Japanese drugmaker Astellas and US biopharmaceutical group Cytokinetics have signed a $490-million pact to work on new drugs for muscle disorders.

The firms announced they are collaborating on the research, development and commercialisation of skeletal muscle activators to treat diseases and medical conditions linked with muscle weakness.

Under the deal, Astellas has gained exclusive rights to develop and commercialise drug candidates arising from the partnership (subject to certain rights held by Cytokinetics).

It has also gained an exclusive license to co-develop and market Cytokinetics' existing Phase I experimental drug CK-2127107 for some indications, taking over responsibility for its development in Phase II.

On the financial side, Cytokinetics stands to receive over $40 million in upfront fees and reimbursement of sponsored R&D activities in the first two years of the collaboration, as well as over $450 million in milestones plus royalties. 

Research to identify next-generation skeletal muscle activators to work on will be conducted by both groups, and Astellas is responsible for activities and costs linked with developing any products.

Analysts are looking at the move as positive for Cytokinetics, given that it will bring extra cash to the firm which it can use to develop its own in-house projects, most notably tirasemtiv for amyotrophic lateral sclerosis and other neuromuscular disorders.