Flexion Therapeutics Reports Results from Pivotal Phase 2b, 3 Trials for Zilretta

Results from two Flexion Therapeutics, Inc.

sponsored pivotal clinical trials showed that its lead drug candidate Zilretta (also known as FX006) provided sustained and significant pain relief in patients with moderate to severe osteoarthritis (OA) knee pain. Professor Philip Conaghan, M.B., B.S., Ph.D., F.R.A.C.P., F.R.C.P., Chair of Musculoskeletal Medicine at the University of Leeds, presented the results at the OARSI 2016 World Congress in Amsterdam in a podium presentation that is available at http://flexiontherapeutics.com/programs-pipeline/scientific-publications. Following the presentation Professor Conaghan said, "Consistent results across two pivotal clinical trials with Zilretta suggest that, at last, we have a long-lasting intra-articular therapy that is highly effective and has the potential to change the treatment paradigm for osteoarthritis." "We are delighted to be able to now share the detailed data from these studies which clearly demonstrate clinically meaningful and statistically significant pain relief in patients with knee OA. In addition, we are especially gratified by the Phase 3 data that demonstrate clear differentiation of Zilretta from immediate-release TCA," said Michael Clayman, M.D., Flexion Therapeutics' President and CEO. "Based on these data we have scheduled a pre-New Drug Application (NDA) meeting in May with the U.S. Food and Drug Administration (FDA) with the intent to gain the Agency's endorsement to submit an NDA in the second half of 2016." The Phase 3 trial was a randomized, double-blind, placebo-controlled, active-comparator trial that enrolled 486 patients at approximately 40 centers worldwide. Patients were randomized to one of three treatment groups (1:1:1) and received either a single intra-articular injection of 40 mg of Zilretta, normal saline (placebo) or 40 mg of immediate-release TCA. Each patient was evaluated for efficacy and safety during seven outpatient visits over 24 weeks after receiving an injection. The primary objective of the study was to assess the magnitude of pain relief of Zilretta at 12 weeks against placebo as measured by the weekly mean of the average daily pain (ADP) score. The secondary objectives of the study assessed the magnitude and duration of pain relief and effect of Zilretta against placebo and immediate-release TCA in additional pre-specified measures. Phase 3 study data from the OARSI podium presentation and from additional company analyses are summarized below and posted to the Flexion website at http://flexiontherapeutics.com/programs-pipeline/scientific-publications. In the Phase 3 study, Zilretta: Met its primary endpoint at week 12, demonstrating highly significant (p < 0.0001, 2-sided) and clinically meaningful pain relief against placebo as measured by the weekly mean of the ADP score. Achieved statistically significant pain relief against placebo as measured by the weekly mean of the ADP score at weeks 1 through 16 and demonstrated, on average, an approximately 50 percent reduction in pain from baseline over weeks 1 through 12. Achieved numerically superior pain relief against immediate-release TCA at weeks 2 through 12 as measured by the weekly mean of the ADP score, but did not achieve statistical significance in that measure. Achieved statistical significance against placebo and immediate-release TCA at each time point through 12 weeks on WOMAC A (pain), WOMAC B (stiffness) and WOMAC C (function) and the Knee injury and Osteoarthritis Outcome Score (KOOS) quality of life subscale. Demonstrated in a pre-specified subset analysis of patients with unilateral knee pain (35 percent of subjects in the study), substantially magnified effects in the weekly mean of the ADP score, WOMAC A, B and C and KOOS quality of life and significantly enhanced separation from placebo and immediate-release TCA in all of these measures. Demonstrated reduced rescue medicine consumption compared with placebo and immediate-release TCA. The Phase 3 data were also evaluated for clinical relevance by applying established AAOS criteria. In its 2013 publication, "Evidence-Based Guideline: Treatment of Osteoarthritis of the Knee," the AAOS comprehensively reviewed the available literature on existing treatments and determined a minimal relative improvement in WOMAC A, B and C measures that would be meaningful to patients. This is referred to as the Minimal Clinically Important Improvement (MCII). The Phase 3 data show that Zilretta exceeds the MCII in WOMAC A, B and C and thus demonstrates a clinically important effect, whereas immediate-release TCA in this study does not. The Phase 2b trial enrolled 310 participants in a multi-center, randomized, double-blind study, in which the participants received an injection of either 40 mg or 20 mg of FX006, or a placebo (saline). The 40 mg arm of Zilretta, compared to placebo, demonstrated statistical significance in average pain relief over weeks 1 through 12 (p = 0.0012; 2-sided) and over weeks 1 through 24 (p = 0.0209; 2-sided). At weekly time points, 40 mg of Zilretta also demonstrated superiority to placebo in pain relief beginning at week 1, continuing to week 11 and also at week 13 (p < 0.05 at each time point; 2-sided). The primary endpoint of the trial, superiority in pain relief at 12 weeks, did not reach statistical significance (p = 0.0821; 2-sided). A pre-specified, commonly applied sensitivity analysis (Baseline Observation Carried Forward/Last Observation Carried Forward (BOCF/LOCF)) that addresses patient dropouts, however, did demonstrate statistical significance for the primary endpoint at 12-weeks (p = 0.042). Across both the Phase 2b and Phase 3 studies, there were no drug related serious adverse events for Zilretta and the frequency of treatment-related side effects was comparable across all study arms. Conference Call Flexion's management will host a conference call today at 9:00 a.m. EDT. The dial-in number for the conference call is (855) 770-0022 for domestic participants and (908) 982-4677 for international participants, with Conference ID # 84943960. A live webcast of the conference call can also be accessed through the "Investors" tab on the Flexion Therapeutics website. A webcast replay will be available online after the call.