UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM 10-Q

(Mark One)

For the quarterly period ended March 31, 2021

OR

For the transition period from                  to                 

Commission File Number: 001-38537

AVROBIO, INC.

(Exact Name of Registrant as Specified in its Charter)

Registrant’s telephone number, including area code: (617) 914-8420

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    Yes  ☒    No  ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).    Yes  ☒    No  ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).    Yes  ☐    No  ☒

As of May 6, 2021, the registrant had 41,766,122 shares of common stock, $0.0001 par value per share, outstanding.

Table of Contents

i

Summary of the Material Risks Associated with Our Business

Our business is subject to numerous risks and uncertainties that you should be aware of in evaluating our business. These risks include, but are not limited to, the following:

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The summary risk factors described above should be read together with the text of the full risk factors below, in the section entitled “Risk Factors” and the other information set forth in this Quarterly Report on Form 10-Q, including our consolidated financial statements and the related notes, as well as in other documents that we file with the Securities and Exchange Commission (the “SEC”). The risks summarized above or described in full below are not the only risks that we face. Additional risks and uncertainties not precisely known to us, or that we currently deem to be immaterial may also materially adversely affect our business, financial condition, results of operations and future growth prospects.

iii

Note Regarding Forward-looking Statements

This Quarterly Report on Form 10-Q contains forward-looking statements which are made pursuant to the safe harbor provisions of Section 27A of the Securities Act of 1933, as amended (the “Securities Act”), and Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”). These statements may be identified by such forward-looking terminology as “aims,” “anticipates,” “believes,” “continue,” “could,” “designed to,” “estimates,” “expects,” “intends,” “may,” “plans,” “potential,” “predicts,” “strives,” “should,” or the negative of these terms or other comparable terminology. Our forward-looking statements are based on a series of expectations, assumptions, estimates and projections about our company, are not guarantees of future results or performance and involve substantial risks and uncertainty. We may not actually achieve the plans, intentions or expectations disclosed in our forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in these forward-looking statements. Our business and our forward-looking statements involve substantial known and unknown risks and uncertainties, including the risks and uncertainties inherent in our statements regarding:

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All of our forward-looking statements are as of the date of this Quarterly Report on Form 10-Q only. In each case, actual results may differ materially from such forward-looking information. We can give no assurance that such expectations or forward-looking statements will prove to be correct. An occurrence of or any material adverse change in one or more of the risk factors or risks and uncertainties referred to in this Quarterly Report on Form 10-Q or included in our other public disclosures or our other periodic reports or other documents or filings filed with or furnished to the Securities and Exchange Commission (the “SEC”) could materially and adversely affect our business, prospects, financial condition and results of operations. Except as required by law, we do not undertake or plan to update or revise any such forward-looking statements to reflect actual results, changes in plans, assumptions, estimates or projections or other circumstances affecting such forward-looking statements occurring after the date of this Quarterly Report on Form 10-Q, even if such results, changes or circumstances make it clear that any forward-looking information will not be realized. Any public statements or disclosures by us following this Quarterly Report on Form 10-Q that modify or impact any of the forward-looking statements contained in this Quarterly Report on Form 10-Q will be deemed to modify or supersede such statements in this Quarterly Report on Form 10-Q.

Note Regarding Trademarks

All brand names or trademarks appearing in this report are the property of their respective holders. Unless the context requires otherwise, references in this report to the “Company,” “we,” “us,” and “our” refer to AVROBIO, Inc.

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PART I—FINANCIAL INFORMATION

CONDENSED CONSOLIDATED BALANCE SHEETS

(unaudited)

(in thousands, except per share data)

The accompanying notes are an integral part of these unaudited condensed consolidated financial statements.

1

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS

(unaudited)

(in thousands, except per share data)

The accompanying notes are an integral part of these unaudited condensed consolidated financial statements.

2

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY

(unaudited)

(in thousands)

The accompanying notes are an integral part of these unaudited condensed consolidated financial statements.

3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

(unaudited)

(in thousands)

The accompanying notes are an integral part of these unaudited condensed consolidated financial statements.

4

AVROBIO, INC.

NOTES TO UNAUDITED CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(in thousands, except share and per share data)

5

AVROBIO, INC.

NOTES TO UNAUDITED CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

(in thousands, except share and per share data)

6

AVROBIO, INC.

NOTES TO UNAUDITED CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

(in thousands, except share and per share data)

7

AVROBIO, INC.

NOTES TO UNAUDITED CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

(in thousands, except share and per share data)

8

AVROBIO, INC.

NOTES TO UNAUDITED CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

(in thousands, except share and per share data)

9

AVROBIO, INC.

NOTES TO UNAUDITED CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

(in thousands, except share and per share data)

10

AVROBIO, INC.

NOTES TO UNAUDITED CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

(in thousands, except share and per share data)

11

AVROBIO, INC.

NOTES TO UNAUDITED CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

(in thousands, except share and per share data)

12

AVROBIO, INC.

NOTES TO UNAUDITED CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

(in thousands, except share and per share data)

13

AVROBIO, INC.

NOTES TO UNAUDITED CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

(in thousands, except share and per share data)

14

AVROBIO, INC.

NOTES TO UNAUDITED CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (CONTINUED)

(in thousands, except share and per share data)

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You should read the following discussion and analysis of our financial condition and results of operations together with our consolidated financial statements and the related notes appearing elsewhere in this Quarterly Report on Form 10-Q and our audited consolidated financial statements and related notes for the year ended December 31, 2020 included in our Annual Report on Form 10-K for the year ended December 31, 2020. Some of the information contained in this discussion and analysis or set forth elsewhere in this report, including information with respect to our plans and strategy for our business, includes forward-looking statements that involve risks, uncertainties and assumptions. Factors that might cause future results to differ materially from those projected in the forward-looking statements include, but are not limited to, those set forth in our Annual Report on Form 10-K for the year ended December 31, 2020, as supplemented by our subsequent filings with the SEC.

Overview

We are a leading clinical-stage gene therapy company with a mission to free people from a lifetime of genetic disease. Our company is focused on developing potentially curative ex vivo lentiviral-based gene therapies to treat patients with rare diseases following a single dose treatment regimen. Our gene therapies employ hematopoietic stem cells that are harvested from the patient and then modified with a lentiviral vector to insert the equivalent of a functional copy of the gene that is defective in the target disease. We believe that our approach, which is designed to transform stem cells from patients into therapeutic products, has the potential to provide curative benefit for a range of diseases. Our initial focus is on a group of rare genetic diseases referred to as lysosomal disorders, some of which today are primarily managed with enzyme replacement therapies, or ERTs. These lysosomal disorders have well-understood biologies, identified patient populations, established standards of care yet with significant unmet needs, and represent large market opportunities with approximately $4.8 billion in worldwide net sales in 2020.

Our initial pipeline is comprised of six lentiviral-based gene therapy programs: AVR-RD-01 for the treatment of Fabry disease; AVR-RD-04 for the treatment of cystinosis; AVR-RD-02 for the treatment of Gaucher disease type 1; AVR-RD-05 for the treatment of Hunter syndrome; AVR-RD-06 for the treatment of Gaucher disease type 3; and AVR-RD-03 for the treatment of Pompe disease. AVR-RD-01 is currently being evaluated for the treatment of Fabry disease in an investigator-sponsored Phase 1 clinical trial and a Company-sponsored Phase 2 clinical trial. Five patients have been dosed in the investigator-sponsored Phase 1 clinical trial of AVR-RD-01, and enrollment is complete. Seven patients have been dosed in our Company-sponsored Phase 2 clinical trial of AVR-RD-01, which we refer to as the FAB-GT clinical trial, and we are actively recruiting additional potential patients for our currently active sites in Australia, Canada and the United States. AVR-RD-04 is currently being studied for the treatment of cystinosis by our collaborators at the University of California, San Diego, or UCSD, in a Phase 1/2 investigator-sponsored clinical trial, and three patients have been dosed. One patient has been dosed in our Company-sponsored Phase 1/2 clinical trial of AVR-RD-02 for the treatment of Gaucher disease type 1, which we refer to as the Guard1 clinical trial, and we are actively recruiting in Australia and Canada, with additional sites planned in the United States, Israel and Europe. AVR-RD-05 is being studied for the treatment of Hunter syndrome by our collaborators at The University of Manchester, and a Phase 1/2 investigator-sponsored clinical trial is expected to commence in the first half of 2022. AVR-RD-06 is our preclinical program for the treatment of Gaucher disease type 3, for which we expect to request a meeting with the Food and Drug Administration, or FDA, this year to discuss a potential path to the clinic. Our AVR-RD-03 program for Pompe disease is currently in preclinical development, and in 2020 we completed IND-enabling proof-of-concept preclinical studies, with toxicology studies expected to be completed in 2021. We currently expect to have dosed an aggregate of 20 to 25 patients across our pipeline by the end of 2021.

