• A 9.7-month median progression-free survival (mPFS) was reached for the 50mg twice-daily (BID) casdatifan monotherapy cohort of the Phase 1/1b ARC-20 study; mPFS was not yet reached for other cohorts
• Across all three monotherapy cohorts presented, casdatifan demonstrated improvements in the rate of primary progression, overall response rate (ORR) and progression-free survival (PFS) relative to published data from studies with HIF-2a inhibitors to date
• Arcus will host a conference call to discuss these data at 5:00 AM PT / 8:00 AM ET on Tuesday, February 18, 2025

Arcus Biosciences, Inc. (NYSE:RCUS), a clinical-stage, global biopharmaceutical company focused on developing differentiated molecules and combination therapies for people with cancer, today presented new data for casdatifan, a HIF-2a inhibitor with best-in-class potential, in an oral plenary session by Dr. Toni K. Choueiri, Dana-Farber Cancer Institute, at the 2025 American Society of Clinical Oncology (ASCO) Genitourinary (GU) Cancers Symposium.

"The newest data are from the 100mg cohort using the tablet formulation and the expected go-forward dose for pivotal studies, which showed a 33% confirmed response rate despite the relatively short follow-up," said Richard Markus, M.D., Ph.D., chief medical officer at Arcus Biosciences. "Casdatifan continues to be well tolerated, with a very low discontinuation rate, supporting its strong potential in combination therapy. We look forward to sharing initial results for the casdatifan plus cabozantinib cohort later this year."

ARC-20 is a Phase 1/1b dose-escalation and expansion study. New data include mPFS and ORR for the 50mg BID cohort, and ORR for the 50mg once-daily (QD) and 100mg QD (tablet) cohorts, all of which evaluated casdatifan in patients with metastatic clear cell renal cell carcinoma (ccRCC), most of whom had progressed on at least two prior lines of therapy, including both an anti-PD-1 and a VEGFR tyrosine kinase inhibitor (TKI) therapy. The patient population was heavily pretreated; more than half (52-59%) of subjects received at least three prior lines of therapy and approximately one quarter (24-29%) had received at least four prior lines of therapy. Most patients (70-76%) had an International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) risk factor of intermediate or poor.

Casdatifan showed improvement in primary progressive disease rate (progressed at or before their first disease assessment), ORR and mPFS relative to published data from studies with HIF-2a inhibitors to date. At the time of data cut off (DCO, January 3, 2025), most patients (81-87%) experienced disease control with either a partial response or stable disease, and most were still on treatment. The median duration of response had not been reached, with all but two of the 26 responders across all three cohorts still on treatment.