressing cancers from Innovative Cellular Therapeutics. At the highest dose level studied to date, patients with mCRC treated with LYL273 in a Phase 1 clinical trial conducted in the United States achieved a 67% confirmed overall response rate (ORR) and an 83% disease control rate per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 based on local site review, with a manageable safety profile. LYL273 is a GCC-targeted CAR T-cell product candidate enhanced with CD19 CAR expression and controlled cytokine release designed to improve cell expansion, immune cell infiltration and cell killing in the hostile tumor microenvironment. “Lyell is well positioned with two next-generation CAR T-cell product candidates, each with promising clinical data. We look forward to effectively executing on both clinical programs taking full advantage of our expertise in CAR T-cell clinical development and our wholly-owned manufacturing facility capable of commercial launch,” said Lynn Seely, MD, President and CEO of Lyell. “We will be presenting new ronde-cel clinical and translational data at the upcoming ASH meeting and exposition and are focused on rapidly advancing the pivotal development of ronde-cel through our two pivotal programs: PiNACLE – H2H, which is expected to begin enrolling patients receiving treatment in the 2L setting by early 2026, and PiNACLE, our ongoing single-arm pivotal trial for patients receiving treatment in the 3L+ setting.” Third Quarter Updates and Recent Business Highlights Lyell is advancing a pipeline of next-generation CAR T-cell product candidates targeting cancers with large unmet need and substantial patient populations. Ronde-cel is in pivotal development for patients with R/R LBCL and LYL273 is in Phase 1 clinical development for refractory mCRC. Lyell’s pipeline also includes additional preclinical programs targeting undisclosed solid tumor indications. Ronde-cel: A next-generation dual-targeting CD19/CD20 CAR T-cell product candidate designed to increase complete response rates and prolong the duration of response as compared to approved CD19‑targeted CAR T-cell therapies for the treatment of LBCL Ronde-cel is an autologous CAR T-cell product candidate with a true ‘OR’ logic gate to target B cells that express either CD19 or CD20 with full potency. It is manufactured with a process that enriches for CD62L-positive cells to generate more naïve and central memory CAR T cells with enhanced stemlike features and antitumor activity. Following successful End-of-Phase 1 meetings with the U.S. Food and Drug Administration (FDA), Lyell announced the initiation of two pivotal trials – PiNACLE and PiNACLE – H2H. PiNACLE is a single-arm pivotal trial that is currently underway. It is a seamless expansion of the 3L+ cohort of the Phase 1/2 trial of patients with R/R LBCL. PiNACLE – H2H is a Phase 3 head-to-head CAR T-cell therapy randomized controlled trial for LBCL in the 2L. Enrollment in PiNACLE – H2H is expected to begin by early 2026 and until then the Phase 1/2 trial continues to enroll patients with R/R LBCL receiving treatment in the 2L setting. The FDA has granted ronde-cel Regenerative Medicine Advanced Therapy (RMAT) and Fast Track designations for the treatment of R/R diffuse LBCL in the 3L+ setting. RMAT provides all the benefits of the Fast Track and Breakthrough Therapy designation programs and enables increased frequency of communications with the FDA on the development of ronde-cel. PiNACLE is a single-arm pivotal trial evaluating ronde-cel at a dose of 100 x 106 CAR T cells in patients with LBCL receiving treatment in the 3L+ setting. The trial is expected to enroll approximately 120 patients with R/R LBCL. Patients may be treated with ronde-cel in either the inpatient or outpatient setting, and there is no upper age limit for eligibility. The primary endpoint of the trial is the overall response rate, including an evaluation of duration of response. Two abstracts highlighting new clinical and translational data from the Phase 1/2 trial of ronde-cel for the treatment of aggressive LBCL have been accepted for oral presentation at the ASH 67th Annual Meeting and Exposition in December 2025. Updated data from the PiNACLE trial will be presented at ASH. Data from this trial are expected to form the basis of a Biologics License Application submission to the FDA in 2027 for patients with R/R LBCL receiving treatment in the 3L+ setting. The FDA has granted ronde-cel RMAT designation for the treatment of patients with relapsed or refractory LBCL receiving treatment in the 2L setting. RMAT designation recognizes the potential of ronde-cel to address significant unmet needs of patients with LBCL and enables an increased frequency of communications with the FDA on the development of ronde-cel. PiNACLE – H2H is a Phase 3 head-to-head CAR T-cell therapy trial, which will evaluate ronde-cel versus an investigator’s choice of approved CD19 CAR T-cell therapies (lisocabtagene maraleucel or axicabtagene ciloleucel) in patients with aggressive LBCL receiving treatment in the 2L setting. Patients randomized to ronde-cel will be treated with a dose of 100 x 106 CAR T cells. The primary endpoint of the trial is event-free survival. The trial is expected to enroll approximately 400 patients with R/R LBCL (200 per arm). Patients may be treated with ronde-cel in either the inpatient or outpatient setting. Clinical site initiation is underway for PiNACLE – H2H in the United States, Canada and Australia, and the first patient is expected to be enrolled by early 2026. Lyell recently announced the formation of an expert steering committee comprised of a distinguished group of lymphoma and cell therapy experts who will collaborate with the Company on the design and conduct of PiNACLE – H2H. LYL273: A next-generation GCC-targeted CAR T-cell product candidate enhanced with CD19 CAR expression and controlled cytokine release designed to improve outcomes for patients with mCRC LYL273 is a GCC-targeted CAR T-cell therapy enhanced with CD19 CAR expression and controlled cytokine release to increase cell expansion, immune cell infiltration and cancer cell killing in the hostile tumor microenvironment. LYL273 was granted Fast Track designation for the treatment of mCRC by the FDA. Dose-dependent clinical activity was observed in patients with refractory mCRC in a U.S. Phase 1 clinical trial. Across both dose levels, the overall response rate was 50% (6 of 12 patients), and the disease control rate was 83%. At Dose Level 2, the highest dose tested to-date, the overall response rate was 67%, including one patient with a pathological complete response, one patient with complete reduction in tumor volume of the target lesions (100% partial response) and two additional patients with confirmed partial responses. For patients treated at Dose Level 2, the disease control rate was 83%, and the median progression-free survival was 7.8 months. The incidence and severity of treatment-related adverse events were highest at Dose Level 2, where the most common treatment-related adverse events were cytokine release syndrome in 83% (5/6) of patients (Grade 1, 67%; Grade 2, 17%) and diarrhea in 83% (5/6) of patients (Grade 1, 33%; Grade 2, 33%; Grade 3, 17%). The median duration of diarrhea was 11 days. Immune effector cell-associated neurotoxicity syndrome occurred in 33% (2/6) of patients (Grade 2, 17%; Grade 3, 17%) and resolved rapidly with treatment. One patient experienced a dose-limiting toxicity at Dose Level 2, including Grade 3 diarrhea, Grade 4 enterocolitis and death from fungal sepsis 48 days post-infusion. No Grade 3 or higher diarrhea occurred in the last three patients treated since establishing an optimized management protocol