Arcus Biosciences announced a publication in Nature describing new research from the ARC-20 study evaluating casdatifan, an investigational HIF-2a inhibitor, as a monotherapy in patients with metastatic clear cell renal cell carcinoma (ccRCC). The study is the first to comprehensively describe the relationship between HIF-2a inhibitor-associated changes in circulating serum erythropoietin (EPO), tumor biology and corresponding clinical activity. The findings indicate that deeper suppression of HIF-2a-associated production of serum EPO correlated with clinical benefit, including higher response rates and longer progression-free survival (PFS).

"This is the first study to comprehensively assess the relationship between HIF-2a inhibitor-associated suppression of serum EPO production with tumor biology and clinical outcomes," said Toni K. Choueiri, M.D., director of the Lank Center for Genitourinary (GU) Oncology at Dana-Farber Cancer Institute and lead investigator of ARC-20. "Patients treated with casdatifan had a median progression-free survival of over one year despite half of patients having progressed on three or more prior treatments."

Clinical Efficacy Results

A pooled analysis from four monotherapy cohorts (n=121) of the ARC-20 study showed that advanced kidney cancer patients treated with casdatifan lived beyond a year without cancer progression (median PFS of 12.2 months). The patient population was heavily pretreated; more than half (55%) of patients received at least three prior lines of therapy, and more than one quarter (29%) had received at least four prior lines of therapy. Most patients (71%) had an International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) risk factor of intermediate or poor.

At the time of the data cutoff (DCO, August 15, 2025), casdatifan produced durable antitumor activity. In the 100mg QD tablet cohort, the confirmed objective response rate (cORR) was 35% and median PFS had not yet been reached, with 60% of patients remaining progression-free at 12 months. In a later analysis with a January 30, 2026 DCO, median PFS was 15.1 months in the 100mg QD cohort, the same dose and formulation being used in the ongoing PEAK-1 Phase 3 study.

Safety Profile

At the time of the August 2025 DCO, no unexpected safety signals were observed, and casdatifan had an acceptable and manageable safety profile across all doses. The most common class-effect events were anemia and hypoxia; across all four cohorts, no patients discontinued treatment due to anemia, and three patients (2%) discontinued due to hypoxia.

Development Strategy

"The comprehensive translational work published in Nature validates EPO as a biomarker for HIF-2a suppression and correlates dramatic and sustained EPO suppression to durable response with monotherapy casdatifan," said Richard Markus, M.D., Ph.D., chief medical officer at Arcus Biosciences. "We believe this new research provides unambiguous evidence that casdatifan is a best-in-class HIF-2a inhibitor."

Arcus is enrolling PEAK-1, the global Phase 3 study evaluating casdatifan plus cabozantinib versus cabozantinib in IO-experienced patients with metastatic ccRCC. The company expects to complete enrollment in PEAK-1 and to initiate a Phase 3 study in the first-line metastatic ccRCC setting by year-end 2026. Casdatifan is an investigational molecule and has not received approval from any regulatory authority.

Arcus Biosciences, Inc. granted employment inducement awards to two new employees, consisting of options to purchase 18,400 shares and restricted stock units to acquire 9,250 shares of common stock. The options carry an exercise price of $28.18 per share, which was the closing price on June 23, 2026. These equity awards were granted pursuant to the company’s 2020 Inducement Plan.

The Compensation Committee of the Board of Directors approved the grants. The 2020 Inducement Plan was authorized by the Board in January 2020 under the "inducement exception" outlined in NYSE Listed Company Manual Rule 303A.08. This exception allows companies to issue equity awards as a material inducement to new employees without requiring shareholder approval.

Breakdown of Awards

Arcus Biosciences is a clinical-stage, global biopharmaceutical company focused on developing differentiated molecules and combination therapies for cancer and inflammatory and autoimmune diseases. The company was founded in 2015 and has advanced multiple investigational medicines into registrational clinical trials.