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Cemsidomide’s Ongoing Phase 2 MOMENTUM Trial and Phase 1b Trial in Combination With Elranatamab Remain on Track to Deliver Clinical Data Readouts in 2027 Phase 1 Data Presented at European Hematology Association (EHA) 2026 Congress Further Support Cemsidomide’s Potential Best-in-Class Profile in Multiple Myeloma Phase 1b Trial of Cemsidomide in Combination With Approved Standard of Care Multiple Myeloma Therapies On Track to Initiate in 1H 2027 WATERTOWN, Mass., Aug. 11, 2026 (GLOBE NEWSWIRE) -- C4 Therapeutics, Inc. (C4T) (Nasdaq: CCCC), a clinical-stage biopharmaceutical company dedicated to advancing targeted protein degradation (TPD) science, today reported financial results for the second quarter ended June 30, 2026, as well as recent business highlights. “The first half of 2026 was a period of execution for cemsidomide, our next-generation IKZF1/3 degrader, and our clinical development plan. At the EHA Congress in June, we presented clinical data that further supported cemsidomide’s differentiated and potential best-in-class profile for the treatment of relapsed refractory multiple myeloma. In addition, insights from our June KOL webinar underscored the importance of IKZF1/3 degradation as a foundational mechanism in multiple myeloma and highlighted the potential for next-generation IKZF1/3 degraders to become a cornerstone therapy across the disease continuum,” said Andrew Hirsch, president and chief executive officer of C4 Therapeutics. “As we enter the second half of the year, we remain focused on advancing the Phase 2 MOMENTUM trial, the Phase 1b combination trial with elranatamab and start-up activities for our additional Phase 1b combination trial with approved standard-of-care multiple myeloma therapies. Together, these studies are expected to generate clinical milestones in 2027 and beyond and will support our vision of establishing cemsidomide as a potential backbone therapy for combination regimens in multiple myeloma.” SECOND QUARTER 2026 UPDATES AND RECENT ACHIEVEMENTS The ongoing Phase 2 MOMENTUM trial evaluating cemsidomide in combination with dexamethasone in late-line multiple myeloma (MM) treatment is on track to complete enrollment in the first quarter of 2027. The initial investigator-assessed overall response rate (ORR) data are expected in the second half of 2027. The ongoing Phase 1b trial evaluating cemsidomide and dexamethasone in combination with elranatamab (ELREXFIO®), a B-cell maturation antigen CD3 targeted bispecific antibody, in earlier lines of MM treatment continues to progress. C4T expects to provide an update on the dose escalation progress in the second half of 2026 with data from all cohorts expected in mid-2027. Study start-up activities are underway for an additional Phase 1b trial evaluating cemsidomide across two treatment arms for relapsed refractory MM patients: (1) cemsidomide, dexamethasone, daratumumab, a CD38 antibody, and (2) cemsidomide, dexamethasone, carfilzomib, a proteasome inhibitor. The trial is expected to initiate in the first half of 2027 with the goal to characterize cemsidomide’s dose and safety with approved standard of care MM therapies. A poster presentation was accepted at the International Myeloma Society (IMS) Annual Meeting, featuring additional biomarker data on cemsidomide’s immunomodulatory effects on T cells and natural killer (NK) cells in combination with dexamethasone. These data further support cemsidomide’s potential as a combination partner for immune-based therapies. The meeting will take place September 23–26, 2026, in Glasgow, Scotland. Further analysis from the Phase 1 trial evaluating cemsidomide in combination with dexamethasone was presented at the EHA 2026 Congress supporting its differentiated safety profile and compelling anti-myeloma activity in a heavily pretreated relapsed refractory MM patient population. At the two highest dose levels evaluated (75 µg and 100 µg), responses deepened over time and demonstrated a 40% ORR and a 53% ORR, respectively, including one stringent complete response and two complete responses. Two patients also achieved minimal residual disease negativity. Across all doses there were no cemsidomide-related discontinuations and minimal dose reductions were observed. These data further support cemsidomide’s potential best-in-class profile. C4T entered into a new collaboration agreement with Roche in April 2026 to advance research in the emerging degrader-antibody conjugate (DAC) modality. C4T and Roche are combining antibody-drug conjugation and targeted protein degradation to develop a new way to treat cancers. In May 2026, C4T received an upfront payment of $20 million. C4T raised approximately $33.5 million in net proceeds in the second quarter through its at-the-market (ATM) program. The proceeds are expected to support the continued advancement of cemsidomide, including the additional Phase 1b trial and Phase 3 trial planning activities and execution efforts. C4T hosted an educational KOL webinar featuring Nisha Joseph, M.D., associate professor at the Winship Cancer Institute at Emory University and investigator in the cemsidomide clinical trials. The event highlighted the evolving MM landscape, the foundational role of IKZF1/3 degradation and cemsidomide’s differentiated profile. An archived replay of the webinar is available under “Events and Presentations” within the Investors section of C4T’s website. UPCOMING MILESTONES IMS Annual Meeting, September 23 - 26, 2026: Present a poster featuring additional biomarker data on cemsidomide’s immunomodulatory effects on T cells and NK cells in combination with dexamethasone. 2H 2026: Provide an update on the dose escalation progress from the Phase 1b trial evaluating the combination of cemsidomide, dexamethasone, and elranatamab. By year-end 2026: Deliver at least one development candidate to a collaboration partner and advance collaborations toward key milestones. UPCOMING INVESTOR EVENTS September 9, 2026: Management will participate in the 2026 Cantor Global Healthcare Conference taking place in New York, NY from September 9 – September 11, 2026. September 10, 2026, at 11:00 am ET: Management will participate in a fireside chat at the 2026 Wells Fargo Healthcare Conference taking place in Boston, MA from September 8 – September 10, 2026. SECOND QUARTER 2026 FINANCIAL RESULTS Revenue: Total revenue for the second quarter of 2026 was $6.6 million, compared to $6.5 million for the second quarter of 2025. The increase was primarily related to revenue recognized under the new Roche DAC collaboration agreement, offset by a decrease in revenue from the conclusion of certain research activities associated with the collaborations with Merck and Merck KGaA, Darmstadt Germany. Research and Development (R&D) Expense: R&D expense for the second quarter of 2026 was $24.5 million, compared to $26.2 million for the second quarter of 2025. The decrease in R&D expense was primarily due to lower personnel costs resulting from reduced stock-based compensation expense. General and Administrative (G&A) Expense: G&A expense for the second quarter of 2026 was $8.6 million, compared to $8.8 million for the second quarter of 2025. The decrease in G&A expense was primarily due to lower personnel costs resulting from reduced stock-based compensation expense. Net Loss and Net Loss per Share: Net loss for the second quarter of 2026 was $23.6 million, compared to $26.0 million for the second quarter of 2025. Net loss per share for the second quarter of 2026 was $0.18, compared to $0.37 for the second quarter of 2025. Cash Position and Financial Guidance: Cash, cash equivalents and marketable securities as of June 30, 2026, were $300.4 million, compared to $268.3 million as of March 31, 2026, and $297.1 million as of December 31, 2025. The increase in cash, cash equivalents and marketable securities during the second quarter of 2026 primarily reflects $33.5 million in net proceeds from the company’s ATM program and a $20.0 million upfront payment related to its collaboration with Roche, offset by cash used to fund operations and advance programs. The company expects that its current cash, cash equivalents and marketable securities will fund its operations to the end of 2028. About CemsidomideCemsidomide is an investigational, next-generation orally bioavailable MonoDAC® degrader (molecular glue) of IKZF1/3, transcription factors foundational to multiple myeloma biology. Data from the fully enrolled Phase 1 trial show cemsidomide’s differentiated safety and tolerability profile and potentially class-leading anti-myeloma activity that supports the potential for durable outcomes. About the MOMENTUM TrialMOMENTUM (Multi-center trial Of cemsidoMidE iN relapsed/refracTory mUltiple Myeloma) is a Phase 2, open-label, single-arm study to evaluate the efficacy and safety of cemsidomide in combination with dexamethasone in patients with relapsed/refractory multiple myeloma. Data from the Phase 1 trial identified 100 µg as the recommended Phase 2 dose. The primary endpoint is overall response rate per International Myeloma Working Group response criteria, as assessed by an independent review committee. Approximately 100 patients who have received at least three prior anti-myeloma regimens that must have included an IKZF1/3 degrader, a proteasome inhibitor, an anti-CD38 antibody, and a T-cell engager or CAR-T therapy will be enrolled in the trial. More information is available at clinicaltrials.gov (NCT07284758). About Cemsidomide in Combination With Elranatamab (ELREXFIO®)The Phase 1b trial is designed to evaluate the safety, tolerability and preliminary efficacy of cemsidomide and dexamethasone in combination with elranatamab, an FDA-approved B-cell maturation antigen CD3 targeted bispecific antibody. Data generated from the cemsidomide Phase 1 trial in relapsed/refractory multiple myeloma demonstrate robust T-cell activation and cytokine expression across multiple doses. By activating immune T-cells, cemsidomide, when combined with a BCMAxCD3 bispecific such as elranatamab, may amplify the anti-myeloma immune response and lead to deeper and more durable responses. The study will