Epcoritamab is a subcutaneously administered CD3xCD20 T-cell-engaging, bispecific antibody that activates T cells, directing them to kill malignant CD20 B cells. Single-agent epcoritamab previously demonstrated potent antitumor activity in dose escalation across B-cell non-Hodgkin lymphoma subtypes.

In the dose-expansion cohort of a phase I/II study (ClinicalTrials.gov identifier: NCT03625037), adults with relapsed or refractory CD20 large B-cell lymphoma and at least two prior therapy lines (including anti-CD20 therapies) received subcutaneous epcoritamab in 28-day cycles (once weekly step-up doses in weeks 1-3 of cycle 1, then full doses once weekly through cycle 3, once every 2 weeks in cycles 4-9, and once every 4 weeks in cycle 10 and thereafter) until disease progression or unacceptable toxicity. The primary end point was overall response rate by the independent review committee.

As of January 31, 2022, 157 patients were treated (median age, 64 years [range, 20-83]; median of three [range, 2-11] prior therapy lines; primary refractory disease: 61.1%; prior chimeric antigen receptor (CAR) T-cell exposure: 38.9%). At a median follow-up of 10.7 months, the overall response rate was 63.1% (95% CI, 55.0 to 70.6) and the complete response rate was 38.9% (95% CI, 31.2 to 46.9). The median duration of response was 12.0 months (among complete responders: not reached). Overall and complete response rates were similar across key prespecified subgroups. The most common treatment-emergent adverse events were cytokine release syndrome (49.7%; grade 1 or 2: 47.1%; grade 3: 2.5%), pyrexia (23.6%), and fatigue (22.9%). Immune effector cell-associated neurotoxicity syndrome occurred in 6.4% of patients with one fatal event.

Subcutaneous epcoritamab resulted in deep and durable responses and manageable safety in highly refractory patients with large B-cell lymphoma, including those with prior CAR T-cell exposure.