Flexion Therapeutics, Inc. recently announced updated interim findings from its ongoing Phase 3b, open-label study to evaluate the overall safety and general tolerability of repeat administration of ZILRETTA (triamcinolone acetonide extended-release injectable suspension) in patients with osteoarthritis (OA) of the knee. The data was presented during a poster session on Friday, April 27 at the Osteoarthritis Research Society International (OARSI) 2018 World Congress in Liverpool, England.

Flexion previously reported top line results indicating that 95% (195/205) of evaluable patients in the study experienced clinical benefit by Week 12, following the initial injection of ZILRETTA, as determined by self-assessment and with the agreement of their physician, and 92% (179/195) received a second dose between Weeks 12 and 24. The new data presented at OARSI build on these results and demonstrate:
-The average time to administration of the second administration of ZILRETTA was 16.6 weeks;

-74% of patients received their second administration of ZILRETTA between Weeks 16 and 24;

-The magnitude and duration of pain relief based on WOMAC1-A (pain) from  the initial injection of ZILRETTA are in line with those observed in the pivotal Phase 3 trial with the exploratory WOMAC-A measure;

-By Week 4, the first post-treatment assessment time point, patients experienced a 64% improvement in WOMAC-A (pain), a 66% improvement in WOMAC-B (stiffness), a 64% improvement on WOMAC-C (function), and improvement represented by a doubling of the KOOS2 Quality of Life subscale score. These responses were maintained in a substantial proportion of patients through Week 12.

The study enrolled a broad population of “real-world” patients with knee OA, including a significant percentage of patients who were previously treated with intra-articular corticosteroids (51.9%) and/or intra-articular hyaluronic acid therapy (17.3%) and individuals classified as Kellgren-Lawrence Grade 4 (30.3%), which is the most radiographically severe form of OA.

“These results demonstrate ZILRETTA’s ability to provide deep and sustained relief to a patient population that reflects real-world clinical experience,” said Michael Clayman, MD, President and Chief Executive Officer of Flexion. “In particular, we are delighted to see an average time to second administration of greater than 16 weeks, which is especially notable given the high proportion of patients in this study with the most advanced stage of OA.”

The primary endpoint of the trial is overall safety and general tolerability of repeat administration of ZILRETTA in patients with symptomatic OA of the knee. Participants received an initial intra-articular injection of ZILRETTA followed by evaluation at Weeks 12, 16, 20 or 24 to determine their eligibility for a second injection. Repeat administration occurred when, in the opinion of the patient and physician, the patient benefited from and tolerated the initial administration without safety concerns and was clinically indicated to receive additional treatment.

Participants who received repeat administration of ZILRETTA are followed for a total of 52 weeks after the initial injection, regardless of when the second injection is administered. At specified times throughout the trial, participants undergo physical examinations, knee assessments and X-rays.

As of April 5, 2018, (minimum follow-up of 11 weeks post second injection), ZILRETTA has been well tolerated, no drug-related serious adverse events have been observed, and the overall safety profile is similar to that observed in the single injection pivotal Phase 3 trial. The full study results are expected in the third quarter of 2018.

Flexion Therapeutics 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, a type of degenerative arthritis. The company’s core values are focus, ingenuity, tenacity, transparency and fun.