PASG

Enrolled first three FTD-GRN patients in Cohort 3 of ongoing upliFT-D study Treated first FTD-C9orf72 patient with Dose 2 PBFT02 in Cohort 4 of upliFT-D study On track to report updated interim safety and biomarker data from upliFT-D and obtain regulatory feedback on FTD-GRN registrational trial design in 1H 2026 Advancing differentiated preclinical program for Huntington’s with clinical candidate selection expected in 2H 2026 Cash runway through 1Q 2027 PHILADELPHIA, March 03, 2026 (GLOBE NEWSWIRE) -- Passage Bio, Inc. (Nasdaq: PASG), a clinical stage genetic medicines company focused on improving the lives of patients with neurodegenerative diseases, today reported financial results for the fourth quarter and year ended December 31, 2025, and provided recent business highlights. “We are proud of the progress made in 2025 as we meaningfully advanced our PBFT02 clinical program for the treatment of genetic forms of frontotemporal dementia,” said Will Chou, M.D., president and chief executive officer of Passage Bio. “As we enter 2026, we are excited by the strong enrollment momentum in our upliFT-D clinical study and look forward to sharing important data and regulatory updates in the first half of the year. FTD is a devastating disease, and the clinical unmet need remains substantial. We remain committed to advancing our program in the hope that we might one day offer patients and their families a therapy to redefine the course of their disease.” Recent Highlights Enrolled first three FTD-GRN patients in Cohort 3 of ongoing upliFT-D study: The first three patients in Cohort 3 of the upliFT-D trial have been enrolled and patient dosings are anticipated over the coming weeks. Cohort 3 will evaluate Dose 2 PBFT02 and is expected to consist of a total of 10 patients, with patient enrollment occurring in parallel across current active trial sites in Australia, Brazil, Canada, Portugal, and the United States. The cohort will be enrolled under the recently amended protocol, which focuses on patients earlier in their disease progression and includes a short course of low-dose prophylactic anticoagulation. The company plans to report updated interim safety and biomarker data from upliFT-D and obtain regulatory feedback on registrational trial design for FTD-GRN in the first half of 2026. Treated first FTD-C9orf72 patient with Dose 2 PBFT02 in Cohort 4 of upliFT-D study: Cohort 4 is expected to consist of up to a total of five patients, and multiple prospective study participants have been identified and are being evaluated for trial eligibility. Initial safety data from the first Cohort 4 patient will be reviewed by the Independent Data Monitoring Committee, IDMC, given this is the first administration of PBFT02 to this patient population. Upon completion of the IDMC review, we expect to enroll subsequent Cohort 4 patients in parallel. Advancing differentiated preclinical program for Huntington’s disease: Huntington’s disease, HD, is an autosomal dominant, progressive neurodegenerative disease caused by a mutation in the huntingtin gene, HTT, in which a CAG trinucleotide repeat tract in the DNA is expanded. Elongation of these CAG repeat tracts over time, termed somatic instability, above a certain threshold leads to neurodegeneration. MSH3, a DNA repair protein, has been shown to play a key role in driving somatic instability in HD by erroneously incorporating extra CAG repeats into the HTT gene. The company’s approach aims to slow neurodegeneration in HD by delivering an AAV containing a miRNA gene to suppress expression of MSH3 and decrease somatic instability in the HTT gene. The company expects to declare a clinical candidate for this program in the second half of 2026. Huntington’s disease is estimated to affect approximately 70,000 individuals across the United States and Europe with no disease-modifying therapies currently approved. Anticipated Upcoming Milestones: Report updated interim safety and biomarker data from Dose 2 in 1H 2026 Seek regulatory feedback on registrational trial design in FTD-GRN in 1H 2026 Declare clinical candidate for Huntington’s disease in 2H 2026 Fourth Quarter and Full-Year 2025 Results Cash Position: Cash and cash equivalents were $46.3 million as of December 31, 2025, as compared to cash, cash equivalents, and marketable securities of $76.8 million as of December 31, 2024. The company expects current cash and cash equivalents to fund operations through 1Q 2027. Research and Development (R&D) Expenses: R&D expenses were $5.4 million for the quarter ended December 31, 2025, and $23.3 million for the year ended December 31, 2025, compared to $9.6 million and $40.2 million for the same quarter and year ended in 2024, respectively. General and Administrative (G&A) Expenses: G&A