Given no truly novel drug classes have emerged in decades, the identification of nerve growth factor (NGF) as a key molecule in mediating pain represents an exciting target for pain developers.
NGF was discovered 50 years ago as a molecule that promoted growth, survival and differentiation of nerves during the development of fetuses and young children; preclinical and clinical studies inhibiting NGF, however, have demonstrated a strong analgesic effect. With growing investment from ‘Big Pharma’, it is anticipated NGF drugs could be an important growth driver in the future pain market.
Independent market analyst Datamonitor has identified five molecules at various stages of clinical development: the most advanced pipeline candidate is Pfizer’s monoclonal antibody, tanezumab, which could launch as early as 2012. This could be the first biological treatment of pain and follows an industry-wide trend towards developing more complex and targeted therapies.
Dr Trung Huynh, healthcare analyst at Datamonitor, commented: ‘With tanezumab entering Phase III trials in chronic pain, NGF therapy is entering a crucial stage of development. 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.’
In Phase II trials, tanezumab adverse events included headache, upper respiratory tract infection, paresthesia (abnormal sensations), hypoesthesia (decreased sensations) and arthralgia (joint aches). Importantly, there is a risk of reproductive toxicology issues, which might lead to a black box warning for use in pregnant women.
In addition to safety concerns, cost presents the biggest barrier to widespread use. It is anticipated these drugs will be priced high because they are biologics, and this will make them inappropriate for first-line use because of the vast array of cheaper analgesics. As such, NGF therapies will be initially positioned as last-line therapies for patients not responding to traditional painkillers.
‘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,’ concludes Dr Huynh.