Tafasitamab as Monotherapy or in Combination in Japanese Patients With B‐Cell Non‐Hodgkin Lymphoma: Results From the Phase 1b J‐ <scp>MIND</scp> Study

We conducted a phase 1b study evaluating safety and tolerability of tafasitamab, a CD19-targeting immunotherapy, in Japanese patients with B-cell non-Hodgkin lymphoma (NHL). Eligible patients were ≥ 18 years old with relapsed/refractory (R/R) B-cell NHL (Group 1), R/R diffuse large B-cell lymphoma (DLBCL; Groups 3 and 4), or untreated DLBCL (Group 5). Patients received tafasitamab starting at 12 mg/kg qw (Group 1, n = 6), tafasitamab + lenalidomide starting at 25 mg qd for ≤ 12 cycles (Group 3, n = 6), tafasitamab + parsaclisib starting at 20 mg qd (Days 1-56) then 2.5 mg qd (Group 4, n = 6), or tafasitamab + lenalidomide combined with R-CHOP for ≤ 6 cycles (Group 5, n = 6). Primary objective was safety and tolerability of tafasitamab alone and in combination; exploratory objectives included efficacy. At data cutoff (August 31, 2023), 24 patients were treated. All patients experienced treatment-emergent adverse events (TEAEs). Two patients experienced a dose-limiting toxicity; liver disorder (grade 4) considered related to lenalidomide (Group 3, n = 1), and febrile neutropenia (grade 3) considered related to lenalidomide and R-CHOP (Group 5, n = 1). Most common TEAEs across groups were hematological and included neutropenia, leukopenia, thrombocytopenia, and anemia; most common non-hematological TEAEs included increased alanine aminotransferase, increased aspartate aminotransferase, diarrhea, nausea, constipation, and infusion-related reactions. No serious tafasitamab treatment-related or fatal TEAEs were observed. Results suggest tafasitamab alone or in combination demonstrates a manageable safety profile in Japanese patients with B-cell NHL. Preliminary efficacy results from the study are reported. However, results should be interpreted with caution due to the small sample size, with further studies warranted to confirm these findings. Trial Registration: NCT04661007; jRCT2031200357.