A phase III double blinded, placebo controlled, randomized trial of gabapentin in patients with chemotherapy-induced peripheral neuropathy: A North Central Cancer Treatment Group study

Abstract

8001 Background: The purpose of this study was to determine if gabapentin, an anti-convulsant used for neuropathic pain, is effective in improving pain and symptoms due to chemotherapy-induced peripheral neuropathy. Methods: 115 patients with chemotherapy-induced peripheral neuropathy (for ≥1 month, with average pain rating of ≥4/10 or ECOG sensory neuropathy ≥1/3) were randomized in this double-blind, placebo-controlled trial to either: 1) gabapentin (target dose=900 mg TID) for 6 weeks then cross-over to placebo for 6 weeks (n=57) or 2) treatment in the reverse order (n=58). A 2-week washout occurred between cross over treatments. The co-primary endpoints were the average daily pain numerical analogue intensity rating (0=no pain to 10=worst pain imaginable) and the ECOG toxicity rating for sensory neuropathy (0=none to 3=severe). The study was designed for 100 total patients, providing 80% power to detect an average pain score difference of 0.58 standard deviations (a moderate effect size) using a two-sided t-test with 0.05 Type I error rate. Results: Gabapentin did not significantly improve the co-primary endpoints of pain intensity (-0.5 versus -1.0 change from baseline to week 6 for patients on gabapentin and placebo respectively, p=0.18) or the ECOG toxicity rating for sensory neuropathy (-0.2 versus -0.1 for gabapentin and placebo respectively, p=0.38). Patients on gabapentin reported significantly more nystagmus (p=0.009) and dizziness (p=0.02). Conclusion: Gabapentin did not significantly improve the primary endpoints of pain intensity or sensory neuropathy due to chemotherapy-induced peripheral neuropathy in this study. No significant financial relationships to disclose.