Persistent pain represents a major health problem, and most current therapeutic 
approaches are associated with unwanted effects and unsatisfactory pain relief. 
Therefore, an urgent need exists to develop more effective drugs that are 
directed toward new molecular targets. Nerve growth factor (NGF) is involved in 
pain transduction mechanisms, playing a key role as a master switch in many 
chronic and inflammatory pain states; the NGF ligand and its receptor TrkA 
constitute well-validated targets for pain therapy. Tanezumab (RN-624), a 
first-in-class recombinant humanized mAb targeting NGF, is being developed by 
Pfizer Inc for the potential treatment of pain associated with several 
conditions. In preclinical studies, tanezumab, and its murine precursor 
muMab-911, effectively targeted the NGF pathway in various chronic and 
inflammatory pain models. Phase I and II clinical trials in osteoarthritic pain 
and chronic lower back pain demonstrated good efficacy for the compound, as well 
as a good safety and tolerability profile. Given that tanezumab is an antibody, 
the drug demonstrates the general advantages of this class of products 
(including good specificity and favorable pharmacokinetics), and also appears to 
be particularly well suited for targeting the chronic and inflammatory-mediating 
pain actions of NGF and its receptor system.