αvβ3 CAR-T Cells Simultaneously Targeting Tumor and Metastases Produce Highly Effective Control in Preclinical Models of Melanoma and Triple-Negative Breast Cancer

Abstract One of the many barriers to successful chimeric antigen receptor (CAR) T-cell immunotherapy against solid tumors is the scarcity of targetable molecules common to multiple types of cancer. The purpose of this study was to determine the efficacy of αvβ3 CAR-T cells against solid tumors, particularly melanoma and triple-negative breast cancer, two malignancies recognized for dependence on the αvβ3 pathway for tumor progression and metastases. A novel αvβ3 CAR-T cell developed in our lab and demonstrated to be effective and safe in preclinical models of glioblastoma and pediatric diffuse intrinsic pontine glioma was utilized in this study. Two versions of the αvβ3 CAR-T construct, containing either a CD28 or 4-1BB co-stimulation domain, were tested here. Multiple xenograft studies consisting of melanoma and orthotopic breast tumor models were conducted to evaluate the efficacy of systemically administered αvβ3 CAR-T cells. In this study, we demonstrate that the integrin αvβ3 is a highly attractive target for CAR-T cells as we found it to be highly expressed on various cancer types, including melanoma and triple-negative breast cancer, and susceptible to CAR-T cell–mediated control in multiple xenograft models. In vivo antitumor efficacy of αvβ3 CAR-T cells was underscored by the ability of CARs to circumvent tumor metastasis and to persist long term. Surprisingly, co-stimulation provided by CD28, rather than 4-1BB, led to more robust antitumor efficacy typified by superior long-term control, better persistence, and improved durability against continuous antigen exposure. These results strengthen the rationale for clinical translation and deployment of αvβ3 CAR-T cells against multiple cancer types.