evaluate different cemsidomide dose levels (beginning with 75 µg, with the opportunity to simultaneously explore 50 µg and 100 µg) in patients who have received one to four prior lines of therapy, which must have consisted of at least one IKZF1/3 degrader. Exclusion criteria for patients include those who have received prior treatment with a BCMA-directed T-cell engager or BCMA-directed CAR-T therapy. More information is available at clinicaltrials.gov (NCT07280013). About Multiple MyelomaMultiple myeloma is a blood cancer that affects plasma cells in the bone marrow. It is the second most common blood cancer, with approximately 36,000 people in the United States diagnosed each year. Multiple myeloma is characterized by cycles of remission and relapses, which leads to patients needing multiple lines of therapy to manage this persistent disease. More than 175,000 patients in the United States are estimated to be living with or in remission from myeloma. However, despite treatment advances, approximately 40% of patients do not survive beyond five years. About C4 TherapeuticsC4 Therapeutics (C4T) (Nasdaq: CCCC) is a clinical-stage biopharmaceutical company dedicated to delivering on the promise of targeted protein degradation science to create a new generation of medicines that transforms patients’ lives. C4T is progressing targeted oncology programs through clinical studies and leveraging its TORPEDO® platform to efficiently design and optimize small-molecule medicines to address difficult-to-treat diseases. C4T’s degrader medicines are designed to harness the body’s natural protein recycling system to rapidly degrade disease-causing proteins, offering the potential to overcome drug resistance, drug undruggable targets and improve patient outcomes. For more information, please visit www.c4therapeutics.com. Forward Looking StatementsThis press release contains “forward-looking statements” of C4 Therapeutics, Inc., within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements may include, but may not be limited to, express or implied statements regarding the Company’s ability to develop potential therapies for patients; the design and potential efficacy of the Company’s therapeutic approaches; the predictive capability of the Company’s TORPEDO® platform in the development of novel, selective, orally bioavailable BiDAC™ and MonoDAC® degraders; the potential timing, design and advancement of the Company’s preclinical studies and clinical trials, including the Company’s Phase 2 MOMENTUM trial, Phase 1b combination trials, and Phase 3 trial planning activities, and the potential timing for and receipt of regulatory authorization, clinical trial initiation and patient enrollment; the potential timing and/or receipt of regulatory approval for the Company’s product candidates; the anticipated timing and content of presentations of data from the Company’s clinical trials; and expectations for the Company’s uses of capital, expenses and financial results, including its cash runway to the end of 2028. Any forward-looking statements in this press release are based on management’s current expectations and beliefs of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in or implied by such forward-looking statements. These risks and uncertainties include, but are not limited to: uncertainties related to the initiation, timing, advancement and conduct of preclinical and clinical studies and other development requirements for the Company’s product candidates; the risk that any one or more of the Company’s product candidates will cost more to develop or may not be successfully developed and commercialized; and the risk that sufficient capital to fund the Company’s future operations will be available to the Company on acceptable terms or at the times required. For a discussion of these and other risks and uncertainties, and other important factors, any of which could cause the Company’s actual results to differ from those contained in the forward-looking statements, see the section entitled “Risk Factors” in C4 Therapeutics’ most recent Annual Report on Form 10-K and/or Quarterly Report on Form 10-Q, as filed with the Securities and Exchange Commission. All information in this press release is as of the date of the release, and C4 Therapeutics undertakes no duty to update this information unless required by law. Contacts:Investors: Courtney SolbergAssociate Director, Investor [email protected] Media: Loraine Spreen Senior Director, Corporate Communications & Patient Advocacy [email protected]

WATERTOWN, Mass., May 12, 2026 (GLOBE NEWSWIRE) -- C4 Therapeutics, Inc. (C4T) (Nasdaq: CCCC), a clinical-stage biopharmaceutical company dedicated to advancing targeted protein degradation (TPD) science, today reported financial results for the first quarter ended March 31, 2026, as well as recent business highlights. “During the first quarter, we made strong progress advancing cemsidomide as a potential best-in-class IKZF1/3 degrader for the treatment of multiple myeloma, highlighted by the initiation of two new clinical trials and plans to begin an additional combination trial next year. We believe our clinical development path further supports the advancement of IKZF1/3 degradation – the only mechanism targeting a central transcriptional dependency in multiple myeloma – and will help position cemsidomide as a potentially foundational therapy for these patients with relapsed refractory disease,” said Andrew Hirsch, president and chief executive officer of C4 Therapeutics. “In addition to these clinical advances, we also expanded our partnership with Roche through a new collaboration focused on degrader-antibody conjugates, broadening the reach of targeted protein degradation in cancer. Supported by a strong balance sheet through key value inflection points, we remain focused on advancing our portfolio to deliver the next generation of targeted protein degrader medicines to patients.” FIRST QUARTER 2026 HIGHLIGHTS AND RECENT ACHIEVEMENTS Planning is underway to initiate an additional Phase 1b trial evaluating cemsidomide in combination with approved multiple myeloma (MM) therapies. The trial will include two treatment arms: (1) cemsidomide, dexamethasone, and a proteasome inhibitor, and (2) cemsidomide, dexamethasone, and a CD38 antibody, for the relapsed refractory (RR) MM patients. Trial initiation is expected in the first half of 2027 with the goal of further establishing cemsidomide’s profile as a potentially foundational therapy across multiple lines of MM treatment. Data from the Phase 1 trial evaluating cemsidomide in combination with dexamethasone in RRMM was accepted as a poster presentation at the European Hematology Annual (EHA) Congress taking place from June 11 – June 14, 2026, in Stockholm, Sweden. Enrollment was completed in September 2025, and the poster presentation will include further analysis from the ongoing trial. A trial-in-progress poster highlighting the Phase 2 MOMENTUM trial evaluating cemsidomide in combination with dexamethasone in RRMM was accepted at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting taking place from May 29 – June 2, 2026, in Chicago, Illinois. The first patient was dosed in the Phase 1b trial in March 2026. The trial is evaluating cemsidomide and dexamethasone in combination with elranatamab (ELREXFIO®), B-cell maturation antigen CD3 targeted bispecific antibody, for earlier lines of MM treatment. The first patient was dosed in the Phase 2 MOMENTUM trial in February 2026. The trial is evaluating cemsidomide in combination with dexamethasone in MM for the fourth line or later. The trial is expected to enroll approximately 100 patients and is on track to complete enrollment by the end of Q1 2027. Based on the evolving treatment landscape for EGFR mutated non-small cell lung cancer (NSCLC), capital priorities, and available clinical data to date, C4T has made the decision to not advance CFT8919, an EGFR L858R degrader, into the next phase of clinical development outside of Greater China at this time. C4T entered into a new collaboration agreement with Roche in April 2026, to advance research in the emerging degrader-antibody conjugate (DAC) modality. C4T and Roche will combine antibody-drug conjugation and targeted protein degradation to develop a new way to treat cancers. In May 2026, C4T received an upfront payment of $20 million. UPCOMING MILESTONES EHA Congress, June 11 – 14, 2026: Dr. Sagar Lonial, MD, FACP, FASCO, Chief Medical Officer at the Winship Cancer Institute at Emory University, will present a poster titled “Updated Results of a Phase 1 First-In-Human Study of Cemsidomide, a Novel MonoDAC® Degrader, with Dexamethasone in Patients with RRMM” at the EHA Congress on Friday, June 12, 2026 at 6:45 pm CEST / 12:45 pm ET. 2H 2026: Provide an update on the dose escalation progress from the Phase 1b trial evaluating the combination of cemsidomide, dexamethasone, and elranatamab. By year-end 2026: Deliver at least one development candidate to a collaboration partner and advance collaborations toward key milestones. UPCOMING INVESTOR EVENTS May 26th at 2:30 pm ET: Management will participate in a virtual fireside chat at TD Cowen’s 7th Annual Oncology Innovation Summit: Insights for ASCO & EHA, taking place virtually from May 26 – May 27, 2026. June 3rd at 8:45 am ET: Management will participate in a fireside chat at the 2026 Jefferies Global Healthcare Conference taking place in New York, NY from June 2 – June 4, 2026. June 10th: Management will participate in 1x1 meetings at the Goldman Sachs 47th Annual Global Healthcare Conference taking place in Miami, FL from June 8 – 10, 2026. FIRST QUARTER 2026 FINANCIAL RESULTS Revenue: Total revenue for the first quarter of 2026 was $6.2 million, compared to $7.2 million for the first quarter of 2025. The decrease in revenue resulted from the conclusion of the research collaboration with Merck and the prioritization of one KRAS project under the collaboration with Merck KGaA, Darmstadt, Germany (MKDG). This was partially offset by a $2.0 million milestone that was earned from Biogen during the period ended March 31, 2026. Research and Development (R&D) Expense: R&D expense for the first