Efficacy and Safety of LX9211 for Relief of Diabetic Peripheral Neuropathic Pain (RELIEF-DPN 1): Results of a Double-Blind, Randomized, Placebo-Controlled, Proof-of-Concept Study

OBJECTIVE To evaluate the efficacy of LX9211 in reducing pain related to diabetic peripheral neuropathy. RESEARCH DESIGN AND METHODS In this double-blind, multicenter, proof-of-concept trial, 319 individuals with diabetic peripheral neuropathic pain (DPNP) were randomized (1:1:1) to LX9211 10 mg (n = 106), LX9211 20 mg (n = 106), or matching placebo (n = 107), administered once daily for 6 weeks. DPNP was rated daily with an 11-point numerical rating scale. The primary end point was change from baseline to week 6 in the average daily pain score. The difference between each LX9211 group and placebo was evaluated with mixed-model re-peated-measures analysis. RESULTS For those on low-dose LX9211 the primary efficacy end point was achieved: 21.39 vs. 20.72 points for placebo, least squares mean (SE) difference 20.67 (0.249), 95% CI 21.16 to 20.18, P = 0.007; results for high-dose LX9211 demonstrated improvement in pain severity versus placebo (21.27 vs. 20.72 points, respectively), but the between-group LS mean difference did not reach the prespecified statistical signifi-cance (20.55 [0.254], 95% CI 21.06 to 20.05, P = 0.030). Treatment benefit was ob-served beginning at week 1 and maintained thereafter. Results for LX9211 also demonstrated improvement in several patient-reported secondary outcomes. Most common adverse events (AEs) were dizziness, nausea, and headache. More participants treated with LX9211 (20 mg, n = 28 [26.4%]; 10 mg, 17 [16.0%]) than placebo (3 [2.8%]) discontinued study drug prematurely due to AEs; serious AEs were uncom-mon (2 [1.9%], 0, and 1 [0.9%], respectively). CONCLUSIONS These preliminary findings of improvement in DPNP with LX9211 support further investigation in larger trials.