Since our inception in 2015, we have devoted substantially all of our resources to organizing and staffing our company, business planning, raising capital, acquiring or discovering product candidates and securing related intellectual property rights, conducting discovery, research and development activities for our programs and planning for potential commercialization. To date, we have not generated any product revenue and have financed our operations primarily through the private placement of our securities and through public offerings of our common stock. Through March 31, 2021, we had received gross cash proceeds of $87.5 million from sales of our preferred stock; gross cash proceeds, before deducting underwriting discounts and commissions and expenses, of $428.1 million from sales of our common stock through our initial public offering and follow-on offerings; and gross cash proceeds, before deducting commissions and expenses, of $8.5 million from sales of our common stock through our “at-the-market” (ATM) facility.

Additionally, we have incurred significant operating losses. Our ability to generate product revenue sufficient to achieve profitability will depend heavily on the successful development and eventual commercialization of one or more of our current or future product candidates and programs. Our net losses were $26.9 million and $26.0 million for the three months ended March 31, 2021 and 2020, respectively. As of March 31, 2021, we had an accumulated deficit of $291.3 million. We expect to continue to incur significant expenses for at least the next several years as we advance our current and future product candidates from discovery through preclinical development and clinical trials and seek regulatory approval of our product candidates. We have expanded the number of programs in our pipeline to a total of six investigational gene therapies, three of which are currently in clinical development. As a result, further development of these programs will require us to expend significant resources to advance these candidates. In addition, if we obtain marketing approval for any of our product candidates, we expect to incur significant commercialization expenses related

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to product manufacturing, marketing, sales and distribution. We may also incur expenses in connection with the in-licensing or acquisition of additional product candidates.

We will need substantial additional funding to support our continuing operations and pursue our growth strategy. Until such time as we can generate significant revenue from product sales, if ever, we expect to finance our operations with proceeds from outside sources, with a majority of such proceeds to be derived from sales of equity, including the net proceeds from our follow-on offerings and sales of common stock under our “at-the-market” facility, or ATM. We also plan to pursue additional funding from outside sources, including our expansion of, or our entry into, new borrowing arrangements; research and development incentive payments from the Australian government; and our entry into potential future collaboration agreements for one or more of our programs. We may be unable to raise additional funds or enter into such other agreements or arrangements when needed on favorable terms, or at all. If we fail to raise capital or enter into such agreements as, and when, needed, we may have to significantly delay, scale back or discontinue the development and commercialization of one or more of our product candidates or delay our pursuit of potential in-licenses or acquisitions.

Because of the numerous risks and uncertainties associated with product development, we are unable to predict the timing or amount of increased expenses or when or if we will be able to achieve or maintain profitability. Even if we are able to generate product sales, we may not become profitable. If we fail to become profitable or are unable to sustain profitability on a continuing basis, we may be unable to continue our operations at planned levels and be forced to reduce or terminate our operations.

As of March 31, 2021, we had cash and cash equivalents of $233.0 million. We believe that our existing cash and cash equivalents as of March 31, 2021 will enable us to fund our operating expenses and capital expenditure requirements into the first quarter of 2023. We have based this estimate on assumptions that may prove to be wrong, and we could exhaust our available capital resources sooner than we expect. See “—Liquidity and Capital Resources.” To finance our operations beyond that point, we will need to raise additional capital, which cannot be assured.

AVR-RD-01 (Fabry) Regulatory Update

On March 11, 2021, approximately three weeks before our End-of-Phase 1 meeting for AVR-RD-01 held on March 31, 2021, the FDA granted full (also referred to as traditional) approval of Fabrazyme^® (agalsidase beta) more than 18 years after the enzyme replacement therapy, or ERT, received accelerated approval on the basis of a surrogate endpoint: reduction of globotriaosylceramide, or GL-3 (also referred to as Gb3), inclusions in biopsied renal peritubular capillaries, or PTCs. We believe the conversion of Fabrazyme to full approval opens a new pathway for potential full approval of ERTs based on this surrogate endpoint, rather than the endpoint of estimated glomerular filtration rate, or eGFR, which would typically require a longer study period. In addition, the conversion to full approval limits the accelerated approval pathways available for new therapies to treat Fabry disease, which must now show therapeutic benefit over Fabrazyme, such as for an unmet need, on a surrogate endpoint. Reduction of GL-3 in PTCs is the only surrogate endpoint that has been accepted as a basis for approval for Fabry ERTs at this time.

As a result of the Fabrazyme full approval, together with the FDA’s feedback on our original proposed trial design, we cannot pursue an accelerated approval pathway for AVR-RD-01 with the FAB-GT Phase 2 trial as designed and submitted to the FDA in our briefing book for our End-of-Phase 1 meeting. Instead, we believe there is a new potential regulatory pathway to full approval of AVR-RD-01 with a single registration trial using a kidney biopsy endpoint, similar to the primary endpoint of our ongoing FAB-GT trial. Although we have not discussed this proposed trial design with the FDA, we intend to engage with the FDA in the second half of 2021 to discuss and obtain alignment on our revised approach. While FDA guidance provides that the acceptability of surrogate endpoints is determined on a case-by-case basis, and a particular surrogate endpoint that may be appropriate for use in a particular drug or biologic clinical development program should not be assumed to be appropriate for use in a different program that is in a different clinical setting, we believe the recent full approval of Fabrazyme on the basis of a surrogate endpoint of complete/near complete reduction of GL-3 inclusions in biopsied renal PTCs may potentially support use of this endpoint in a registration trial of AVR-RD-01. Subject to FDA review and feedback, we intend to conduct a single, head-to-head potential registration trial versus Fabrazyme using a kidney biopsy surrogate endpoint, with the goal of initiating the clinical trial in mid-2022. We plan to propose to the FDA that such registration trial have a scope, size and duration comparable to other gene therapy trials.

In addition, based on feedback provided by the FDA during our End-of-Phase 1 meeting, we plan to request a Type C meeting with the FDA for the second half of 2021 to discuss chemistry, manufacturing and controls, or CMC, information with respect to AVR-RD-01 that would support initiation of the registration trial we are planning along with a potential BLA submission in the future. In parallel, we intend to seek scientific advice from the European Medicines Agency, or EMA, on the planned registration trial of AVR-RD-01.

As of May 6, 2021, we have dosed seven patients in the FAB-GT trial, with additional participants currently enrolled. To support the potential use of AVR-RD-01 in a broad Fabry disease population, we plan to amend the FAB-GT trial protocol in the second quarter of 2021 to allow enrollment of female participants, eliminate antibody-status exclusions and add the collection of data on additional parameters that are recognized to be limitations of ERT, such as endpoints to assess the potential ability of AVR-RD-01

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to address cardiovascular and central nervous system manifestations. Upon amendment, we plan to enroll a total of up to 14 participants in the FAB-GT trial.

COVID-19 Update

As the global healthcare community responded to the COVID-19 pandemic, in 2020 many hospitals, including our clinical sites, temporarily paused elective medical procedures, including dosing of new patients in clinical trials of our investigational gene therapies. While dosing of new patients and data collection from enrolled patients have begun to resume at clinical sites, the extent to which clinical activities continue to be delayed or interrupted will depend on future developments that are highly uncertain and cannot be accurately predicted, including new information that may emerge concerning COVID-19, the actions taken to contain it or treat its impact and the economic impact on local, regional, national and international markets. We have continued our work-from-home policy for most employees, excluding our laboratory staff and a limited number of non-laboratory employees. For those employees, we have implemented safety measures designed to comply with applicable federal, state and local guidelines in response to the COVID-19 pandemic. We may be required to take additional actions that impact our operations as required by applicable laws or regulations, or which we determine to be in the best interests of our employees.

We continue to closely monitor this rapidly evolving situation and the potential impact on our Company. For additional information regarding the impact of the COVID-19 pandemic on our business, please see the section titled “Risk Factors” in Part II, Section 1.A of this Quarterly Report.

Other Updates

On January 19, 2021, we announced the appointment of Diana M. Escolar, M.D., FAAN, as our Chief Medical Officer.

On February 8, 2021, we announced new data from our clinical trials of AVR-RD-01 for the treatment of Fabry disease, AVR-RD-01 for the treatment of Gaucher disease type 1 and AVR-RD-04 for the treatment of cystinosis. We presented these data virtually at the 17th annual WORLDSymposium™, held the week of February 8, 2021.

On February 25, 2021, we announced that the European Commission has granted orphan drug designation for AVR-RD-04 for the treatment of cystinosis.

