Arcus Biosciences, Inc.

Item 8.01 Other Events. On October 20, 2026, Arcus Biosciences, Inc. presented new data from the ARC-20 platform study evaluating casdatifan, alone or in combination, as a first-, second- and late-line treatment for clear cell renal cell carcinoma (“ccRCC”). This presentation included the following data as of the data cutoff date of September 4, 2026: First-line TKI-free combinations • Casdatifan plus anti-PD-1 zimberelimab (n=30): with 11.5 months of median follow up, landmark progression-free survival (“PFS”) was 86% and 69% at six and 12 months, respectively, the confirmed objective response rate (“cORR”) was 50%, and the rate of primary progression (progression at or before the first scan) was 6.7%. No unexpected safety signals were observed at the time of data cutoff. The regimen showed safety data that are consistent with those observed in other cohorts or prior studies of each molecule. • Casdatifan plus anti-CTLA-4 ipilimumab and zimberelimab: with three months of median follow up, only one patient out of 24 patients (4%) who had reached a first scan experienced primary progression. There were no unexpected safety signals observed in the 31 patients enrolled that received at least one dose of casdatifan plus ipilimumab and zimberelimab at the time of data cutoff. Grade 3 and higher immune-mediated adverse events were generally consistent with those associated with ipilimumab and nivolumab in frequency, severity and timing. Second-line combination • Casdatifan plus tyrosine kinase inhibitor (“TKI”) cabozantinib: with 21.3 months of median follow up (n=43), median PFS was 14.5 months, 18-month landmark overall survival was 77%, cORR was 44% and primary progression was 5%. Casdatifan plus cabozantinib demonstrated similar efficacy, whether or not patients previously received TKI therapy. TKI-pretreated patients represent approximately 60% of 2L patients in current practice and derive diminished benefit from subsequent TKI therapies. No unexpected safety signals were observed at the time of data cutoff (n=44). The regimen showed safety data that are consistent with those observed in other cohorts or prior studies of each molecule. Late-line monotherapy • Casdatifan monotherapy (n=121): with 28 months of median follow up in the four pooled monotherapy cohorts, median overall survival was 35 months, median PFS was 13 months and cORR was 36%. PFS data were similar whether patients had received one, two or three prior TKI-inclusive treatments. No unexpected safety signals were observed, and casdatifan showed acceptable and manageable adverse events across all doses.