quarter of 2026 was $24.6 million, compared to $27.1 million for the first quarter of 2025. The decrease in R&D expense was primarily related to the conclusion of the Merck collaboration and the prioritization of one KRAS project under the collaboration with MKDG. General and Administrative (G&A) Expense: G&A expense for the first quarter of 2026 was $9.3 million, which was unchanged compared to the first quarter of 2025. Net Loss and Net Loss per Share: Net loss for the first quarter of 2026 was $25.1 million, compared to $26.3 million for the first quarter of 2025. Net loss per share for the first quarter of 2026 was $0.20, compared to $0.37 for the first quarter of 2025. Cash Position and Financial Guidance: Cash, cash equivalents and marketable securities as of March 31, 2026 were $268.3 million, compared to $297.1 million as of December 31, 2025. The decrease in cash, cash equivalents and marketable securities during the first quarter of 2026 was primarily the result of the cash used to fund operations and advance our programs. The company expects that its current cash, cash equivalents and marketable securities will fund its operations to the end of 2028. About Cemsidomide Cemsidomide is an investigational, orally bioavailable molecular glue degrader (MonoDAC® degrader) of IKZF1/3, transcription factors foundational to multiple myeloma biology. Data from the Phase 1 trial, which has completed enrollment, show cemsidomide’s differentiated safety and tolerability profile and potentially class-leading anti-myeloma activity that support the potential for durable outcomes. About the MOMENTUM Trial MOMENTUM (Multi-center trial Of cemsidoMidE iN relapsed/refracTory mUltiple Myeloma) is a Phase 2, open-label, single-arm study to evaluate the efficacy, safety, pharmacokinetics and pharmacodynamics of cemsidomide in combination with dexamethasone in patients with relapsed/refractory multiple myeloma. Data from the Phase 1 trial identified 100 µg as the recommended Phase 2 dose. The primary endpoint is overall response rate per International Myeloma Working Group response criteria, as assessed by an independent review committee. Approximately 100 patients who have received at least three prior anti-myeloma regimens that must have included an IKZF1/3 degrader, a proteasome inhibitor, an anti-CD38 antibody, and a T-cell engager or CAR-T therapy will be enrolled in the trial. More information is available at clinicaltrials.gov (NCT07284758). About Cemsidomide in Combination With Elranatamab (ELREXFIO®) The Phase 1b trial is designed to evaluate the safety, tolerability and preliminary efficacy of cemsidomide and dexamethasone in combination with elranatamab, an FDA-approved B-cell maturation antigen CD3 targeted bispecific antibody. Data generated from the cemsidomide Phase 1 trial in relapsed/refractory multiple myeloma demonstrate robust T-cell activation and cytokine expression across multiple doses. By activating immune T-cells, cemsidomide, when combined with a BCMAxCD3 bispecific such as elranatamab, may amplify the anti-myeloma immune response and lead to deeper and more durable responses. The study will evaluate different cemsidomide dose levels (beginning with 75 µg, with the opportunity to simultaneously explore 50 µg and 100 µg) in patients who have received one to four prior lines of therapy, which must have consisted of at least one IKZF1/3 degrader. Exclusion criteria for patients include those who have received prior treatment with a BCMA-directed T-cell engager or BCMA-directed CAR-T therapy. More information is available at clinicaltrials.gov (NCT07280013). About Multiple Myeloma Multiple myeloma (MM) is a rare blood cancer affecting plasma cells. Approximately 36,000 people in the United States are diagnosed with MM each year. Approved IKZF1/3 degraders remain foundational therapies across lines of MM treatment. Despite advances, including immune-directed approaches, most patients ultimately relapse, underscoring a growing need for new therapeutics options that continue to leverage IKZF1/3 degradation to drive myeloma cell death and T-cell activation. About C4 Therapeutics C4 Therapeutics (C4T) (Nasdaq: CCCC) is a clinical-stage biopharmaceutical company dedicated to delivering on the promise of targeted protein degradation science to create a new generation of medicines that transforms patients’ lives. C4T is progressing targeted oncology programs through clinical studies and leveraging its TORPEDO® platform to efficiently design and optimize small-molecule medicines to address difficult-to-treat diseases. C4T’s degrader medicines are designed to harness the body’s natural protein recycling system to rapidly degrade disease-causing proteins, offering the potential to overcome drug resistance, drug undruggable targets and improve patient outcomes. For more information, please visit www.c4therapeutics.com. Forward Looking Statements This press release contains “forward-looking statements” of C4 Therapeutics, Inc., within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements may include, but may not be limited to, express or implied statements regarding our ability to develop potential therapies for patients; the design and potential efficacy of our therapeutic approaches; the predictive capability of our TORPEDO® platform in the development of novel, selective, orally bioavailable BiDAC™ and MonoDAC® degraders; the potential timing, design and advancement of our preclinical studies and clinical trials, including the potential timing for and receipt of regulatory authorization related to clinical trials and other clinical development activities including clinical trial commencement and patient enrollment; our ability and the potential to successfully manufacture and supply our product candidates for clinical trials; our ability to replicate results achieved in our preclinical studies or clinical trials in any future studies or trials; our ability to replicate interim or early-stage results from our clinical trials in the results obtained when those clinical trials are completed or when those therapies complete later-stage clinical trials; the potential timing and/or receipt of regulatory approval for our product candidates; regulatory developments in the United States and foreign countries; the anticipated timing and content of presentations of data from our clinical trials; and our ability to fund our future operations. Any forward-looking statements in this press release are based on management’s current expectations and beliefs of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in or implied by such forward-looking statements. These risks and uncertainties include, but are not limited to: uncertainties related to the initiation, timing, advancement and conduct of preclinical and clinical studies and other development requirements for our product candidates; the risk that any one or more of our product candidates will cost more to develop or may not be successfully developed and commercialized; and the risk that sufficient capital to fund our future operations will be available to us on acceptable terms or at the times required. For a discussion of these and other risks and uncertainties, and other important factors, any of which could cause our actual results to differ from those contained in the forward-looking statements, see the section entitled “Risk Factors” in C4 Therapeutics’ most recent Annual Report on Form 10-K and/or Quarterly Report on Form 10-Q, as filed with the Securities and Exchange Commission. All information in this press release is as of the date of the release, and C4 Therapeutics undertakes no duty to update this information unless required by law. Contacts: Investors: Courtney Solberg Associate Director, Investor Relations [email protected] Leah Gibson Vice President, Investor Relations & Communications [email protected] Media: Loraine Spreen Senior Director, Corporate Communications & Patient Advocacy [email protected]

Cemsidomide Advancing into Later-stage Development with Potential for Accelerated Approval; First Patient Dosed in the Phase 2 MOMENTUM Trial for Multiple Myeloma in the Fourth Line or Later Phase 1b Trial of Cemsidomide in Combination with Elranatamab on Track to Initiate in Q2 2026 to Support Use in Earlier Lines of Multiple Myeloma Therapy Second Degrader Designed and Delivered to Biogen Entered Clinical Development for Autoimmune Diseases Strong Balance Sheet Provides Runway to the End of 2028; Cash, Cash Equivalents and Marketable Securities of $297.1 million as of December 31, 2025 WATERTOWN, Mass., Feb. 26, 2026 (GLOBE NEWSWIRE) -- C4 Therapeutics, Inc. (C4T) (Nasdaq: CCCC), a clinical-stage biopharmaceutical company dedicated to advancing targeted protein degradation (TPD) science, today reported financial results for the year ended December 31, 2025, as well as business updates. “We made significant progress in 2025, notably demonstrating cemsidomide’s best-in-class potential, establishing an efficient and differentiated regulatory path for cemsidomide, and extending our cash runway beyond key value‑inflection milestones, further positioning us to become a fully integrated biopharmaceutical company,” said Andrew Hirsch, president and chief executive officer of C4 Therapeutics. “As cemsidomide progresses into later-stage clinical trials across multiple lines of therapy in multiple myeloma, we believe it is well positioned to become the IKZF1/3 degrader of choice. We continue to advance our discovery strategy, focused on targets that have a strong degrader rationale with first-in-class potential in inflammation, neuroinflammation and neurodegeneration diseases. Together, these achievements will bring us closer to delivering transformative TPD medicines for patients with significant unmet needs.” FOURTH QUARTER 2025 HIGHLIGHTS AND RECENT ACHIEVEMENTS In February 2026, the first patient was dosed in the Phase 2 MOMENTUM trial evaluating cemsidomide in combination with dexamethasone in the fourth line or later MM setting. The MOMENTUM trial was designed for potential accelerated approval with a recommended Phase 2 dose of 100 µg. The trial will enroll approximately 100 patients with enrollment expected