Rigel Pharmaceuticals Inc. has received a milestone payment from Merck & Co. Inc. as part of their collaboration to investigate ubiquitin ligases, a new class of drug targets, to find treatments for cancer and potentially other diseases.

Under the terms of the agreement, Rigel received an initial cash payment and funding for Rigel research scientists for two and a half years and is also eligible to receive milestone payments for preclinical and clinical events, states the company release.

Merck is responsible for worldwide development and commercialisation of any resulting compounds and will pay Rigel royalties on future product sales, if any. The collaboration is based on a number of new targets designated by Merck and do not include Rigel's current ligase targets.

Rigel is a leader in investigating and characterising the ubiquitin ligase system for the discovery and development of potential new therapeutics. The collaboration with Merck combines Rigel's capabilities in ubiquitin ligases with Merck's molecular profiling technology and downstream clinical infrastructure to explore this promising new class of drug targets.

"We believe this is one of the largest dedicated efforts focused on ligases by a pharmaceutical or biotech enterprise and it is proving to be a highly productive collaboration exploring ligases and potential therapeutics in cancer," said Donald G. Payan, executive vice president and chief scientific officer of Rigel.

Ubiquitin ligases are enzymes that regulate protein degradation within the cell.

Rigel is a clinical-stage drug development company that discovers and develops novel, small-molecule drugs for the treatment of inflammatory diseases, cancer and viral diseases.