Flexion submits supplemental NDA for ZILRETTA

Flexion Therapeutics announced it submitted a supplemental new drug application to the U.S. Food and Drug Administration to revise the product label for ZILRETTA. The sNDA is based on data from an open-label Phase 3b clinical trial, which indicated that repeat administration of ZILRETTA for treatment of osteoarthritis knee pain was safe and well tolerated with no deleterious impact on cartilage or joint structure observed through X-ray analysis. The primary endpoint of the Phase 3b single-arm, open-label trial was the safety and tolerability of repeat administration of ZILRETTA in patients with symptomatic OA of the knee. The patients enrolled in the study generally had longstanding and extensive disease, with more than two-thirds of the participants presenting with Kellgren-Lawrence Grade 3 or Grade 4, the most radiographically severe form of OA. Participants received an initial intra-articular injection of ZILRETTA followed by evaluation at Weeks 12, 16, 20 and 24 to determine their eligibility for a second injection. In the trial, 95% of patients experienced clinical benefit after initial injection of ZILRETTA and 92% of these patients received a second injection on or after Week 12. The median time to a second injection was 16.6 weeks, with 74% of patients receiving their second administration of ZILRETTA between Weeks 16 and 24. There were no serious adverse events related to ZILRETTA reported during the trial, and the patterns of treatment emergent adverse events were consistent with those reported in previous clinical studies of ZILRETTA. An analysis of X-rays taken at baseline and Week 52 showed no harmful effects on cartilage or joint structure, as no incidences of chondrolysis, osteonecrosis, insufficiency fractures or clinically significant subchondral bone changes were observed. The trial also indicated that the magnitude and duration of pain relief experienced by patients after both the first and second injections was similar to results from the pivotal Phase 3 trial.

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