for diarrhea, including prophylaxis. The U.S. Phase 1 clinical trial is continuing to enroll patients to determine the recommended Phase 2 dose. The next data update from this Phase 1 clinical trial is expected in the first half of 2026. Preclinical Pipeline, Technologies and Manufacturing Protocols Lyell is advancing next-generation fully-armed CAR T-cell product candidates, each including multiple technologies, designed to overcome T-cell exhaustion and the lack of durable stemness, as well as immune suppression within the hostile tumor microenvironment. The first IND for a fully-armed CAR T-cell product candidate with an undisclosed target for solid tumors is expected in 2026. Third Quarter 2025 Financial Results Lyell reported a net loss of $38.8 million for the third quarter ended September 30, 2025, compared to a net loss of $44.6 million for the same period in 2024. The $5.7 million decrease in net loss was primarily due to decreased personnel expenses, including a $2.4 million reduction in stock-based compensation expense attributable to lower headcount and the reduced value of new equity awards granted. The decrease was partially offset by a $4.0 million loss related to the put/call asset issued to certain institutional and other accredited investors as part of our July 2025 securities purchase agreement. Non‑GAAP net loss, which excludes stock-based compensation, non-cash expenses related to the change in the estimated fair value of success payment liabilities and certain non-cash investment gains and charges, decreased to $29.1 million for the third quarter ended September 30, 2025, compared to $37.1 million for the same period in 2024, primarily due to decreased personnel expenses resulting from lower headcount and lower interest income primarily driven by decreased interest rates in 2025 coupled with lower cash equivalent and marketable securities balances. GAAP and Non-GAAP Operating Expenses Research and development (R&D) expenses were $28.2 million for the third quarter ended September 30, 2025, compared to $39.5 million for the same period in 2024. The decrease in third quarter 2025 R&D expenses of $11.3 million was primarily due to a $4.4 million reduction in research activities, collaborations and outside services due primarily to a reduction in costs associated with research and laboratory supplies, collaboration agreement expenses and consulting expenses and a $4.2 million decrease in personnel‑related expenses primarily due to lower headcount. Non‑GAAP R&D expenses, which exclude non-cash stock-based compensation and non-cash expenses related to the change in the estimated fair value of success payment liabilities for the third quarter ended September 30, 2025, were $26.2 million, compared to $35.9 million for the same period in 2024. General and administrative (G&A) expenses were $10.7 million for the third quarter ended September 30, 2025, compared to $11.8 million for the same period in 2024. The decrease in third quarter 2025 G&A expenses of $1.1 million was primarily due to a $0.8 million decrease in stock-based compensation expense primarily related to a decrease in the value of new awards granted and a $0.2 million decrease in outside services primarily due to a reduction in legal expenses. Non‑GAAP G&A expenses, which exclude non-cash stock‑based compensation, for the third quarter ended September 30, 2025 were $7.5 million, compared to $7.8 million for the same period in 2024. A discussion of non-GAAP financial measures, including reconciliations of the most comparable U.S. generally accepted accounting principles (GAAP) measures to non‑GAAP financial measures, is presented below under “Non-GAAP Financial Measures.” Cash, cash equivalents and marketable securities Cash, cash equivalents and marketable securities as of September 30, 2025 were approximately $320 million, compared to approximately $384 million as of December 31, 2024. Lyell believes that its current cash, after the $40 million payment related to the acquisition of the license to LYL273, cash equivalents and marketable securities balances will be sufficient to meet working capital and capital expenditure needs into 2027. About Lyell Immunopharma, Inc. Lyell is a late-stage clinical company advancing a pipeline of next-generation CAR T-cell therapies for patients with hematologic malignancies and solid tumors. To realize the potential of cell therapy for cancer, Lyell utilizes a suite of technologies to endow CAR T cells with attributes needed to drive durable tumor cytotoxicity and high rates of long‑lasting clinical responses, including the ability to resist exhaustion, maintain qualities of durable stemness and function in the hostile tumor microenvironment. The Lyell LyFE Manufacturing Center™ has commercial launch capability and can manufacture more than 1,200 CAR T-cell doses at full capacity. To learn more, please visit www.lyell.com. Forward-Looking Statements This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements expressed or implied in this press release include, but are not limited to, statements regarding: Lyell’s expectations around the progress of the PiNACLE trial, including expectations around enrollment and timing of progress update in late 2025, and using data from the trial to form the basis of a Biologics License Application submission to the FDA in 2027 for patients with relapsed and/or refractory LBCL receiving treatment in the 3L+ setting; Lyell’s expectations around the progress of the PiNACLE H2H trial in patients with aggressive LBCL receiving treatment in the 2L setting, including Lyell’s initiation by early 2026 of the trial and its expectations around enrollment; Lyell’s expectations around the progress of the U.S. Phase 1 trial for LYL273, including the timing of its data update in the first half of 2026; the anticipated benefits of RMAT and Fast Track designations for ronde-cel and Fast Track designation for LYL273; Lyell’s expectations around presenting new clinical and translational data at the upcoming ASH meeting; Lyell’s advancement of its pipeline and its research, development and clinical capabilities; Lyell’s submission of an IND in 2026 for a CAR T-cell product candidate with an undisclosed target for solid tumors; Lyell’s plans for its existing cash, cash equivalents and marketable securities, and its expectation that its financial position and cash runway will support advancement of its pipeline into 2027 through key clinical milestones; the sufficiency of the capacity of LyFE to manufacture drug supply for Lyell’s ongoing and planned pivotal trials and through potential commercial launch; Lyell’s anticipated progress, business plans, business strategy and clinical trials; the potential clinical benefits and therapeutic potential of Lyell’s product candidates; and other statements that are not historical fact. These statements are based on Lyell’s current plans, objectives, estimates, expectations and intentions, are not guarantees of future performance and inherently involve significant risks and uncertainties. Actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of these risks and uncertainties, which include, but are not limited to, risks and uncertainties related to: Lyell’s limited experience as a company in enrolling and conducting clinical trials, and lack of experience in completing clinical trials; the nonclinical profiles of Lyell’s product candidates or technology not translating in clinical trials; the potential for results from clinical trials to differ from nonclinical, early clinical, preliminary or expected results; significant adverse events, toxicities or other undesirable side effects associated with Lyell’s product candidates; Lyell’s ability