BMS sues Merck over cancer immunotherapy patent

The battle for supremacy in the field of anti-PD-1 cancer immunotherapy has just intensified, with Bristol Myers Squibb suing rivals Merck over an alleged patent infringement.

BMS was the first company to launch an anti-PD-1 drug, launching its Opdiva (nivolumab) in Japan with its marketing and development partner Ono in May as a treatment for melanoma.

But Merck has beaten its rival to be first with a US approval, gaining accelerated marketing approval from the FDA for Keytruda (pembrolizumab) on Thursday, also for the treatment of melanoma. The move looked like a major coup for the firm, however BMS filed its legal action with a district court in Delaware on the same day, alleging Merck had infringed a key patent for the novel drug.

BMS' drug is not likely to be approved until early-to mid-2015, giving Merck's Keytruda a head start which could prove crucial in the market.

The immunotherapy drugs are seen as one of the most exciting developments in oncology for some time, and analysts believe the new treatments will be multi-billion dollar blockbusters. Melanoma is expected to be just the first of the indications the drugs could be used against. Another player in the field is AstraZeneca, whose MED14736 entered phase 3 trials for non-small cell lung cancer in May.

In its submission to the Delaware court, BMS said Merck was "preparing to infringe" its patent for methods of treating cancer with anti-PD-1 antibodies, specifically its 474 patent relating to how its antibody binds to the PD-1 and blocks the checkpoint pathway.

Merck has responded to the legal action by saying it is without foundation, and that it will not delay the launch of Keytruda in the US and other global markets.