expenses were $4.9 million for the quarter ended December 31, 2025, and $19.9 million for the year ended December 31, 2025, compared to $4.7 million and $25.0 million for the same quarter and year ended in 2024, respectively. Net Loss: Net loss was $13.0 million, or $4.09 per basic and diluted share, for the quarter ended December 31, 2025 and $45.5 million, or $14.35 per basic and diluted share, for the year ended December 31, 2025, compared to a net loss of $12.7 million, or $4.00 per basic and diluted share, for the quarter ended December 31, 2024 and $64.8 million, or $21.04 per basic and diluted share, for the year ended December 31, 2024. About upliFT-D (NCT04747431) upliFT-D is a Phase 1/2 global, multi-center, open-label clinical trial of PBFT02 administered by single injection into the cisterna magna in patients aged 35 to 75 years with FTD-GRN or FTD-C9orf72. The clinical trial will sequentially enroll three FTD-GRN cohorts and two FTD-C9orf72 cohorts. Enrollment is currently ongoing. The primary endpoint of the clinical trial is to evaluate the safety and tolerability of PBFT02. Secondary endpoints include disease biomarkers and clinical outcome measures. upliFT-D is a two-year clinical trial with a three-year safety extension. Passage Bio is pursuing several initiatives to support clinical trial recruitment and enrollment, including a collaborative partnership with InformedDNA to provide no-cost genetic counseling and testing for adults who have been diagnosed by their physicians with FTD. More information about upliFT-D can be found here. About Passage Bio Passage Bio (Nasdaq: PASG) is a clinical stage genetic medicines company on a mission to improve the lives of patients with neurodegenerative diseases. Our primary focus is the development and advancement of cutting-edge, one-time therapies designed to target the underlying pathology of these conditions. Passage Bio’s lead product candidate, PBFT02, seeks to treat neurodegenerative conditions, including frontotemporal dementia, by elevating progranulin levels to restore lysosomal function and slow disease progression. To learn more about Passage Bio and our steadfast commitment to protecting patients and families against loss in neurodegenerative conditions, please visit: passagebio.com. Forward-Looking Statements This press release contains “forward-looking statements” within the meaning of, and made pursuant to the safe harbor provisions of, the Private Securities Litigation Reform Act of 1995, including, but not limited to: our expectations about timing and execution of anticipated milestones, including the progress of clinical studies and the availability of clinical data from such trials; enrollment timing; timing of feedback from regulatory authorities; our expectations about our collaborators’ and partners’ ability to execute key initiatives; our expectations about cash runway; the ability of our product candidates to treat their respective target CNS disorders; and the potential development of other product candidates. These forward-looking statements may be accompanied by such words as “aim,” “anticipate,” “believe,” “continue,” “could,” “should,” “target,” “estimate,” “expect,” “forecast,” “goal,” “intend,” “may,” “might,” “plan,” “potential,” “possible,” “will,” “would,” and other words and terms of similar meaning. These statements involve risks and uncertainties that could cause actual results to differ materially from those reflected in such statements, including: our ability to develop and obtain regulatory approval for our product candidates; the timing and results of preclinical studies and clinical trials; risks associated with clinical trials, including our ability to adequately manage clinical activities, unexpected concerns that may arise from additional data or analysis obtained during clinical trials, regulatory authorities may require additional information or further studies, or may fail to approve or may delay approval of our drug candidates; the occurrence of adverse safety events; the risk that positive results in a preclinical study or clinical trial may not be replicated in subsequent trials or success in early stage clinical trials may not be predictive of results in later stage clinical trials; failure to protect and enforce our intellectual property, and other proprietary rights; our dependence on collaborators and other third parties for the development and manufacture of product candidates and other aspects of our business, which are outside of our full control; risks associated with current and potential delays, work stoppages, or supply chain disruptions; and the other risks and uncertainties that are described in the Risk Factors section in documents the company files from time to time with the Securities and Exchange Commission (SEC), and other reports as filed with the SEC. Passage Bio undertakes no obligation to publicly update any forward-looking statement, whether written or oral, that may be made from time to time, whether as a result of new information, future developments or otherwise. For further information, please contact: Investors: Stuart Henderson Passage Bio [email protected] Media: Mike Beyer Sam Brown Inc. Healthcare Communications 312.961.2502 [email protected]

