In this randomized double-blind trial, patients received placebo (N=409), subcutaneous tanezumab (5mg [N=407] or 10mg [N=407] every 8 weeks), or oral tramadol prolonged-release (100-300mg/day; N=602). Efficacy (Low Back Pain Intensity [LBPI] and Roland Morris Disability Questionnaire [RMDQ]) was assessed through week 56. Safety, including joint safety, was assessed through week 80. Week 16 data is presented here; week 56 data is presented in our companion abstract.

Compared with placebo, tanezumab 10mg significantly improved LBPI (primary endpoint; LS mean [95% CI] difference = -0.40 [-0.76,-0.04]; p=0.0281) and RMDQ (key secondary; LS mean [95% CI] difference = -1.74 [-2.64,-0.83]; p=0.0002) at week 16. Changes in LBPI with tanezumab 5mg were not significant versus placebo (LS mean [95% CI] difference = -0.30 [-0.66,0.07]; p=0.1117). Although mean changes in RMDQ were larger with tanezumab 5mg than placebo (LS mean [95% CI] difference = -1.32 [-2.21,-0.43]; p=0.0035), superiority could not be concluded per the pre-defined testing strategy. Changes in LBPI and RMDQ with tramadol (mean dose=203mg/day) were not significant versus placebo. Changes in LBPI for both tanezumab groups were not significant versus tramadol. Both tanezumab groups significantly improved RMDQ compared with tramadol (unadjusted for multiplicity). Adverse event rates through 16 weeks were 46.2%, 46.9%, 51.8%, and 56.3% in the placebo, tanezumab 5mg, tanezumab 10mg, and tramadol groups, resulting in treatment discontinuation rates of 3.9%, 4.4%, 4.7%, and 8.5%.

Tanezumab 10mg significantly improved pain and function at week 16 versus placebo, while tramadol did not. Incidence of AEs and treatment discontinuations due to AEs in both tanezumab groups were lower than tramadol, but higher than placebo.