to submit planned INDs or initiate or progress clinical trials on the anticipated timelines, if at all; RMAT and Fast Track designations may not actually lead to faster development, regulatory review or approval process, and do not assure ultimate FDA approval; the significant uncertainty associated with Lyell’s product candidates ever receiving any regulatory approvals; Lyell’s ability to obtain, maintain or protect intellectual property rights related to its product candidates; the complexity of manufacturing cellular therapies and Lyell’s ability to manufacture and supply its product candidates for its clinical trials; implementation of Lyell’s strategic plans for its business and product candidates; Lyell’s realization of the expected benefits of its strategic plans for its business and product candidates, including the license of LYL273; the potential reduction of Lyell’s cash resources and fluctuations in Lyell’s operating results and financial condition as a result of Lyell’s milestone, royalty and success payment obligations; the sufficiency of Lyell’s capital resources and need for additional capital to achieve its goals; the effects of macroeconomic conditions, including the effects of disruption between the U.S. and its trading partners due to tariffs or other policies, and any geopolitical instability; potential changes to U.S. drug pricing, including the potential for “most-favored nations” pricing limitations; other risks, including general economic conditions and regulatory developments, not within our control; and other risks, including those described under the heading “Risk Factors” in Lyell’s Annual Report on Form 10‑K for the fiscal year ended December 31, 2024, filed with the Securities Exchange Commission (SEC) on March 11, 2025, and Lyell’s Quarterly Report on Form 10-Q for the quarter ended September 30, 2025, being filed with the SEC today. Forward-looking statements contained in this press release are made as of this date, and Lyell undertakes no duty to update such information except as required under applicable law. Lyell Immunopharma, Inc. Unaudited Selected Consolidated Financial Data (in thousands) Statement of Operations Data: (1) As of October 1, 2024, the Company’s success payment liability was recognized at fair value as Stanford had provided the requisite service obligation to earn the potential success payment consideration. The change in the estimated fair value of Stanford success payment liabilities for the three and nine months ended September 30, 2025 was recognized within other (expense) income, net in the Condensed Consolidated Statements of Operations and Comprehensive Loss. The change in the estimated fair value of Stanford success payment liabilities for the three and nine months ended September 30, 2024 was recognized within research and development expenses in the Condensed Consolidated Statements of Operations and Comprehensive Loss. Balance Sheet Data: Non-GAAP Financial Measures To supplement our financial results and guidance presented in accordance with GAAP, we present non-GAAP net loss, non-GAAP R&D expenses and non-GAAP G&A expenses. Non‑GAAP net loss and non-GAAP R&D expenses exclude non-cash stock-based compensation expense and non-cash expenses related to the change in the estimated fair value of success payment liabilities from GAAP net loss and GAAP R&D expenses, respectively. Non-GAAP net loss is further adjusted by non‑cash investment gains and charges and change in the estimated fair value of our securities purchase agreement put/call, as applicable. Non‑GAAP G&A expenses exclude non-cash stock-based compensation expense from GAAP G&A expenses. We believe that these non‑GAAP financial measures, when considered together with our financial information prepared in accordance with GAAP, can enhance investors’ and analysts’ ability to meaningfully compare our results from period to period, and to identify operating trends in our business. We have excluded stock-based compensation expense, changes in the estimated fair value of success payment liabilities, non-cash investment gains and charges and change in the estimated fair value of our securities purchase agreement put/call from our non‑GAAP financial measures because they are non-cash gains and charges that may vary significantly from period to period as a result of changes not directly or immediately related to the operational performance for the periods presented. We also regularly use these non‑GAAP financial measures internally to understand, manage and evaluate our business and to make operating decisions. These non-GAAP financial measures are in addition to, and not a substitute for or superior to, measures of financial performance prepared in accordance with GAAP. In addition, these non‑GAAP financial measures have no standardized meaning prescribed by GAAP and are not prepared under any comprehensive set of accounting rules or principles and, therefore, have limits in their usefulness to investors. We encourage investors to carefully consider our results under GAAP, as well as our supplemental non-GAAP financial information, to more fully understand our business. (1) There was no income tax effect related to the adjustments made to calculate non-GAAP net loss because of the full valuation allowance on our net deferred tax assets for all periods presented. (1) As of October 1, 2024, the Company’s success payment liability was recognized at fair value as Stanford had provided the requisite service obligation to earn the potential success payment consideration. The change in the estimated fair value of Stanford success payment liabilities for the three and nine months ended September 30, 2025 was recognized within other (expense) income, net in the Condensed Consolidated Statements of Operations and Comprehensive Loss. The change in the estimated fair value of Stanford success payment liabilities for the three and nine months ended September 30, 2024 was recognized within research and development expenses in the Condensed Consolidated Statements of Operations and Comprehensive Loss. Contact: Ellen Rose Senior Vice President, Communications and Investor Relations [email protected]

Presented positive new clinical data demonstrating high rates of durable complete responses from the Phase 1/2 trial of LYL314 for the treatment of aggressive large B-cell lymphoma Initiated the PiNACLE pivotal trial of LYL314 in patients with large B-cell lymphoma receiving treatment in the third‑ or later-line (3L+) setting; remain on track to initiate a pivotal trial in the second-line (2L) setting by early 2026 Entered into a securities purchase agreement for a private placement for gross proceeds of up to approximately $100 million Pro-forma cash of approximately $347 million inclusive of the initial proceeds from the private placement to support advancing pipeline into mid-2027 through key clinical milestones SOUTH SAN FRANCISCO, Calif., Aug. 12, 2025 (GLOBE NEWSWIRE) -- Lyell Immunopharma, Inc. (Nasdaq: LYEL), a late-stage clinical company advancing next-generation CAR T-cell therapies for patients with cancer, today reported financial results and business highlights for the second quarter ended June 30, 2025. Lyell’s lead clinical program, LYL314, is a next-generation autologous dual-targeting CD19/CD20 CAR T-cell product candidate under evaluation in PiNACLE, a single-arm pivotal trial enrolling patients with relapsed and/or refractory (R/R) large B-cell lymphoma (LBCL) in the 3L+ setting and in a Phase 1/2 study in the 2L setting. “Based on the high rate of durable complete responses achieved by LYL314 in patients with aggressive LBCL presented at the International Conference on Malignant Lymphoma in