AVROBIO, Inc. Announces FDA Clearance of Investigational New Drug Application for AVR-RD-01 Gene Therapy for the Treatment of Fabry Disease

The plato™ platform represents a significant advance towards a
commercial-stage gene therapy solution designed to treat thousands of
patients

AVROBIO to incorporate U.S. clinical sites into its ongoing global
FAB-201 Phase 2 clinical trial in Fabry disease

CAMBRIDGE, Mass.–(BUSINESS WIRE)–AVROBIO,
Inc. (NASDAQ: AVRO) (the “Company”), a Phase 2 clinical-stage gene
therapy company, today announced that the U.S. Food and Drug
Administration (FDA) has cleared the Company’s Investigational New Drug
(IND) application for AVR-RD-01, its gene therapy candidate for the
treatment of Fabry disease. The Company now expects to move forward on
two key initiatives in its Fabry clinical program: the incorporation of
AVROBIO’s plato™ platform into its FAB-201 Phase 2 trial, and the dosing
of patients at clinical sites in the U.S. The plato platform consists of
a state-of-the-art four-plasmid vector system, automation of a closed
cell manufacturing process and a conditioning regimen that utilizes
therapeutic drug monitoring (TDM).

“We are very pleased that FAB-201 remains on track to expand into sites
in the U.S in the second half of 2019,” said Geoff
MacKay, President and CEO of AVROBIO. “Importantly, we believe this
U.S. FDA clearance represents a major milestone as we transition to
plato, our optimized commercial-scale platform for our anticipated
future worldwide commercialization activities. We have now achieved
initial regulatory clearances for clinical trials in Australia, Canada
and the U.S. which incorporate our plato platform.”

Clinical data presented at WORLDSymposium in February 2019
continued to support the potential of AVR-RD-01 as a gene therapy for
Fabry disease. A total of 7 patients have been dosed with AVR-RD-01
across the investigator-sponsored Phase 1 clinical study and FAB-201,
the Phase 2 clinical trial of AVR-RD-01 in Fabry disease, which is
currently underway in Australia. The Company plans to provide additional
preliminary clinical data from these trials this summer.

About AVR-RD-01

AVR-RD-01
is an ex vivo lentiviral gene therapy candidate being investigated as a
single-dose therapy with the potential to provide durable and
potentially life-long therapeutic benefit for patients with Fabry
disease. AVR-RD-01 is designed to employ a state-of-the-art lentiviral
vector system that is an efficient gene transfer technology for the
permanent integration of functional copies of the gene into the
patient’s own stem cells. In patients with Fabry disease, hematopoietic
stem cells are collected from the patient, and then transduced with
lentiviral vector carrying a functional version of the GLA gene that
encodes active α-galactosidase A (AGA) – the enzyme that is deficient in
Fabry disease – to create AVR-RD-01 gene therapy. AVR-RD-01 is then
infused back into the patient with the goal of restoring normal GLA gene
expression such that functional AGA enzyme is sufficiently produced by
the patient’s own body.

About FAB-201

FAB-201 is an open-label, multinational study of the efficacy and safety
of AVR-RD-01 in approximately 8 to 12 treatment-naïve males, aged 16
years and older, with classic Fabry disease. The subjects will have a
confirmed diagnosis of classic Fabry disease based on deficient AGA
enzyme activity who have not yet received treatment with enzyme
replacement therapy (ERT) within the past ten years and/or chaperone
therapy at the time of screening.

The study will expand into the U.S. in the second half of 2019 and
includes five study periods: Screening, Baseline, Pre-transplant,
Transplant, and Post-transplant Follow-up at 48 weeks. Patients will
undergo a conditioning regimen administration with busulfan
intravenously for four days to achieve myeloablation prior to the
transplant. After study completion, consenting subjects will continue
periodic safety and efficacy assessments for approximately 14 years, for
a total of 15 years post-transplant follow-up.