to be completed in Q1 2027. In October 2025, C4T entered into a clinical trial collaboration and supply agreement with Pfizer Inc. Under the terms of the agreement, Pfizer will supply elranatamab (ELREXFIO®), a B-cell maturation antigen CD3 targeted bispecific antibody, for the upcoming Phase 1b trial of cemsidomide in combination with elranatamab in earlier lines of MM treatment. C4T has continued to execute operational steps necessary for the initiation of the Phase 1b trial, which is expected in Q2 2026. In October 2025, C4T raised $125 million in gross proceeds through an underwritten offering with the potential to earn up to $225 million in additional proceeds if the outstanding warrants are exercised. In January 2026, C4T earned a $2 million milestone payment from Biogen related to BIIB145, a BTK degrader, designed by C4T and delivered to Biogen for clinical development. This is the second degrader that Biogen has advanced into the clinic under the Biogen and C4T collaboration. KEY UPCOMING MILESTONES Cemsidomide: IKZF1/3 Degrader for Relapsed Refractory Multiple Myeloma (RRMM) On track to initiate the Phase 1b trial of cemsidomide in combination with elranatamab in Q2 2026 with plans to provide incremental progress throughout 2026. Present further analysis of the data from the completed Phase 1 trial of cemsidomide in combination with dexamethasone in mid-2026. Share the plan to initiate an additional Phase 1b trial to evaluate cemsidomide in combination with other anti-myeloma agents in mid-2026. CFT8919: EGFR L858R Degrader for Non-Small-Cell Lung Cancer (NSCLC) By end of Q1 2026, utilize data from the Phase 1 dose escalation trial conducted by Betta Pharmaceuticals to inform potential ex-China clinical development. Research & Discovery: Internal Discovery Efforts Focused on Inflammation, Neuroinflammation & Neurodegeneration (INN) with Collaboration Efforts Focused on Oncology & Non-oncology Optimize indication selection for multiple targets across discovery portfolio focused on INN in 2026. Deliver at least one development candidate to a collaboration partner by year-end 2026. Advance existing collaborations toward key milestones by year-end 2026. UPCOMING INVESTOR EVENTS March 3, 2026, at 11:50 AM ET: Management will participate in a presentation and fireside chat at the TD Cowen 46th Annual Health Care Conference taking place in Boston, Massachusetts. March 10, 2026, at 8:00 AM ET: Management will participate in a fireside chat at the Barclays 28th Annual Global Healthcare Conference taking place in Miami, Florida. FOURTH QUARTER AND FULL YEAR 2025 FINANCIAL RESULTS Revenue: Total revenue for the fourth quarter and full year ended December 31, 2025, was $11.0 million and $35.9 million, respectively, compared to $5.2 million and $35.6 million for the prior year periods. The increase in revenue for the fourth quarter of 2025, as compared to the prior year period, reflects the prioritization of one KRAS project under the collaboration with Merck KGaA, Darmstadt, Germany. Research and Development (R&D) Expense: R&D expense for the fourth quarter and full year ended December 31, 2025, was $25.0 million and $104.2 million, respectively, compared to $32.5 million and $110.6 million for the prior year periods. The decrease in R&D expense for the fourth quarter of 2025, as compared to the prior year period, was primarily related to the completion of the CFT1946 Phase 1 clinical trial. General and Administrative (G&A) Expense: G&A expense for the fourth quarter and full year ended December 31, 2025, was $9.2 million and $36.2 million, respectively, compared to $10.4 million and $42.1 million for the prior year periods. The decrease in G&A expense for the fourth quarter of 2025, as compared to the prior year period, was primarily related to lower stock-based compensation expense. Net Loss and Net Loss per Share: Net loss for the fourth quarter and full year ended December 31, 2025, was $20.5 million and $105.0 million, respectively, compared to $34.6 million and $105.3 million for the prior year periods. Net loss per share for the fourth quarter and full year ended December 31, 2025, was $0.18 and $1.27, respectively, compared to $0.49 and $1.52 for the prior year periods. Cash Position and Financial Guidance: Cash, cash equivalents and marketable securities as of December 31, 2025, was $297.1 million, compared to $199.8 million as of September 30, 2025, and $267.3 million as of December 31, 2024. The increase in cash, cash equivalents and marketable securities during 2025 was primarily the result of the net proceeds from the October equity offering partially offset by the cash used to fund operations and advance our programs. The company expects that its current cash, cash equivalents and marketable securities will enable it to fund its operating plan to the end of 2028. About Cemsidomide Cemsidomide is an investigational, orally bioavailable molecular glue degrader (MonoDAC® degrader) of IKZF1/3, transcription factors foundational to multiple myeloma biology. Data from the Phase 1 trial, which has completed enrollment, show cemsidomide’s differentiated safety and tolerability profile and potentially class-leading anti-myeloma activity that support the potential for durable outcomes. About the MOMENTUM Trial MOMENTUM (Multi-center trial Of cemsidoMidE iN relapsed/refracTory mUltiple Myeloma) is a Phase 2, open-label, single-arm study to evaluate the efficacy, safety, pharmacokinetics and pharmacodynamics of cemsidomide in combination with dexamethasone in patients with relapsed/refractory multiple myeloma. Data from the Phase 1 trial identified 100 µg as the recommended Phase 2 dose. The primary endpoint is overall response rate per International Myeloma Working Group response criteria, as assessed by an independent review committee. Approximately 100 patients who have received at least three prior anti-myeloma regimens that must have included an IKZF1/3 degrader, a proteasome inhibitor, an anti-CD38 antibody, and a T-cell engager or CAR-T therapy will be enrolled in the trial. More information is available at clinicaltrials.gov (NCT07284758). About Cemsidomide in Combination With Elranatamab (ELREXFIO®) The Phase 1b trial is designed to evaluate the safety, tolerability and preliminary efficacy of cemsidomide in combination with elranatamab, an FDA-approved B-cell maturation antigen CD3 targeted bispecific antibody. The study will evaluate different cemsidomide dose levels (beginning with 75 µg, with the opportunity to simultaneously explore 50 µg and 100 µg) in patients who have received one to four prior lines of therapy, which must have consisted of at least one IKZF1/3 degrader. Exclusion criteria for patients include those who have received prior treatment with a BCMA-directed T-cell engager or BCMA-directed CAR-T therapy. More information is available at clinicaltrials.gov (NCT07280013). About Multiple Myeloma Multiple myeloma (MM) is a rare blood cancer affecting plasma cells. Approximately 36,000 people in the United States are diagnosed with MM each year. Approved IKZF1/3 degraders remain foundational therapies across lines of MM treatment. Despite advances, including immune-directed approaches, most patients ultimately relapse, underscoring a growing need for new therapeutics options that continue to leverage IKZF1/3 degradation to drive myeloma cell death and T-cell activation. About C4 Therapeutics C4 Therapeutics (C4T) (Nasdaq: CCCC) is a clinical-stage biopharmaceutical company dedicated to delivering on the promise of targeted protein degradation science to create a new generation of medicines that transforms patients’ lives. C4T is progressing targeted oncology programs through clinical studies and leveraging its TORPEDO® platform to efficiently design and optimize small-molecule medicines to address difficult-to-treat diseases. C4T’s degrader medicines are designed to harness the body’s natural protein recycling system to rapidly degrade disease-causing proteins, offering the potential to overcome drug resistance, drug undruggable targets and improve patient outcomes. For more information, please visit www.c4therapeutics.com. Forward Looking Statements This press release contains “forward-looking statements” of C4 Therapeutics, Inc., within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements may include, but may not be limited to, express or implied statements regarding our ability to develop potential therapies for patients; the design and potential efficacy of our therapeutic approaches; the predictive capability of our TORPEDO® platform in the development of novel, selective, orally bioavailable BiDAC™ and MonoDAC® degraders; the potential timing, design and advancement of our preclinical studies and clinical trials, including the potential timing for and receipt of regulatory authorization related to clinical trials and other clinical development activities including clinical trial commencement and patient enrollment; our ability and the potential to successfully manufacture and supply our product candidates for clinical trials; our ability to replicate results achieved in our preclinical studies or clinical trials in any future studies or trials; our ability to replicate interim or early-stage results from our clinical trials in the results obtained when those clinical trials are completed or when those therapies complete later-stage clinical trials; regulatory developments in the United States and foreign countries; the anticipated timing and content of presentations of data from our clinical trials; and our ability to fund our future operations. Any forward-looking statements in this press release are based on management’s current expectations and beliefs of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in or implied by such forward-looking statements. These risks and uncertainties include, but are not limited to: uncertainties related to the initiation, timing, advancement and conduct of preclinical and clinical studies and other development requirements for our product candidates; the risk that any one or more of our product candidates will cost more to develop or may not be successfully developed and commercialized; and the risk that sufficient capital to fund our future operations will be available to us on acceptable terms or at the times required. For a discussion of these and other risks and uncertainties, and other important factors, any of which could cause our actual results to differ from those contained in the forward-looking statements, see the section entitled “Risk Factors” in C4 Therapeutics’ most recent Annual Report on Form 10-K and/or Quarterly Report on Form 10-Q, as filed with the Securities and Exchange Commission. All information in this press release is as of the date of the release, and C4 Therapeutics undertakes no duty to update this information unless required by law. Contacts: Investors: Courtney Solberg Associate Director, Investor Relations [email protected] Media: Loraine Spreen Senior Director, Corporate Communications & Patient Advocacy [email protected]

