Long-term safety and effectiveness of tanezumab as treatment for chronic low back pain.

A noncontrolled, randomized, multicenter study (NCT00924664) evaluated long-term safety and effectiveness of tanezumab in patients with chronic low back pain following a randomized placebo- and active-controlled parent study that evaluated analgesic efficacy. Patients were randomized to tanezumab 10mg (n=321) or 20mg (n=527) administered at 8-week intervals via 3 intravenous injections followed by 4 subcutaneous injections. Effectiveness analyses included change from parent study baseline in Brief Pain Inventory Short Form, Roland Morris Disability Questionnaire, and Patient's Global Assessment of low back pain. Safety assessments included adverse event documentation, physical/neurological examinations, and laboratory tests. Mean treatment duration during the extension study was 194 and 202 days with tanezumab 10 and 20mg, respectively. Both tanezumab doses provided similar and sustained improvements in all effectiveness outcomes. The most frequently reported adverse events were arthralgia, paresthesia, and hypoesthesia. Adverse events initially described as osteonecrosis were reported in 6 patients (tanezumab 10mg, n=2; tanezumab 20mg, n=4); 9 additional patients (tanezumab 10mg, n=7; tanezumab 20mg, n=2) underwent total joint replacement (TJR). A blinded, independent adjudication committee reviewed all 6 patients with reported osteonecrosis and 4 of the 9 patients undergoing TJR. Adjudication outcomes were osteonecrosis (n=0), worsening osteoarthritis (n=5; 1 rapidly progressive), and another diagnosis or indeterminate (n=5). Tanezumab 10mg had better tolerability than tanezumab 20mg, and may represent an effective long-term treatment for chronic low back pain.