About the plato™ platform

The plato
platform, AVROBIO’s commercial-scale platform for anticipated future
worldwide commercialization and pipeline expansion activities, consists
of a proprietary state-of-the-art four-plasmid vector system, automation
of a closed cell manufacturing process and a conditioning regimen that
utilizes therapeutic drug monitoring (TDM). The plato platform is
designed to enhance the potency, safety, efficacy, and long-term
durability of AVROBIO’s gene therapies, and may additionally provide the
capability to address central nervous system (CNS) manifestations that
accompany many lysosomal storage diseases. The platform is additionally
being incorporated in the planned Phase 1/2 clinical trial of AVR-RD-02
(GAU-201) in Canada and Australia. That trial is expected to begin in
the second half of 2019.

About AVROBIO, Inc.

AVROBIO,
Inc., is a Phase 2 clinical-stage gene therapy company developing
gene therapies to potentially cure rare diseases with a single dose.
AVROBIO’s lentiviral-based gene therapies employ hematopoietic stem
cells that are collected from the patient and then modified with a lentiviral
vector to insert a functional copy of the gene that is defective in the
target disease. AVROBIO is focused on the development of its gene
therapy, AVR-RD-01, in Fabry
disease, as well as additional gene therapy programs in other lysosomal
storage disorders including Gaucher
disease, Cystinosis and
Pompe disease. AVROBIO is
headquartered in Cambridge, MA and has offices in Toronto, ON. For
additional information, visit www.avrobio.com.

Forward-Looking Statements

This press release contains forward-looking statements, including
statements made pursuant to the safe harbor provisions of the Private
Securities Litigation Reform Act of 1995. These statements may be
identified by words such as “aims,” “anticipates,” “believes,” “could,”
“estimates,” “expects,” “forecasts,” “goal,” “intends,” “may,” “plans,”
“possible,” “potential,” “seeks,” “will,” and variations of these words
or similar expressions that are intended to identify forward-looking
statements. These forward-looking statements include, without
limitation, statements regarding our business strategy, prospective
products and goals, the therapeutic potential of our product candidates,
anticipated benefits of our gene therapy platform including potential
impact on our commercialization and pipeline expansion activities, the
design, commencement, enrollment and timing of ongoing or planned
clinical trials, and the timing, scope and likelihood of regulatory
filings and approvals. Any such statements in this press release that
are not statements of historical fact may be deemed to be
forward-looking statements. Results in preclinical or early stage
clinical trials may not be indicative of results from later stage or
larger scale clinical trials and do not ensure regulatory approval. You
should not place undue reliance on these statements, or the scientific
data presented.

Any forward-looking statements in this press release are based on
AVROBIO’s current expectations, estimates and projections about our
industry as well as management’s current beliefs and expectations of
future events only as of the date of this release and are subject to a
number of risks and uncertainties that could cause actual results to
differ materially and adversely from those set forth in or implied by
such forward-looking statements. These risks and uncertainties include,
but are not limited to, the risk that any one or more of AVROBIO’s
product candidates will not be successfully developed or commercialized,
the risk of cessation or delay of any ongoing or planned clinical trials
of AVROBIO or our collaborators, the risk that AVROBIO may not realize
the intended benefits of our gene therapy platform, including the
features of our plato platform, the risk that our product candidates or
procedures in connection with the administration thereof will not have
the safety or efficacy profile that we anticipate, the risk that prior
results, such as signals of safety, activity or durability of effect,
observed from preclinical or clinical trials, will not be replicated or
will not continue in ongoing or future studies or trials involving
AVROBIO’s product candidates and the risk that we will be unable to
obtain and maintain regulatory approval for our product candidates. For
a discussion of these and other risks and uncertainties, and other
important factors, any of which could cause AVROBIO’s actual results to
differ materially and adversely from those contained in the
forward-looking statements, see the section entitled “Risk Factors” in
AVROBIO’s Annual Report on Form 10-K for the fiscal year ended December
31, 2018, as well as discussions of potential risks, uncertainties and
other important factors in AVROBIO’s subsequent filings with the
Securities and Exchange Commission. AVROBIO explicitly disclaims any
obligation to update any forward-looking statements except to the extent
required by law.

Contacts

Investor:
Christopher F. Brinzey
Westwicke Partners
339-970-2843
[email protected]

Media:
Kathryn Morris
The Yates Network
914-204-6412
[email protected]