Completed Equity Offering Resulted in $125 Million in Gross Proceeds, Extending Runway to End of 2028, Beyond Key Value Inflection Points; Potential to Earn up to an Additional $225 Million in Proceeds Cemsidomide Phase 1 Multiple Myeloma Data Support Potential Best-in-Class Profile With a 53% Overall Response Rate at the Highest Dose Level (100 µg) and Differentiated Safety and Tolerability Profile Entered Into Clinical Trial Collaboration and Supply Agreement With Pfizer to Evaluate Cemsidomide in Combination With Elranatamab On Track to Initiate Next Phase of Cemsidomide Multiple Myeloma Development Including Registrational Phase 2 MOMENTUM Trial in Combination with Dexamethasone in Q1 2026 and Phase 1b Trial in Combination with Elranatamab in Q2 2026 WATERTOWN, Mass., Nov. 06, 2025 (GLOBE NEWSWIRE) -- C4 Therapeutics, Inc. (C4T) (Nasdaq: CCCC), a clinical-stage biopharmaceutical company dedicated to advancing targeted protein degradation science, today reported financial results for the third quarter ended September 30, 2025, as well as business updates. “Recent months have been transformative for C4T, and we are in a strong position to rapidly advance cemsidomide registrational development and progress our discovery pipeline of degraders against non-oncology and oncology targets,” said Andrew Hirsch, president and chief executive officer of C4 Therapeutics. “We remain laser-focused on initiating cemsidomide’s next phase of development in early 2026, which includes a Phase 1b trial in combination with elranatamab as well as the Phase 2 MOMENTUM trial in combination with dexamethasone, which has potential for accelerated approval. With a successful raise of $125 million in upfront proceeds, we have extended our runway to the end of 2028, beyond important data from cemsidomide’s Phase 2 trial with dexamethasone and the Phase 1b in combination with elranatamab, strengthening our balance sheet to continue to deliver on the promise of targeted protein degradation to improve patients’ lives.” THIRD QUARTER 2025 HIGHLIGHTS AND RECENT ACHIEVEMENTS Clinical: Presented Phase 1 data of cemsidomide in combination with dexamethasone in multiple myeloma (MM) demonstrating a potential best-in-class profile in a heavily pre-treated patient population and supports cemsidomide’s advancement to a Phase 1b trial in combination with elranatamab and a Phase 2 MOMENTUM (Multi-center trial Of cemsidoMidE iN relapsed/refracTory mUltiple Myeloma) trial in combination with dexamethasone. C4T has completed enrollment and dose escalation for the Phase 1 trial. In the Phase 1 trial, cemsidomide in combination with dexamethasone achieved a 40% and 53% overall response rate at the two highest dose levels, 75 µg and 100 µg, respectively. One patient at the 100 µg dose level achieved a minimal residual disease (MRD) negative complete response. Cemsidomide was well-tolerated and achieved a median duration of response of 9.3 months across all doses, supporting differentiation from other IKZF1/3 degraders. Entered into a clinical trial collaboration and supply agreement with Pfizer for the combination of cemsidomide and elranatamab for the treatment of relapsed/refractory MM. Under the terms of the agreement, C4T will sponsor and conduct the Phase 1b trial while Pfizer will supply elranatamab (ELREXFIO®), a B-cell maturation antigen CD3 targeted bispecific antibody (BCMAxCD3 bispecific), at no cost to C4T for the upcoming trial. Continued to execute operational steps necessary for the initiation of the Phase 2 MOMENTUM trial of cemsidomide in combination with dexamethasone in the fourth line or later for the first quarter of 2026 and the Phase 1b trial of cemsidomide in combination with elranatamab in the second line or later for the second quarter of 2026. Presented data analyzing population pharmacokinetic and exposure-response relationships for cemsidomide in MM and non-Hodgkin’s lymphoma (NHL) in a poster at the 2025 American Conference on Pharmacometrics (ACoP 2025). The analysis indicated an increased anti-myeloma effect at higher exposures and a clinically manageable exposure-safety relationship, supporting the risk-benefit analysis in heavily pre-treated MM patients. Completed dose escalation for the Phase 1 trial of cemsidomide in NHL. Monotherapy cemsidomide demonstrated a well-tolerated profile, consistent with previous disclosures, and achieved compelling anti-lymphoma activity across all dose levels as assessed by investigators. In peripheral T-cell lymphoma (PTCL), 9 out of 22 patients achieved a partial response or better with a PET-CT-based assessment. Partner Betta Pharmaceuticals continues to advance the CFT8919 Phase 1 dose escalation trial in Greater China. Research and Discovery: Highlighted leadership in designing targeted heterobivalent degraders, including CFT1946, that penetrate the blood brain barrier to achieve high central nervous system (CNS) exposures and compelling efficacy in CNS models in presentations delivered by C4T leadership at Fierce Biotech Week and the 8th Annual Targeted Protein Degradation Summit. Earned a $2 million milestone payment from Biogen related to a patient dosing milestone for the Phase 1 trial of BIIB142, a degrader of IRAK4, which was designed by C4T. Notified by Merck of their decision to conclude the research collaboration, which will end in late November 2025. Financing: Raised $125 million in gross proceeds through an underwritten offering that was led by RA Capital Management with participation from existing shareholders including OrbiMed, Soleus Capital, Lynx1 Capital Management, and Bain Capital Life Sciences. As part of the offering, there is the potential to earn up to $225 million in additional proceeds if the outstanding warrants are exercised. KEY UPCOMING MILESTONES Formally align with the U.S. Food & Drug Administration (FDA) on the recommended Phase 2 dose of cemsidomide for the registrational Phase 2 trial of cemsidomide in combination with dexamethasone by year-end 2025. Initiate a Phase 2 single-arm registrational trial in the first quarter of 2026 to evaluate cemsidomide in combination with dexamethasone. Initiate a Phase 1b trial in the second quarter of 2026 to evaluate the safety and tolerability of cemsidomide in combination with elranatamab. UPCOMING INVESTOR EVENTS: November 12, 2025, at 8:30 AM ET: Management will participate in a fireside chat at the Guggenheim Second Annual Healthcare Conference taking place in Boston, Massachusetts. December 3, 2025, at 3:25 PM ET: Management will participate in a fireside chat at the 8th Evercore Healthcare Conference taking place in Coral Gables, Florida. THIRD QUARTER 2025 FINANCIAL RESULTS Revenue: Total revenue for the third quarter of 2025 was $11.2 million, compared to $15.4 million for the third quarter of 2024. The decrease in revenue was a result of an $8.0 million milestone from Biogen recognized in the third quarter 2024 offset by the recognition of all deferred revenue from our collaboration with Merck and the continued progress on our other collaboration programs during the third quarter of 2025. Research and Development (R&D) Expense: R&D expense for the third quarter of 2025 was $26.0 million compared to $31.8 million for the third quarter of 2024. The decrease in R&D expense was primarily related to reduced clinical trial expense for CFT1946 as the Phase 1 trial neared completion. General and Administrative (G&A) Expense: G&A expense for the third quarter of 2025 was $8.9 million compared to $11.8 million for the third quarter of 2024. The decrease was primarily related to lower stock-based compensation expense. Net Loss and Net Loss per Share: Net loss for the third quarter of 2025 was $32.2 million, compared to $24.7 million for the third quarter of 2024. Net loss per share for the third quarter of 2025 was $0.44 compared to $0.35 for the third quarter of 2024. Cash Position and Financial Guidance: Cash, cash equivalents and marketable securities as of September 30, 2025 were $199.8 million, compared to $223.0 million as of June 30, 2025 and $267.3 million as of December 31, 2024. The decrease during the third quarter was primarily the result of cash used to fund operations and advance our programs, partially offset by $7.5 million of net proceeds from our at-the-market (ATM) equity program. Cash, cash equivalents and marketable securities as of September 30, 2025 does not include $125 million of gross proceeds raised through an equity offering in October 2025. The company expects that its current cash, cash equivalents and marketable securities will enable the company to fund its operating plan to the end of 2028. About the MOMENTUM Trial MOMENTUM (Multi-center trial Of cemsidoMidE iN relapsed/refracTory mUltiple Myeloma) is a Phase 2, open-label, single-arm, multicenter study to evaluate efficacy, safety, pharmacokinetics and pharmacodynamics of cemsidomide in combination with dexamethasone in patients with relapsed/refractory multiple myeloma. The primary endpoint is overall response rate per International Myeloma Working Group response criteria, as assessed by an independent review committee. Approximately 100 patients who have received at least three prior lines of therapy will be enrolled in the trial. About Cemsidomide Cemsidomide is an investigational, orally bioavailable small-molecule