A Study of MT-2111 in Patients With Relapsed/Refractory DLBCL

Inclusion Criteria: Patients who were diagnosed pathologically with DLBCL, NOS, DLBCL transformed from indolent B-cell lymphoma, or high-grade B-cell lymphoma with DLBCL morphology and with MYC and BCL2 and/or BCL6 rearrangements, based on the 2017 WHO classification. Patients with relapsed or refractory disease despite 2 or more prior systemic therapies. Japanese patients aged ≥ 18 years at the time of informed consent. For Japanese subjects, it should be confirmed that the parents who are related by blood to the subject must be Japanese. Patients who have a lesion that can be assessed for staging and evaluated for response according to the Lugano criteria (2014). A lesion that has received radiotherapy as the most recent treatment will be considered as a measurable lesion only when progression has been documented following completion of the radiotherapy. Patients with an Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1, or 2 at screening. Exclusion Criteria: Patients with a pathological diagnosis of Burkitt's lymphoma. Patients with bulky disease with the longest dimension of ≥ 10 cm. Patients with a history or complication of post-transplant lymphoproliferative disorders. Patients with lymphoma with active central nervous system involvement at the time of screening, including leptomeningeal disease. Patients complicated with other active malignancies or patients with a history of other malignancies within 3 years before informed consent. However, the following are exceptional: Non-melanoma skin cancer Non-metastatic prostate cancer Cervical carcinoma in situ Ductal carcinoma in situ or lobular carcinoma in situ Patients with clinically significant third space fluid accumulation (e.g., ascites requiring drainage or pleural effusion requiring drainage or associated with shortness of breath). Patients who underwent autologous hematopoietic stem cell transplantation (AHSCT) within 30 days prior to the start of study drug administration (Cycle 1 Day 1). For the Phase I part, patients with prior allogeneic stem cell transplantation (Allo-HSCT) before the start of study drug administration (Cycle 1 Day 1). For the Phase II part, patients undergoing Allo-HSCT within 60 days prior to the start of study drug administration (Cycle 1 Day 1). Patients who had a positive HIV antigen-antibody test or HIV antibody test. Patients positive for HBs antigen, HBc antibody, or HBs antibody. However, patients who meet any of the following are eligible: The patient's HBs antibody positivity is clearly due to vaccination. Patients who are positive for HBs antibody and/or HBc antibody with HBV-DNA not detected and agree to undergo HBV-DNA tests once a month from the start of study drug administration to at least 12 months after the completion of study drug administration. Patients positive for HCV antibody. However, patients with negative HCV-RNA are eligible. Patients who received anticancer therapy during the following periods prior to the start of study drug administration (Cycle 1 Day 1). Cytotoxic chemotherapy: within 14 days. Antibody therapy: within 5 half-lives or 14 days, whichever is longer (including monoclonal antibody preparations, radioimmunoconjugates, or antibody-drug conjugates). Within 14 days for rituximab. Radiotherapy: within 14 days CAR-T therapy: within 100 days Other anticancer therapy: within 14 days Patients who received treatment with any other investigational product within 14 days prior to the start of study drug administration (Cycle 1 Day 1). However, for the Phase I part, patients who received any other investigational product within 14 days or 5 half-lives, whichever is longer, before the start of study drug administration (Cycle 1 Day 1).