Flexion Therapeutics Announces Presentation of Preliminary FX201 Clinical Data at the Upcoming 2021 American Society of Gene & Cell Therapy (ASGCT) Annual Meeting

• Findings from a Phase 1 single ascending dose trial indicate the low dose of FX201, an intra-articular gene therapy candidate for osteoarthritis (OA), was generally well-tolerated
• Two of five patients (40%) treated with FX201 in the low-dose, single ascending dose cohort reported substantial improvement in pain out to Week 24
• No evidence of systemic biodistribution of FX201 in plasma or shedding in urine or at the injection site was observed in any patient
• Longer term follow-up data from the low-dose cohort will be presented at ASGCT on May 11

BURLINGTON, Mass., April 28, 2021 (GLOBE NEWSWIRE) -- Flexion Therapeutics, Inc. (Nasdaq:FLXN) will present preliminary data from a Phase 1 single ascending dose (SAD) trial of FX201 at the 2021 American Society of Gene & Cell Therapy (ASGCT) annual meeting taking place virtually May 11-14, 2021.

“We are pleased to share preliminary clinical data from our FX201 single ascending dose trial at the American Society of Gene & Cell Therapy annual meeting,” said Michael Clayman, M.D., President and Chief Executive Officer of Flexion. “While the Phase 1 SAD study is principally designed to evaluate the safety and tolerability of FX201, it is encouraging to see an early signal of clinical activity in the low-dose cohort with two of the five patients treated reporting substantial pain relief that lasted through at least Week 24. We look forward to providing updated data from this cohort at ASGCT on May 11.”

The clinical data will be presented in a digital presentation entitled, Interim Data from the First-in-Human Phase 1 Trial of FX201, An Intra-Articular, Helper-Dependent Adenoviral Gene Therapy for Osteoarthritis - Safety, Tolerability, Biodistribution, and Preliminary Evaluation of Clinical Activity in 5 Patients (Abstract 594). Key findings included in the ASCGT abstract:

• FX201 was generally well-tolerated in the initial low-dose cohort.
  • Two patients had self-limited Grade 2 index-knee AEs (pain, swelling, effusion) possibly related to treatment, managed conservatively.
• No evidence of systemic biodistribution of FX201 in plasma or shedding in urine or at the injection site was observed in any patient, indicating that the vector remained in the encapsulated joint space.
• Based on IMMPACT¹ criteria, two out of the five patients (40%) demonstrated substantial improvement in knee OA pain at Weeks 8, 12, and 24 following treatment with FX201.

Flexion will present longer term follow-up data from the low-dose cohort in a video presentation available on the ASGCT website at the start of the conference on May 11.

About FX201
FX201 is an investigational gene therapy which utilizes a helper-dependent adenovirus (HDAd) vector devoid of all viral genes that carries a coding sequence for an anti-inflammatory protein called interleukin-1 receptor antagonist (IL-1Ra) under the control of an inflammation-responsive promoter. FX201 is injected directly into the joint space (also termed the intra-articular space) and is intended to deliver as-needed anti-inflammatory activity to joint tissues, with the goal of providing at least 6 to 12 months of meaningful pain relief and functional improvement following a single injection with the possibility of slowing disease progression.

About Flexion Therapeutics
Flexion Therapeutics (Nasdaq:FLXN) is a biopharmaceutical company focused on the development and commercialization of novel, local therapies for the treatment of patients with musculoskeletal conditions, beginning with OA, the most common form of arthritis. The company's core values are focus, ingenuity, tenacity, transparency, and fun. Please visit flexiontherapeutics.com.

Forward-Looking Statements
This press release contains forward-looking statements that are based on the current expectations and beliefs of Flexion. Statements in this press release regarding matters that are not historical facts, including, but not limited to, statements relating to the future of Flexion; timing and plans with respect to the Phase 1 clinical trial of FX201; and the potential therapeutic and other benefits of FX201, are forward-looking statements. These forward-looking statements are based on management’s expectations and assumptions as of the date of this press release and are subject to numerous risks and uncertainties, which could cause actual results to differ materially from those expressed or implied by such statements. These risks and uncertainties include, without limitation, the fact that the impacts and expected duration of the COVID-19 pandemic are uncertain and rapidly changing; the risk that we may not be able to maintain and enforce our intellectual property, including intellectual property related to FX201; risks related to clinical trials, including potential delays, safety issues, or negative results; the fact that future results may not be consistent with preliminary results or results from prior studies or trials; and other risks and uncertainties described in our filings with the Securities and Exchange Commission (SEC), including under the heading “Risk Factors” in our Annual Report on Form 10-K for the year ended December 31, 2020, filed with the SEC on March 10, 2021, and subsequent filings with the SEC. The forward-looking statements in this press release speak only as of the date of this press release, and we undertake no obligation to update or revise any of the statements. We caution investors not to place considerable reliance on the forward-looking statements contained in this press release.

Contacts:

Scott Young
Vice President, Corporate Communications & Investor Relations
Flexion Therapeutics, Inc.
T: 781-305-7194
[e-mail]

Julie Downs
Associate Director, Corporate Communications & Investor Relations
Flexion Therapeutics, Inc.
T: 781-305-7137
[e-mail]

1. The Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) recommended that six core outcome domains should be considered when designing chronic pain clinical trials. These six core outcome domains were: (1) pain; (2) physical functioning; (3) emotional functioning; (4) participant ratings of improvement and satisfaction with treatment; (5) symptoms and adverse events; and (6) participant disposition.