Actively enrolling Cohort 3 (FTD-GRN) and Cohort 4 (FTD-C9orf72) patients in ongoing upliFT-D study Aligned with the U.S. Food and Drug Administration (FDA) on an analytical approach to establish comparability of a high-productivity, suspension-based PBFT02 manufacturing process On track to obtain regulatory feedback on FTD-GRN registrational trial design in 1H 2026 Cash runway into 1Q 2027 PHILADELPHIA, Nov. 10, 2025 (GLOBE NEWSWIRE) -- Passage Bio, Inc. (Nasdaq: PASG), a clinical stage genetic medicines company focused on improving the lives of patients with neurodegenerative diseases, today reported financial results for the third quarter ended September 30, 2025, and provided recent business highlights. “We are pleased to report that we have opened enrollment in our third FTD-GRN and first FTD-C9orf72 patient cohorts in our ongoing upliFT-D clinical trial of PBFT02. We recognize the urgent need for the development of disease-modifying therapies for the FTD patient community, and we remain focused on advancing our study expeditiously,” said Will Chou, M.D., president and chief executive officer of Passage Bio. “In addition, we completed a successful meeting with the FDA where we aligned on key elements of an analytical comparability plan to support the future use of our high-productivity, suspension-based manufacturing process for PBFT02 in a registrational study. As we look towards the first half of 2026, we are excited to share additional data to further inform our understanding of the potential of PBFT02 and initiate discussions with the FDA on a registrational study design in FTD-GRN.” Recent Highlights Actively enrolling Cohort 3 (FTD-GRN) and Cohort 4 (FTD-C9orf72) patients in upliFT-D study: Cohort 3 is expected to consist of five to 10 FTD-GRN patients, with patient enrollment occurring in parallel; Cohort 4 is expected to consist of three to five FTD-C9orf72 patients. Both cohorts will evaluate Dose 2 PBFT02. The company recently amended the upliFT-D trial protocol to introduce a short course of low-dose prophylactic anticoagulation and revise study inclusion criteria to allow for enrollment of patients who are prodromal or have mild cognitive impairment and to exclude patients who are more severely progressed. The amended protocol was submitted to all global trial sites and relevant health authorities and has been implemented at initial trial sites. The company plans to report updated interim safety and biomarker data from Dose 2 in the first half of 2026. Aligned with the FDA on an analytical approach to establish comparability of a high-productivity, suspension-based PBFT02 manufacturing process: The company completed a Type D Chemistry, Manufacturing, and Controls (CMC) meeting with FDA, during which the company aligned with FDA on key elements of the analytical plan to establish process comparability of its suspension-based process. The GMP-ready, suspension-based PBFT02 manufacturing process has been executed at 200-liter scale and substantially improved productivity, capsid purity, and percentage of full capsids compared to the current adherent-based manufacturing process. A single batch of the suspension-based process is estimated to yield more than 1,000 doses of PBFT02 at Dose 2 with over 90% purity and over 70% full capsids. On track to obtain regulatory feedback on an FTD-GRN registrational trial design in 1H 2026: The company intends to engage with the FDA in the first half of 2026 to gain feedback on key elements of a registrational study design of PBFT02 for FTD-GRN, including the FDA’s perspective on the possibility of a single-arm registrational design with a comparison to a natural history control. Anticipated Upcoming Milestones: Report updated interim safety and biomarker data from Dose 2 in 1H 2026 Seek regulatory feedback on registrational trial design in FTD-GRN in 1H 2026 Third Quarter 2025 Financial Results Cash Position: Cash, cash equivalents and marketable securities were $52.8 million as of September 30, 2025, as compared to $84.8 million as of September 30, 2024. The company expects current cash, cash equivalents and marketable securities to fund operations into 1Q 2027. Research and Development (R&D) Expenses: R&D expenses were $4.3 million for the quarter ended September 30, 2025, as compared to $8.7 