Expanding anti-CD38 immunotherapy for lymphoid malignancies.

Background: Lymphoid neoplasms, including multiple myeloma (MM), non-Hodgkin lymphoma (NHL), and NK/T cell neoplasms, are a major cause of blood cancer morbidity and mortality. CD38 (cyclic ADP ribose hydrolase) is a transmembrane glycoprotein expressed on the surface of plasma cells and MM cells. The high expression of CD38 across MM and other lymphoid malignancies and its restricted expression in normal tissues make CD38 an attractive target for immunotherapy. CD38-targeting antibodies, like daratumumab, have been approved for the treatment of MM and tested against lymphoma and leukemia in multiple clinical trials.

Methods: We generated chimeric antigen receptor (CAR) T cells targeting CD38 and tested its cytotoxicity against multiple CD38 and CD38 lymphoid cancer cells. We evaluated the synergistic effects of all-trans retinoic acid (ATRA) and CAR T cells or daratumumab against cancer cells and xenograft tumors.

Results: CD38-CAR T cells dramatically inhibited the growth of CD38 MM, mantle cell lymphoma (MCL), Waldenstrom's macroglobulinemia (WM), T-cell acute lymphoblastic leukemia (T-ALL), and NK/T-cell lymphoma (NKTCL) in vitro and in mouse xenografts. ATRA elevated CD38 expression in multiple CD38 cancer cells and enhanced the anti-tumor activity of daratumumab and CD38-CAR T cells in xenograft tumors.

Conclusions: These findings may expand anti-CD38 immunotherapy to a broad spectrum of lymphoid malignancies and call for the incorporation of ATRA into daratumumab or other anti-CD38 immunological agents for cancer therapy.