Tanezumab, a nerve growth factor inhibitor, was investigated for osteoarthritis (OA) of the hip or knee in a study with 24-week treatment and 24-week safety follow-up.This double-blind, randomised, phase III study enrolled adults in Europe and Japan with moderate-to-severe OA who had not responded to or could not tolerate standard-of-care analgesics. Patients were randomised to tanezumab 2.5 mg or 5 mg subcutaneously or matching placebo every 8 weeks (three doses). Co-primary end points were change from baseline to week 24 in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Pain and Physical Function, and Patient's Global Assessment of OA (PGA-OA). Joint safety and neurological assessments continued throughout the 48-week study.From March 2016 to December 2017, 849 patients were randomised and evaluated (placebo n=282, tanezumab 2.5 mg n=283, tanezumab 5 mg n=284). At week 24, there was a statistically significant improvement from baseline for tanezumab 5 mg compared with placebo for WOMAC Pain (least squares mean difference±SE -0.62±0.18, p=0.0006), WOMAC Physical Function (-0.71±0.17, p<0.0001) and PGA-OA (-0.19±0.07, p=0.0051). For tanezumab 2.5 mg, there was a statistically significant improvement in WOMAC Pain and Physical Function, but not PGA-OA. Rapidly progressive osteoarthritis (RPOA) was observed in 1.4% (4/283) and 2.8% (8/284) of patients in the tanezumab 2.5 mg and tanezumab 5 mg groups, respectively and none receiving placebo. Total joint replacements (TJRs) were similarly distributed across all three treatment groups (6.7%-7.8%). Tanezumab-treated patients experienced more paraesthesia (5 mg) and hypoaesthesia (both doses) than placebo.Tanezumab 5 mg statistically significantly improved pain, physical function and PGA-OA, but tanezumab 2.5 mg only achieved two co-primary end points. RPOA occurred more frequently with tanezumab 5 mg than tanezumab 2.5 mg. TJRs were similarly distributed across all three groups.NCT02709486.