million for the quarter ended September 30, 2024. General and Administrative (G&A) Expenses: G&A expenses were $4.3 million for the quarter ended September 30, 2025, as compared to $7.3 million for the quarter ended September 30, 2024. Net Loss: Net loss was $7.7 million, or $2.44 per basic and diluted share (as adjusted for the 1-for-20 reverse stock split effected on July 14, 2025), for the quarter ended September 30, 2025, as compared to a net loss of $19.3 million, or $6.15 per basic and diluted share (as adjusted for the 1-for-20 reverse stock split effected on July 14, 2025), for the quarter ended September 30, 2024. About upliFT-D (NCT04747431) upliFT-D is a Phase 1/2 global, multi-center, open-label clinical trial of PBFT02 administered by single injection into the cisterna magna in patients aged 35 to 75 years with FTD-GRN or FTD-C9orf72. The clinical trial will sequentially enroll three FTD-GRN cohorts and two FTD-C9orf72 cohorts. Enrollment is currently ongoing. The primary endpoint of the clinical trial is to evaluate the safety and tolerability of PBFT02. Secondary endpoints include disease biomarkers and clinical outcome measures. upliFT-D is a two-year clinical trial with a three-year safety extension. Passage Bio is pursuing several initiatives to support clinical trial recruitment and enrollment, including a collaborative partnership with InformedDNA to provide no-cost genetic counseling and testing for adults who have been diagnosed by their physicians with FTD. More information about upliFT-D can be found here. About Passage Bio Passage Bio (Nasdaq: PASG) is a clinical stage genetic medicines company on a mission to improve the lives of patients with neurodegenerative diseases. Our primary focus is the development and advancement of cutting-edge, one-time therapies designed to target the underlying pathology of these conditions. Passage Bio’s lead product candidate, PBFT02, seeks to treat neurodegenerative conditions, including frontotemporal dementia, by elevating progranulin levels to restore lysosomal function and slow disease progression. To learn more about Passage Bio and our steadfast commitment to protecting patients and families against loss in neurodegenerative conditions, please visit: passagebio.com. Forward-Looking Statements This press release contains “forward-looking statements” within the meaning of, and made pursuant to the safe harbor provisions of, the Private Securities Litigation Reform Act of 1995, including, but not limited to: our expectations about timing and execution of anticipated milestones, including the progress of clinical studies and the availability of clinical data from such trials; the initiation of dosing of FTD-C9orf72 patients; timing of feedback from regulatory authorities; our expectations about our collaborators’ and partners’ ability to execute key initiatives; our expectations about cash runway; and the ability of our product candidates to treat their respective target CNS disorders. These forward-looking statements may be accompanied by such words as “aim,” “anticipate,” “believe,” “continue,” “could,” “should,” “target,” “estimate,” “expect,” “forecast,” “goal,” “intend,” “may,” “might,” “plan,” “potential,” “possible,” “will,” “would,” and other words and terms of similar meaning. These statements involve risks and uncertainties that could cause actual results to differ materially from those reflected in such statements, including: our ability to develop and obtain regulatory approval for our product candidates; the timing and results of preclinical studies and clinical trials; risks associated with clinical trials, including our ability to adequately manage clinical activities, unexpected concerns that may arise from additional data or analysis obtained during clinical trials, regulatory authorities may require additional information or further studies, or may fail to approve or may delay approval of our drug candidates; the occurrence of adverse safety events; the risk that positive results in a preclinical study or clinical trial may not be replicated in subsequent trials or success in early stage clinical trials may not be predictive of results in later stage clinical trials; failure to protect and enforce our intellectual property, and other proprietary rights; our dependence on collaborators and other third parties for the development and manufacture of product candidates and other aspects of our business, which are outside of our full control; risks associated with current and potential delays, work stoppages, or supply chain disruptions; and the other risks and uncertainties that are described in the Risk Factors section in documents the company files from time to time with the Securities and Exchange Commission (SEC), and other reports as filed with the SEC. Passage Bio undertakes no obligation to publicly update any forward-looking statement, whether written or oral, that may be made from time to time, whether as a result of new information, future developments or otherwise. For further information, please contact: Investors: Stuart Henderson Passage Bio [email protected] Media: Mike Beyer Sam Brown Inc. Healthcare Communications 312.961.2502 [email protected]

