AB598

P1, N=87, Recruiting, Arcus Biosciences, Inc. | Trial completion date: Aug 2025 --> Mar 2026 | Trial primary completion date: Aug 2025 --> Mar 2026

In cynomolgus monkeys, systemically dosed AB598 results in effective enzymatic inhibition in tissues, full peripheral and tissue target engagement, and a reduction in cell surface CD39 both in tissues and in the periphery. Taken together, these data support a promising therapeutic strategy of harnessing the eATP generated by standard-of-care chemotherapies to prime the tumor microenvironment for a productive anti-tumor immune response.

P1, N=81, Recruiting, Arcus Biosciences, Inc. | Trial completion date: Nov 2025 --> Aug 2025 | Trial primary completion date: Nov 2025 --> Aug 2025

P1, N=81, Recruiting, Arcus Biosciences, Inc. | Not yet recruiting --> Recruiting

P1, N=81, Not yet recruiting, Arcus Biosciences, Inc.

Results Real-time measurement of ATP showed the ability of oxaliplatin to induce ATP release in MC38 tumor cells in vitro . Relative percentages of the immune cells in the lymph nodes were unaffected, suggesting internalization or downregulation, not cellular depletion, as the mechanism for the decrease in cell-surface CD39. Conclusions Our results indicate the superb ability of AB598 to inhibit enzymatic activity and tumor growth in vivo and provide a rationale for the combination of CD39 inhibition with ICD-inducing chemotherapy in the clinic.