Treatment with brentuximab vedotin in vitro and CAR T-cell function and viability: Implications for combination or sequential therapeutic approaches for lymphoma.

e15014 Background: Brentuximab vedotin (BV), an antibody-drug conjugate targeting CD30, demonstrates potent cytotoxicity against CD30-expressing cancer cells, and remains a standard of care for lymphoma. Recently, chimeric antigen receptor (CAR) T-cell therapy has shown efficacy as monotherapy for lymphoma and could be a viable option for patients with refractory disease after failure of conventional treatment options. Despite the progress made with CAR T-cell therapy, resistance mechanisms and adverse events associated with CAR T cells remain significant hurdles. Combination of CAR T-cell therapy with BV for lymphoma treatment could be an attractive new therapy paradigm, taking advantage of both modalities to drive responses, particularly in populations with relapsed/refractory disease. However, potential impacts of BV treatment on the viability and function of CAR T cells have not been elucidated. Herein, we describe the effects of BV treatment on CAR T cells in vitro to better understand the potential combinations and/or sequencing with CAR T-cell therapies. Methods: This study investigated the cytotoxic and functional effects of BV treatment on several types of CAR T cells in vitro. Previously frozen, commercially generated CAR T cells targeting BCMA, CD19, CD20, or mesothelin were stimulated with a human CD2/CD3/CD28 activator for 48 h. Following stimulation, CAR T cells were then exposed to increasing concentrations of BV for 96 h. Viability, cytokine production, and surface marker expression of CAR T cells and untransduced donor T cells were measured following BV treatment. A nontargeting vedotin ADC and a CD30-targeting ADC known for increased T-cell cytotoxicity were included as negative and positive controls, respectively. Results: CAR T cells were characterized as a mixture of CD4 and CD8 T cells. BV treatment in a dose titration of 1–10,000 ng/mL, including and exceeding clinical exposures, resulted in little to no cytotoxicity against any CAR T-cell type at all concentrations tested. Primary untransduced T cells from the same CAR T-cell donors also displayed no cytotoxicity when treated with BV in vitro. The positive control ADC targeting CD30 showed increased, dose-dependent T-cell cytotoxicity in the same assay. Functional assays revealed that BV-treated CAR T cells retained cytokine production and cytolytic activity compared with controls, regardless of CD30 expression. Conclusions: Preclinical data from this study demonstrated no adverse changes in viability or functionality of CAR T cells with BV treatment in vitro. Collectively, these results suggest the potential to either combine or sequentially use BV and CAR T-cell therapies. Further investigation into optimal combination dosing and/or sequencing strategies is warranted.