OBJECTIVE: To assess the efficacy and safety of tanezumab, a humanized 
monoclonal antibody directed against the pain-mediating neurotrophin, nerve 
growth factor, to treat pain and other symptoms of chronic prostatitis/chronic 
pelvic pain syndrome in a Phase IIa, proof-of-concept clinical trial powered to 
provide 2-sided 90% confidence interval around the primary endpoint.
METHODS: Patients received a single intravenous dose of tanezumab (20 mg) or 
placebo. The primary efficacy endpoint was the change from baseline to week 6 in 
average daily numerical rating scale pain score. The secondary endpoints 
included the change from baseline to week 6 in the National Institutes of Health 
Chronic Prostatitis Symptom Index and urinary symptoms. Safety was also 
assessed.
RESULTS: Overall, 62 patients were randomized (30 to tanezumab and 32 to 
placebo). At week 6, tanezumab marginally improved the average daily pain 
(least-squares mean difference from placebo -0.47, 90% confidence interval 
-1.150-0.209) and urgency episode frequency (least-squares mean difference from 
placebo -1.37, 90% confidence interval -3.146-0.401). No difference was seen in 
the National Institutes of Health chronic prostatitis symptom index total score 
or micturition frequency at week 6. The most common adverse events were 
paresthesia and arthralgia. The odds of having a ≥ 30% reduction in pain were 
1.75-fold greater (90% confidence interval 0.65-4.69) for patients receiving 
tanezumab versus placebo.
CONCLUSION: Tanezumab might improve symptoms for some patients with chronic 
prostatitis/chronic pelvic pain syndrome. Although proof of concept was not 
demonstrated in the present study, additional studies with larger populations 
and stricter inclusion criteria according to patient phenotype might identify 
populations in which antinerve growth factor treatment will provide clinical 
benefit.