VISTA‐targeted antibody‐drug conjugates exhibit potent antitumor effects on malignant pleural mesothelioma

Abstract Malignant pleural mesothelioma (MPM) is a malignant tumor of the pulmonary pleural tissue for which there is a lack of effective targeted therapy. In this study, moderate to high V‐domain immunoglobulin T‐cell activation suppressor (VISTA) expression levels were observed in most MPM clinical tumor samples. We prepared two high‐affinity anti‐VISTA monoclonal antibodies (mAbs) and generated two novel VISTA‐targeted antibody‐drug conjugates (ADCs) by conjugating anti‐VISTA mAbs with the potent cytotoxic drug monomethyl auristatin E (MMAE). αV1‐MMAE and αV2‐MMAE showed potent killing effects to VISTA‐positive cell lines in vitro, with half‐maximal inhibitory concentration (IC50) of nanomolar levels. αV1‐MMAE and αV2‐MMAE were also able to significantly induce apoptosis and cause G2/M phase arrest in VISTA‐positive cells. In the VISTA‐positive human MPM xenograft model, both αV1‐MMAE and αV2‐MMAE showed significant antitumor activity, led to a significant survival advantage compared to mice in the control group, and effectively induced apoptosis in the tumor tissues of mice. In conclusion, we demonstrated that the novel VISTA‐targeted ADCs (αV1‐MMAE and αV2‐MMAE), especially αV1‐MMAE, had potent killing effects against VISTA‐positive MPM cells both in vitro and in vivo. Therefore, through further development, they may have the potential to become new drugs for the treatment of MPM.