NGF and osteoarthritis: Nerve growth factor (NGF) is a neurotrophic protein with numerous pro-nociceptive effects.1, –3 The role of NGF in perpetuating chronic pain states has been shown by multiple studies in the past, and this has given rise to the development of several NGF inhibitor therapies, although none of these have achieved regulatory approval.1, –3 The most advanced therapies are NGF-sequestering antibodies, of which several are in later stages of clinical development for the treatment of pain associated with osteoarthritis (OA) or programs that have recently been discontinued.3, , , , , –9