Daiichi Sankyo is hitting the acquisition trail, buying the USA's Plexxikon and rights to its much-touted late-stage melanoma drug partnered with Roche.

Under the terms of the deal, the purchase price for privately-held Plexxikon is $805 million on a debt-free basis and will be internally funded. Additional potential payments totaling $130 million will be made based on near-term launch milestones with respect to PLX4032 in malignant melanoma.

The deal gives Daiichi Sankyo certain co-promotion rights in the USA for PLX4032, also known as RG7204, which is being jointly developed by Plexxikon and Roche. Interim results from a Phase III trial published in January demonstrated that PLX4032 met co-primary endpoints of overall survival and progression-free survival among patients with previously untreated metastatic melanoma expressing the BRAF mutation.

The Tokyo-headquartered group said PLX4032 is "an elegant example of a targeted therapeutic designed to be administered to patients likely to respond to treatment on the basis of a companion diagnostic test that can detect the presence of a specific genetic mutation". The company also praised Plexxikon's "unique, systematic, cost-effective" drug discovery platform which "uses structural data to guide chemistry to develop early leads for multiple targets".

Daiichi Sankyo chief executive Joji Nakayama said the acquisition "not only accelerates our entry into the oncology market but strengthens our pipeline". Plexxikon, which was established in 2001 and has 45 employees, is also conducting Phase I studies of kinase inhibitors for rheumatoid arthritis and metastatic cancer.