Rigel Pharmaceuticals, Inc. received milestone payments totaling $1 million from Merck based on progress in the companies’ 2004 collaboration to explore ubiquitin ligases to find treatments for cancer and potentially other diseases. The collaboration with Merck combines Rigel’s capabilities in ubiquitin ligases with Merck’s molecular profiling technology and downstream drug development capabilities.

“Merck and Rigel believe the ligase target class represents a potentially significant new source of oncology opportunities,” said Donald G. Payan, M.D., executive vice president and chief scientific officer of Rigel. “Rigel is pleased with the potency and selectivity of its hits against the various ligase targets and therefore with the potential for drug-ability of this target class.”

Under the terms of the 2004 agreement, Rigel received an initial cash payment from Merck and funding for Rigel research scientists for two-and-a-half years. Rigel is also eligible to receive milestone payments for preclinical and clinical events. Merck is responsible for worldwide development and commercialization of any resulting compounds and will pay Rigel royalties on any future product sales. The collaboration is based on a number of new targets designated by Merck and does not include Rigel’s current ligase targets. Additional terms were not disclosed.