Abstract 5079: Comparative studies of chemotherapy and immuno-oncology combinations in multiple mouse syngeneic tumor models

Abstract The development of immune checkpoint inhibitors (ICIs) and combinations of immuno-oncology therapies with standard-of-care (SoC) chemotherapeutic agents has shifted therapeutic paradigms for patients with multiple cancer indications. For many patients, these combinations have shown a beneficial effect on clinical outcomes and disease management. However, additional combination therapies are still needed. Preclinically, a comparison of responses from SoC chemotherapies and ICI combinations in multiple disease models may be helpful in identifying optimal treatment combinations in the clinic. Here we report the results of multiple SoC/ICI in vivo combination efficacy studies in a large panel of mouse syngeneic models spanning seven tissue origins: 1) Colon: CT26, MC38; 2) Breast: EMT6, 4T1; 3) Kidney: Renca; 4) Bladder: MB49, MBT2; 5) Skin: B16F10, CM3; 6) Lung: TC1, LL/2, M109; 7) Brain: GL261. The advantage of using syngeneic models is not limited to the rapid and reproducible tumor growth, but importantly that the animals also have an intact immune system and clinically relevant tumor microenvironment, which are required for ICI combination studies. We tested > 10 chemo SoC combinations with a murinized anti-PD-1 antibody (DX400) in 14 syngeneic mouse models. We found that multiple SoC regimens combined well with DX400 treatment, including FOLFIRI, FOLFOX (colon), Carboplatin/Paclitaxel, Carboplatin/Pemetrexed (lung), Capecitabine/Docetaxel, Cisplatin/Gemcitabine (bladder), Cisplatin/5-FU/or capecitabine, and Oxaliplatin/5-FU/or capecitabine (gastric). Specifically, we observed that the SOC/ICI combinations resulted in enhanced antitumor activities compared to single-agent treatments in many of the models. These data, particularly specific SoC combination regimens that combine well with ICIs in each disease, are useful for optimizing promising combination approaches for clinical development and will be presented here. Citation Format: Eunsil Park, Marlene Hinton, Mingmei Cai, Malgorzata A. Gil, Gustave Hebert, Long Cui, Doug Linn, Brian J. Long, Evan R. Barry. Comparative studies of chemotherapy and immuno-oncology combinations in multiple mouse syngeneic tumor models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5079.