Components of Our Consolidated Results of Operations

Operating Expenses

Research and Development Expenses

Research and development expenses consist primarily of costs incurred in connection with the discovery and development of our product candidates. We expense research and development costs as incurred. These expenses consist of costs incurred in connection with the development of our product candidates, including:

We recognize external development costs based on an evaluation of the progress to completion of specific tasks using information provided to us by our service providers.

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Our direct research and development expenses are tracked on a program-by-program basis for our product candidates and consist primarily of external costs, such as fees paid to outside consultants, CROs, CMOs, and central laboratories in connection with our preclinical development, process development, manufacturing and clinical development activities. Our direct research and development expenses by program also include fees incurred under license agreements. We do not allocate employee costs or facility expenses, including depreciation or other indirect costs, to specific programs because these costs are deployed across multiple programs and, as such, are not separately classified. We use internal resources primarily to oversee the research and discovery as well as for managing our preclinical development, process development, manufacturing and clinical development activities. These employees work across multiple programs and, therefore, we do not track their costs by program.

The table below summarizes our research and development expenses related to our product candidates (in thousands):

Research and development activities are central to our business model. Product candidates in later stages of clinical development generally have higher development costs than those in earlier stages of clinical development, primarily due to the increased size and duration of later-stage clinical trials. As a result, we expect that our research and development expenses will increase substantially over the next several years, particularly as we increase personnel costs, including stock-based compensation, contractor costs and facilities costs, as we continue to advance the development of our product candidates. We also expect to incur additional expenses related to milestone and royalty payments payable to third parties with whom we have entered into license agreements to acquire the rights to our product candidates.

The successful development and commercialization of our product candidates is highly uncertain. At this time, we cannot reasonably estimate or know the nature, timing and costs of the efforts that will be necessary to complete the preclinical and clinical development of any of our product candidates or when, if ever, material net cash inflows may commence from any of our product candidates. This uncertainty is due to the numerous risks and uncertainties associated with product development and commercialization, including the uncertainty of:

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We may never succeed in achieving regulatory approval for any of our product candidates. We may obtain unexpected results from our clinical trials. We may elect to discontinue, delay or modify clinical trials of some product candidates or focus on others. Any changes in the outcome of any of these variables with respect to the development of our product candidates in preclinical and clinical development could mean a significant change in the costs and timing associated with the development of these product candidates. For example, if the FDA or another regulatory authority were to delay our planned start of clinical trials or require us to conduct clinical trials or other testing beyond those that we currently expect, or if we experience significant delays in enrollment in any of our planned clinical trials for any reason, including as a result of the ongoing COVID-19 pandemic, we could be required to expend significant additional financial resources and time on the completion of clinical development of that product candidate. Identifying potential product candidates and conducting preclinical testing and clinical trials is a time-consuming, expensive and uncertain process that takes years to complete, and we may never generate the necessary data or results required to obtain marketing approval and achieve product sales. In addition, our product candidates, if approved, may not achieve commercial success.

General and Administrative Expenses

General and administrative expenses consist primarily of salaries, related benefits, travel and stock-based compensation expense for personnel in executive, finance and administrative functions. General and administrative expenses also include professional fees for legal, consulting, accounting and audit services.

We anticipate that our general and administrative expenses will increase in the future as we increase our headcount to support our continued research activities and development of our product candidates. We also anticipate that we will continue to incur increased accounting, audit, legal, regulatory, compliance, director and officer insurance costs as well as investor and public relations expenses associated with being a public company. We anticipate the additional costs for these services will substantially increase our general and administrative expenses. Additionally, if and when we believe a regulatory approval of a product candidate appears likely, we anticipate an increase in payroll and expense as a result of our preparation for commercial operations, especially as it relates to the sales and marketing of our product candidate.

Other (Expense) Income, Net

Other (expense) income, net primarily consists of interest income earned on our cash and cash equivalents and changes in foreign currency.

Consolidated Results of Operations

Comparison of the three months ended March 31, 2021 and 2020

The following table summarizes our consolidated results of operations (in thousands):

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Research and Development Expenses

Research and development expenses increased by approximately $0.3 million to $18.5 million for the three months ended March 31, 2021, from $18.3 million for the three months ended March 31, 2020. This increase was attributable to increased program development activities related to the advancement of our pipeline programs, including a $1.8 million increase in personnel-related costs, a $0.8 million increase in consulting fees, a $0.7 million increase in non-cash stock-based compensation and a $0.6 million increase in clinical costs. These increases were partially offset by a $2.1 million decrease in manufacturing costs and a $1.4 million decrease in preclinical costs.

General and Administrative Expenses

General and administrative expenses were $8.4 million for the three months ended March 31, 2021, compared to $8.3 million for the three months ended March 31, 2020. The increase of $0.1 million was attributable to an increase of $1.1 million in personnel-related costs and a $1.1 million increase in non-cash stock-based compensation, offset by a decrease of $1.1 million in consulting costs and a decrease in other expenses, primarily related to facilities costs, professional fees and legal fees, of $1.0 million.

Other (Expense) Income, Net

Other (expense), net, was less than $0.1 million for the three months ended March 31, 2021, which primarily consists of foreign currency losses recognized during the period, compared to other income, net of $0.6 million for the three months ended March 31, 2020. The decrease was primarily a result of lower yields on our money market funds.

Liquidity and Capital Resources

Since our inception, we have not generated any revenue and have incurred significant operating losses and negative cash flows from our operations. We have funded our operations to date primarily with proceeds from the sale of preferred stock and our common stock through our IPO, and we have raised additional capital through subsequent follow-on offerings and our “at-the-market” facility, or ATM facility. Through March 31, 2021, we had received gross cash proceeds of $87.5 million from sales of our preferred stock; gross cash proceeds, before deducting underwriting discounts and commissions and expenses, of $428.1 million from sales of our common stock through our initial public offering and follow-on offerings; and gross cash proceeds, before deducting commissions and expenses, of $8.5 million from sales of our common stock under our ATM facility.

On July 1, 2019, we filed a shelf registration statement on Form S-3 with the SEC, or the July 2019 Shelf, which covers the offering, issuance and sale by us of up to an aggregate of $200.0 million of our common stock, preferred stock, debt securities, warrants and/or units. We simultaneously entered into a Sales Agreement with Cowen and Company, LLC, as sales agent, to provide for the offering, issuance and sale by us of up to $50.0 million of our common stock from time to time in ATM offerings under the July 2019 Shelf. The July 2019 Shelf was declared effective by the SEC on July 10, 2019.

On December 20, 2019, we filed a shelf registration statement on Form S-3 with the SEC, or the December 2019 Shelf, which covers the offering, issuance and sale by us of up to an aggregate of $250.0 million of our common stock, preferred stock, debt securities, warrants and/or units. The December 2019 Shelf was declared effective by the SEC on January 14, 2020.

In July 2019, we closed an underwritten public offering, or the July 2019 Follow-On Offering, under the July 2019 Shelf of 7,475,000 shares of our common stock at a public offering price of $18.50 per share, which included 975,000 shares of our common stock resulting from the full exercise of the underwriters’ option to purchase additional shares at the public offering price, less underwriting discounts and commissions. The net proceeds to us from this offering, after deducting underwriting discounts and commissions and other offering expenses payable by us, were $129.5 million.

In February 2020, we closed an underwritten public offering, or the February 2020 Follow-On Offering, under the December 2019 Shelf of 4,350,000 shares of our common stock at a public offering price of $23.00 per share, less underwriting discounts and commissions. The net proceeds to us from this offering, after deducting underwriting discounts and commissions and other offering expenses payable by us, were $93.6 million.

In June 2020, we sold an aggregate of 384,140 shares of common stock under the ATM Facility for net proceeds, after deducting commissions and other offering expenses payable by us, of $8.1 million. As of December 31, 2020, approximately $41.5 million of common stock remained available for future issuance under the ATM Facility.

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In November 2020, we closed an underwritten public offering, or the November 2020 Follow-On Offering, of 5,000,000 shares of our common stock at a public offering price of $15.00 per share, less underwriting discounts and commissions. The net proceeds to us from the November 2020 Follow-On Offering, after deducting underwriting discounts and commissions and other offering expenses payable by us, were $70.2 million.

As of March 31, 2021, we had cash and cash equivalents of $233.0 million. Cash in excess of immediate requirements is invested primarily with a view to liquidity and capital preservation. We believe that our existing cash and cash equivalents as of March 31, 2021 will enable us to fund our operating expenses and capital expenditure requirements into the first quarter of 2023.

