Losartan rewires the tumor-immune microenvironment and suppresses IGF-1 to overcome resistance to chemo-immunotherapy in ovarian cancer

Ovarian cancer (OvCa) is the most lethal of the gynecologic malignancies. Immune checkpoint inhibitors, which have revolutionized the treatment of multiple malignancies, have had limited efficacy in OvCa patients. This lack of effectiveness is partly due to the abnormal ovarian tumor microenvironment (TME), displaying a desmoplastic, highly fibrotic extracellular matrix. High extracellular matrix deposition leads to a buildup of compressive forces that cause tumor blood vessel collapse, reduced vessel perfusion, poor delivery of drugs, and compromised trafficking of cytotoxic T-cells to these tumors. Using two syngeneic OvCa models, we tested the effect of losartan, a widely prescribed anti-hypertensive drug, on reprogramming the TME and chemosensitizing the cancer cells. Losartan treatment (i) reprograms the TME leading to increased vascular perfusion, and thus enhances drug delivery and immune effector cell intratumoral infiltration and function; and (ii) rewires the OvCa cells by suppressing the IGF-1 signaling, resulting in enhanced chemosensitivity. As a result of the combined tumor and stromal effects, losartan treatment enhances the efficacy of chemo-immunotherapy in OvCa models. The safety and low cost ( < $1-2/day) of losartan warrant rapid translation of our findings to patients with OvCa.