CD19-directed CART Therapy for T Cell/histiocyte Rich Large B-cell Lymphoma

T-cell/histiocyte-rich large B-cell lymphoma (THRLBCL) is a rare histologic variant of LBCL. Limited data regarding CD19-directed chimeric antigen receptor T-cell (CART) therapy in relapsed/refractory (R/R) THRLBCL suggest poor efficacy. We investigated CART outcomes for R/R THRLBCL through the CIBMTR registry. A total of 58 adult patients with R/R THRLBCL who received commercial CD19-CART between 2018-2022 were identified. Most patients (67%) had early relapse of disease (45% primary refractory) with a median of 3 (range: 1-7) prior therapies and were treated with Axicabtagene ciloleucel (69%). At median follow-up of 23 months post-CART, 2-year overall and progression-free survival were 42% (95% CI: 27-57) and 29% (95% CI: 17-43), respectively. In univariable analysis, poor performance status pre-CART was associated with higher mortality (HR 2.35, 95%CI 1.02-5.5). The 2-year cumulative incidences of relapse/progression and non-relapse mortality were 69% and 2%, respectively. Grade ≥3 CRS and ICANS occurred in 7% and 15% of patients, respectively. In this largest analysis of CD19-CART for R/R THRLBCL, approximately 30% of patients were alive and progression-free 2 years post-CART. Despite a high incidence of progression (69% at 2 years), these results suggest a subset of patients with R/R THRLBCL may have durable responses with CART.