Tanezumab is a humanized monoclonal antibody that specifically inhibits nerve 
growth factor as a treatment for chronic pain. This phase IIB study investigated 
the efficacy and safety of tanezumab for chronic low back pain vs placebo and 
naproxen. Patients (N=1347) received intravenous tanezumab (5, 10, or 20mg every 
8weeks), naproxen (500mg twice daily), or placebo. The primary efficacy end 
point was mean change in daily average low back pain intensity (LBPI) from 
baseline to week 16. Secondary end points included mean change from baseline to 
week 16 in the Roland Morris Disability Questionnaire and Patient's Global 
Assessment (PGA) of low back pain. Tanezumab 10 and 20mg had similar efficacy 
profiles and significantly improved LBPI, Roland Morris Disability 
Questionnaire, and PGA scores vs both placebo and naproxen (P⩽.05). Tanezumab 
5mg provided improvement of PGA scores vs placebo (P⩽.05), and naproxen resulted 
in significant improvement of LBPI vs placebo (P⩽.05). Adverse event incidence 
was comparable across tanezumab doses but higher than with placebo or naproxen. 
Arthralgia, pain in extremity, headache, and paresthesia were the most commonly 
reported adverse events by tanezumab-treated patients. The most frequently 
reported adverse events resulting in discontinuation of tanezumab treatment were 
arthralgia and paresthesia; the highest frequency was observed with tanezumab 
20mg (both 1.4%). Serious adverse event incidence was similar across treatments. 
In conclusion, tanezumab provided significantly greater improvement in pain, 
function, and global scores vs placebo and naproxen in patients with chronic low 
back pain.