degrader in clinical development for the treatment of relapsed/refractory multiple myeloma. Cemsidomide is a potent and selective degrader of IKZF1/3, transcription factors that drive multiple myeloma, with unique pharmacokinetic properties. Data from the Phase 1 trial of cemsidomide in combination with dexamethasone demonstrated a differentiated safety and tolerability profile and class-leading anti-myeloma activity with durable responses. Two clinical trials are planned to further evaluate cemsidomide in relapsed/refractory multiple myeloma: the registrational Phase 2 MOMENTUM trial to evaluate cemsidomide in combination with dexamethasone expected to initiate in the first quarter of 2026 and a Phase 1b trial to evaluate cemsidomide in combination with elranatamab expected to initiate the second quarter of 2026. About CFT8919 CFT8919 is an orally bioavailable allosteric degrader that is designed to be potent and selective against EGFR bearing an oncogenic L858R mutation. In preclinical studies, CFT8919 is active in in vitro and in vivo models of L858R driven non-small cell lung cancer. Importantly, CFT8919 retains full activity against additional EGFR mutations that confer resistance against approved EGFR inhibitors including L858R-C797S, L858R-T790M and L858R-T790M-C797S. C4T and Betta Pharmaceuticals have established a strategic partnership to develop CFT8919 in Greater China, where the Phase 1 clinical trial is underway. C4T retains development and commercialization rights for CFT8919 in the United States, European Union and rest of the world. About C4 Therapeutics C4 Therapeutics (C4T) (Nasdaq: CCCC) is a clinical-stage biopharmaceutical company dedicated to delivering on the promise of targeted protein degradation science to create a new generation of medicines that transforms patients’ lives. C4T is progressing targeted oncology programs through clinical studies and leveraging its TORPEDO® platform to efficiently design and optimize small-molecule medicines to address difficult-to-treat diseases. C4T’s degrader medicines are designed to harness the body’s natural protein recycling system to rapidly degrade disease-causing proteins, offering the potential to overcome drug resistance, drug undruggable targets and improve patient outcomes. For more information, please visit www.c4therapeutics.com. Forward-Looking Statements This press release contains “forward-looking statements” of C4 Therapeutics, Inc. within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements may include, but may not be limited to, express or implied statements regarding our ability to develop potential therapies for patients; the design and potential efficacy of our therapeutic approaches; the predictive capability of our TORPEDO® platform in the development of novel, selective, orally bioavailable BiDAC™ and MonoDAC® degraders; the potential timing, design and advancement of our preclinical studies and clinical trials, including the potential timing for and receipt of regulatory advice or authorization related to clinical trials and other clinical development activities including clinical trial commencement or cohort initiation; our ability and the potential to successfully manufacture and supply our product candidates for clinical trials; our ability to replicate results achieved in our preclinical studies or clinical trials in any future studies or trials; our ability to replicate interim or early-stage results from our clinical trials in the results obtained when those clinical trials are completed or when those therapies complete later-stage clinical trials; regulatory developments in the United States and foreign countries; the anticipated timing and content of presentations of data from our clinical trials; and our ability to fund our future operations, including through the potential future exercise of outstanding warrants. Any forward-looking statements in this press release are based on management’s current expectations and beliefs of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in or implied by such forward-looking statements. These risks and uncertainties include, but are not limited to: uncertainties related to the initiation, timing, advancement and conduct of preclinical and clinical studies and other development requirements for our product candidates; the risk that any one or more of our product candidates will cost more to develop or may not be successfully developed and commercialized; and the risk that sufficient capital to fund our future operations will be available to us on acceptable terms or at the times required. For a discussion of these and other risks and uncertainties, and other important factors, any of which could cause our actual results to differ from those contained in the forward-looking statements, see the section entitled “Risk Factors” in C4 Therapeutics’ most recent Annual Report on Form 10-K and/or Quarterly Report on Form 10-Q, as filed with the Securities and Exchange Commission. All information in this press release is as of the date of the release, and C4 Therapeutics undertakes no duty to update this information unless required by law. Contacts: Investors: Courtney Solberg Associate Director, Investor Relations [email protected] Media: Loraine Spreen Senior Director, Corporate Communications & Patient Advocacy [email protected]

Cemsidomide Phase 1 Data in Multiple Myeloma Accepted as an Oral Presentation at the International Myeloma Society (IMS) Annual Meeting; As of the July 23, 2025, Data Cutoff, Phase 1 ORR Remains at 40% at the 75 µg Dose Level and at 50% at the 100 µg Dose Level Productive Type C Meeting Held With FDA; Registrational Development of Cemsidomide in Multiple Myeloma on Track to Initiate in Early 2026 Preclinical Milestone Achieved Under the Collaboration With Merck KGaA, Darmstadt, Germany, Which Is Focused on Two Projects Within the KRAS Family Disciplined Capital Allocation Extends Runway to Mid-2027 WATERTOWN, Mass., Aug. 07, 2025 (GLOBE NEWSWIRE) -- C4 Therapeutics, Inc. (C4T) (Nasdaq: CCCC), a clinical-stage biopharmaceutical company dedicated to advancing targeted protein degradation science, today reported financial results for the second quarter ended June 30, 2025, as well as business updates. “The first half of 2025 was driven by focused execution across our business with the achievement of several research milestones with our collaborators and within our internal preclinical pipeline, the advancement of cemsidomide toward label-enabling trials and continued financial discipline that resulted in extending cash runway. We recently completed enrollment in the ongoing cemsidomide Phase 1 trials in multiple myeloma and non-Hodgkin’s lymphoma and look forward to sharing the full Phase 1 multiple myeloma data in September, which we believe further demonstrate cemsidomide’s best-in-class potential. Our recent Type C meeting with the FDA enabled refinement of our cemsidomide registrational development plans and we remain on track to initiate registrational development in early 2026,” said Andrew Hirsch, president and chief executive officer of C4 Therapeutics. “Additionally, as part of C4T’s commitment to strategic capital allocation and despite cemsidomide’s compelling response rates observed in non-Hodgkin’s lymphoma, we are prioritizing cemsidomide multiple myeloma registrational development as we believe this has the highest potential for patient impact and value creation.” SECOND QUARTER 2025 HIGHLIGHTS AND RECENT ACHIEVEMENTS Cemsidomide: Completed enrollment and dose escalation for the Phase 1 trial of cemsidomide in multiple myeloma (MM) and non-Hodgkin’s Lymphoma (NHL). Cemsidomide continued to demonstrate a well-tolerated profile and compelling response rates in MM and NHL. The highest dose level studied in both indications was 100 µg once daily (QD). Data from the cemsidomide Phase 1 trial in MM was accepted as an oral presentation at the International Myeloma Society (IMS) Annual Meeting taking place from September 17 – September 20, 2025 in Toronto, Canada. The presentation will include data from all safety and efficacy evaluable MM patients from all dose levels studied. C4T had a productive Type C meeting with the U.S. Food and Drug Administration (FDA) that enabled further refinement of the cemsidomide registrational development plan. By year-end 2025, C4T expects to align with the FDA on a recommended Phase 2 dose based on the existing Phase 1 MM data. Additionally, C4T is on track to initiate registrational development in early 2026. The next phase of development will evaluate cemsidomide in combination with dexamethasone in the late-line MM setting and in combination with a B-cell maturation antigen bispecific T-cell engager (BCMA BiTE) for earlier lines of MM treatment. CFT8919: Partner Betta Pharmaceuticals continues to advance the CFT8919 Phase 1 dose escalation trial in Greater China. Research and Discovery Collaborations: C4T advanced its collaboration with Merck KGaA, Darmstadt, Germany (MKDG), which is focused on two projects within the KRAS family, to a milestone on one of these projects. C4T earned $1 million upon achieving this milestone. C4T has identified multiple degraders against two novel targets outside of oncology, which are now advancing into the next phase of discovery. KEY UPCOMING MILESTONES AND DATA PRESENTATIONS Present data from full cemsidomide Phase 1 dose escalation in MM at IMS taking place from September 17 – September 20, 2025. Binod Dhakal, M.D., M.S., associate professor of medicine, Medical College of Wisconsin, Division of Hematology, will present an oral presentation titled “Updated Results of a Phase 1 First-in-Human Study of Cemsidomide (CFT7455), a Novel MonoDAC® Degrader, with Dexamethasone in Patients with Relapsed/Refractory Multiple Myeloma.” Management will host an investor call to discuss cemsidomide data in MM in conjunction with the IMS presentation. Present data from cemsidomide Phase 1 dose escalation in NHL in Q4 2025. Enable initiation of the next phase of cemsidomide clinical development in MM with new studies expected to initiate in early 2026. Present poster analyzing cemsidomide clinical data of population pharmacokinetic and