CD70-directed CAR-T

We then use orthogonal approaches to increase binding on both the tumor and CAR-T cell sides of the immune synapse: a pharmacologic approach (azacitidine) to increase antigen density of CD70 in myeloid tumors, and an engineering approach to stabilize binding of the CAR to CD70. Our CD8 hinge and transmembrane-modified CD70 CAR-T cells are less prone to cleavage, have enhanced binding avidity, and increased expansion, leading to more potent in vivo activity. This enhanced CD70-targeted CAR is a promising candidate for further clinical development.

The TNF-alpha family member CD70 has emerged as a promising surface target antigen in AML after high complete response rates (CR) were seen in a Phase 1 trial of the CD70 antibody cusatuzumab (Riether et al, Nature Medicine 2020). Our findings demonstrate that natural-ligand binding domains of CARs targeting CD70 in AML can be effective but require mechanisms to overcome surface cleavage. CD70-targeted CARs comprised of a fusion of truncated CD27 to a CD8 hinge and transmembrane domain have promise in patients with AML, with and without combination with azacitidine.