Passage Bio Reports Second Quarter 2023 Financial Results and Provides Recent Business Highlights Reported promising interim data from Cohorts 1-4 in the Imagine-1 clinical trial for GM1 gangliosidosis (GM1); PBGM01 cont

Passage Bio Reports Second Quarter 2023 Financial Results and Provides Recent Business Highlights

PHILADELPHIA - August 7, 2023 - Passage Bio, Inc. (Nasdaq: PASG), a clinical-stage genetic medicines company focused on developing transformative therapies for central nervous system (CNS) disorders, today reported financial results for the second quarter ended June 30, 2023 and provided recent business highlights.

"We continued to make steady progress advancing our lead clinical programs in the second quarter and further improved our financial strength, extending our cash runway into the fourth quarter of 2025. By extending our operating runway, we can continue to focus on strong execution of our GM1 and FTD programs and delivering meaningful clinical data from each program over the coming quarters," said William Chou, M.D., president and chief executive officer of Passage Bio. "In GM1, we are encouraged by the promising data shared from Cohorts 1 through 4, further validating the potential of PBGM01 as a transformative therapy in both early and late infantile GM1 gangliosidosis. Additionally, we are thrilled to have already dosed the first patient at Dose 3, demonstrating effective execution across the program. In FTD, we are excited by emerging data from initial treated patients, which indicates translation from preclinical models into the clinic. We are experiencing strong momentum in the FTD program with six clinical trial sites in Brazil, Canada, and the United States now initiated, and several GRN positive patients undergoing evaluation for study eligibility. We remain dedicated to progressing our two lead clinical programs in our mission to bring transformative therapies to those affected by devastating CNS disorders."

Anticipated Upcoming Milestones

Second Quarter 2023 Financial Results

PBGM01 is an AAV-delivery gene therapy currently being developed for the treatment of infantile GM1, in which patients have mutations in the GLB1 gene causing little or no residual beta-galactosidase enzyme activity and subsequent neurodegeneration. PBGM01 utilizes a next-generation AAVhu68 capsid administered through the cisterna magna to deliver a functional GLB1 gene encoding beta-galactosidase to the brain and peripheral tissues. By increasing beta-galactosidase activity, PBGM01 has the potential to reduce accumulation of toxic GM1 gangliosides and reverse neuronal toxicity, thereby restoring developmental potential. In preclinical models, PBGM01 has demonstrated broad brain distribution and high levels of expression of the beta-galactosidase enzyme in both the CNS and critical peripheral organs, suggesting potential treatment for both the CNS and peripheral manifestations of GM1.

GM1, a rare monogenic lysosomal storage disease, is caused by mutations in the GLB1 gene, which encodes the lysosomal enzyme beta-galactosidase ( -gal). Reduced -gal activity results in the accumulation of toxic levels of GM1 gangliosides in neurons throughout the brain, causing rapidly progressive neurodegeneration. GM1 accumulation also results in progressive damage to other tissues including the heart, liver, and bones and manifests with hypotonia (reduced muscle tone), progressive CNS dysfunction, seizures, and rapid developmental regression. Life expectancy for infants with GM1 ranges from 2-10 years, and infantile GM1 represents approximately 60 percent of the global GM1 incidence of 0.5 to 1 in 100,000 live births.

Passage Bio (Nasdaq: PASG) is a clinical stage genetic medicines company on a mission to provide life-transforming therapies for patients with CNS diseases with limited or no approved treatment options. Our portfolio spans pediatric and adult CNS indications, and we are currently advancing clinical programs in GM1 gangliosidosis and frontotemporal dementia and our preclinical pipeline, including programs in amyotrophic lateral sclerosis and Huntington's disease. Based in Philadelphia, PA, our company has established a strategic collaboration and licensing agreement with the renowned University of Pennsylvania's Gene Therapy Program to conduct our discovery and IND-enabling preclinical work. Through this collaboration, we have enhanced access to a broad portfolio of gene therapy candidates and future gene therapy innovations that we then pair with our deep clinical, regulatory, manufacturing and commercial expertise to rapidly advance our robust pipeline of optimized gene therapies. As we work with speed and tenacity, we are always mindful of patients who may be able to benefit from our therapies. More information is available at www.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 trials and the availability of clinical data from such trials; our expectations about our collaborators' and partners' ability to execute key initiatives; our expectations about manufacturing plans and strategies; our expectations about cash runway; and the ability of our lead product candidates to treat their respective target monogenic 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 caused by the coronavirus pandemic; 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.

Statements of Operations and Comprehensive Loss

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Sam Brown Inc. Healthcare Communications