MARLBOROUGH, Mass. — Sumitomo Pharma America announced that the U.S. Food and Drug Administration (FDA) has granted Breakthrough Therapy designation to its investigational drug enzomenib (DSP-5336) for the treatment of patients with relapsed or refractory acute leukemia involving KMT2A gene rearrangements.
The designation is intended to accelerate the development and regulatory review of treatments for serious or life-threatening diseases when preliminary clinical evidence suggests they may offer substantial improvements over existing therapies.
Enzomenib is an experimental oral medication designed to inhibit the interaction between two proteins, menin and KMT2A, that play important roles in the development and progression of certain forms of acute leukemia.
By blocking this interaction, the drug aims to interfere with molecular processes that promote the growth and survival of leukemia cells.
The treatment is currently being evaluated in the Phase 2 Horizen-1 clinical trial involving patients with relapsed or refractory acute leukemia carrying KMT2A rearrangements or mutations in the NPM1 gene.
The company is also investigating enzomenib in combination with standard treatments for newly diagnosed and previously treated acute myeloid leukemia (AML) through an ongoing Phase 1/2 clinical study.
“Patients with R/R KMT2A-rearranged acute leukemia continue to face poor outcomes,” said Tsutomu Nakagawa, president and CEO of Sumitomo Pharma America.
“FDA’s decision to grant Breakthrough Therapy designation underscores enzomenib’s potential and enables expedited FDA review that may potentially provide the opportunity to bring this investigational treatment to patients more quickly. We look forward to continued engagement with the FDA to advance clinical research of enzomenib with the goal of bringing it to patients as efficiently as possible,” Nakagawa added.
KMT2A-rearranged acute leukemia is an aggressive form of blood cancer associated with rapid disease progression and poor survival outcomes.
Patients whose leukemia returns after treatment or fails to respond to conventional therapies often face limited treatment options.
Even with intensive chemotherapy and hematopoietic stem cell transplantation, patients with KMT2A-rearranged leukemia frequently experience poor outcomes, highlighting the need for new targeted treatments.
Enzomenib belongs to a class of drugs known as menin inhibitors, which are being developed to target specific molecular pathways involved in leukemia.
Preclinical studies have shown that enzomenib can selectively inhibit the growth of leukemia cells carrying KMT2A rearrangements or NPM1 mutations.
Laboratory research has also demonstrated that the drug reduces the activity of leukemia-associated genes, including HOXA9 and MEIS1, while increasing expression of CD11b, a gene associated with cellular differentiation.
The FDA previously granted enzomenib Fast Track designation in June 2024 for relapsed or refractory AML involving KMT2A rearrangements or NPM1 mutations.
The drug also received FDA Orphan Drug designation for acute myeloid leukemia in June 2022 and acute lymphoblastic leukemia in July 2026.
Japan’s Ministry of Health, Labour and Welfare granted enzomenib Orphan Drug designation in September 2024 for relapsed or refractory AML involving KMT2A rearrangements or NPM1 mutations.
The ongoing clinical development program includes studies evaluating enzomenib as a standalone treatment and in combination with established leukemia therapies.
Sumitomo Pharma America said the latest FDA designation will provide opportunities for more frequent regulatory interaction and guidance as the company advances enzomenib through clinical development.
The drug remains investigational, and its safety and effectiveness have not yet been established for commercial use.
