Rigel's Lilly termination reshapes hematology pipeline priorities

Rigel Pharmaceuticals' termination of its Eli Lilly collaboration on ocadusertib, effective June 15, 2026, removes a RIPK1 inhibitor program from the company's development slate and sharpens the question of how mid-size biotechs absorb pipeline contraction while sustaining commercial momentum.

Lilly terminates ocadusertib collaboration, effective June 2026

Eli Lilly notified Rigel in April that it will terminate the collaboration agreement covering ocadusertib (previously R552 or LY3871801), an investigational RIPK1 inhibitor. The termination, initiated by Lilly, becomes effective June 15, 2026. No clinical or regulatory rationale was disclosed in Rigel's Q1 2026 earnings release.

Against that backdrop, Rigel reported Q1 2026 net product sales of $54.9 million, a 26% increase year-over-year across its three commercial products: TAVALISSE (fostamatinib), GAVRETO (pralsetinib), and REZLIDHIA (olutasidenib). Total Q1 revenues reached $58.8 million, including $3.9 million in collaboration contract revenues. The company posted net income of $8.7 million for the quarter.

Rigel also restructured its credit facility in early May, replacing a $40.0 million term loan with a revolving credit facility of $40.0 million through MidCap Financial, with an option to expand to $60.0 million. The company repaid the outstanding term loan balance in full and drew $8.0 million on the new facility at close.

The pipeline read for hematology development teams

With ocadusertib returning to Rigel or exiting the portfolio entirely, development resources concentrate on R289, a dual IRAK1/4 inhibitor in Phase 1b for relapsed or refractory lower-risk myelodysplastic syndrome. Enrollment in the dose expansion phase is ongoing; Rigel has guided to recommended Phase 2 dose selection in the second half of 2026, with preliminary dose-expansion data anticipated before year-end.

For hematology development teams tracking MDS programs, the IRAK1/4 mechanism and the lower-risk MDS patient population represent a distinct clinical niche from standard-of-care options. The Phase 1b design covers safety, tolerability, pharmacokinetics, and preliminary efficacy, meaning the H2 2026 data readout will be the first signal on whether the program supports a registrational pathway.

Pralsetinib's data from the TAPISTRY study (NCT04589845), presented at ASCO-GI in January 2026, extended its evidence base into RET fusion-positive solid tumors including pancreatic, colorectal, and hepatobiliary cancers, reinforcing the commercial asset's relevance beyond its approved indications.

The R289 Phase 2 dose decision anchors H2 2026 planning

Rigel's full-year 2026 revenue guidance of $275 to $290 million, with net product sales of $255 to $265 million, reflects confidence in the commercial portfolio independent of the Lilly collaboration loss. The credit facility restructuring provides additional liquidity headroom for in-licensing activity, which management flagged explicitly as a strategic option.

The recommended Phase 2 dose selection for R289, expected in H2 2026, will be the definitive checkpoint for assessing whether Rigel's pipeline can sustain long-term growth once the collaboration revenue line contracts following the June 15 termination date.