A Phase Ib, Open-Label, Randomized Study to Assess Safety and Preliminary Efficacy of Tafasitamab (MOR208) or Tafasitamab + Lenalidomide in Addition to R-CHOP in Patients with Newly Diagnosed Diffuse Large B-Cell Lymphoma: Analysis of the Safety Run-in Phase

Introduction

Approximately 15-20% of treatment-naïve patients with diffuse large B-cell lymphoma (DLBCL) have CD20-low tumors, while CD19 is homogeneously expressed in >90% of cases of DLBCL. CD20-low DLBCL is associated with poor response to rituximab-based regimens (Johnson NA, et al. 2009). CD19 functions as a positive regulator of B-cell receptor signaling and is important for B-cell activation and proliferation and is therefore an attractive therapeutic target in addition to CD20. Tafasitamab (MOR208) is a humanized, Fc-enhanced, anti-CD19 monoclonal antibody with improved antibody-dependent cellular cytotoxicity and phagocytosis. Monotherapy with tafasitamab has shown clinical activity in relapsed/refractory (R/R) non-Hodgkin's lymphoma (Jurczak W, et al. 2018). In the Phase II, single-arm L-MIND study (NCT02399085) in patients with R/R DLBCL, combined treatment of tafasitamab with lenalidomide resulted in a high proportion of patients having a complete response (Salles GA, et al. 2020). First-MIND (NCT04134936) is a Phase Ib, randomized study of tafasitamab + R-CHOP (Arm A) or tafasitamab + lenalidomide + R-CHOP (Arm B) in patients with newly diagnosed DLBCL. Here, we report data from the safety run-in phase.

Study design and methods

Patients must be aged ≥18 years, treatment naïve, with histologically confirmed DLBCL not otherwise specified and have intermediate- to high-risk disease (International Prognostic Index [IPI] 2-5) and an ECOG performance status of 0-2. Known double- or triple-hit lymphoma and transformed lymphoma are excluded. Treatment consists of six 21-day cycles of tafasitamab (12 mg/kg intravenously [IV], on Day [D] 1, 8 and 15) in addition to R-CHOP (Arm A) or tafasitamab (12 mg/kg IV, on D1, 8 and 15) + lenalidomide (25 mg orally, on D1-10) in addition to R-CHOP (Arm B). Granulocyte-colony stimulating factor prophylaxis was mandatory in all patients. The study includes a safety run-in phase and a main phase. In the safety run-in phase, 24 patients were enrolled. The primary objective is to assess safety; secondary objectives include ORR, PET-CR rate at end of treatment, PFS, event-free survival, long-term safety, pharmacokinetics and immunogenicity of tafasitamab. Exploratory objectives include the assessment of circulating cell-free tumor DNA. Approximately 60 patients will be recruited in 9 countries across Europe and the US.

Results

Recruitment is ongoing. Thirty-six patients were randomized; 18 in each arm. The data presented for the safety run-in phase consist of 24 patients: 13 patients in Arm A and 11 patients in Arm B. All completed the first treatment cycle; 88% of patients entered into Cycle 2 and 50% of patients entered into Cycle 3 of treatment. At baseline, their median age was 67 years (range: 47-76; Arm A) and 65 years (range: 40-74; Arm B). Overall, 33% of patients were male and 67% female; IPI scores were: IPI 2, 33%; IPI 3, 42%; IPI 4, 25%. Most patients had advanced stages III/IV (92%) and approximately 50% had bulky disease. Cell of origin was determined to be germinal center B-cell (GCB) DLBCL in 13%, non-GCB DLBCL in 42% and not yet classified in 46% of cases. A total of 248 treatment-emergent adverse events (AEs) by system organ class were documented: 111 in Arm A and 137 in Arm B. Grade ≥3 neutropenia was observed in 54% (Arm A) and 46% (Arm B) of patients. Thrombocytopenia Grade ≥3 was observed in 8% (Arm A) and 18% (Arm B) of patients. Diarrhea, fatigue and vomiting were comparable between the two arms. Febrile neutropenia was uncommon in both arms, with one event each (Figure 1). To date, 23 serious AEs were observed: 11 in Arm A (Grade 2, 1; Grade 3, 6; Grade 4, 4) and 12 in Arm B (Grade 2, 3; Grade 3, 7; Grade 4, 2). One suspected unexpected serious adverse reaction was reported in Arm B - pneumocystis jirovecii pneumonia. No treatment-associated deaths occurred.

Conclusions

R-CHOP can be safely combined with tafasitamab or tafasitamab + lenalidomide in patients with treatment-naïve DLBCL. Toxicities appear to be similar to what is expected with R-CHOP alone or in combination with lenalidomide. Enrollment is ongoing and updated safety and early efficacy data will be presented at the meeting.

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