AVROBIO Receives Rare Pediatric Disease Designation from the U.S. FDA for AVR-RD-05, a Gene Therapy for Mucopolysaccharidosis Type II (MPSII) or Hunter Syndrome

CAMBRIDGE, Mass.–(BUSINESS WIRE)–AVROBIO, Inc. (Nasdaq: AVRO), a leading clinical-stage gene therapy company with a mission to rid people of a lifelong genetic disease, today announced that the U.S. Food and Drug Administration (FDA) has approved AVR-RD-05, the lentiviral gene therapy for the treatment of mucopolysaccharidosis type II (MPSII), or Hunter syndrome, a rare and severely debilitating lysosomal disorder that primarily affects young boys, has been awarded the rare pediatric disease designation.

The FDA’s Rare Pediatric Disease Designation and Voucher Program aims to facilitate the development of new drugs and biologics for the prevention and treatment of rare childhood diseases. Companies that receive approval for a new drug application or Biologics License Application (BLA) for a rare pediatric disease may be eligible to receive a voucher for a priority review of a subsequent marketing application for another product. The Priority Review voucher can be used by the company or sold to a third party.

The planned investigator-sponsored Phase 1/2 clinical trial for Hunter syndrome is expected to begin in the second half of 2022. The program was developed by Brian Bigger, Ph.D., Professor of Cell and Gene Therapy at the University of Manchester, UK Prof. Bigger has published preclinical data showing that ex vivo lentiviral gene therapy with an optimized, proprietary tag has the potential to correct peripheral diseases and normalize brain pathology.

Hunter syndrome, which affects an estimated one in 100,000 to one in 170,000 men worldwide, causes devastating complications throughout the body and brain, including severe heart and respiratory failure, skeletal malformations and hearing impairment. Children with severe cases of Hunter syndrome typically show early symptoms of the disease in their toddler years and begin to develop a decline, losing basic motor skills and cognitive function for a few years. The current standard of care is weekly enzyme replacement therapy (ERT), which can slow some health complications but does not stop the overall progression of the disease and has not been shown to address central nervous system (CNS) problems. Even with ERT, people with Hunter syndrome face life-limiting symptoms and a significantly shorter lifespan.

About AVROBIO

Our vision is to bring personalized gene therapy to the world. We aim to prevent, stop or reverse disease throughout the body with a single dose of gene therapy designed to stimulate sustained expression of therapeutic proteins, even in hard-to-reach tissues and organs, including brain, muscle and bone. Our pipeline of ex vivo lentiviral gene therapy includes clinical programs for Fabry disease, type 1 Gaucher disease and cystinosis, as well as preclinical programs for Hunter syndrome, type 3 Gaucher disease and Pompe disease. AVROBIO is powered by our industry-leading plato® gene therapy platform, our foundation designed to deliver gene therapy worldwide. Our headquarters are in Cambridge, Massachusetts, with an office in Toronto, Ontario. For more information, visit avrobio.com and follow us on Twitter and LinkedIn.

Forward-Looking Statements

This press release contains forward-looking statements, including statements made in accordance with the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. These statements can be identified by words and expressions such as “ensures,” “anticipates,” “believes, “could”, “designed to”, “estimate”, “expect”, “forecast”, “goal”, “plan”, “may”, “plan”, “potential”, “seeks “, “will”, and variations of these words and phrases or similar expressions that are intended to identify forward-looking statements. These forward-looking statements include, without limitation, statements regarding our business strategy for and the potential therapeutic benefits of our product candidates, the design, initiation, enrollment and timing of ongoing or planned clinical trials, clinical trial results, product approvals and regulatory pathway and , anticipated benefits of the FDA’s Rare Pediatric Disease Designation for AVR-RD-05, our plans and expectations regarding the development of AVR-RD-05, including timing of our planned investigator-sponsored clinical trial for such candidate product, expected benefits of our gene therapy platform, including potential impact on our commercialization activities, timing and likelihood of success, the expected benefits and results of our implementation of the plato® platform in our clinical trials and gene therapy programs, and the expected safety profile of our investigational gene therapies . Such statements in this press release that are not historical facts may be considered forward-looking statements. Results in preclinical or early clinical trials may not be indicative of results from later stage or larger scale clinical trials and do not warrant regulatory approval. You should not place undue reliance on these statements or the scientific data presented.

All forward-looking statements in this press release are based on AVROBIO’s current expectations, estimates and projections of our industry, as well as management’s current beliefs and expectations about future events, as of today and are subject to a number of risks and uncertainties that could lead to actual results could 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, the risk that one or more AVROBIO product candidates will not be successfully developed or commercialized, the risk of discontinuation or delay of ongoing or planned clinical trials of AVROBIO or our employees, the risk regulatory authorities disagree with our anticipated development approach for our product candidates such as AVR-RD-05, the risk that AVROBIO will not successfully recruit or enroll a sufficient number of patients in our clinical trials, the risk that AVROBIO may not achieve the intended benefits of realize our gene therapy platform, including the features of our plato® platform, the risk that our product candidates or procedures associated with their administration may not have the safety or efficacy profile we expect, the risk that previous results, such as signs of safety, activity or durability of the effect, where taken in preclinical or clinical studies, will not be replicated or will not proceed with ongoing or future studies or trials of AVROBIO’s product candidates, the risk that we will not be able to obtain and maintain regulatory approval for our product candidates, the risk that the size and growth potential of the market for our product candidates not turning out as expected, risks related to our reliance on third party suppliers and manufacturers, risks related to the accuracy of our estimates of costs and future revenues, risks related to our capital requirements and additional financing needs, risks related to clinical trials and business interruptions due to the COVID-19 outbreak or similar public health crises, including that such interruptions could significantly delay our enrollment and development timelines and/or increase our development costs or that data collection efforts could be hampered or otherwise affected by such crises, and risks related to our ability to obtain and maintain intellectual property protection for: our product candidates. For a discussion of these and other risks and uncertainties, and other important factors, which could cause AVROBIO’s actual results to differ materially or adversely from those in the forward-looking statements, see the section entitled “Risk Factors” in AVROBIO’s most recent recent quarterly report, as well as discussions about potential risks, uncertainties and other important factors in AVROBIO’s subsequent filings with the Securities and Exchange Commission. AVROBIO expressly disclaims any obligation to update any forward-looking statements, except to the extent required by law.