AVROBIO Reports Fourth Quarter and Fiscal Year 2022 Financial Results and Provides Business Update Following positive regulatory feedback, plan to initiate registrational global Phase 2/3 clinical trial for Gaucher disea

AVROBIO Reports Fourth Quarter and Fiscal Year 2022 Financial Results and

Provides Business Update

Following positive regulatory feedback, plan to initiate registrational global Phase 2/3 clinical trial for Gaucher disease type 3 (GD3) in second

half 2023, subject to regulatory alignment

Patient dosing completed in collaborator-sponsored Phase 1/2 clinical trial for cystinosis; plan to initiate late-stage clinical trial activities in

second half 2023, subject to regulatory alignment; expect to provide clinical and regulatory update at the American Society of Gene & Cell Therapy (ASGCT) annual meeting in May 2023

Plan to initiate collaborator-sponsored Phase 1/2 clinical trial for mucopolysaccharidosis type II (MPS-II), or Hunter syndrome, in 2023

CAMBRIDGE, Mass., March 23, 2023 -- AVROBIO, Inc. (Nasdaq: AVRO), a leading clinical-stage gene therapy company working to free people from a lifetime of genetic disease, today reported financial results for the

fourth quarter and year ended Dec. 31, 2022 and provided a business update.

"2022 was a transformative year for AVROBIO, topped in December with a robust clinical and regulatory update for our Gaucher disease program. Gaucher disease is one of the most common lysosomal disorders, and the data presented highlighted the potential systemic impact of hematopoietic stem cell (HSC) gene therapy, including data

suggesting certain improvements in some significant refractory elements of disease, for people living with Gaucher disease type 1 (GD1) and Gaucher disease type 3

(GD3)," said Geoff MacKay, president and CEO of AVROBIO. "Additionally, we're excited the collaborator-sponsored Phase 1/2 clinical trial for cystinosis has

completed dosing and that data to date show the potential of the HSC gene therapy approach to stabilize or reduce the impact of cystinosis on different tissues throughout the body with a one-time dose. In 2023, we have already started and look

forward to continuing to advance our Gaucher disease and cystinosis programs through anticipated near-term milestones."

Presented new and encore clinical and preclinical data for AVROBIO's lysosomal disorder pipeline at the 19th annual WORLDSymposium , Feb. 22-26, 2023:

Announced new positive clinical data and outlined clinical development plan for AVR-RD-02 in Gaucher disease on Dec. 7, 2022:

Approval received from MHRA, Research Ethics Committee (REC) and Health Research Authority (HRA) for the clinical trial application (CTA) submitted by AVROBIO's

collaborators at UoM for initiation of the Phase 1/2 clinical trial of investigational HSC gene therapy for infants diagnosed with MPS-II or Hunter syndrome

Regulatory Designations Obtained in 2022

Investigational AVR-RD-02 for Gaucher disease

Investigational AVR-RD-04 for cystinosis

AVR-RD-05 for Hunter syndrome

Upcoming Milestones Over Next 12 Months

Fourth Quarter and Year End 2022 Financial Results

AVROBIO reported a net loss of $25.0 million for the fourth quarter of 2022, and a net loss of $105.9 million for the year ended 2022, as compared to a net

loss of $28.2 million and a net loss of $119.1 million for the comparable periods in 2021, respectively.

Research and development expenses were $18.1 million for the fourth quarter of 2022, and $72.2 million for the year ended 2022, as compared to $19.0 million

and $83.1 million for the comparable periods in 2021, respectively. This decrease was driven by a reduction in program development expenses and personnel-related costs, including non-cash stock-based compensation.

General and administrative expenses were $7.1 million for the fourth quarter of 2022, and $33.2 million for the year ended 2022, as compared to $9.0 million

and $35.7 million for the comparable periods in 2021, respectively. This decrease was attributable to a decrease in personnel-related costs, including non-cash stock-based compensation, and a decrease in other expenses, primarily related to

Other income (expense), net was $0.2 million for the fourth quarter of 2022 and ($0.5) million for the year ended 2022, as compared to ($0.3) million and

($0.3) million for the comparable periods in 2021, respectively. This increase in expense for the year is due to interest expense related to our term loan which was partially offset by an increase in interest income.

As of Dec. 31, 2022, AVROBIO had $92.6 million in cash and cash equivalents, as compared to $189.6 million in cash and cash equivalents as of Dec. 31, 2021.

Based on AVROBIO's current operating plan, AVROBIO expects its cash and cash equivalents as of Dec. 31, 2022, will enable AVROBIO to fund its operating expenses and capital expenditure requirements into the first quarter of 2024.