Lugano, Switzerland, in June, we believe that our CD19/CD20 CAR T-cell therapy will disrupt the therapeutic landscape by delivering meaningfully increased complete response rates and improved durability over the currently approved CD19 CAR T-cell therapies,” said Lynn Seely, M.D., President and CEO of Lyell. “Our recent private placement with well-respected investors significantly derisks our business, extends our cash runway into mid-2027 and enables us to focus on rapidly advancing the clinical development of LYL314. We have initiated the PiNACLE single-arm pivotal trial for patients with LBCL receiving treatment in the third- or later-line setting and are on track to begin a second pivotal trial of LYL314 for patients with LBCL in the second-line setting by early 2026.” Second Quarter Updates and Recent Business Highlights Lyell is advancing a pipeline of next-generation CAR T-cell product candidates targeting cancers with large unmet need and substantial patient populations. Its lead program, LYL314, is in pivotal development for patients with R/R LBCL and its preclinical programs target solid tumor indications. LYL314: A next-generation dual-targeting CD19/CD20 CAR T-cell product candidate designed to increase complete response rates and prolong the duration of response as compared to approved CD19‑targeted CAR T-cell therapies for the treatment of LBCL LYL314 is an autologous CAR T-cell product candidate with a true ‘OR’ logic gate to target B cells that express either CD19 or CD20 with full potency and that is manufactured with a process that enriches for CD62L-positive cells to generate more naïve and central memory CAR T cells with enhanced stemlike features and antitumor activity. Following a successful End-of-Phase 1 meeting with the U.S. Food and Drug Administration (FDA), LYL314 is currently being evaluated in the pivotal PiNACLE trial, which is a seamless expansion of the 3L+ cohort of the Phase 1/2 trial of patients with R/R LBCL. The Phase 1/2 trial continues to enroll CAR T-cell therapy naïve patients receiving treatment in the 2L setting and a pivotal trial for these 2L patients is expected be initiated by early 2026. The FDA has granted LYL314 Regenerative Medicine Advanced Therapy (RMAT) and Fast Track designations for the treatment of R/R diffuse LBCL in the 3L+ setting. RMAT provides all the benefits of the Fast Track and Breakthrough Therapy designation programs and enables increased frequency of communications with the FDA on the development of LYL314. PiNACLE is a single-arm pivotal trial evaluating LYL314 at a dose of 100 x 106 CAR T cells in patients with LBCL receiving treatment in the 3L+ setting. The trial is expected to enroll approximately 120 patients with R/R diffuse large B-cell lymphoma, high grade B-cell lymphoma, primary mediastinal large B-cell lymphoma, transformed follicular lymphoma or Grade 3B follicular lymphoma who have not previously received CAR T-cell therapy. Patients may be treated with LYL314 in either the inpatient or outpatient setting and there is no upper age limit for eligibility. The primary endpoint of the trial is the overall response rate, including an evaluation of duration of response. New clinical data from the Phase 1/2 multi-center clinical trial of LYL314 in patients with R/R LBCL were presented at the 18th International Conference on Malignant Lymphoma in June and included more mature data from patients treated in the 3L+ setting and initial data from patients treated in the 2L setting. The data were presented in an oral presentation titled “LYL314, a CD19/CD20 CAR T‑cell candidate enriched for CD62L+ stem-like cells, achieves high rates of durable complete responses in relapsed and/or refractory large B-cell lymphoma”. Highlights include: Fifty-one CAR T-naive patients with R/R LBCL received LYL314 as of April 15, 2025 (the data cutoff date for the presentation). The efficacy evaluable population consisted of 36 patients with Day 84 assessments or prior disease progression or death. Patient demographics and baseline disease characteristics were consistent with high-risk patient populations: median ages of 65 and 69 years in the 3L+ and 2L, respectively, 41% of 3L+ and 65% of 2L patients had Stage IV disease at trial entry, and 47% of 3L+ and 82% of 2L patients had primary refractory disease. In efficacy-evaluable 3L+ patients, with a median follow-up of 9 months (N = 25): The overall response rate was 88% (22/25 patients), with 72% (18/25) of patients achieving a complete response. 71% (10/14) of patients with complete response remained in complete response at ≥ 6 months. In initial data from efficacy-evaluable 2L patients, with a median follow-up of 5 months (N = 11): The overall response rate was 91% (10/11 patients), with 64% (7/11) achieving a complete response. 100% (7/7) of patients with complete response were in complete response at their last assessment, including 3/3 patients at ≥ 6 months. In patients with primary refractory disease, a difficult to treat population, 70% (7/10) achieved a complete response. In 51 patients, including patients from both the 3L+ and the 2L cohorts, a manageable safety profile appropriate for outpatient administration was observed. No Grade ≥ 3 and low rates of Grade 1 (22%) or Grade 2 (35%) cytokine release syndrome (CRS) were reported. Immune effector cell-associated neurotoxicity syndrome (ICANS) was reported in 6% (Grade 1), 2% (Grade 2), and 14% (Grade ≥ 3) of patients. The median time to complete resolution of all reports of ICANS was 5 days, with rapid improvement (median of 2 days) to Grade 2 or lower with standard therapy. No deaths were related to LYL314 administration. LYL314 demonstrated robust expansion with a time to peak of 10 days. The final drug product contained the desired CD62L-positive naïve T-cell phenotype (median, 95%). Rapid and durable depletion of B cells was demonstrated through month 6 and up to the month 12 assessment. An update on the progress of the PiNACLE trial is planned for late 2025. Data from this trial is expected to form the basis of a Biologics License Application submission to the FDA in 2027 for patients with R/R LBCL receiving treatment in the 3L+ setting. More mature data from the ongoing Phase 1/2 trial in the 2L setting are expected to be presented in late 2025. A Phase 3 randomized controlled trial of LYL314 is expected to be initiated by early 2026 in patients receiving treatment in the 2L setting with R/R LBCL. Preclinical Pipeline, Technologies and Manufacturing Protocols Lyell is advancing next-generation fully-armed CAR T-cell product candidates, each including multiple technologies, designed to overcome T-cell exhaustion and lack of durable stemness, as well as immune suppression within the hostile tumor microenvironment. The first IND for a fully-armed CAR T-cell product candidate with an undisclosed target for solid tumors is expected in 2026. Corporate Updates In July, Lyell entered into a securities purchase agreement for a private placement with certain institutional and other accredited investors, for gross proceeds of up to approximately $100 million. The initial closing of approximately $50 million of common stock at a price of $13.32 per share occurred on July 25, 2025. After deducting offering expenses, Lyell expects to use net proceeds from the private placement, together with its existing cash, cash equivalents, and marketable securities, to advance two pivotal-stage clinical trials of LYL314 as well as working capital for other general corporate purposes. Second Quarter 2025 Financial Results Lyell reported a net loss of $42.7 million for the second quarter ended June 30, 2025, compared to a net loss of $45.8 million for the same period in 2024. The $3.1 million decrease in net loss was primarily due to a decrease of $3.3 million in stock-based compensation expense resulting from lower headcount and the reduced value of new equity awards. Non‑GAAP net loss, which excludes stock-based compensation, non-cash expenses related to the change in the estimated fair value of success payment liabilities and certain non-cash investment gains and charges, decreased to $37.8 million for the second quarter ended June 30, 2025, compared to $39.1 million for the same period in 2024, primarily due to lower interest income primarily driven by decreased interest rates in 2025 coupled with lower cash equivalent and marketable securities balances. GAAP and Non-GAAP Operating Expenses Research and development (R&D) expenses were $34.9 million for the second quarter ended June 30, 2025, compared to $40.3 million for the same period in 2024. The decrease in second quarter 2025 R&D expenses of $5.4 million was primarily due to a $2.9 million reduction in research activities, collaborations and outside services due primarily to a reduction in costs associated with research and laboratory supplies and collaboration agreements and a $2.4 million decrease in personnel‑related expenses primarily due to reduced stock-based compensation expense resulting from lower headcount and the reduced value of new equity awards. Non‑GAAP R&D expenses, which exclude non-cash stock-based compensation and non-cash expenses related to the change in the estimated fair value of success payment liabilities for the second quarter ended June 30, 2025 were $32.6 million, compared to $37.2 million for the same period in 2024. General and administrative (G&A) expenses were $9.8 million for the second quarter ended June 30, 2025, compared to $12.3 million for the same period in 2024. The decrease in second quarter 2025 G&A expenses of $2.5 million was primarily due to a $1.7 million decrease in stock-based compensation expense primarily related to a decrease in the value of new awards granted and a $0.8 million decrease in outside services primarily due to a reduction in legal expenses. Non‑GAAP G&A expenses, which exclude non-cash stock‑based compensation, for the second quarter ended June 30, 2025 were $7.1 million, compared to $7.8 million for the same period in 2024. A discussion of non-GAAP financial measures, including reconciliations of the most comparable GAAP measures to non‑GAAP financial measures, is presented below under “Non-GAAP Financial Measures.” Cash, cash equivalents and marketable securities Cash, cash equivalents and marketable securities as of June 30, 2025 were approximately $297 million, compared to approximately $384 million as of December 31, 2024. Lyell believes that its cash, cash equivalents and marketable securities balances totaling approximately $347 million inclusive of the initial $50 million of proceeds from its recent private placement, will be sufficient to meet working capital and capital expenditure needs into mid-2027. About Lyell Immunopharma, Inc. Lyell is a late-stage clinical company advancing a pipeline of next-generation CAR T-cell therapies for patients with hematologic malignancies and solid tumors. To realize the potential of cell therapy for cancer, Lyell utilizes a suite of technologies to endow CAR T cells with attributes needed to drive durable tumor cytotoxicity and high rates of long‑lasting clinical responses, including the ability to resist exhaustion, maintain qualities of durable stemness and function in the hostile tumor microenvironment. The Lyell LyFE Manufacturing Center™ has commercial launch capability and can manufacture more than 1,200 CAR T-cell doses at full capacity. To learn more, please visit www.lyell.com. Forward-Looking Statements This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements expressed or implied in this press release include, but are not limited to, statements regarding: Lyell’s initiation by early 2026 of a pivotal trial for LYL314 for patients with LBCL in the 2L setting; expectations around the potential for CD19/CD20 CAR T-cell therapies to disrupt the therapeutic landscape; the anticipated benefits of RMAT and Fast Track designations for LYL314; Lyell’s expectations around the progress of the PiNACLE trial, including expectations around enrollment and timing of progress update in late 2025, and using data from the trial to form the basis of a Biologics License Application submission to the FDA in 2027 for patients with relapsed and/or refractory LBCL receiving treatment in the 3L+ setting; Lyell’s expectations around continued enrollment for and timing of more mature clinical data from its ongoing Phase 1/2 trial for LYL314 in the 2L setting in late 2025; the advancement of Lyell’s technology platform; Lyell’s advancement of its pipeline and its research, development and clinical capabilities; Lyell’s submission of an IND in 2026 for a CAR T-cell product candidate with an undisclosed target for solid tumors; Lyell’s plans for using the net proceeds from the private placement and its existing cash, cash equivalents and marketable securities, and its expectation that its financial position and cash runway will support advancement of its pipeline into mid-2027 through key clinical milestones; the sufficiency of the capacity of LyFE to manufacture drug supply for Lyell’s ongoing and planned pivotal trials and through potential commercial launch; Lyell’s anticipated progress, business plans, business strategy and clinical trials; the potential clinical benefits and therapeutic potential of Lyell’s product candidates, including meaningful increased complete response rates and prolonged duration of response; and other statements that are not historical fact. These statements are based on Lyell’s current plans, objectives, estimates, expectations and intentions, are not guarantees of future performance and inherently involve significant risks and uncertainties. Actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of these risks and uncertainties, which include, but are not limited to, risks and uncertainties related to: Lyell’s ability to submit planned INDs or initiate or progress clinical trials on the anticipated timelines, if at all; Lyell’s limited experience as a company in enrolling and conducting clinical trials, and lack of experience in completing clinical trials; the complexity of manufacturing cellular therapies, which subjects us to a multitude of manufacturing risks, any of which could substantially increase our costs, delay our programs or limit supply of our product candidates; the nonclinical profiles of Lyell’s product candidates or technology not translating in clinical trials; the potential for results from clinical trials to differ from nonclinical, early clinical, preliminary or expected results; significant adverse events, toxicities or other undesirable side effects associated with Lyell’s product candidates; the significant uncertainty associated with Lyell’s product candidates ever receiving any regulatory approvals; RMAT and Fast Track designations may not actually lead to faster development, regulatory review or approval process, and does not assure ultimate FDA approval; Lyell’s ability to obtain, maintain or protect intellectual property rights related to its product candidates; implementation of Lyell’s strategic plans for its business and product candidates; the sufficiency of Lyell’s capital resources and need for additional capital to achieve its goals; the effects of macroeconomic conditions, including the effects of disruption between the U.S. and its trading partners due to tariffs or other policies, and any geopolitical instability; potential changes to U.S. drug pricing, including