Arcus Biosciences (RCUS) Q1 2026 earnings review
TIGIT Program Collapses, Forcing a High-Stakes Pivot to Casdatifan
Arcus suffered a catastrophic clinical setback this quarter: the Phase 3 STAR-121 trial for domvanalimab (anti-TIGIT) in first-line lung cancer was discontinued due to futility after failing to improve overall survival versus pembrolizumab. This effectively wipes out a major pillar of the company's historical investment thesis. Management is now aggressively pivoting the narrative to casdatifan (HIF-2a inhibitor) and an emerging early-stage immunology pipeline. Ironically, the closure of massive TIGIT trials will drastically reduce R&D burn, extending the company's $876M cash runway into H2 2028. However, Arcus is now essentially a 'show-me' story resting heavily on a single late-stage oncology asset competing directly with Merck.
🐂 Bull Case
The ARC-20 cohort evaluating casdatifan plus zimberelimab showed a primary progression rate of just 7% (2 of 30 patients), which compares very favorably to historical rates of anti-PD-1 monotherapy or competitor combos. If this holds in Phase 3, it validates the TKI-free strategy.
With the expensive TIGIT trials winding down, Arcus expects to end 2026 with $600M in cash. This ensures full funding for casdatifan's pivotal readouts without immediate dilution risk.
🐻 Bear Case
The futility of STAR-121 in 1L NSCLC removes a multi-billion dollar addressable market from Arcus's pipeline. It also casts a dark shadow over the remaining domvanalimab trials (like STAR-221 in gastric cancer).
With TIGIT sidelined, the company's valuation relies almost entirely on out-executing Merck (belzutifan) in the renal cell carcinoma market—a formidable challenge for a smaller biotech.
⚖️ Verdict: 🔴
Bearish. The TIGIT failure fundamentally damages the pipeline's diversity. While the cash preservation is a mechanical silver lining and casdatifan shows promise, the margin for error has evaporated. Arcus must execute perfectly on its renal cancer strategy.
Key Themes
Domvanalimab (TIGIT) Discontinued in Lung Cancer
The Phase 3 STAR-121 study (domvanalimab + zimberelimab + chemo vs pembrolizumab + chemo) in 1L NSCLC was abruptly halted by the IDMC for futility. The combination failed to improve overall survival. Consequently, Arcus is entirely abandoning the EDGE-Lung study as well. This Reversing trend from a highly touted late-stage asset to total discontinuation forces a harsh recalibration of the company's intrinsic value.
Casdatifan Upgraded to Foundational Asset
Management is pulling forward its strategy to establish casdatifan as a TKI-free regimen in first-line clear cell renal cell carcinoma (ccRCC). Data from the ARC-20 cohort evaluating casdatifan + zimberelimab yielded a 7% primary progression rate, significantly lower than the 20-35% typically seen in competitor and IO/IO regimens. A new cohort adding ipilimumab is enrolling to finalize the design for a 1L Phase 3 study initiating by year-end 2026.
Pivoting Capital to Immunology & Inflammation (I&I)
To diversify away from oncology risk, Arcus is rapidly accelerating its small-molecule I&I pipeline. The company selected AB102 (an MRGPRX2 antagonist) for atopic dermatitis, entering the clinic in Q3 2026. Two additional oral candidates—a selective TNFR1 inhibitor and a CCR6 antagonist—are scheduled to enter the clinic in H1 2027. This represents a strategic shift leveraging their internal discovery engine.
Gilead Collaboration Revenue Decelerating
Q1 2026 revenue fell to $17M (down from $28M in 25Q1), driven primarily by lower development services revenue from Gilead. As Gilead-led activities represent a larger share of joint costs, and as Arcus shifts toward wholly-owned programs (like I&I), the predictable collaboration revenue stream is Decelerating. Management guides to only $50-65M for the full year.
Other KPIs
Stable YoY. However, the composition of this spend is undergoing a massive shift. Spend on early-stage development and TIGIT trials is dropping, offset entirely by aggressive scaling of casdatifan (ARC-20 expansions) and the Phase 3 PRISM-1 study for quemliclustat. Management explicitly noted that R&D expenses will 'decline in the near term' as domvanalimab studies wind down.
Widened from $112 million in 25Q1. Despite flat R&D and flat G&A, the top-line collaboration revenue drop (from $28M to $17M) directly hit the bottom line. Per-share loss improved slightly (-$1.02 vs -$1.14) but only due to significant share dilution from 98.4M to 125.4M shares outstanding.
Guidance
Decelerating. This is a massive drop from the ~$225-235M guided and achieved in FY25, though FY25 was heavily skewed by a one-time $143M catch-up payment from Gilead returning the etrumadenant license. The underlying run-rate of collaboration revenue is shrinking.
Decelerating burn. Ending Q1 2026 with $876M and targeting $600M by year-end implies an average quarterly cash burn of roughly $92M for the remaining three quarters. This is a significant improvement from the $134M burned in Q1, reflecting the immediate cash-saving impact of discontinuing the Phase 3 TIGIT trials.
Key Questions
Fate of the Remaining TIGIT Pipeline
With STAR-121 failing in lung cancer, what is your level of confidence in the ongoing STAR-221 trial (domvanalimab in gastric cancer)? Are there interim futility analyses scheduled for that trial that investors should brace for?
Quantifying the TIGIT Wind-Down Savings
Can you quantify the exact quarter-over-quarter R&D cost savings expected from shutting down the STAR-121 and EDGE-Lung trials? How much of that absolute dollar savings will be immediately reallocated to the new 1L Phase 3 for casdatifan?
Gilead Partnership Dynamics
Given the discontinuation of the lead domvanalimab indication, how does this alter the strategic and financial dynamics of the Gilead partnership moving forward? Are there renegotiations expected regarding shared development costs?