exposure-response relationships in MM and NHL at the 2025 American Conference on Pharmacometrics (ACoP 2025) on October 20, 2025. SECOND QUARTER 2025 FINANCIAL RESULTS Revenue: Total revenue for the second quarter of 2025 was $6.5 million, compared to $12.0 million for the second quarter of 2024. The decrease in revenue was primarily due to an $8.0 million milestone that was earned from Biogen in the second quarter of 2024 partially offset by achievement of a preclinical milestone under our MKDG collaboration and continued progress on our other collaboration programs. Research and Development (R&D) Expense: R&D expense for the second quarter of 2025 was $26.2 million compared to $23.8 million for the second quarter of 2024. The increase in R&D expense was primarily related to clinical trial expenses for cemsidomide, in addition to increased preclinical spend as the company’s research collaborations continue to advance. General and Administrative (G&A) Expense: G&A expense for the second quarter of 2025 was $8.8 million compared to $9.7 million for the second quarter of 2024. The decrease was primarily related to lower stock-based compensation expense. Net Loss and Net Loss per Share: Net loss for the second quarter of 2025 was $26.0 million, compared to $17.7 million for the second quarter of 2024. Net loss per share for the second quarter of 2025 was $0.37 compared to $0.26 for the second quarter of 2024. Cash Position and Financial Guidance: Cash, cash equivalents and marketable securities as of June 30, 2025 were $223.0 million, compared to $234.7 million as of March 31, 2025 and $267.3 million as of December 31, 2024. The decrease during the second quarter was primarily the result of cash used to fund operations and advance our programs, partially offset by cash received for milestones under our Roche and MKDG collaborations. The company expects that its cash, cash equivalents and marketable securities as of June 30, 2025 will enable the company to fund its operating plan to mid-2027. About C4 Therapeutics C4 Therapeutics (C4T) (Nasdaq: CCCC) is a clinical-stage biopharmaceutical company dedicated to delivering on the promise of targeted protein degradation science to create a new generation of medicines that transforms patients’ lives. C4T is progressing targeted oncology programs through clinical studies and leveraging its TORPEDO® platform to efficiently design and optimize small-molecule medicines to address difficult-to-treat diseases. C4T’s degrader medicines are designed to harness the body’s natural protein recycling system to rapidly degrade disease-causing proteins, offering the potential to overcome drug resistance, drug undruggable targets and improve patient outcomes. For more information, please visit www.c4therapeutics.com. About Cemsidomide Cemsidomide is an investigational, orally bioavailable small-molecule degrader designed to be a more potent and selective degrader of IKZF1/3, transcription factors that drive multiple myeloma (MM) and non-Hodgkin’s lymphomas (NHL), with unique pharmacokinetic properties. Clinical data has shown that cemsidomide is well-tolerated. In MM, cemsidomide displays compelling evidence of anti-myeloma activity and immunomodulatory effects. In NHL, cemsidomide displays compelling evidence of anti-lymphoma activity. More information may be accessed at www.clinicaltrials.gov (identifier: NCT04756726). About CFT8919 CFT8919 is an orally bioavailable allosteric degrader that is designed to be potent and selective against EGFR bearing an oncogenic L858R mutation. In preclinical studies, CFT8919 is active in in vitro and in vivo models of L858R driven non-small cell lung cancer. Importantly, CFT8919 retains full activity against additional EGFR mutations that confer resistance against approved EGFR inhibitors including L858R-C797S, L858R-T790M and L858R-T790M-C797S. C4T and Betta Pharmaceuticals have established a strategic partnership to develop CFT8919 in Greater China, where the Phase 1 clinical trial is underway. C4T retains development and commercialization rights for CFT8919 in the United States, European Union and rest of the world. Forward-Looking Statements This press release contains “forward-looking statements” of C4 Therapeutics, Inc. within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements may include, but may not be limited to, express or implied statements regarding our ability to develop potential therapies for patients; the design and potential efficacy of our therapeutic approaches; the predictive capability of our TORPEDO® platform in the development of novel, selective, orally bioavailable BiDAC™ and MonoDAC® degraders; the potential timing, design and advancement of our preclinical studies and clinical trials, including the potential timing for and receipt of regulatory advice or authorization related to clinical trials and other clinical development activities including clinical trial commencement or cohort initiation; our ability and the potential to successfully manufacture and supply our product candidates for clinical trials; our ability to replicate results achieved in our preclinical studies or clinical trials in any future studies or trials; our ability to replicate interim or early-stage results from our clinical trials in the results obtained when those clinical trials are completed or when those therapies complete later-stage clinical trials; regulatory developments in the United States and foreign countries; the anticipated timing and content of presentations of data from our clinical trials; and our ability to fund our future operations. Any forward-looking statements in this press release are based on management’s current expectations and beliefs of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in or implied by such forward-looking statements. These risks and uncertainties include, but are not limited to: uncertainties related to the initiation, timing, advancement and conduct of preclinical and clinical studies and other development requirements for our product candidates; the risk that any one or more of our product candidates will cost more to develop or may not be successfully developed and commercialized; and the risk that sufficient capital to fund our future operations will be available to us on acceptable terms or at the times required. For a discussion of these and other risks and uncertainties, and other important factors, any of which could cause our actual results to differ from those contained in the forward-looking statements, see the section entitled “Risk Factors” in C4 Therapeutics’ most recent Annual Report on Form 10-K and/or Quarterly Report on Form 10-Q, as filed with the Securities and Exchange Commission. All information in this press release is as of the date of the release, and C4 Therapeutics undertakes no duty to update this information unless required by law. Contacts: Investors: Courtney Solberg Associate Director, Investor Relations [email protected] Media: Loraine Spreen Senior Director, Corporate Communications & Patient Advocacy [email protected]

Updated Cemsidomide Multiple Myeloma Data Further Demonstrate Compelling Response Rates at Multiple Doses and Potential for Best-in-Class Profile; 50% ORR Observed at the Highest Dose Level of 100 µg, Including One Patient With a Minimal Residual Disease Negative Complete Response; 40% ORR Achieved at the 75 µg Dose Level Cemsidomide Multiple Myeloma Dose Escalation is Complete; FDA Feedback Expected by Mid-Year 2025 to Support Initiation of Next Phase of Development in Early 2026 Portfolio Decision to Prioritize Cemsidomide Development; C4T to Seek Partnership Opportunities to Advance BRAF Program CFT8919 Phase 1 Trial Continues to Advance in Partnership with Betta Pharmaceuticals; Discovery Platform Achieves Two Preclinical Milestones Under the Roche Collaboration Cash, Cash Equivalents and Marketable Securities of $234.7 Million as of March 31, 2025 Expected to Provide Runway Into 2027 WATERTOWN, Mass., May 07, 2025 (GLOBE NEWSWIRE) -- C4 Therapeutics, Inc. (C4T) (Nasdaq: CCCC), a clinical-stage biopharmaceutical company dedicated to advancing targeted protein degradation science, today reported financial results for the first quarter ended March 31, 2025, as well as business updates. “2025 has been marked by focused execution across C4T to generate key data to optimize development plans across our clinical portfolio. With cemsidomide demonstrating compelling overall response rates at multiple dose levels, including one multiple myeloma patient at 100 µg who achieved a minimal residual disease negative complete response, we are prioritizing progressing cemsidomide to the next phase of development to realize its potential to be a best-in-class IKZF1/3 degrader,” said Andrew Hirsch, president and chief executive officer of C4 Therapeutics. “With the achievement of two preclinical milestones in our Roche collaboration, we continue to demonstrate the productivity of our TORPEDO platform to discover highly catalytic, orally bioavailable, and brain penetrant degraders. We remain focused on maximizing our cash runway, which includes advancing cemsidomide and pursuing our internal discovery pipeline focused on targets with a clear degrader rationale and compelling biology applicable to a broad range of therapeutic areas.” FIRST QUARTER 2025 HIGHLIGHTS AND RECENT ACHIEVEMENTS Cemsidomide: Phase 1 dose escalation is complete in multiple myeloma (MM) with the 100 µg once daily (QD) dose level declared safe for expansion; 10 additional patients will be treated in a 100 µg QD expansion cohort to further characterize cemsidomide’s safety and efficacy profile at this dose level. Cemsidomide MM topline data demonstrate compelling responses rates at multiple doses: As of the data cutoff date of April 30, 2025, 10 patients have been treated at the 100 µg QD dose level, achieving an overall response rate (ORR) of 50 percent. Notably, one patient who previously progressed on two prior T-cell engager therapies achieved a minimal residual disease (MRD) negative complete response (measured by flow cytometry). Eight patients (80 percent) treated at this dose level received prior CAR-T or T-cell engager therapy. Since