Fulranumab in Patients With Pain Associated With Postherpetic Neuralgia and Postraumatic Neuropathy: Efficacy, Safety, and Tolerability Results From a Randomized, Double-blind, Placebo-controlled, Phase-2 Study.

Abstract

Fulranumab is an antibody that specifically neutralizes the biological activity of human nerve growth factor. This multicenter, phase-2, randomized, double-blind (DB), placebo-controlled study evaluated the analgesic efficacy and safety of fulranumab in postherpetic neuralgia (PHN) and posttraumatic neuropathy (PTN) patients. Patients (18 to 80 y) with inadequately controlled moderate-to-severe pain received study medication (subcutaneous injection) every 4 weeks. PHN patients were randomized (3:2:2:3) to receive either placebo or one of 3 doses of fulranumab: 1 mg (1 mgQ4 wk), 3 mg (3 mgQ4 wk), or 10 mg (10 mgQ4 wk). PTN patients were randomized (1:1) to receive either placebo or fulranumab 10 mgQ4 wk. The US Food and Drug Administration placed a clinical hold (December 23, 2010) on all trials of antinerve growth factor drugs, including fulranumab, due to identified risks of osteonecrosis or rapidly progressing osteoarthritis; therefore, only 49 (of 150 planned) PHN patients and 34 (of 50 planned) PTN patients completed the DB efficacy evaluation. There was no significant difference (P>0.05, fulranumab vs. placebo) for change in 7-day average of daily pain intensity scores from DB baseline to end of 12-week DB efficacy phase in PHN or PTN patients (primary endpoint). No significant difference was found with fulranumab versus placebo (P>0.05) in other efficacy measures in either PHN or PTN patients. The most common treatment-emergent adverse events (>10% incidence) in PTN patients were sinusitis, carpal tunnel syndrome, and headache, whereas in PHN patients it was arthralgia. Fulranumab did not demonstrate efficacy in either PHN or PTN patients, but was generally well-tolerated in this small underpowered and abbreviated study.