Post-hoc analysis of Phase III trial of Zilretta to treat osteoarthritis knee pain

Flexion Therapeutics, Inc.announced that the results from a post-hoc analysis of data from the pivotal Phase III trial of Zilretta (triamcinolone acetonide extended-release injectable suspension) were published in Advances in Therapy. The findings indicated that patients with unilateral osteoarthritis (OA) knee pain experienced significant and durable pain relief with a single intra-articular injection of Zilretta compared to immediate-release triamcinolone acetonide in crystalline suspension (TAcs), as measured by Average Daily Pain (ADP) intensity scores. The analysis also indicated that Zilretta patients in this subgroup experienced improvements on OA-specific measures of pain, stiffness, function, and quality of life scores that lasted up to six months. The objective of the analysis was to characterize the primary endpoint of the trial, change in ADP, within a subgroup of randomized patients with unilateral OA knee pain. The analysis showed that patients in this subgroup who were treated with Zilretta experienced a profound magnitude of analgesic effect, with ADP scores that were reduced by >60% at Week 3-17. These results suggest that bilateral knee pain may have been a confounding factor in the pivotal trial, which assessed the impact of Zilretta treatment in only one knee.

Key topline results from the post-hoc analysis of the Phase III study : A single intra-articular injection of Zilretta provided significant improvement in pain at Week 12 compared with placebo (P<0.0001) and TAcs (P<0.01) to patients with unilateral knee OA, as measured by ADP-intensity scores;Zilretta provided participants with unilateral knee OA improvements in WOMAC-A (pain), WOMAC-B (stiffness), WOMAC-C (physical function), and quality of life scores (KOOS-QoL) at Weeks 4, 8, and 12 (measured through standardized, verified instruments; P<0.05 for all instruments) compared with TAcs and up to six months compared with placebo (P<0.05); Patients treated with Zilretta used less rescue medication for pain compared with both the placebo and TAcs groups; and Adverse events (AEs) were similar in frequency across treatment groups, with most AEs reported as mild or moderate and unrelated to the study agent.