ASH 2023: High Complete Response Rates in High-Risk Relapsed/Refractory Follicular Lymphoma Treated with Loncastuximab Tesirine

Loncastuximab tesirine is an antibody-drug conjugate that has demonstrated synergistic properties when used in combination with rituximab. Interim results from an ongoing phase 2 study of loncastuximab tesirine plus ritxumab in patients with relapsed or refractory high-risk follicular lymphoma (FL) were presented by LRF grantee Juan Pablo Alderuccio, MD of University of Miami Health System. In this study, high-risk FL was defined based on the progression of disease within 24 months of frontline immunotherapy, or a high burden of disease.

At the time results were reported, 26 patients had been enrolled; response data were available for 21 of these patients. Most patients (77%) had advanced stage disease and 46% demonstrated progression of disease within 24 months of initial immunotherapy. The median number of prior lines of therapy was 1 but ranged from 1 to 6.

Among the 21 patients with an evaluable response, the overall response rate at week 12 was 95.2%; the complete response rate was 66.7% and the partial response rate was 28.6%. All complete responses were maintained at week 21 and at least 4 of the 6 partial responders improved to a complete response by this time point. With these improvements in response, the investigators reported a complete metabolic response rate of 86% with short-duration loncastuximab tesirnie plus rituximab therapy in patients with relapsed/refractory CLL, including those with high-risk disease.

Among 25 patients with available safety data, most adverse events were mild (grade 1 or 2). All toxicities were able to be resolved with supportive care and dose delays

This study also included contributions from LRF SAB member Izidore Lossos, MD of University of Miami Health System; former SAB member Craig Moskowitz, MD of Sylvester Comprehensive Cancer Center; and LRF grantee Jonathan Schatz, MD of University of Miami.