Patients with metastatic bone cancer report life-altering pain. Nerve growth factor is involved in pain signaling. Tanezumab, a nerve growth factor monoclonal antibody, has demonstrated efficacy in chronic pain. Placebo-controlled parent (NCT00545129; study 1003) and noncontrolled open-label extension (NCT00830180; study 1029) studies evaluated efficacy and safety of tanezumab in patients with painful bone metastases taking daily opioids. Patients in study 1003 received a single intravenous injection of 10 mg tanezumab or placebo and were followed up to 16 weeks. Efficacy analyses included change from baseline in daily average and worst pain at week 6 on an 11-point numeric rating scale. At week 8, patients could enroll in study 1029 and receive 4 infusions of 10 mg tanezumab at 8-week intervals with follow-up to 40 weeks. Safety assessments included adverse events and physical and neurologic examinations. Overall, 59 patients were randomized and treated (placebo, n = 30; tanezumab, n = 29). At the primary endpoint of study 1003, least squares mean (SE) difference in change from baseline in daily average pain vs placebo was -0.26 (0.45; P = 0.569). Post hoc analyses suggested that tanezumab had greater efficacy in patients with lower baseline opioid use and/or higher baseline pain. Mean (SE) pain scores in study 1029 were reduced through week 40 compared with study 1029 or 1003 baselines (-0.21 [0.76] and -1.27 [0.68], respectively). Adverse event incidence of study 1003 was similar between groups. Although the primary endpoint was not achieved, tanezumab may provide additional sustained analgesia in patients with metastatic bone pain taking daily opioids. Additional larger studies are warranted.