Cash Flows

The following table summarizes our cash flows for each of the periods presented (in thousands):

Operating Activities

During the three months ended March 31, 2021, operating activities used $27.3 million of cash, cash equivalents and restricted cash, resulting from our net loss of $26.9 million and cash used by changes in our operating assets and liabilities of $5.3 million partially offset by non-cash charges of $4.9 million. The net changes in our operating assets and liabilities were primarily due to a decrease in accrued expenses and other liabilities of $3.8 million and a $1.5 million increase in prepaids and other current assets. The non-cash charges primarily included $4.6 million of stock-based compensation expense and $0.3 million of depreciation and amortization expense.

During the three months ended March 31, 2020, operating activities used $22.4 million of cash, cash equivalents and restricted cash, resulting from our net loss of $26.0 million partially offset by cash provided by changes in our operating assets and liabilities of $0.5 million and non-cash charges of $3.1 million. The net changes in our operating assets and liabilities were primarily due to decreases in prepaid expenses and other current assets of $1.0 million due to ongoing preclinical, manufacturing, and clinical trial efforts, a decrease in other assets of $0.3 million and an increase in accrued expenses and other liabilities of $0.6 million, partially offset by a decrease in accounts payable of $1.4 million. The non-cash charges primarily included $2.8 million of stock-based compensation expense and $0.3 million of depreciation expense.

Investing Activities

Net cash used in investing activities was $0.1 million for the three months ended March 31, 2021 compared to $0.6 million for the three months ended March 31, 2020. The decrease in cash used in investing activities was primarily due to a reduction in purchases of property and equipment.

Financing Activities

Net cash provided by financing activities was $0.8 million for the three months ended March 31, 2021 compared to $93.7 million for the three months ended March 31, 2020. The decrease in cash provided by financing activities was primarily due to the proceeds of $93.6 million raised from the February Follow-On Offering in the comparative period, partially offset an increase of $0.8 million in proceeds from exercises of stock options.

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Funding Requirements

Notwithstanding the impact of the evolving COVID-19 pandemic on our company and the global economy generally, we expect our expenses to increase substantially in connection with our ongoing activities, particularly as we advance the preclinical activities and clinical trials of our product candidates. Our expenses will also increase as we:

We believe that our $233.0 million of existing cash and cash equivalents as of March 31, 2021 will enable us to fund our operating expenses and capital expenditure requirements into the first quarter of 2023. We have based these estimates on assumptions that may prove to be wrong, and we could utilize our available capital resources sooner than we expect. If we receive regulatory approval for any of our product candidates, we expect to incur significant commercialization expenses related to product manufacturing, sales, marketing and distribution, depending on where we choose to commercialize.

Until such time, if ever, that we can generate product revenue sufficient to achieve profitability, we expect to finance our cash needs through a combination of equity offerings, debt financings, collaboration agreements, government and other third-party funding, strategic alliances, licensing arrangements or marketing and distribution arrangements. Debt financing and preferred equity financing, if available, may involve agreements that include covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends. If we raise additional funds through government and other third-party funding, collaboration agreements, strategic alliances, licensing arrangements or marketing and distribution arrangements, we may have to relinquish valuable rights to our technologies, future revenue streams, research programs or product candidates or grant licenses on terms that may not be favorable to us. If we are unable to raise additional funds through equity or debt financings when needed, we may be required to delay, limit, reduce or terminate our product development or future commercialization efforts or grant rights to develop and market products or product candidates that we would otherwise prefer to develop and market ourselves.

Contractual Obligations and Commitments

The disclosure of our contractual obligations and commitments is set forth under the heading “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Contractual Obligations and Commitments” in our Annual Report on Form 10-K for the fiscal year ended December 31, 2020, filed with the SEC on March 18, 2021. There have been no significant changes to the table contained therein as of March 31, 2021.

Critical Accounting Policies and Significant Judgments and Estimates

Our consolidated financial statements are prepared in accordance with generally accepted accounting principles in the United States. The preparation of our consolidated financial statements and related disclosures requires us to make estimates and judgments that affect the reported amounts of assets, liabilities, revenue, costs and expenses, and the disclosure of contingent assets and liabilities in our financial statements. We base our estimates on historical experience, known trends and events and various other factors that we believe are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. We evaluate our estimates and assumptions on an ongoing basis.

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Our actual results may differ from these estimates under different assumptions or conditions. During the three months ended March 31, 2021, there were no material changes to our critical accounting policies. Our critical accounting policies are described under the heading “Management’s Discussion and Analysis of Financial Condition and Results of Operations— Critical Accounting Policies and Significant Judgments and Estimates” in our Annual Report on Form 10-K for the fiscal year ended December 31, 2020, which was filed with the SEC on March 18, 2021, and the notes to the consolidated financial statements included in Item 1, “Condensed Consolidated Unaudited Financial Statements,” of this Quarterly Report on Form 10-Q.

Emerging Growth Company Status

We are an “emerging growth company,” as defined in the Jumpstart Our Business Startups Act of 2012, or the JOBS Act, and we may take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not emerging growth companies. We may take advantage of these exemptions until we are no longer an emerging growth company. Section 107 of the JOBS Act provides that an emerging growth company can take advantage of the extended transition period afforded by the JOBS Act for the implementation of new or revised accounting standards. We have elected to use the extended transition period for complying with new or revised accounting standards and, as a result of this election, our financial statements may not be comparable to companies that comply with public company effective dates. We may take advantage of these exemptions up until the last day of the fiscal year following the fifth anniversary of our IPO or such earlier time that we are no longer an emerging growth company. We would cease to be an emerging growth company if we have more than $1.07 billion in annual revenue, we have more than $700.0 million in market value of our stock held by non-affiliates (and we have been a public company for at least 12 months and have filed one annual report on Form 10-K) or we issue more than $1.0 billion of non-convertible debt securities over a three-year period.

Off-Balance Sheet Arrangements

As of March 31, 2021, we did not have any significant off-balance sheet arrangements, as defined in Item 303(a)(4)(ii) of Regulation S-K promulgated under the Exchange Act.

Recently Issued Accounting Pronouncements

A description of recently issued accounting pronouncements that may potentially impact our financial position and results of operations is disclosed in Note 2, “Summary of Significant Accounting Policies” to our consolidated financial statements appearing at the beginning of this Quarterly Report on Form 10-Q.

Interest Rate Risk

As of March 31, 2021, we had cash and cash equivalents of $233.0 million, which consisted of primarily money market funds. Our primary exposure to market risk is interest rate sensitivity, which is affected by changes in the general level of U.S. interest rates, particularly because our cash equivalents are in held in short-term money market funds. Due to short-term duration of our investment portfolio and the low risk profile of our investments, an immediate 100 basis point change in interest rates would not have a material effect on the fair market value of our portfolio.

Foreign Currency Exchange Risk

We are exposed to foreign exchange rate risk. Our headquarters are located in the United States, where the majority of our general and administrative expenses and research and development costs are incurred in U.S. dollars. A portion of our research and development costs are incurred by our subsidiaries in Australia and Canada, whose functional currencies are the U.S. dollar but engage in transactions in Australian dollars and Canadian dollars, respectively. During each of the three months ended March 31, 2021 and 2020, we recognized foreign currency transaction losses of $25 thousand and $16 thousand, respectively. These losses primarily related to unrealized and realized foreign currency gains and losses as a result of transactions entered into by our Australian and Canadian subsidiaries in currencies other than the U.S. dollar. These foreign currency transaction gains and losses were recorded in other expense, net in our consolidated statements of operations. We believe that a 10% change in the exchange rate between the U.S. dollar, Australian dollar, Great British Pound, and Canadian dollar would not have a material impact on our financial position or results of operations.

As we continue to grow our business, our results of operations and cash flows will be subject to fluctuations due to changes in foreign currency exchange rates, which could adversely impact our results of operations. To date, we have not entered into any foreign currency hedging contracts to mitigate our exposure to foreign currency exchange risk.

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Evaluation of Disclosure Controls and Procedures

Our management, with the participation of our Chief Executive Officer and our Chief Financial Officer (our principal executive officer and principal financial officer, respectively), evaluated the effectiveness of our disclosure controls and procedures as of March 31, 2021. The term “disclosure controls and procedures,” as defined in Rules 13a-15(e) and 15d-15(e) under the Exchange Act, means controls and other procedures of a company that are designed to ensure that information required to be disclosed by a company in the reports that it files or submits under the Exchange Act is recorded, processed, summarized and reported, within the time periods specified in the SEC’s rules and forms. Disclosure controls and procedures include, without limitation, controls and procedures designed to ensure that information required to be disclosed by a company in the reports that it files or submits under the Exchange Act is accumulated and communicated to the company’s management, including its principal executive and principal financial officers, as appropriate to allow timely decisions regarding required disclosure. Management recognizes that any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving their objectives and management necessarily applies its judgment in evaluating the cost-benefit relationship of possible controls and procedures. While we continue to evaluate our disclosure controls and procedures, including new procedures and processes relating to our internal control over financial reporting, based on the evaluation of our disclosure controls and procedures as of March 31, 2021, our Chief Executive Officer and Chief Financial Officer concluded that our disclosure controls and procedures were effective at the reasonable assurance level as of March 31, 2021.

