Despite concerns about safety and price, drugs which target nerve growth factor, headed by Pfizer’s tanezumab, represent a major advance in the pain relief field, claims a new report.

This latest analysis is from Datamonitor and one of its healthcare analysts, Trung Huynh, noted that “whilst scientific research over the past four decades has led to some progress in the management of pain, key unmet needs still remain.” The report claims that “given no truly novel drug classes have emerged in decades, the identification of NGF as a key molecule in mediating pain represents an exciting target for pain developers”.

NGF was discovered 50 years ago, Datamonitor states, as a molecule that promoted growth, survival and differentiation of nerves during development of foetuses and young children. However, “preclinical and clinical studies inhibiting NGF have demonstrated strong analgesic effect [and] it is anticipated NGF drugs could be an important growth driver in the future pain market”.

Leading the pack is Pfizer’s monoclonal antibody tanezumab, that could launch as early as 2012 and would be the first biological treatment of pain. However, Dr Huynh adds that “one of the big question marks is whether these drugs are safe for longer-term use”. Phase III results in 2011 “are eagerly awaited and will help establish the risk-benefit of chronic usage”, he says.

The report notes that in Phase II trials, tanezumab adverse events included headache, upper respiratory tract infection and joint aches. Importantly, it states, “there is a risk of reproductive toxicology issues, which may lead to a black box warning for use in pregnant women”.

Dr Huynh said that “opinion leaders we spoke to have raised concerns about using this class in women of child-bearing age” as lowering NGF levels “might compromise the normal development of their unborn offspring.” In addition to safety concerns, “cost presents the biggest barrier to widespread use”, the analysis argues, as the price of these biologics “will make them inappropriate for first-line use due to the vast array of cheaper analgesics”.

Still, “despite hurdles of safety and price, we see this novel approach as one of the most positive steps for the future direction of chronic pain therapy,” Dr Huynh concludes.