Our vision is to bring personalized gene therapy to the world. We target the root cause of genetic disease by introducing a functional copy of the affected

gene into patients' own hematopoietic stem cells (HSCs), with the goal of durably expressing the therapeutic protein throughout the body, including the central nervous system. Our first-in-class pipeline includes clinical programs for Gaucher disease

and cystinosis, as well as preclinical programs for Hunter syndrome and Pompe disease. Our proprietary plato gene therapy platform is scalable for planned global commercialization. We are headquartered in Cambridge, Mass. For additional information,

Forward-Looking Statement

This press release contains forward-looking statements, including statements made pursuant to the safe harbor provisions of the Private Securities

Litigation Reform Act of 1995. These statements may be identified by forward-looking terminology such as "aims," "anticipates," "believes," "continue," "could," "designed to," "estimates," "expects," "forecasts," "goal," "intends," "may," "plans,"

"possible," "potential," "predicts," "projects," "seeks," "strives," "should," "will," and similar expressions or the negative of these terms. These forward-looking statements include, without limitation, statements regarding our business strategy

for and the potential therapeutic benefits of our current and prospective preclinical and clinical product candidates, the expected safety profile of our investigational gene therapies, results of preclinical studies, the design, commencement,

enrollment and timing of ongoing or planned clinical trials, preclinical, compassionate use or clinical trial results, product approvals and regulatory pathways, the timing of patient recruitment and enrollment activities, our expectations with

respect to our plans with collaborators, our plans and expectations with respect to interactions with regulatory agencies and the timing and likelihood of success thereof, the expected benefits and results of our implementation of the plato

platform in our clinical trials and gene therapy programs and its potential impact on our manufacturing and commercialization activities, and statements regarding our financial and cash position and expected cash runway, including impact on

anticipated milestones. Any such statements in this press release that are not statements of historical fact may be deemed to be forward-looking statements. Results in preclinical or early-stage clinical trials may not be indicative of results from

later stage or larger scale clinical trials and do not ensure regulatory approval. You should not place undue reliance on these statements, or the scientific data presented.

Any forward-looking statements in this press release are based on AVROBIO's current

expectations, estimates and projections about our industry as well as management's current beliefs and expectations of future events only as of today 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, the risk that any one or more of AVROBIO's product candidates will not be successfully

developed or commercialized, the risk of cessation or delay of any ongoing or planned clinical trials of AVROBIO or our collaborators, the risk that AVROBIO may not successfully recruit or enroll a sufficient number of patients for our clinical

trials, the risk that AVROBIO may not realize the intended benefits of our gene therapy platform, including the features of our plato platform, the risk that our product candidates or procedures in connection with the administration thereof will not have the safety or efficacy profile that we anticipate, the risk that prior results, such as

signals of safety, activity or durability of effect, observed from preclinical or clinical trials, will not be replicated or will not continue in ongoing or future studies or trials involving AVROBIO's product candidates, the risk that we will be

unable to obtain and maintain regulatory approval for our product candidates, the risk that we may be unable to realize the potential benefits associated with rare pediatric disease designation, the Innovative Licensing and Access

Pathway, or any other regulatory strategy, the risk that the size and growth potential of the market for our product candidates will not materialize as expected, risks

associated with our dependence on third-party suppliers and manufacturers, including sole source suppliers, risks regarding the accuracy of our estimates of expenses and future revenue, risks relating to our capital requirements and needs for

additional financing, including our ability to continue as a going concern, risks relating to our identification and pursuit of any strategic opportunities with respect to one or more of our programs, our technology or our plato platform, risks relating to clinical trial and business interruptions resulting from the COVID-19 outbreak or similar public health

crises, including that such interruptions may materially delay our enrollment and development timelines and/or increase our development costs or that data collection efforts may be impaired or otherwise impacted by such crises, and risks relating

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, any of which could cause AVROBIO's actual results to

differ materially and adversely from those contained in the forward-looking statements, see the section entitled "Risk Factors" in AVROBIO's most recent Annual or Quarterly Report, as well as discussions of potential risks, uncertainties and

other important factors in AVROBIO's subsequent filings with the Securities and Exchange Commission. AVROBIO explicitly disclaims any obligation to update any forward-looking statements except to the extent required by law.

Christopher F. Brinzey

Westwicke, an ICR Company

Ten Bridge Communications

CONDENSED CONSOLIDATED BALANCE SHEETS

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS

(In thousands, except per share data)