Changes in Internal Control over Financial Reporting

No change in our internal control over financial reporting (as defined in Rules 13a-15(f) and 15d-15(f) under the Exchange Act) occurred during the three months ended March 31, 2021 that has materially affected, or is reasonably likely to materially affect, our internal control over financial reporting.

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PART II—OTHER INFORMATION

From time to time, we may become subject to various legal proceedings and claims that arise in the ordinary course of our business activities. Although the results of litigation and claims cannot be predicted with certainty, as of March 31, 2021, we are not presently subject to any pending or threatened litigation that we believe, if determined adversely to us, would individually or in the aggregate be reasonably expected to have a material adverse effect on our business. Regardless of the outcome, litigation can have an adverse impact on us because of defense and settlement costs, diversion of management resources and other factors.

Investing in our common stock involves a high degree of risk. You should carefully consider the following risks and uncertainties, together with all other information in this Quarterly Report on Form 10-Q, including our consolidated financial statements and related notes and “Management’s Discussion and Analysis of Financial Condition and Results of Operations,” as well as our other filings with the Securities and Exchange Commission, or the SEC, before investing in our common stock. Any of the risk factors we describe below could adversely affect our business, financial condition or results of operations. The market price of our common stock could decline if one or more of these risks or uncertainties were to occur, which may cause you to lose all or part of the money you paid to buy our common stock. Additional risks that are currently unknown to us or that we currently believe to be immaterial may also impair our business. Certain statements below are forward-looking statements. See “Forward-Looking Information” in this Quarterly Report on Form 10-Q.

Risks related to our business, financial position and need for additional capital

We have incurred net losses since inception. We expect to incur net losses for the foreseeable future and may never achieve or maintain profitability.

Since inception, we have incurred net losses. We incurred net losses of $119.7 million and $73.0 million for the years ended December 31, 2020 and 2019, respectively and $26.9 million for the three months ended March 31, 2021. We historically financed our operations primarily through private placements of our preferred stock and, more recently, our initial public offering and follow-on public offerings of our common stock, as well as sales of our common stock under our “at-the-market” facility. We have devoted substantially all of our efforts to research and development, including clinical and preclinical development of our product candidates, as well as assembling our team. We expect that it will be several years, if ever, before we have commercialized any product candidates. We expect to continue to incur significant expenses and increasing operating losses for the foreseeable future. We anticipate that our expenses will increase substantially if, and as, we:

To become and remain profitable, we must develop and eventually commercialize product candidates with significant market potential. This will require us to be successful in a range of challenging activities, and our expenses will increase substantially as we seek to complete preclinical and clinical trials of our product candidates, and manufacture, market and sell these or any future product candidates for which we may obtain marketing approval, if any, and satisfy any post-marketing requirements. We may never succeed

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in any or all of these activities and, even if we do, we may never generate revenues that are significant or large enough to achieve profitability. If we do achieve profitability, we may not be able to sustain or increase profitability on a quarterly or annual basis. Our failure to become and remain profitable would decrease the value of our Company and could impair our ability to raise capital, maintain our research and development efforts, expand our business or continue our operations. A decline in the value of our Company also could cause you to lose all or part of your investment.

We have never generated revenue from product sales and do not expect to do so for the next several years, if ever.

Our ability to generate revenue from product sales and achieve profitability depends on our ability, alone or with collaborative partners, to successfully complete the development of, and obtain the regulatory approvals necessary to commercialize, our product candidates. We do not anticipate generating revenues from product sales for the next several years, if ever. Our ability to generate future revenues from product sales depends heavily on our, or our collaborators’, success in:

Even if one or more of the product candidates that we develop is approved for commercial sale, we anticipate incurring significant costs associated with commercializing any approved product candidate. Our expenses could increase beyond expectations if we are required by the FDA or other foreign regulatory authorities to perform clinical and other studies in addition to those that we currently anticipate. Even if we are able to generate revenues from the sale of any approved products, we may not become profitable and may need to obtain additional funding to continue operations.

We will need additional funding, which may not be available on acceptable terms, or at all. Failure to obtain this necessary capital when needed may force us to delay, limit or terminate our product development efforts or other operations.

As of March 31, 2021, we had cash and cash equivalents of $233.0 million. We believe that our existing cash and cash equivalents as of March 31, 2021 will enable us to fund our operating expenses and capital expenditure requirements into the first quarter of 2023. This forecast of cash resources is forward-looking information that involves risks and uncertainties, and the actual amount of our expenses could vary materially and adversely as a result of a number of factors. We have based our estimates on assumptions that may prove to be wrong, and our expenses could prove to be significantly higher than we currently anticipate. 

We expect our expenses to increase in connection with our ongoing activities, particularly as we continue the research and development of, initiate further clinical trials of and seek marketing approval for, our product candidates and continue to enhance and optimize our vector technology and manufacturing processes. Furthermore, we have expanded the number of programs in our pipeline to a total of six investigational gene therapies, three of which are in clinical development. As a result, further development of these programs will require us to expend significant resources to advance these candidates. In addition, if we obtain marketing approval for any of our product candidates, we expect to incur significant expenses related to product sales, medical affairs, marketing, manufacturing and distribution. Furthermore, we expect to continue to incur additional costs associated with operating as a public company. Accordingly, we will need to obtain substantial additional funding in connection with our continuing operations. If we are unable to raise capital when needed or on reasonable terms, we would be forced to delay, reduce or eliminate certain of our research and development programs. Our future capital requirements will depend on many factors, including:

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Identifying potential product candidates and conducting preclinical testing and clinical trials is a time-consuming, expensive and uncertain process that takes years to complete, and we may never generate the necessary data or results required to obtain marketing approval and achieve product sales. In addition, our product candidates, if approved, may not achieve commercial success. Our product revenues, if any, will be derived from or based on sales of products that may not be commercially available for many years, if at all. Accordingly, we will need to continue to rely on additional financing to achieve our business objectives. Adequate additional financing may not be available to us on acceptable terms, or at all.

Raising additional capital may cause dilution to our existing stockholders, restrict our operations or cause us to relinquish valuable rights.

We may seek additional capital through a combination of public and private equity offerings, debt financings, strategic partnerships and alliances and licensing arrangements. To the extent that we raise additional capital through the sale of equity, convertible debt securities or other equity-based derivative securities, your ownership interest will be diluted and the terms may include liquidation or other preferences that adversely affect your rights as a stockholder. Any additional indebtedness we incur would result in increased fixed payment obligations and could involve restrictive covenants, such as limitations on our ability to incur additional debt, limitations on our ability to acquire or license intellectual property rights and other operating restrictions that could adversely impact our ability to conduct our business. Furthermore, the issuance of additional securities, whether equity or debt, by us, or the possibility of such issuance, may cause the market price of our common stock to decline and existing stockholders may not agree with our financing plans or the terms of such financings. If we raise additional funds through strategic partnerships and alliances and licensing arrangements with third parties, we may have to relinquish valuable rights to our technologies, or our product candidates, or grant licenses on terms unfavorable to us. Adequate additional financing may not be available to us on acceptable terms, or at all.

Our limited operating history may make it difficult for you to evaluate the success of our business to date and to assess our future viability.

We are a clinical-stage company founded in November 2015. Our operations to date have been limited to corporate organization, recruiting key personnel, business planning, raising capital, acquiring rights to our technology, identifying potential product candidates, undertaking preclinical studies and planning and supporting clinical trials of certain of our product candidates and establishing research and development and manufacturing capabilities. We have not yet demonstrated the ability to complete clinical trials of our product candidates, obtain marketing approvals, manufacture products on a clinical or commercial scale or conduct sales and marketing activities necessary for successful commercialization. Consequently, any predictions you make about our future success or viability may not be as accurate as they could be if we had a longer operating history. In addition, as an early-stage company, we may encounter unforeseen expenses, difficulties, complications, delays and other known and unknown factors.

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Risks related to the discovery and development of our product candidates

Business interruptions resulting from the coronavirus disease (COVID-19) pandemic or similar public health crises have caused and may continue to cause a disruption of the development of our product candidates and adversely impact our business.