Completed dosing of FTD-GRN Cohort 2 in upliFT-D study Reported updated interim data showing that PBFT02 continued to demonstrate robust, durable elevation in CSF PGRN levels and improvement in plasma NfL, a disease progression biomarker, compared to natural history Submitted amended upliFT-D study protocol to global trial sites and health authorities Cash runway into 1Q 2027 PHILADELPHIA, Aug. 12, 2025 (GLOBE NEWSWIRE) -- Passage Bio, Inc. (Nasdaq: PASG), a clinical stage genetic medicines company focused on improving the lives of patients with neurodegenerative diseases, today reported financial results for the second quarter ended June 30, 2025, and provided recent business highlights. “We continue to be encouraged by the emerging data from our upliFT-D clinical trial, which underscore the potential of PBFT02 to offer differentiated therapy for the FTD-GRN patient community. As we remain focused on execution, we are pleased to have completed dosing of Cohort 2 and submitted the amended protocol to global trial sites and health authorities as planned,” said Will Chou, M.D., president and chief executive officer of Passage Bio. “We look forward to initiating enrollment of our third FTD-GRN and first FTD-C9orf72 patient cohorts once the protocol amendment is approved at trial sites and remain on track to engage with health authorities in the first half of 2026 to seek guidance on the registrational pathway for the program in FTD-GRN.” Recent Highlights Completed dosing of FTD-GRN Cohort 2 in upliFT-D study: Patient 9 was treated with Dose 2 PBFT02 in July, thereby completing dosing of Cohort 2. Cohort 2 consists of a total of four FTD-GRN patients split equally between Dose 1 and Dose 2 PBFT02. Reported updated interim data showing that PBFT02 demonstrated robust, durable elevation in cerebrospinal fluid (CSF) progranulin (PGRN) levels and improvement in a disease progression biomarker: Dose 1 PBFT02 treatment resulted in a robust and durable increase in CSF PGRN expression through 18 months post-treatment, increasing expression in all patients. CSF PGRN levels for the first patient treated with Dose 2 PBFT02 (50% of Dose 1) increased substantially at one-month post-treatment, approaching the upper limit of a healthy adult reference range. In addition, patients who received Dose 1 PBFT02 experienced a reduced annual rate of change in plasma neurofilament light chain (NfL) levels compared to rates observed in natural history studies. These data were also shared in a poster presentation at the Alzheimer’s Association International Conference in July in Toronto, Canada. Submitted amended upliFT-D study protocol to global trial sites and health authorities: The company amended the upliFT-D clinical trial protocol to introduce a short course of low dose prophylactic anticoagulation and to revise study inclusion criteria to allow for enrollment of patients who are prodromal or have mild cognitive impairment and to exclude patients who are more severely progressed. The amended protocol has been submitted to all active global trial sites and associated health authorities. Following review and acceptance of the amended protocol at trial sites, the company plans to begin enrollment of Cohort 3 (FTD-GRN) and Cohort 4 (FTD-C9orf72), which will continue to evaluate Dose 2 PBFT02. Anticipated Upcoming Milestones: Seek regulatory feedback on suspension-based manufacturing process comparability in 2H 2025 Report updated interim safety and biomarker data from Dose 2 in 1H 2026 Seek regulatory feedback on registrational trial design in FTD-GRN in 1H 2026 Second Quarter 2025 Financial Results Cash Position: Cash, cash equivalents and marketable securities were $57.6 million as of June 30, 2025, as compared to $91.8 million as of June 30, 2024. The company expects current cash, cash equivalents and marketable securities to fund operations into 1Q 2027. Research and Development (R&D) Expenses: R&D expenses were $5.8 million for the quarter ended June 30, 2025, as compared to $10.4 million for the quarter ended June 30, 2024. General and Administrative (G&A) Expenses: G&A expenses were $4.5 million for the quarter ended June 30, 2025, as compared to $6.5 million for the quarter ended June 30, 2024. Net Loss: Net loss was $9.4 million, or $2.96 per basic and diluted share (as adjusted for the 1-for-20 reverse