NRD.E1, an innovative non-opioid therapy for painful diabetic peripheral neuropathy—A randomized proof of concept study

Abstract

Background: Painful diabetic peripheral neuropathy (PDPN) affects up to 26% of patients with diabetes mellitus, with major impacts on their general health and well-being. Most available drugs fail to deliver acceptable pain reduction in the majority of patients and are often poorly tolerated. NRD.E1 is a novel product that has shown anti-nociceptive preclinical effects and good tolerability in healthy volunteer studies. Methods: This phase 2a, randomized, dose-finding, Proof of Concept study enrolled patients with PDPN of ≥3 months duration. After at least one treatment-free week (WO week), 88 patients entered a 1-week single-blind (SB)-placebo run-in period, followed by 3 weeks' double-blind (DB) treatment, during which they received NRD.E1 at 10, 40 or 150 mg/day or placebo. Results: The primary endpoint (change from SB-placebo run-in week to week 3 in weekly mean of daily average numerical rating scale [NRS] pain intensity) showed clinically relevant placebo-corrected treatment effect pain reductions at 40 mg and 150 mg/day of 0.82 (95% CI: 0.07, 1.58, p = 0.034) and 0.66 (95% CI: −0.03, 1.35; p = 0.061) NRS points, respectively, though did not meet the pre-specified value of p = 0.016 required due to multiplicity. An additional post hoc endpoint looking at the change from WO baseline to week 3 in weekly mean of daily average NRS showed the placebo-corrected treatment effect was 1.46 (95% CI: 0.26, 2.66), and 1.20 (95% CI: 0.10, 2.29) NRS points, respectively. Secondary and post hoc analyses of NRS pain data (including 30 & 50% responder rate and NNT), sleep interference, Short-form McGill pain questionnaire (especially pain intensity assessed on Visual Analogue Scale), Patient's and Clinician's Global Impression of Change showed effects consistent with the primary findings. NRD.E1 was well tolerated, with only headache reported in more than two patients and more frequently on NRD.E1 than placebo. Conclusions: The data suggest that NRD.E1 potentially represents a novel non-opioid therapeutic option for patients with PDPN, with at least similar efficacy and better tolerability than available therapies, justifying its further evaluation in larger-scale confirmatory studies. Significance: NRD.E1 is a novel non-opioid therapeutic which is being developed for the treatment of PDPN. In this randomized, controlled, dose-finding, Proof of Concept study, NRD.E1 induced a clinically relevant pain reduction and it was well tolerated. Available data suggest that NRD.E1 has at least similar efficacy and better tolerability than the currently available therapies, potentially offering a promising new therapeutic option to patients with PDPN and possibly other neuropathic pain indications.