the potential for “most-favored nations” pricing limitations; and other risks, including those described under the heading “Risk Factors” in Lyell’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2025, being filed with the SEC today. Forward-looking statements contained in this press release are made as of this date, and Lyell undertakes no duty to update such information except as required under applicable law. Balance Sheet Data: Non-GAAP Financial Measures To supplement our financial results and guidance presented in accordance with U.S. generally accepted accounting principles (GAAP), we present non-GAAP net loss, non-GAAP R&D expenses and non-GAAP G&A expenses. Non‑GAAP net loss and non-GAAP R&D expenses exclude non-cash stock-based compensation expense and non-cash expenses related to the change in the estimated fair value of success payment liabilities from GAAP net loss and GAAP R&D expenses, respectively. Non-GAAP net loss is further adjusted by non‑cash investment gains and charges, as applicable. Non‑GAAP G&A expenses exclude non-cash stock-based compensation expense from GAAP G&A expenses. We believe that these non‑GAAP financial measures, when considered together with our financial information prepared in accordance with GAAP, can enhance investors’ and analysts’ ability to meaningfully compare our results from period to period, and to identify operating trends in our business. We have excluded stock-based compensation expense, changes in the estimated fair value of success payment liabilities, and non-cash investment gains and charges from our non‑GAAP financial measures because they are non-cash gains and charges that may vary significantly from period to period as a result of changes not directly or immediately related to the operational performance for the periods presented. We also regularly use these non‑GAAP financial measures internally to understand, manage and evaluate our business and to make operating decisions. These non-GAAP financial measures are in addition to, and not a substitute for or superior to, measures of financial performance prepared in accordance with GAAP. In addition, these non‑GAAP financial measures have no standardized meaning prescribed by GAAP and are not prepared under any comprehensive set of accounting rules or principles and, therefore, have limits in their usefulness to investors. We encourage investors to carefully consider our results under GAAP, as well as our supplemental non-GAAP financial information, to more fully understand our business. Contact: Ellen Rose Senior Vice President, Communications and Investor Relations [email protected]

Presenting new clinical data from Phase 1/2 multi-center clinical trial of LYL314, a next-generation dual‑targeting CD19/CD20 CAR T-cell product candidate for the treatment of relapsed and/or refractory large B‑cell lymphoma at the 18th International Conference on Malignant Lymphoma. Received Regenerative Medicine Advanced Therapy (RMAT) designation from the United States Food and Drug Administration (FDA) for LYL314 for the treatment of relapsed and/or refractory diffuse large B-cell lymphoma in the third- or later-line setting. LYL314 clinical supply now manufactured at Lyell’s LyFE Manufacturing Center™, following successful technology transfer and clearance by the FDA of an Investigational New Drug Amendment. Remain on track to initiate a pivotal trial of LYL314 in the third- or later-line setting in mid-2025 and expect to initiate a pivotal trial in the second-line setting by early 2026. Cash, cash equivalents and marketable securities of $330.1 million as of March 31, 2025 support advancing pipeline into 2027 through multiple clinical milestones. SOUTH SAN FRANCISCO, Calif., May 13, 2025 (GLOBE NEWSWIRE) -- Lyell Immunopharma, Inc. (Nasdaq: LYEL), a clinical-stage company advancing a pipeline of next-generation CAR T-cell therapies for patients with cancer, today reported financial results and business highlights for the first quarter ended March 31, 2025. Lyell’s lead clinical program, LYL314 (formerly known as IMPT-314), is an autologous CD19/CD20 dual-targeting CAR T-cell product candidate under evaluation in a Phase 1/2 trial enrolling patients with relapsed and/or refractory large B-cell lymphoma (LBCL). LYL314 was recently granted RMAT designation by the United States FDA in recognition of its potential to address significant unmet needs in patients with aggressive LBCL in the third- or later-line setting. “We are pleased with the progress we are making with our LYL314 clinical development strategy and look forward to presenting new clinical data from patients with aggressive large B-cell lymphoma who have not previously received CAR T-cell therapy at the International Conference on Malignant Lymphoma in Lugano, Switzerland in June,” said Lynn Seely, M.D., President and CEO of Lyell. “Based on promising clinical data, Lyell remains on track to initiate two pivotal programs for LYL314: one for patients in the third- or later-line setting by mid-2025 and a second for patients in the second-line setting by early 2026. In addition, our LyFE Manufacturing Center in Bothell, Washington is now manufacturing the LYL314 clinical supply following completion of a successful technology transfer and FDA clearance of an IND amendment.” First Quarter Updates and Recent Business Highlights Lyell is advancing a pipeline of next-generation CAR T-cell product candidates. Its lead program, LYL314, is in Phase 1/2 clinical development for relapsed and/or refractory LBCL and its preclinical programs target solid tumor indications. Lyell’s programs target cancers with large unmet need with substantial patient populations. LYL314: A next-generation dual-targeting CD19/CD20 CAR T-cell product candidate designed to increase complete response rates and prolong the duration of response as compared to the approved CD19‑targeted CAR T-cell therapies for the treatment of LBCL LYL314 is an autologous CAR T-cell product candidate with a true ‘OR’ logic gate to target B cells that express either CD19 or CD20 with full potency and that is manufactured with a process that enriches for CD62L-positive cells to generate more naïve and central memory CAR T cells with enhanced stemlike features and antitumor activity. LYL314 is currently being evaluated in a multi-center, open-label trial that is enrolling patients in the third- or later-line and second-line settings who have not previously received CAR T-cell therapy. The trial is designed to evaluate the tolerability and clinical benefit of LYL314 in patients with relapsed and/or refractory LBCL and determine a recommended Phase 2 dose. The FDA has granted LYL314 RMAT and Fast Track designations for the treatment of relapsed and/or refractory diffuse LBCL in the third- or later-line setting. RMAT provides all the benefits of the Fast Track and Breakthrough Therapy designation programs and enables increased frequency of communications with the FDA on the development of LYL314. New clinical data from the Phase 1/2 multi-center clinical trial of LYL314 in patients with relapsed and/or refractory LBCL will be presented at the 18th International Conference on Malignant Lymphoma in June, including more mature data from patients treated in the third- or later-line setting and initial data from patients treated in the second-line setting. The data will be highlighted in an oral presentation titled “LYL314, a CD19/CD20 CAR T-cell candidate enriched for CD62L+ stem-like cells, achieves high rates of durable complete responses in R/R large B-cell lymphoma” to be presented on June 18th at 5:40 pm CEST. Initial clinical data in 23 patients treated with LYL314 from the ongoing Phase 1/2 clinical trial were