stock split effected on July 14, 2025), for the quarter ended June 30, 2025, as compared to a net loss of $16.0 million, or $5.09 per basic and diluted share (as adjusted for the 1-for-20 reverse stock split effected on July 14, 2025), for the quarter ended June 30, 2024. About upliFT-D (NCT04747431) upliFT-D is a Phase 1/2 global, multi-center, open-label clinical trial of PBFT02 administered by single injection into the cisterna magna in patients aged 35 to 75 years with FTD-GRN or FTD-C9orf72. The clinical trial will sequentially enroll three FTD-GRN cohorts and two FTD-C9orf72 cohorts. Enrollment is currently ongoing. The primary endpoint of the clinical trial is to evaluate the safety and tolerability of PBFT02. Secondary endpoints include disease biomarkers and clinical outcome measures. upliFT-D is a two-year clinical trial with a three-year safety extension. Passage Bio is pursuing several initiatives to support clinical trial recruitment and enrollment, including a collaborative partnership with InformedDNA to provide no-cost genetic counseling and testing for adults who have been diagnosed by their physicians with FTD. More information about upliFT-D can be found here. About PBFT02 PBFT02 is a gene replacement therapy that utilizes an AAV1 viral vector to deliver, through ICM administration, a functional GRN gene that encodes PGRN. This vector construct and delivery approach aim to elevate PGRN levels in the central nervous system to alter the course of neurodegenerative diseases. Interim clinical data from the upliFT-D Phase 1/2 study in FTD-GRN participants shows that ICM administration of PBFT02 resulted in robust PGRN elevations in the CSF. The potential clinical benefit of PBFT02 is supported by extensive preclinical studies. In non-human primates, a single ICM administration of PBFT02 led to broad vector distribution throughout the CNS, and robust, dose-dependent elevations in PGRN levels in CSF. An NHP study also demonstrated that AAV1 was particularly proficient at transducing ependymal cells. In a murine FTD model, PBFT02 administration improved lysosomal function and reduced neuroinflammation. About Passage Bio Passage Bio (Nasdaq: PASG) is a clinical stage genetic medicines company on a mission to improve the lives of patients with neurodegenerative diseases. Our primary focus is the development and advancement of cutting-edge, one-time therapies designed to target the underlying pathology of these conditions. Passage Bio’s lead product candidate, PBFT02, seeks to treat neurodegenerative conditions, including frontotemporal dementia, by elevating progranulin levels to restore lysosomal function and slow disease progression. To learn more about Passage Bio and our steadfast commitment to protecting patients and families against loss in neurodegenerative conditions, please visit: passagebio.com. Forward-Looking Statements This press release contains “forward-looking statements” within the meaning of, and made pursuant to the safe harbor provisions of, the Private Securities Litigation Reform Act of 1995, including, but not limited to: our expectations about timing and execution of anticipated milestones, including the progress of clinical studies and the availability of clinical data from such trials; the initiation of dosing of FTD-C9orf72 patients; timing of feedback from regulatory authorities; our expectations about our collaborators’ and partners’ ability to execute key initiatives; our expectations about cash runway; and the ability of our product candidates to treat their respective target CNS disorders. These forward-looking statements may be accompanied by such words as “aim,” “anticipate,” “believe,” “could,” “estimate,” “expect,” “forecast,” “goal,” “intend,” “may,” “might,” “plan,” “potential,” “possible,” “will,” “would,” and other words and terms of similar meaning. These statements involve risks and uncertainties that could cause actual results to differ materially from those reflected in such statements, including: our ability to develop and obtain regulatory approval for our product candidates; the timing and results of preclinical studies and clinical trials; risks associated with clinical trials, including our ability to adequately manage clinical activities, unexpected concerns that may arise from additional data or analysis obtained during clinical trials, regulatory authorities may require additional information or further studies, or may fail to approve or may delay approval of our drug candidates; the occurrence of adverse safety events; the risk that positive results in a preclinical study or clinical trial may not be replicated in subsequent trials or success in early stage clinical trials may not be predictive of results in later stage clinical trials; failure to protect