October 11, 2024, six additional patients have been treated for a total of 20 patients treated at the 75 µg QD dose level. As of the data cutoff date of April 30, 2025, the 75 µg QD dose level achieved an ORR of 40 percent. Cemsidomide remains well-tolerated with manageable neutropenia. For the non-Hodgkin’s lymphoma (NHL) arm, the Phase 1 dose escalation is ongoing at the 87.5 µg QD dose level and the maximum tolerated dose has not yet been reached. C4T expects to receive regulatory feedback on registrational development by mid-year 2025. CFT1946: Phase 1 dose escalation is complete with 640 mg BID declared as the maximum administered dose. Across the trial, which includes the dose escalation, melanoma and colorectal cancer cohorts, 89 patients were treated. The pharmacodynamic and safety data, including the data presented at the European Society for Medical Oncology (ESMO) Congress 2024, supports proof of mechanism and the therapeutic potential of degrading the BRAF V600 mutant protein. Given emerging clinical data and the company’s focus on strategic capital allocation, C4T will not advance CFT1946 beyond the ongoing Phase 1 trial. C4T has made the decision to seek partnership opportunities to advance the BRAF program given the high unmet need and strong degrader rationale for treating BRAF V600 mutant solid tumors. The CFT1946 Phase 1 data will be presented at a future medical meeting. CFT8919: Partner Betta Pharmaceuticals continues to advance the CFT8919 Phase 1 dose escalation trial in Greater China. Research and Discovery Collaborations: Advanced Roche collaboration to preclinical milestones. In March 2025, C4T earned a total of $4 million in payments upon achieving certain preclinical milestones for two programs. C4T and Roche continue to advance these programs. C4T continues to advance its internal research pipeline focused on targets in therapeutic areas in and beyond oncology with a strong degrader rationale and genetic link to disease. KEY UPCOMING MILESTONES Present data from completed cemsidomide Phase 1 dose escalation in MM in Q3 2025. Complete cemsidomide Phase 1 dose escalation in NHL and present data in Q4 2025. Open expansion cohort(s) in PTCL as part of the current cemsidomide Phase 1/2 trial in the second half of 2025. Enable initiation of the next phase of clinical development for cemsidomide with new studies expected to initiate in early 2026. UPCOMING INVESTOR EVENTS June 4, 2025: Management will participate in the Jefferies Global Healthcare Conference taking place from June 3 – June 5, 2025 in New York, New York. FIRST QUARTER 2025 FINANCIAL RESULTS Revenue: Total revenue for the first quarter of 2025 was $7.2 million, compared to $3.0 million for the first quarter of 2024. The increase in revenue was primarily due to our collaborations with Merck KGaA, Darmstadt, Germany (MKDG), which commenced in March 2024, as well as our achievement of two preclinical milestones under our Roche collaboration. Research and Development (R&D) Expense: R&D expense for the first quarter of 2025 was $27.1 million compared to $22.5 million for the first quarter of 2024. The increase in R&D expense was primarily related to clinical trial expenses for cemsidomide and CFT1946, in addition to increased preclinical spend as our research collaborations continue to advance. General and Administrative (G&A) Expense: G&A expense for the first quarter of 2025 was $9.3 million compared to $10.3 million for the first quarter of 2024. The decrease was primarily a result of reduced personnel costs related to our 2024 restructuring activities. Net Loss and Net Loss per Share: Net loss for the first quarter of 2025 was $26.3 million, compared to $28.4 million for the first quarter of 2024. Net loss per share for the first quarter of 2025 was $0.37 compared to $0.41 for the first quarter of 2024. Cash Position and Financial Guidance: Cash, cash equivalents and marketable securities as of March 31, 2025 were $234.7 million, compared to $267.3 million as of December 31, 2024. The decrease was primarily the result of cash used in operating activities. The balance as of March 31, 2025 is exclusive of the $4.0 million in milestones earned under our Roche collaboration, which the company expects to receive in the second quarter of 2025. The company expects that its cash, cash equivalents and marketable securities as of March 31, 2025 will enable the company to fund its operating plan into 2027. About C4 TherapeuticsC4 Therapeutics (C4T) (Nasdaq: CCCC) is a clinical-stage biopharmaceutical company dedicated to delivering on the promise of targeted protein degradation science to create a new generation of medicines that transforms patients’ lives. C4T is progressing targeted oncology programs through clinical studies and leveraging its TORPEDO® platform to efficiently design and optimize small-molecule medicines to address difficult-to-treat diseases. C4T’s degrader medicines are designed to harness the body’s natural protein recycling system to rapidly degrade disease-causing proteins, offering the potential to overcome drug resistance, drug undruggable targets and improve patient outcomes. For more information, please visit www.c4therapeutics.com. About CemsidomideCemsidomide is an investigational, orally bioavailable small-molecule degrader designed to be a more potent and selective degrader of IKZF1/3, transcription factors that drive multiple myeloma (MM) and non-Hodgkin’s lymphomas (NHL), with unique pharmacokinetic properties. Clinical data has shown that cemsidomide is well-tolerated. In MM, cemsidomide displays evidence of anti-myeloma activity and immunomodulatory effects. In NHL, cemsidomide displays evidence of anti-lymphoma activity. More information may be accessed at www.clinicaltrials.gov (identifier: NCT04756726). About CFT1946C4T has advanced preclinical and clinical research to explore how targeted protein degradation may offer improvement over approved therapies that inhibit mutant BRAF V600. C4T advanced CFT1946, an investigational, orally bioavailable brain penetrant small molecule degrader of BRAF V600 mutations in solid tumors into a Phase 1/2 global clinical trial in patients refractory to BRAF inhibitors. CFT1946 is designed to be potent and selective against the BRAF V600 mutant form. In May 2025, C4T announced the decision to not advance its BRAF program beyond the current Phase 1 trial of CFT1946 and seek partnership opportunities to maximize its potential given the high unmet need and strong degrader rationale for treating BRAF V600 mutant solid tumors. About CFT8919CFT8919 is an orally bioavailable allosteric degrader that is designed to be potent and selective against EGFR bearing an oncogenic L858R mutation. In preclinical studies, CFT8919 is active in in vitro and in vivo models of L858R driven non-small cell lung cancer. Importantly, CFT8919 retains full activity against additional EGFR mutations that confer resistance against approved EGFR inhibitors including L858R-C797S, L858R-T790M and L858R-T790M-C797S. C4T and Betta Pharmaceuticals have established a strategic partnership to develop CFT8919 in Greater China, where the Phase 1 clinical trial is underway. C4T retains development and commercialization rights for CFT8919 in the United States, European Union and rest of the world. Forward-Looking StatementsThis press release contains “forward-looking statements” of C4 Therapeutics, Inc. within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements may include, but may not be limited to, express or implied statements regarding our ability to develop potential therapies for patients; the design and potential efficacy of our therapeutic approaches; the predictive capability of our TORPEDO® platform in the development of novel, selective, orally bioavailable BiDAC™ and MonoDAC® degraders; the potential timing, design and advancement of our preclinical studies and clinical trials, including the potential timing for and receipt of regulatory advice or authorization related to clinical trials and other clinical development activities including clinical trial commencement or cohort initiation; our ability and the potential to successfully manufacture and supply our product candidates for clinical trials; our ability to replicate results achieved in our preclinical studies or clinical trials in any future studies or trials; our ability to replicate interim or early-stage results from our clinical trials in the results obtained when those clinical trials are completed or when those therapies complete later-stage clinical trials; regulatory developments in the United States and foreign countries; the anticipated timing and content of presentations of data from our clinical trials; and our ability to fund our future operations. Any forward-looking statements in this press release are based on management’s current expectations and beliefs of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in or implied by such forward-looking statements. These risks and uncertainties include, but are not limited to: uncertainties related to the initiation, timing, advancement and conduct of preclinical and clinical studies and other development requirements for our product candidates; the risk that any one or more of our product candidates will cost more to develop or may not be successfully developed and commercialized; and the risk that sufficient capital to fund our future operations will be available to us on acceptable terms or at the times required. For a discussion of these and other risks and uncertainties, and other important factors, any of which could cause our actual results to differ from those contained in the forward-looking statements, see the section entitled “Risk Factors” in C4 Therapeutics’ most recent Annual Report on Form 10-K and/or Quarterly Report on Form 10-Q, as filed with the Securities and Exchange Commission. All information in this press release is as of the date of the release, and C4 Therapeutics undertakes no duty to update this information unless required by law. Contacts:Investors:Courtney SolbergAssociate Director, Investor [email protected] Media:Loraine SpreenSenior Director, Corporate Communications & Patient [email protected]