Bisphosphonate drugs could make a dramatic mark on the sector in a new indication – to prevent cancer spreading to the bone in early-stage patients – according to a new report from market analysts Datamonitor.

Four of the major tumour types commonly metastatise to the bone – breast, lung, prostate and thyroid – affecting almost 250,000 people in the seven major pharmaceutical markets alone. When this happens, patients have a very poor outlook: for example, 70% of patients with advanced breast or prostate cancer are likely to develop bone metastases, with just one-quarter still alive after five years. In addition there are potentially severe consequences for patients’ quality of life, as they are often affected with skeletal complications such as bone pain, fractures and spinal cord compression.

Bisphosphonates have been used effectively for a number of years in patients with advanced cancers to cut the risk of skeletal complications by up to 50% - but have not improved survival in the majority of patients. Third-generation compounds, such as Roche and GlaxoSmithKline’s Bondronat (ibandronate) and Novartis’ Zometa (zolendronate) are now being investigated for their potential to prevent bone metastases in early-stage cancer patients which, says Datamonitor analyst Chandno Surti, could completely transform the management of this complication. This would not only translate in to a significant survival benefit, but also improve the quality of life for patients.

Market opportunities
Two of the four bisphosphonates currently used for bone metastases have already undergone patent expiry, with Bondronat and Zometa to see patent expiry in 2011 and 2012 respectively. “It may be that the availability of cheaper generic bisphosphonates poses a threat to newer, more costly agents in development,” Ms Surti says, “on the other hand, new agents could see rapid uptake if they demonstrate higher efficacy and/or safety profiles compared to bisphosphonates.” Indeed the approaching patent expiries could provide an opportunity for drug developers previously put off by the presence of big pharma.

One promising agent spotlighted by Datamonitor is Amgen and Daiichi Sankyo’s denosumab, a fully-human monoclonal antibody that selectively targets a major mediator in bone breakdown, dubbed RANKL, which is currently in Phase III development. In addition to its more targeted approach, its subcutaneous administration route could prove an advantage over the intravenous compounds currently on the market.