Public health crises such as pandemics or similar outbreaks could adversely impact our business. The COVID-19 pandemic has continued to disrupt normal business operations both in and outside of affected areas and has had significant negative impacts on businesses and financial markets worldwide. We continue to monitor our operations and applicable government recommendations and have continued our work-from-home policy for most employees, excluding our laboratory staff and a limited number of non-laboratory employees. Notwithstanding these measures, the COVID-19 pandemic could affect the health and availability of our workforce as well as those of the third parties on which we rely. If members of our management and other key personnel are unable to perform their duties or have limited availability due to COVID-19, we may not be able to execute on our business strategy and/or our operations may be negatively impacted. We may experience limitations in employee resources, including because of sickness of employees or their families or the desire of employees to avoid contact with individuals or large groups of people.

In addition, clinical trial activities, including patient enrollment and data collection, are dependent upon global clinical trial sites which have been and continue to be adversely affected by the COVID-19 pandemic. For example, as the global healthcare community responded to the fluctuations in COVID-19 cases and hospitalizations, many hospitals, including our clinical sites, temporarily paused elective procedures, which included dosing of new patients with our investigational gene therapies. While dosing of new patients has begun to resume, our ability to continue clinical activities without further delay or interruption will depend on future developments that are highly uncertain and cannot be accurately predicted. Additionally, while ongoing data collection has continued for our patients that have been dosed, certain data collection has been delayed and additional delays could result from COVID-19-related interruptions, particularly as new variants of the virus are identified and continue to spread. We are currently conducting clinical trials for our product candidates in the United States, Canada and Australia, and plan to expand to other geographies including Japan, Europe, Israel and Brazil, and each of these regions have been affected by COVID-19.

Additional factors from the COVID-19 pandemic that have delayed and may continue to delay or otherwise adversely affect enrollment in or the progress of the clinical trials of our product candidates, as well as our business generally, include:

Additionally, three vaccines for COVID-19 were granted Emergency Use Authorization by the FDA in late 2020 and early 2021, and more are likely to be authorized in the future. The resultant demand for vaccines and potential for manufacturing facilities and materials to be commandeered under the Defense Production Act of 1950, or equivalent foreign legislation, may make it more difficult to obtain materials or manufacturing slots for the products needed for our clinical trials, which could lead to delays in these trials.

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These and other factors arising from the COVID-19 pandemic could worsen and further adversely impact our ability to conduct clinical trials and our business generally, and could have a material adverse impact on our operations and financial condition and results. The extent to which the COVID-19 pandemic impacts our operations or those of our third party partners will depend on future developments, which are highly uncertain and cannot be predicted with confidence, including the duration of the pandemic, the efficacy and safety of vaccines, the ability of third parties to manufacture and distribute vaccines, and new information that may emerge concerning mutations of the coronavirus that causes COVID-19, among others.

Our lentiviral-based gene therapy product candidates are based on a novel technology, which makes it difficult to predict the time and cost of product candidate development and of subsequently obtaining regulatory approval.

We have concentrated our research and development efforts on our lentiviral-based gene therapy approach, and our future success depends on our successful development of viable gene therapy product candidates. There can be no assurance that we will not experience problems or delays in developing new product candidates and that such problems or delays will not cause unanticipated costs, or that any such development problems can be solved. For example, timely enrollment in our clinical trials is dependent upon global clinical trial sites which have been and may continue to be adversely affected by the COVID-19 pandemic, especially if a resurgence of cases occurs. In addition, the implementation of our plato platform and upgrades, including our transition to Target Concentration Intervention, or TCI, conditioning using busulfan for our single-agent conditioning regimen, may result in delays or setbacks in our research and development activities, and we may not realize the intended benefits of these efforts. In addition, we may also experience delays in developing a sustainable, reproducible and scalable manufacturing process or transferring that process to commercial partners, which may prevent us from completing our clinical studies or commercializing our products on a timely or profitable basis, if at all. For example, as of May 6, 2021 we have only dosed five patients using our plato platform, which we plan to utilize for the majority of patients in our ongoing FAB-GT clinical trial for AVR-RD-01 and all patients in the Guard1 clinical trial of AVR-RD-02. Our implementation of the LV2 lentiviral vector or of our cell processing to an industrialized, automated closed system using disposable supplies may not be successful or may experience unforeseen delays, which may cause shortages or delays in the supply of our products available for clinical trials and future commercial sales, if any, or impair our research and development efforts, including those in our ongoing and future clinical trials. In addition, there is no assurance that products using our proprietary LV2 lentiviral vector or manufactured using this automated system will ultimately achieve the same favorable preliminary results observed to date. Furthermore, the FDA generally prefers that clinical trials be double-blinded and potentially include sham controls. Such a trial design could be challenging to implement due to the nature of the treatment regimen of lentiviral gene therapy.

In addition, the clinical trial requirements of the FDA and other foreign regulatory authorities and the criteria these regulators use to determine the safety and efficacy of a product candidate vary substantially according to the type, complexity, novelty and intended use and market of such product candidates. The regulatory approval process for novel product candidates such as ours can be more expensive and take longer than for other, better known or more extensively studied product candidates. To date, only a limited number of gene therapies have received marketing authorization from the FDA or foreign regulatory authorities. It is difficult to determine how long it will take or how much it will cost to obtain regulatory approvals for our product candidates in the United States, Canada, Europe or other major markets or how long it will take to commercialize our product candidates, if any are approved. Approvals by foreign regulatory authorities may not be indicative of what the FDA may require for approval, and vice versa.

Regulatory requirements governing gene and cell therapy products have changed frequently and may continue to change in the future. The FDA has established the Office of Tissues and Advanced Therapies within its Center for Biologics Evaluation and Research, or CBER, to consolidate the review of gene therapy and related products, and has established the Cellular, Tissue and Gene Therapies Advisory Committee to advise the CBER in its review. Gene therapy clinical trials conducted at institutions that receive funding for recombinant DNA research from the United States National Institutes of Health, or NIH, also are subject to the NIH Guidelines, under which supervision of human gene transfer trials includes evaluation and assessment by an institutional biosafety committee, or IBC, a local institutional committee that reviews and oversees research utilizing recombinant or synthetic nucleic acid molecules at that institution. The IBC assesses the safety of the research and identifies any potential risk to public health or the environment, and such review may result in some delay before initiation of a clinical trial. If we were to engage an NIH-funded institution to conduct a clinical trial, that institution’s IBC as well as its institutional review board, or IRB, would need to review the proposed clinical trial to assess the safety of the trial. In addition, adverse developments in clinical trials of gene therapy products conducted by others may cause the FDA or other oversight bodies to change the requirements for approval of any of our product candidates. Similarly, foreign regulatory authorities may issue new guidelines concerning the development and marketing authorization for gene therapy medicinal products and require that we comply with these new guidelines.

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The FDA, NIH and the European Medicines Agency, or EMA, have each expressed interest in further regulating biotechnology, including gene therapy and genetic testing. For example, the EMA advocates a risk-based approach to the development of a gene therapy product. Agencies at both the federal and state level in the United States, as well as the U.S. congressional committees and other governments or governing agencies, have also expressed interest in further regulating the biotechnology industry. Such action may delay or prevent commercialization of some or all of our product candidates.

These regulatory review committees and advisory groups and any new guidelines they promulgate may lengthen the regulatory review process, require us to perform additional studies, increase our development costs, lead to changes in regulatory positions and interpretations, delay or prevent approval and commercialization of these product candidates or lead to significant post-approval limitations or restrictions. As we advance our product candidates, we will be required to consult with these regulatory and advisory groups, and comply with applicable guidelines. If we fail to do so, we may be required to delay or discontinue development of certain of our product candidates. These additional processes may result in a review and approval process that is longer than we otherwise would have expected. Delay or failure to obtain, or unexpected costs in obtaining, the regulatory approval necessary to bring a potential product to market could decrease our ability to generate sufficient product revenue, and our business, financial condition, results of operations and prospects would be materially and adversely affected.

The FDA continues to develop its approach to assessing gene and cell therapy products. For example, the agency has released a series of draft and final guidance documents relating to, among other topics, various aspects of gene therapy product development, review, and approval, including aspects relating to clinical and manufacturing issues related to gene therapy products. In January 2020, the FDA released a final guidance with recommendations for long-term follow-up studies of patients following human gene therapy administration due to the increased risk of undesirable and unpredictable outcomes with gene therapies that may present as delayed adverse events. We cannot be certain whether such guidance, or other guidance that the FDA may issue, will be relevant to or have an adverse impact on our gene therapy candidates or the duration or expense of any applicable regulatory development and review processes.

Our product candidates and the process for administering our product candidates may cause undesirable side effects or have other properties that could delay or prevent their regulatory approval, limit their commercial potential or result in significant negative consequences following any potential marketing approval.

