Long-term open-label study of tanezumab for moderate to severe osteoarthritic knee pain

Objective: This study was designed to evaluate the long-term safety and effectiveness of repeated doses of the humanized anti-nerve growth factor antibody, tanezumab, during open-label treatment of patients with OA knee pain.

Design: The current study (clinicaltrials.gov identifier: NCT00399490) was a multicenter, phase II, open-label, multiple-dose extension of an earlier randomized clinical trial. All patients (N=281) received infusions of tanezumab 50μg/kg on Days 1 and 56 with subsequent doses administered at 8-week intervals (up to a total of eight infusions). The primary endpoint of this study was safety. Effectiveness evaluations included overall knee pain, Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index subscales, and subject global assessment (SGA) of response to therapy on 0-100 point visual analog scales.

Results: Repeated administration of tanezumab resulted in a low incidence of treatment-related adverse events (AEs; 7.5%). The rate of serious AEs was also low (2.8%) with none considered treatment-related. Few AEs of abnormal peripheral sensation were reported; hypoesthesia was reported by nine patients (3.2%), paresthesia by seven patients (2.5%), and hyperesthesia, peripheral neuropathy, and sensory disturbance were each reported by one patient (0.4% for each). Most AEs of abnormal peripheral sensation were rated as mild (95%) and the majority (65%) resolved before study completion. At Week 8, overall knee pain and SGA improved from baseline by a mean (± standard error) of -12.8 (±1.78) and 8.0 (±1.66), respectively. Similar improvements occurred for WOMAC subscales.

Conclusions: Repeated injections of tanezumab in patients with moderate to severe knee OA provide continued pain relief and improved function with a low incidence of side effects. Additional studies to define the efficacy and duration of pain reduction and to provide a more complete assessment of long-term safety are warranted.