High CAR intensity of expression confers enhanced antitumor effect against lymphoma without functional exhaustion.

Identifying factors that ameliorates clinical outcomes following CART therapy represents an unmet need. We hypothesized that CAR expression level would have a significant impact on CART efficacy and tested this with CAR30+ TSCM-LIKE enriched cells. By sorting T-cells according to CAR mean fluorescence intensity in two markedly different populations (CARHI and CARLO), we showed that a high CAR expression enhances antitumor efficacy in vitro, that is sustained after sequential re-exposures to tumor cells and is not associated with T-cell exhaustion or differentiation. Furthermore, we found a correlation between high surface CAR expression and antitumor effect with CAR19+ T-cells, thus validating our findings with CAR30. Definitive proof of CARHI T-cells improved antitumor efficacy was demonstrated in a human Hodgkin's lymphoma xenograft mouse model, where CAR30-TSCM-LIKE enriched products with high intensity of CAR expression achieved superior tumor control in vivo and longer survival than those with a low intensity of CAR expression. Our data suggest that modulation of CAR intensity of expression represents an additional strategy to increase CART therapy clinical efficacy.

Memory stem T cells modified with a redesigned CD30-chimeric antigen receptor show an enhanced antitumor effect in Hodgkin lymphoma.

OBJECTIVES: Adoptive cell therapy (ACT) with mature T cells modified with a chimeric antigen receptor has demonstrated improved outcome for B-cell malignancies. However, its application for others such as Hodgkin lymphoma remains a clinical challenge. CD30 antigen, expressed in Hodgkin lymphoma cells, is absent in most healthy tissues, representing an ideal target of ACT for this disease. Despite that, efficacy of CD30-chimeric antigen receptor (CAR) T cells for Hodgkin lymphoma remains modest. Here, we have developed and tested a novel CD30-CAR T to improve efficacy of CD30-CAR therapy, using a targeting epitope within the non-cleavable part of CD30 receptor, and memory stem T cells (TSCM) to improve engraftment, persistence and antitumor activity. METHODS: TSCM-like cultures were generated and expanded ex vivo and transduced at day 1 or 2 with a lentiviral vector encoding the CD30-CAR. Therapeutic in vivo experiments were performed using NSG mice injected with L540 (sc) or L428 (iv) and treated with CD30-CAR T cells when the tumor was established. RESULTS: CD30-CAR TSCM-like cells generated and expanded ex vivo, despite CD30 expression and fratricide killing of CD30+ CAR T cells, were not impaired by soluble CD30 and completely eradicated Hodgkin lymphoma in vivo, showing high persistence and long-lasting immunity. In addition, highly enriched CD30-CAR TSCM-like products confer a survival advantage in vivo, in contrast to more differentiated CAR T cells, with higher tumor infiltration and enhanced antitumor effect. CONCLUSION: This study supports the use of a refined CD30-CAR T cells with highly enriched TSCM-like products to improve clinical efficacy of CAR T for Hodgkin lymphoma.