During the conduct of clinical trials, patients may experience changes in their health, including illnesses, injuries, discomforts or a fatal outcome. It is possible that as we test our product candidates in larger, longer and more extensive clinical programs, or as use of our product candidates becomes more widespread if they receive regulatory approval, illnesses, injuries, discomforts and other adverse events that were observed in earlier clinical trials, as well as conditions that did not occur or went undetected in previous clinical trials, will be reported by patients. Gene therapies are also subject to the potential risk that occurrence of adverse events will be delayed following administration of the gene therapy due to persistent biological activity of the genetic material or other components of the vectors used to carry the genetic material. Many times, side effects are only detectable after investigational products are tested in larger scale, pivotal clinical trials or, in some cases, after they are made available to patients on a commercial scale after approval. FDA guidance advises that patients treated with gene therapies undergo long-term follow-up observation for potential adverse events for as long as 15 years. If additional clinical or long-term follow-up experience indicates that any of our product candidates have side effects or cause serious or life-threatening side effects, the development of the product candidate may fail or be delayed, or, if the product candidate has received regulatory approval, such approval may be revoked or limited.

There have been several significant adverse side effects in gene therapy treatments in the past, including multiple reported cases of leukemia, myelodysplastic syndrome and death seen in other clinical trials. For example, a case of transfusion-dependent anemia and a separate case of acute myeloid leukemia were recently reported in a third party’s clinical trials of lentiviral gene therapy for the treatment of sickle cell disease. These safety events are currently under investigation, and while several factors have been posited as potential direct or contributing causes, including the use of busulfan in the conditioning process, no definitive conclusion has been made as of the date of this Quarterly Report on Form 10-Q. Gene therapy is still a relatively new approach to disease treatment and additional adverse side effects could develop. Possible adverse side effects that may occur with treatment with gene therapy products include an immunologic reaction early after administration that could substantially limit the effectiveness of the treatment or represent safety risks for patients. Another traditional safety concern for gene therapies using viral vectors has been the possibility of insertional oncogenesis by the vectors, leading to malignant transformation of transduced cells. In addition, dominant clonal expansion due to vector integration has been observed in third-party ex vivo lentiviral gene therapy clinical trials, including one case of thalassemia and two cases of cerebral adrenoleukodystrophy. Although to date there have been no reports of malignant transformation in these patients, these cases and any similar cases will require further monitoring and follow-up. While our lentiviral gene therapy approach is designed to avoid immunogenicity against the vector after administration, there can be no assurance that patients would not create antibodies that may impair treatment. In addition, although we are investigating a plan to potentially implement molecular cytogenetic screening, there can be no assurance that we will successfully implement such screening procedures in a timely manner or at all, or that, if implemented, they will enhance the safety profile of our gene therapy product candidates. If any of our gene therapy product

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candidates demonstrates adverse side effects at unacceptable rates or degrees of severity, we may decide or be required to halt or delay clinical development of such product candidates.

In addition to side effects caused by our product candidates, the conditioning, administration process or related procedures, which we evaluate from time to time as part of our process improvement and optimization efforts, also can cause adverse side effects. A gene therapy patient is generally administered one or more myeloablative drugs to remove stem cells from the bone marrow to create sufficient space in the bone marrow for the modified gene-corrected stem cells to engraft and produce their progeny. This procedure causes adverse side effects and transiently compromises the patient’s immune system, known as neutropenia, and ability to form blood clots, known as thrombocytopenia.

In 2019 we began transitioning, in connection with our Company-sponsored clinical trials, towards a new conditioning regimen for our product candidates utilizing busulfan as the myeloablative conditioning agent instead of the melphalan that we previously used. The use of this conditioning regimen is designed to utilize a precision dosing program, TCI, to achieve a balance between the removal of a sufficient amount of bone marrow cells from a patient against potential risks such as toxicity or graft failure. While we believe that the conditioning regimen could be performed during a limited hospital stay, we cannot guarantee that the conditioning will not require a lengthier hospitalization. Our conditioning regimens may not be successful or may nevertheless result in adverse side effects. For example, in each of our ongoing clinical trials several adverse events, including suppression of neutrophils and platelet counts following the conditioning process, were observed. While such adverse events in connection with conditioning is expected, if in the future any such adverse events caused by the conditioning process or related procedures continue at unacceptable rates or degrees of severity, the FDA or other foreign regulatory authorities could order us to cease development of, or deny approval of, our product candidates for any or all targeted indications. There have been cases of therapy-related myelodysplastic syndrome, a type of blood disorder that is a potential precursor to acute myeloid leukemia, in patients with preexisting cancer where busulfan treatment was posited to be a contributing factor to this secondary malignancy. Although we are investigating a plan to potentially implement molecular cytogenetic screening as an additional risk reduction measure, there can be no guarantees that these procedures will be implemented in a timely manner or would be successful if implemented. Even if we are able to demonstrate that adverse events are not product-related, such occurrences could adversely affect patient recruitment or the ability of enrolled patients to complete the clinical trial, and lead to a decline in our stock price.

Additionally, if any of our product candidates receives marketing approval, the FDA could require us to adopt a Risk Evaluation and Mitigation Strategy, or REMS, to ensure that the benefits outweigh its risks, which may include, among other things, a medication guide outlining the risks of the product for distribution to patients, a communication plan to health care practitioners, and restrictions on how or where the product can be distributed, dispensed or used. Furthermore, if we or others later identify undesirable side effects caused by our product candidates, several potentially significant negative consequences could result, including:

Any of these events could prevent us from achieving or maintaining market acceptance of our product candidates, lead to a decline in our stock price, and significantly harm our business, prospects, financial condition and results of operations.

Our regulatory approach for AVR-RD-01 for the treatment of Fabry disease recently changed, and there can be no assurance that our new, proposed regulatory pathway will be accepted by regulatory agencies.

On March 11, 2021, approximately three weeks before our End-of-Phase 1 meeting for AVR-RD-01 held on March 31, 2021, the FDA granted full (also referred to as traditional) approval of Fabrazyme^® (agalsidase beta) more than 18 years after the ERT received accelerated approval on the basis of a surrogate endpoint: reduction of GL-3 (also referred to as Gb3) inclusions in biopsied PTCs. The conversion to full approval limits the accelerated approval pathways available for new therapies to treat Fabry disease, which must now show clinical benefit over Fabrazyme on a surrogate endpoint. Reduction of GL-3 in PTCs is the only surrogate endpoint that has been accepted as a basis for approval for Fabry ERTs at this time.

As a result of the Fabrazyme full approval, together with the FDA’s feedback on our original proposed trial design, we cannot pursue an accelerated approval pathway for AVR-RD-01 with the FAB-GT Phase 2 trial as designed and submitted to the FDA in our briefing book for our End-of-Phase 1 meeting. Instead, we intend to engage with the FDA in the second half of 2021 to discuss and

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obtain feedback on a revised regulatory approach. Subject to FDA review and feedback, we intend to conduct a single, head-to-head registration trial versus Fabrazyme using a kidney biopsy surrogate endpoint as the basis for potential full approval of AVR-RD-01, with the goal of initiating the clinical trial in mid-2022. This planned regulatory pathway for AVR-RD-01 is subject to numerous risks, including the following:

Clinical testing is expensive, time-consuming and uncertain as to outcome. We cannot guarantee that any clinical studies, including our proposed registration trial of AVR-RD-01, will be conducted as planned or completed on schedule, if at all. Any inability to successfully conduct our proposed registration trial of AVR-RD-01 using a kidney biopsy surrogate endpoint or other inability to successfully complete our clinical development of AVR-RD-01 could result in additional costs to us and impair our ability to generate revenues. 

We have never completed a pivotal or registration clinical trial, and may be unable to do so for any product candidates we may develop.

We are at an early stage of development for all of our product candidates. As of May 6, 2021, we have dosed only 16 patients across four ongoing clinical trials. These ongoing clinical trials, as well as potentially additional pivotal clinical trials (also referred to as registration trials), must be completed in order to obtain FDA or other regulatory approval to market these product candidates. We have limited experience in preparing, submitting and prosecuting regulatory filings, and have not previously submitted a biologics license application, or BLA, for any product candidate.

