Clinicopathological features of tumour flare with Epcoritamab post CAR-T cell relapse.

Aim: Bispecific antibodies represent a new treatment era for B cell lymphomas and can induce tumour flare before responding to treatment. The clinicopathologic features of tumour flare are not well described. We present the clinicopathological course of tumour flare in a patient with cutaneous DLBCL treated with Epcoritamab post CAR-T cell relapse.

Method:
Sequential clinical and pathological data were collected for a patient with DLBCL receiving Epcoritamab three months post tisagenlecleucel failure. Skin biopsies were obtained pre- and during Epcoritamab dosing. CD19 and CD20 expression were maintained post CAR-T failure. Epcoritamab was administered subcutaneously weekly (0.16mg, 0.8mg, 48mg thereafter).

Conclusion:
The cutaneous distribution of lymphoma has allowed us to demonstrate the clinicopathologic course of tumour flare with Epcoritamab. In this case, Epcoritamab resulted in increased expression of cytotoxic markers without a significant increase in tumour-infiltrating T-lymphocytes. We hypothesize a similar course occurs at other nodal and extra-nodal sites.