Sumitomo Pharma America (SMPA) announced the oral presentation of data from the ongoing Phase 1/2 first-in-human study of DSP-5336 in patients with relapsed or refractory acute leukemia at the European Hematology Association (EHA) 2024 Hybrid Congress.

DSP-5336 is an investigational small molecule inhibitor of the menin and mixed-lineage leukemia (MLL) protein interaction, which plays key roles in biological pathways, including cell growth regulation, cell cycle control, genomic stability, bone development, and hematopoiesis.

Building on preliminary data presented at the 2023 American Society of Hematology (ASH) Annual Meeting, authors presented updated data from the open-label, ongoing dose escalation and optimization portion of the Phase 1/2 study. Patients received oral DSP-5336 in repeating 28-day cycles at doses ranging from 40 mg to 300 mg twice-daily.

The oral presentation at EHA included the results of 57 patients. Responses were more consistently observed in patients who received 140 mg twice-daily or higher, particularly in the 21 patients with either Nucleophosmin 1 (NPM1) mutation or KMT2A (MLL) rearrangement documented by local testing. Objective response was observed in both patient populations with 57% of patients (12/21), with complete remission or complete remission with partial hematologic recovery (CR/CRh) observed in 24% (5/21 patients).

"The response in patients previously untreated with menin inhibitors is encouraging, and competitive with greater than 50% objective response rate alongside a favorable safety profile in patients with relapsed or refractory acute leukemia," said Naval Daver, M.D., Director, Leukemia Research Alliance Program and Professor in the Department of Leukemia at The University of Texas MD Anderson Cancer Center, and lead author on the DSP-5336 poster at EHA. "Menin inhibitors have tremendous potential to improve the outcomes of certain types of acute leukemia, as they reverse the leukemogenic activity of MLL fusion and mutated NPM1 proteins. In addition to promising clinical activity the safety profile of DSP-5336 has been especially encouraging and may differentiate it from other menin inhibitors with no severe DS, DLTs nor treatment-related discontinuations."

Leukemia is a type of cancer that forms in blood-forming tissue, characterized by the uncontrolled growth of blood cells, usually white blood cells, in the bone marrow. Acute leukemia, a form of leukemia, requires immediate treatment as blood cells multiply rapidly leading to a sudden onset of symptoms.4 Approximately 30% of acute myeloid leukemia (AML) patients have NPM1 mutations7 and 5-10% of AML patients have KMT2A (MLL) rearrangements.

"There remains a high unmet need in relapsed or refractory acute leukemia, as there are no approved targeted treatments for AML with KMT2A (MLL) rearrangements or NPM1 mutations," said Jatin Shah, M.D., Chief Medical Officer – Oncology at SMPA. "The biology of menin inhibition is clearly important and we are very early in the rapidly evolving field. We're excited by these early results and aim to provide a needed option that is both efficacious and well-tolerated. We look forward to continuing to progress the study of DSP-5336 in the hopes of improving outcomes in AML and advancing patient care."