presented at the American Society for Hematology 2024 Annual Meeting on December 9, 2024. The efficacy evaluable population consisted of 17 patients with relapsed and/or refractory LBCL in the third- or later-line setting who had not previously received a CAR T-cell therapy prior to LYL314 administration. The overall response rate was 94% (16/17) of patients, and 71% (12/17) of patients achieved a complete response by three months. The median follow up was 6.3 months (range 1.2 – 12.5 months) and 71% of patients experienced a response at last follow-up. In the safety evaluable population of 23 patients, no event of Grade 3 or greater cytokine release syndrome was reported. Grade 3 immune effector cell-associated neurotoxicity syndrome (ICANS) was reported in 13% (3/23) of patients with a median time to ICANS resolution of 5 days, and rapid improvement to Grade 2 or lower with standard therapy. LYL314 clinical supply is now manufactured at the LyFE Manufacturing Center in Bothell, Washington following successful technology transfer and clearance by the FDA of an IND amendment. LyFE is a state-of-the-art cell therapy manufacturing facility with the capacity to provide drug supply for Lyell’s ongoing and planned pivotal trials and through potential commercial launch, with a capacity over 1,000 CAR T-cell therapy doses per year. A pivotal trial in the third- or later-line setting is expected to be initiated in mid-2025 in patients with relapsed and/or refractory LBCL who have not previously received CAR T-cell therapy. More mature data from the ongoing Phase 1/2 trial in the second-line setting are expected to be presented in late-2025. A pivotal trial in the second-line setting is expected to be initiated by early 2026 in patients with relapsed and/or refractory LBCL who have not previously received CAR T-cell therapy. Preclinical Pipeline, Technologies and Manufacturing Protocols Lyell is advancing next-generation fully-armed CAR T-cell product candidates, each including multiple technologies, designed to overcome T-cell exhaustion and lack of durable stemness, as well as immune suppression within the hostile tumor microenvironment. The first IND for a fully-armed CAR T-cell product candidate with an undisclosed target for solid tumors is expected in 2026. An abstract titled “Engineered T Cells Combining Stackable Reprogramming Technologies Enable Durable Anti‑tumor Activity in Xenograft Solid Tumors” has been accepted for an oral presentation at the 28th Annual Meeting of the American Society of Gene & Cell Therapy (ASGCT), on May 16, 2025, in New Orleans, LA. The presentation will highlight preclinical data demonstrating that engineered T cells enhanced with c-Jun overexpression, a chimeric co-stimulatory receptor and localized cytokine signaling technologies exhibit potent tumor cell killing in vitro, T-cell viability in vitro and in vivo without cytokine support and effective durable antitumor activity in preclinical solid tumor models. An abstract titled “Optimizing Stim-R™, a synthetic stimulatory agent, for feeder-free tumor-infiltrating lymphocyte manufacturing” was presented at the American Association for Cancer Research Annual Meeting 2025. The presented work demonstrated that Stim-R, Lyell’s customizable synthetic T-cell activation reagent designed to emulate natural antigen presentation, has the potential to overcome scalability limitations in tumor-infiltrating lymphocyte manufacturing processes by providing a synthetic replacement for feeder cells. First Quarter 2025 Financial Results Lyell reported a net loss of $52.2 million for the first quarter ended March 31, 2025, compared to a net loss of $60.7 million for the same period in 2024. The $8.5 million decrease in net loss was primarily driven by $13.0 million in impairment expenses recognized in the prior year period that did not occur in 2025, partially offset by lower interest income of $3.0 million primarily driven by lower interest rates in 2025, coupled with lower cash equivalent and marketable securities balances. Non‑GAAP net loss, which excludes stock-based compensation, non-cash expenses related to the change in the estimated fair value of success payment liabilities and certain non-cash investment gains and charges, increased to $46.3 million for the first quarter ended March 31, 2025, compared to $37.5 million for the same period in 2024 due primarily to increased personnel costs and lower interest income in 2025. GAAP and Non-GAAP Operating Expenses Research and development (R&D) expenses were $43.4 million for the first quarter ended March 31, 2025, compared to $43.2 million for the same period in 2024. The increase in first quarter 2025 R&D expenses of $0.3 million was primarily due to a $3.1 million increase in personnel expenses, due primarily to severance expenses resulting from Lyell’s 2025 workforce reduction related to the closure of the West Hills manufacturing facility acquired as part of Lyell’s acquisition of ImmPACT in 2024, partially offset by reductions in collaboration agreement and leasehold improvement depreciation costs. Non‑GAAP R&D expenses, which exclude non-cash stock-based compensation and non-cash expenses related to the change in the estimated fair value of success payment liabilities for the first quarter ended March 31, 2025 were $41.1 million compared to $38.9 million for the same period in 2024. General and administrative (G&A) expenses were $14.0 million for the first quarter ended March 31, 2025, respectively, compared to $13.5 million for the same period in 2024. The increase in first quarter 2025 G&A expenses of $0.6 million was primarily driven by an increase of $2.4 million in personnel‑related expenses due to higher headcount associated with Lyell’s acquisition of ImmPACT and severance expenses related to the West Hills facility closure, partially offset by $1.7 million in decreased stock-based compensation expense due to a decrease in the value of awards granted. Non‑GAAP G&A expenses, which exclude non-cash stock‑based compensation, for the first quarter ended March 31, 2025 were $10.4 million, compared to $8.1 million for the same period in 2024. The $2.3 million increase in first quarter 2025 non-GAAP G&A expenses was primarily driven by increased headcount and severance expenses. A discussion of non-GAAP financial measures, including reconciliations of the most comparable GAAP measures to non‑GAAP financial measures, is presented below under “Non-GAAP Financial Measures.” Cash, cash equivalents and marketable securities Cash, cash equivalents and marketable securities as of March 31, 2025 were $330.1 million compared to $383.5 million as of December 31, 2024. Lyell believes that its cash, cash equivalents and marketable securities balances will be sufficient to meet working capital and capital expenditure needs into 2027. About Lyell Immunopharma, Inc. Lyell is a clinical-stage company advancing a pipeline of next-generation CAR T-cell therapies for patients with hematologic malignancies and solid tumors. To realize the potential of cell therapy for cancer, Lyell utilizes a suite of technologies to endow CAR T cells with attributes needed to drive durable tumor cytotoxicity and achieve consistent and long-lasting clinical responses, including the ability to resist exhaustion, maintain qualities of durable stemness and function in the hostile tumor microenvironment. To learn more, please visit www.lyell.com. Forward-Looking Statements This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements expressed or implied in this press release include, but are not limited to, statements regarding: Lyell’s plans to present new LYL314 clinical data from the ongoing Phase 1/2 trial of LYL314; the