and enforce our intellectual property, and other proprietary rights; our dependence on collaborators and other third parties for the development and manufacture of product candidates and other aspects of our business, which are outside of our full control; risks associated with current and potential delays, work stoppages, or supply chain disruptions; and the other risks and uncertainties that are described in the Risk Factors section in documents the company files from time to time with the Securities and Exchange Commission (SEC), and other reports as filed with the SEC. Passage Bio undertakes no obligation to publicly update any forward-looking statement, whether written or oral, that may be made from time to time, whether as a result of new information, future developments or otherwise. (1) Common stock and Additional paid-in-capital balances have been adjusted to reflect the 1-for-20 reverse stock split effected on July 14, 2025. (1) All share and per share information has been adjusted to reflect the 1-for-20 reverse stock split effected on July 14, 2025. For further information, please contact: Investors: Stuart Henderson Passage Bio [email protected] Media: Mike Beyer Sam Brown Inc. Healthcare Communications 312.961.2502 [email protected]

Treated first FTD-GRN patient with Dose 2 PBFT02 and enrolled second patient; several additional patients being evaluated for trial eligibility Announced presentation of process development data of a high productivity, suspension-based manufacturing process for PBFT02 at American Society of Gene and Cell Therapy (ASGCT) 28th Annual Meeting Cash runway into 1Q 2027 PHILADELPHIA, May 13, 2025 (GLOBE NEWSWIRE) -- Passage Bio, Inc. (Nasdaq: PASG), a clinical stage genetic medicines company focused on improving the lives of patients with neurodegenerative diseases, today reported financial results for the first quarter ended March 31, 2025, and provided recent business highlights. “We made steady progress in executing against our core operational objectives this quarter as we focus on the enrollment of FTD-GRN and FTD-C9orf72 patients in our ongoing global Phase 1/2 upliFT-D trial of PBFT02,” said Will Chou, M.D., president and chief executive officer of Passage Bio. “As we turn towards the second half of the year, we look forward to delivering additional data from upliFT-D to add to our understanding of PBFT02’s safety profile, durability of progranulin expression, dose-response, and impact on plasma neurofilament levels, a disease progression biomarker that is well characterized in FTD natural history literature. We expect these data to foster meaningful engagement with health authorities in the first half of 2026 as we seek guidance on the registrational pathway for the program in FTD-GRN.” Recent Highlights Treated first FTD-GRN patient with Dose 2 PBFT02 and enrolled second patient. with several additional patients being evaluated for trial eligibility: Dose 2, which is fifty percent lower than Dose 1, was introduced given the robust CSF progranulin (PGRN) expression achieved at Dose 1 and to aid future discussions with healthy authorities regarding a registrational study design. A total of three patients in Cohort 2 will receive Dose 2. Following completion of Cohort 2, the Independent Data Monitoring Committee will review available safety data prior to the commencement of Cohort 3 (n=3-5). The company plans to report interim safety and biomarker data from Dose 2 and 12-month data from Dose 1 patients in the second half of 2025. Opened enrollment for FTD-C9orf72 patients in upliFT-D study: The company is currently enrolling up to five symptomatic FTD-C9orf72 patients to receive Dose 2 PBFT02 following amendment of the upliFT-D trial protocol to include this patient population. Preclinical studies have demonstrated that overexpression of PGRN can slow neurodegeneration and reduce TDP-43 pathology, which underlies this disease. Announced presentation of process development data of a high productivity, suspension-based manufacturing process for PBFT02 at ASGCT: The internally developed suspension-based, GMP-ready manufacturing process for PBFT02 at 200-liter scale substantially improved productivity, capsid purity and the percentage of full capsids compared to the current adherent-based manufacturing process. A single batch of the suspension process is estimated to yield more than 1,000 doses at Dose 2 with over 90% purity and over 70% full capsids. Additional details will be shared during a poster session from 6:00 – 7:30 p.m. CT today at the ASGCT 28th Annual Meeting, being held in New Orleans, LA and virtually. The company plans to engage with health authorities later this year to obtain feedback on comparability of the suspension process to the original