Eli Lilly and Company (NYSE: LLY) has notified Rigel Pharmaceuticals (NASDAQ: RIGL) of its decision to terminate their license and collaboration agreement covering ocadusertib, a small molecule inhibitor of receptor-interacting serine/threonine protein kinase 1 (RIPK1), originally signed in February 2021. The termination, disclosed in a Form 8-K filed April 21, 2026, becomes effective June 15, 2026. Rigel expects to regain full worldwide rights to ocadusertib and related RIPK1 programs upon that date.
The original 2021 agreement carried an upfront payment of USD 125 million from Lilly to Rigel, with potential milestone payments of up to USD 835 million and tiered royalties ranging from mid-single digits to high-teens percent, scaled to Rigel's level of clinical co-investment. Total headline value reached USD 960 million.
Deal context
Ocadusertib (LY3871801/R552), is described by Rigel as a potent and selective RIPK1 inhibitor. RIPK1 is a serine/threonine kinase with a documented role in regulating necroptosis and downstream inflammatory signaling. The agreement granted Lilly an exclusive worldwide license to develop and commercialize ocadusertib for non-CNS diseases, alongside additional RIPK1 inhibitors targeting CNS indications. The CNS arm of the collaboration was terminated separately by Lilly in November 2025, preceding the full agreement exit by roughly seven months. Financial terms disclosed at the time of the original deal did not specify per-event milestone amounts.
The dual-track structure of the collaboration — one program targeting peripheral inflammatory diseases, a second pursuing CNS-penetrant RIPK1 inhibitor candidates in neurodegenerative conditions — reflected the breadth of RIPK1's mechanistic relevance across tissue compartments. Engineering CNS penetrance into RIPK1 inhibitor scaffolds represents a distinct medicinal chemistry challenge from peripheral programs, and the sequential termination of the CNS arm before the broader agreement suggests neither track reached clinical triggers sufficient to sustain Lilly's continued investment.