anticipated benefits of RMAT designation for LYL314; the sufficiency of the capacity of LyFE to manufacture drug supply for Lyell’s ongoing and planned pivotal trials and through potential commercial launch; Lyell’s initiation of pivotal trials in 2025 and 2026 for LYL314; expectations around enrollment and the timing of additional clinical data from Lyell’s Phase 1/2 trials for LYL314; timing of Lyell’s submission of a new IND in 2026 for a CAR T-cell product candidate with an undisclosed target for solid tumors; Lyell’s anticipated progress, business plans, business strategy and clinical trials; Lyell’s advancement of its pipeline and its research, development and clinical capabilities; the potential clinical benefits and therapeutic potential of Lyell’s product candidates; the advancement of Lyell’s technology platform; Lyell’s expectation that its financial position and cash runway will support advancement of its pipeline through multiple clinical milestones and meet working capital and capital expenditure needs into 2027; and other statements that are not historical fact. These statements are based on Lyell’s current plans, objectives, estimates, expectations and intentions, are not guarantees of future performance and inherently involve significant risks and uncertainties. Actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of these risks and uncertainties, which include, but are not limited to, risks and uncertainties related to: the complexity of manufacturing cellular therapies, which subjects us to a multitude of manufacturing risks, any of which could substantially increase our costs, delay our programs or limit supply of our product candidates; RMAT designation may not actually lead to faster development, regulatory review or approval process, and does not assure ultimate FDA approval; the effects of macroeconomic conditions, including the effects of disruption between the U.S. and its trading partners due to tariffs or other policies, any geopolitical instability and actual or perceived changes in interest rates and economic inflation; Lyell’s ability to submit planned INDs or initiate or progress clinical trials on the anticipated timelines, if at all; Lyell’s limited experience as a company in enrolling and conducting clinical trials, and lack of experience in completing clinical trials; the nonclinical profiles of Lyell’s product candidates or technology not translating in clinical trials; the potential for results from clinical trials to differ from nonclinical, early clinical, preliminary or expected results; significant adverse events, toxicities or other undesirable side effects associated with Lyell’s product candidates; the significant uncertainty associated with Lyell’s product candidates ever receiving any regulatory approvals; Lyell’s ability to obtain, maintain or protect intellectual property rights related to its product candidates; implementation of Lyell’s strategic plans for its business and product candidates; the sufficiency of Lyell’s capital resources and need for additional capital to achieve its goals; and other risks, including those described under the heading “Risk Factors” in Lyell’s Annual Report on Form 10-K for the year ended December 31, 2024, filed with the Securities and Exchange Commission (SEC) on March 11, 2025, and Lyell’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2025, being filed with the SEC today. Forward-looking statements contained in this press release are made as of this date, and Lyell undertakes no duty to update such information except as required under applicable law. (1) As of October 1, 2024, the Company’s success payment liability was recognized at fair value as Stanford had provided the requisite service obligation to earn the potential success payment consideration. The change in the estimated fair value of Stanford success payment liabilities in the first quarter of 2025 was recognized within other income, net in the Condensed Consolidated Statements of Operations and Comprehensive Loss. The change in the estimated fair value of Stanford success payment liabilities in the first quarter of 2024 was recognized within research and development expenses in the Condensed Consolidated Statements of Operations and Comprehensive Loss. The change in the estimated fair value of Fred Hutch success payment liabilities was recognized within other income, net in the Condensed Consolidated Statements of Operations and Comprehensive Loss. Balance Sheet Data: Non-GAAP Financial Measures To supplement our financial results and guidance presented in accordance with U.S. generally accepted accounting principles (GAAP), we present non-GAAP net loss, non-GAAP R&D expenses and non-GAAP G&A expenses. Non‑GAAP net loss and non-GAAP R&D expenses exclude non-cash stock-based compensation expense and non-cash expenses related to the change in the estimated fair value of success payment liabilities from GAAP net loss and GAAP R&D expenses. Non-GAAP net loss further adjusts non‑cash investment gains and charges, as applicable. Non‑GAAP G&A expenses exclude non-cash stock-based compensation expense from GAAP G&A expenses. We believe that these non‑GAAP financial measures, when considered together with our financial information prepared in accordance with GAAP, can enhance investors’ and analysts’ ability to meaningfully compare our results from period to period, and to identify operating trends in our business. We have excluded stock-based compensation expense, changes in the estimated fair value of success payment liabilities, and non-cash investment gains and charges from our non‑GAAP financial measures because they are non-cash gains and charges that may vary significantly from period to period as a result of changes not directly or immediately related to the operational performance for the periods presented. We also regularly use these non‑GAAP financial measures internally to understand, manage and evaluate our business and to make operating decisions. These non-GAAP financial measures are in addition to, and not a substitute for or superior to, measures of financial performance prepared in accordance with GAAP. In addition, these non‑GAAP financial measures have no standardized meaning prescribed by GAAP and are not prepared under any comprehensive set of accounting rules or principles and, therefore, have limits in their usefulness to investors. We encourage investors to carefully consider our results under GAAP, as well as our supplemental non-GAAP financial information, to more fully understand our business. (1) There was no income tax effect related to the adjustments made to calculate non-GAAP net loss because of the full valuation allowance on our net deferred tax assets for all periods presented. (1) As of October 1, 2024, the Company’s success payment liability was recognized at fair value as Stanford had provided the requisite service obligation to earn the potential success payment consideration. The change in the estimated fair value of Stanford success payment liabilities in the first quarter of 2025 was recognized within other income, net in the Condensed Consolidated Statements of Operations and Comprehensive Loss. The change in the estimated fair value of Stanford success payment liabilities in the first quarter of 2024 was recognized within research and development expenses in the Condensed Consolidated Statements of Operations and Comprehensive Loss. The change in the estimated fair value of Fred Hutch success payment liabilities was recognized within other income, net in the Condensed Consolidated Statements of Operations and Comprehensive Loss. Contact: Ellen Rose Senior Vice President, Communications and Investor Relations [email protected]