Exelixis has granted to Merck an exclusive worldwide license to its PI3K-delta research and development program, including XL499, the company’s most advanced preclinical PI3K-delta inhibitor and other related compounds. Under the agreement, Merck will have a worldwide exclusive license and have sole responsibility to research, develop, and commercialize compounds originating from the program.

Merck will make an upfront payment of $12 million to Exelixis and Exelixis will be eligible for potential development and regulatory milestone payments for multiple indications of up to $239 million. Exelixis will also be eligible for potential combined sales performance milestones and royalties on net-sales of products emerging from the agreement. Milestones and royalties are payable on compounds emerging from Exelixis’ PI3K-delta program or from certain compounds that arise from Merck’s internal discovery efforts targeting PI3K-delta during a certain period.

“Our PI3K-delta program builds on our prior interest in the PI3K family, which led to the advancement of pan-PI3K inhibitors into clinical development for cancer. Merck’s global presence and significant resources make it the ideal organization to carry the PI3K-delta program forward. At the same time, this agreement provides Exelixis with resources for the continued development and potential commercialization of our lead compound, cabozantinib, which is in late-stage development for medullary thyroid and prostate cancers," said Michael M. Morrissey, Ph.D., president and chief executive officer of Exelixis.