Counterproductive effects of Daratumumab and checkpoint inhibitor for the treatment of patients with relapsing NK/T lymphoma

Natural killer/T cell lymphoma (NK/T L) is an aggressive malignancy associated with poor prognosis in relapsed patients. Although L-asparaginase based treatments are recommended as first-line treatment in relapsed patients, advances in immunotherapies such as checkpoint inhibitions have provided new therapeutic alternatives. However, as clinical outcomes for checkpoint inhibitors seemed to vary between NK/T L patients, combination therapies have been suggested to improve treatment efficacy. Here, we compared the effects of Daratumumab (anti-CD38)/anti-PD-1 combination therapy versus anti-PD-1 monotherapy on two relapsed NK/T L patients. Anti-PD-1 triggered an upregulation of CD38 on activated T cells, leading to depletion by Daratumumab. Concomittantly, EBV-specific antibody titer was also reduced alongside with depletion of CD38+ B cells and antibody-producing plasmablasts. Taken together, combining anti-CD38 and anti-PD-1 is likely to be antithetic.