Passage Bio Reports First Quarter 2021 Financial Results and Recent Business Highlights - Dosed first patient with infantile GM1 gangliosidosis in Imagine-1 Phase 1/2 trial of PBGM01, initial safety and 30-day biomarker

Passage Bio Reports First Quarter 2021 Financial Results and Recent Business Highlights

Philadelphia, PA - May 5, 2021 - Passage Bio, Inc. (Nasdaq: PASG), a clinical-stage genetic medicines company focused on developing transformative therapies for rare, monogenic central nervous system disorders, today reported financial results for the first quarter ended March 31, 2021 and provided recent business highlights.

"We are particularly proud to have recently dosed our first patient in our global Imagine-1 trial of PBGM01 for infantile GM1 gangliosidosis," said Bruce Goldsmith, Ph.D., president and chief executive officer of Passage Bio. "This accomplishment speaks to the strength of our collaboration with the University of Pennsylvania's Gene Therapy Program. By raising an additional $166 million in the first quarter, we are well funded to advance both our clinical- and research-stage programs.

"Our primary focus in 2021 remains advancing and expanding our differentiated pipeline for patients with rare CNS disorders," Dr. Goldsmith added. "We are pleased to have successfully received a number of clinical trial regulatory approvals in a period of several months for our three most advanced programs. While some impact on clinical site initiations from the Covid-19 pandemic has occurred, which is reflected in adjusted study timelines, we look forward to reporting on several meaningful milestones throughout 2021 as we diligently work toward delivering transformative CNS therapies for patients."

Anticipated Upcoming Milestones

First Quarter 2021 Financial Results

Conference Call Details

Passage Bio will host a conference call and webcast today at 8:30 a.m. ET. To access the live conference call, please dial 833-528-0605 (domestic) or 830-221-9711 (international) and reference conference ID number 6366724. A live audio webcast of the event will be available on the Investors & Media section of Passage Bio's website at investors.passagebio.com. The archived webcast will be available on Passage Bio's website approximately two hours after the completion of the event and for 30 days following the call.

At Passage Bio (Nasdaq: PASG), we are on a mission to provide life-transforming gene therapies for patients with rare, monogenic CNS diseases that replace their suffering with boundless possibility, all while building lasting relationships with the communities we serve. 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. This provides our team with 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 into clinical testing. 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 initiation 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.

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Statements of Operations and Comprehensive Loss