process. Anticipated Upcoming Milestones: FTD-GRN Report 12-month data from Dose 1 and interim safety and biomarker data from Dose 2 in 2H 2025 Seek regulatory feedback on registrational trial design in 1H 2026 FTD-C9orf72 Initiate dosing of FTD-C9orf72 patients in 1H 2025 First Quarter 2025 Financial Results Cash Position: Cash, cash equivalents and marketable securities were $63.4 million as of March 31, 2025, as compared to $104.5 million as of March 31, 2024. The company expects current cash, cash equivalents and marketable securities to fund operations into 1Q 2027. Research and Development (R&D) Expenses: R&D expenses were $7.7 million for the quarter ended March 31, 2025, as compared to $11.5 million for the quarter ended March 31, 2024. General and Administrative (G&A) Expenses: G&A expenses were $6.1 million for the quarter ended March 31, 2025, as compared to $6.5 million for the quarter ended March 31, 2024. Net Loss: Net loss was $15.4 million, or $0.25 per basic and diluted share, for the quarter ended March 31, 2025, as compared to a net loss of $16.7 million, or $0.30 per basic and diluted share, for the quarter ended March 31, 2024. About Passage Bio Passage Bio (Nasdaq: PASG) is a clinical stage genetic medicines company on a mission to improve the lives of patients with neurodegenerative diseases. Our primary focus is the development and advancement of cutting-edge, one-time therapies designed to target the underlying pathology of these conditions. Passage Bio’s lead product candidate, PBFT02, seeks to treat neurodegenerative conditions, including frontotemporal dementia, by elevating progranulin levels to restore lysosomal function and slow disease progression. To learn more about Passage Bio and our steadfast commitment to protecting patients and families against loss in neurodegenerative conditions, please visit: passagebio.com. Forward-Looking Statements This press release contains “forward-looking statements” within the meaning of, and made pursuant to the safe harbor provisions of, the Private Securities Litigation Reform Act of 1995, including, but not limited to: our expectations about timing and execution of anticipated milestones, including the progress of clinical studies and the availability of clinical data from such trials; the initiation of dosing of FTD-C9orf72 patients; timing of feedback from regulatory authorities; our expectations about our collaborators’ and partners’ ability to execute key initiatives; our expectations about cash runway; and the ability of our product candidates to treat their respective target CNS disorders. These forward-looking statements may be accompanied by such words as “aim,” “anticipate,” “believe,” “could,” “estimate,” “expect,” “forecast,” “goal,” “intend,” “may,” “might,” “plan,” “potential,” “possible,” “will,” “would,” and other words and terms of similar meaning. These statements involve risks and uncertainties that could cause actual results to differ materially from those reflected in such statements, including: our ability to develop and obtain regulatory approval for our product candidates; the timing and results of preclinical studies and clinical trials; risks associated with clinical trials, including our ability to adequately manage clinical activities, unexpected concerns that may arise from additional data or analysis obtained during clinical trials, regulatory authorities may require additional information or further studies, or may fail to approve or may delay approval of our drug candidates; the occurrence of adverse safety events; the risk that positive results in a preclinical study or clinical trial may not be replicated in subsequent trials or success in early stage clinical trials may not be predictive of results in later stage clinical trials; failure to protect and enforce our intellectual property, and other proprietary rights; our dependence on collaborators and other third parties for the development and manufacture of product candidates and other aspects of our business, which are outside of our full control; risks associated with current and potential delays, work stoppages, or supply chain disruptions; and the other risks and uncertainties that are described in the Risk Factors section in documents the company files from time to time with the Securities and Exchange Commission (SEC), and other reports as filed with the SEC. Passage Bio undertakes no obligation to publicly update any forward-looking statement, whether written or oral, that may be made from time to time, whether as a result of new information, future developments or otherwise. For further information, please contact: Investors: Stuart Henderson Passage Bio [email protected] Media: Mike Beyer Sam Brown Inc. Healthcare Communications 312.961.2502 [email protected]