Carrying out later-stage clinical trials is a complicated and lengthy process, and we do not expect that all data from patients participating in the clinical trials will be relevant or meaningful. For example, the primary efficacy endpoint of our Phase 2 clinical trial of AVR-RD-01, which we refer to as the FAB-GT clinical trial, is the change, from baseline to one year post-treatment with

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AVR-RD-01, in the average number of Gb3 inclusions per PTC, as measured in a patient kidney biopsy. The second patient in the FAB-GT trial has an N215S genotype, which is associated with a late-onset cardiac variant phenotype and lower plasma lyso-Gb3 levels. This patient’s cardiac variant phenotype does not typically result in Gb3 accumulation in the kidney and skin, and accordingly we do not expect that data obtained from this patient will have a meaningful impact on certain efficacy endpoints in our FAB-GT clinical trial, including kidney and skin biopsies. Nonetheless, there may be other important insights derived from data collected from this patient in the FAB-GT clinical trial. In addition, although a kidney biopsy was performed on the third patient in the FAB-GT clinical trial, as a result of human error in processing the biopsy sample at the external laboratory vendor, the kidney Gb3 inclusions could not be evaluated and will not be available. However, we expect to continue collecting other data from the third patient, including measures of kidney function such as estimated glomerular filtration rate and measured glomerular filtration rate.  

In addition, we have not yet conducted any company-sponsored clinical trials of any of our product candidates in the United States, and our interactions with the FDA have generally been limited. We cannot be certain how many additional clinical trials of AVR-RD-01, AVR-RD-04, AVR-RD-02 or any other product candidates will be required or how such trials should be designed. In order to commence a clinical trial in the United States, we are required to seek FDA acceptance of an IND for each of our product candidates. We cannot be sure any IND we submit to the FDA, or any similar clinical trial application we submit in other countries, will be accepted. While we have received clearance from the FDA to commence clinical testing in the United States for AVR-RD-01 and AVR-RD-02, and the sponsor of the investigator-led clinical trial for AVR-RD-04 has received the same, there can be no assurance that we will be able to submit and secure similar clearances for any of our other product candidates. We may also be required to conduct additional preclinical testing prior to filing an IND for any of our product candidates, and the results of any such testing may not be positive. Consequently, we may be unable to successfully and efficiently execute and complete necessary clinical trials in a way that leads to a BLA submission and approval of any of our product candidates. We may require more time and incur greater costs than our competitors and may not succeed in obtaining regulatory approvals of product candidates that we develop. Failure to commence or complete, or delays in, our planned clinical trials, could prevent us from or delay us in commercializing any of our product candidates.

The ongoing Phase 1 clinical trial of AVR-RD-01 is an investigator-sponsored trial being conducted by University Health Network, and the ongoing Phase 1/2 clinical trial of AVR-RD-04 is also an investigator-sponsored clinical trial, which is being conducted by our collaborators at the University of California, San Diego. In addition, the planned Phase 1/2 clinical trial of AVR-RD-05 will be an investigator-sponsored trial conducted by our collaborators at The University of Manchester. We do not control the design or administration of investigator-sponsored trials, nor the submission or approval of any IND or foreign equivalent required to conduct these trials, and the investigator-sponsored trials could, depending on the actions of such third parties, jeopardize the validity of the clinical data generated, identify significant concerns with respect to our product candidates that could impact our findings or clinical trials, and adversely affect our ability to obtain marketing approval from the FDA or other applicable regulatory authorities. To the extent the results of this or other investigator-sponsored trials are inconsistent with, or different from, the results of our planned Company-sponsored trials or raise concerns regarding our product candidates, the FDA or a foreign regulatory authority may question the results of the Company-sponsored trial, or subject such results to greater scrutiny than it otherwise would. In these circumstances, the FDA or such foreign regulatory authorities may require us to obtain and submit additional clinical data, which could delay clinical development or marketing approval of our product candidates. In addition, while investigator-sponsored trials could be useful to inform our own clinical development efforts, there is no guarantee that we will be able to use the data from these trials to form the basis for regulatory approval of our product candidates.

Success in preclinical studies or early clinical trials may not be indicative of results obtained in later trials.

Results from preclinical studies or early clinical trials are not necessarily predictive of future clinical trial results and are not necessarily indicative of final results. For example, there can be no assurance that prior results, such as signals of safety, activity or durability of effect, observed from preclinical studies or clinical trials will be replicated or will continue in ongoing or future studies or trials. Furthermore, preliminary results may not be indicative of the final results of a trial after all data have been collected and analyzed. There is a high failure rate for gene therapy and biologic product candidates proceeding through clinical trials. Many companies in the pharmaceutical and biotechnology industries have suffered significant setbacks in late-stage clinical trials even after achieving promising results in preclinical testing and earlier-stage clinical trials. Data obtained from preclinical and clinical activities are subject to varying interpretations, which may delay, limit or prevent regulatory approval. In addition, the design of a pivotal clinical trial can determine whether its results will support approval of a product and flaws in the design of a clinical trial may not become apparent until the clinical trial is well advanced. Our Company has limited experience in designing and conducting clinical trials and we may be unable to design and execute a clinical trial to support regulatory approval.

We also may experience regulatory delays or rejections as a result of many factors, including due to changes in regulatory policy or the approval of competitive therapies during the period of our product candidate development. Any of our current or future product candidates may fail to show the desired safety and efficacy in clinical development despite positive results in preclinical studies. Any such failure would cause us to abandon the product candidate.

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Additionally, the clinical trials performed to date have been open-label studies and have been conducted at a limited number of clinical sites on a limited number of patients. An “open-label” clinical trial is one where both the patient and investigator know whether the patient is receiving the investigational product candidate or either an existing approved drug or placebo. Most typically, open-label clinical trials test only the investigational product candidate and sometimes may do so at different dose levels. Open-label clinical trials are subject to various limitations that may exaggerate any therapeutic effect as patients in open-label clinical trials are aware when they are receiving treatment. Open-label clinical trials may be subject to a “patient bias” where patients perceive their symptoms to have improved merely due to their awareness of receiving an experimental treatment. Moreover, patients selected for early clinical studies often include the most severe sufferers and their symptoms may have been bound to improve notwithstanding the new treatment. In addition, open-label clinical trials may be subject to an “investigator bias” where those assessing and reviewing the physiological outcomes of the clinical trials are aware that patients have received treatment and may interpret the information more favorably given this knowledge. Because our clinical trials are ongoing, the data that we report are preliminary and subject to change. As is typical in open-label studies in which interim reports are provided, the safety and efficacy data are regularly reviewed and validated. As a result, certain data may change over time, including reductions or increases in the number of reported safety events, until the database is locked at the end of the study.

We may find it difficult to enroll patients in our clinical trials, which could delay or prevent us from proceeding with clinical trials of our product candidates.

Although we expect to have dosed an aggregate of 20 to 25 patients across all our clinical programs by the end of 2021, there can be no assurance we will achieve that goal. The timing and success of our patient enrollment and clinical trial activities depend on our ability to recruit patients to participate as well as the completion of required follow-up periods. Patients may be unwilling to participate in our gene therapy clinical trials because of negative publicity from adverse events related to the biotechnology or gene therapy fields, such as the recent announcement from a lentiviral gene therapy company regarding cases of transfusion-dependent anemia and acute myeloid leukemia in its clinical trials for sickle cell disease, competitive clinical trials for similar patient populations, clinical trials in product candidates employing our vectors, the existence of current treatments or for other reasons. In addition, the indications that we are currently targeting and may in the future target are rare diseases, which may limit the pool of patients that may be enrolled in our ongoing or planned clinical trials. The timeline for recruiting patients, conducting studies and obtaining regulatory approval of our product candidates may be delayed, including as a result of the ongoing COVID-19 pandemic, which could result in increased costs, delays in advancing our product candidates, delays in testing the effectiveness of our product candidates or termination of the clinical trials altogether. For example, as a result of the COVID-19 pandemic, patient enrollment and dosing was temporarily paused in our ongoing clinical trials and certain data collection has been delayed. While patient enrollment and dosing activities have begun to resume, there could be additional pauses in the future as a result of the COVID-19 pandemic or other factors.

We may not be able to identify, recruit and enroll a sufficient number of patients, or those with required or desired characteristics, to complete our clinical trials in a timely manner. For example, in 2017, the ongoing investigator-sponsored Phase 1 clinical trial of AVR-RD-01 encountered delays in the enrollment of patients due to delays in identifying patients for enrollment and the evaluation of information from screened potential trial participants. In 2019, we encountered delays in the enrollment of patients in the Company-sponsored Phase 1/2 clinical trial of AVR-RD-02 for Gaucher disease, which we refer to as the Guard1 clinical trial. While a number of patients had been identified for the Guard1 clinical trial, we encountered patient pre-screening failures that impacted the commencement of enrollment. Additionally, as a result of the COVID-19 pandemic, in 2020 we encountered protracted timelines with our Guard1 investigational site startup activities, which also impacted patient enrollment.

Patient enrollment and trial completion is affected by factors including the: