secwatch.observer — SEC 8-K summary
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Issuer:     Arcus Biosciences, Inc. (RCUS)
CIK:        0001724521
Form:       8-K
Filed at:   2026-04-20T23:59:59+00:00
Accession:  0001724521-26-000021
Event type: other_material
Sentiment:  negative
Materiality: 0.75
Item codes: 8.01
LLM model:  deepseek-v4-flash:cloud@v2

Arcus discontinues Phase 3 STAR-121 NSCLC trial; Gilead lets option rights lapse
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- STAR-121 evaluating domvanalimab + zimberelimab + chemo vs pembro + chemo in 1L metastatic NSCLC stopped by IDMC for futility.
- Zimberelimab + chemo showed comparable overall survival vs pembro + chemo; trial discontinued despite that.
- Gilead declines option continuation payment; option period ends July 14, 2026; loses rights to CCR6, CD89, CD40L programs.
- Gilead retains time-limited options for AB801 (AXL inhibitor), AB598 (anti-CD39), AB102 (MRGPRX2 antagonist), and TNF small molecule.
- Arcus retains full rights to casdatifan program except Taiho territories (Japan and certain Asian countries).

Source:
  EDGAR index:    https://www.sec.gov/Archives/edgar/data/1724521/000172452126000021/0001724521-26-000021-index.htm
  Primary doc:    https://www.sec.gov/Archives/edgar/data/1724521/000172452126000021/rcus-20260420.htm
  HTML page:      https://secwatch.observer/filing/0001724521-26-000021

License: Source filings: public domain (SEC EDGAR). Summaries (headline + bullets): CC-BY-4.0; attribute https://secwatch.observer