Arcus ends last TIGIT phase 3 as Gilead gives up its three board seats

Arcus Biosciences said on Aug. 5 that it and AstraZeneca will discontinue PACIFIC-8, a phase 3 trial of the anti-TIGIT antibody domvanalimab plus durvalumab against durvalumab alone in PD-L1 positive, stage III unresectable non-small cell lung cancer. The decision ends Arcus's late-stage TIGIT work.

In the same second-quarter report, Arcus said Gilead Sciences had given up its three seats on Arcus's board, effective Aug. 5, in connection with the wind-down of the phase 3 trials and what Arcus called a streamlined operating relationship.

The details

PACIFIC-8 was the third domvanalimab phase 3 to end. Arcus said it followed the discontinuations of STAR-221 in upper gastrointestinal cancer and STAR-121 in lung cancer. In April, Arcus said an independent data monitoring committee recommended stopping STAR-121 after a pre-planned futility analysis. At that analysis, the domvanalimab combination did not improve overall survival compared with pembrolizumab plus chemotherapy.

Gilead also chose not to make an option continuation payment, so its option period under the 2020 collaboration ended on July 14, 2026. Gilead lost option rights to programs including Arcus's CCR6, CD89 and CD40L work but kept time-limited options on AB801, AB598 and a TNF small molecule. Its option on AB102 had expired in the second quarter, the 10-Q says. Gilead remains a large shareholder: the 10-Q says it owned about 24.7% of Arcus's common stock at June 30.

Quarterly revenue fell to $41 million from $160 million a year earlier, when Arcus booked a $143 million catch-up related to Gilead returning etrumadenant. Research and development spending was $113 million, down from $139 million, and the net loss was $91 million. Cash, equivalents and marketable securities were $775 million at June 30, down from $1.0 billion at the end of 2025.

Context

With TIGIT gone, Arcus's plan rests on casdatifan in kidney cancer. The same report listed new collaborations with Bristol Myers Squibb, Summit Therapeutics and AVEO Oncology to test casdatifan combinations, and a $15 million milestone payment due from Taiho in the third quarter tied to PEAK-1 enrollment in Japan. Arcus's second phase 3 asset, the CD73 inhibitor quemliclustat, has results from the PRISM-1 pancreatic cancer trial due in the first half of 2027.

Chief executive Terry Rosen said the company sees "a clear path to be first-to-market" in front-line kidney cancer.

What it means for investors

Stopping PACIFIC-8 removes a cost and an overhang. Arcus said it expects R&D costs to keep falling in the near term as domvanalimab studies wind down, offset partly by more spending on casdatifan and immunology programs. Full-year GAAP revenue guidance rose to $65 million to $75 million, from $50 million to $65 million in May.

Gilead leaving the board loosens a tie that once defined Arcus. The partner still holds about a quarter of the stock, and a large holder with no board seat is freer to reduce its stake, which is a supply risk for the shares. The company now has one main late-stage bet, so a setback in PEAK-1 would hit harder than it would have when TIGIT and adenosine programs shared the load.

What to watch

Arcus guided to ending 2026 with about $600 million in cash, to completing PEAK-1 enrollment and to starting the PEAK-20 first-line trial by year-end. New ARC-20 casdatifan data were promised for the second half of 2026.

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RCUSArcus Biosciences, Inc.NYSE · United StatesOpen the deskGILDGilead Sciences, Inc.NASDAQ · United StatesOpen the deskAZNAstraZeneca PLCLSE · United KingdomOpen the desk