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Syndax Pharmaceuticals to Begin Registrational Study of Menin-MLL Inhibitor in Leukemia

NEW YORK – Syndax Pharmaceuticals said on Tuesday its menin inhibitor, SNDX-5613, produced a response in patients with MLL rearranged and NPM1c mutant relapsed or refractory acute leukemias.

The Waltham, Massachusetts-based firm said it was planning to begin the Phase II registrational trial of SNDX-5613 in Q2 2021 based on the positive interim results from this Phase I study announced on Tuesday.

As of the data cutoff in March, there were 31 evaluable patients in the Phase I/II AUGMENT-101 trial. Among the 31 total, 24 patients had an MLL rearrangement and seven had an NPM1c mutation. The objective response rate in evaluable patients harboring an MLL rearrangement was 54 percent and the response rate in evaluable patients with an NPM1c mutation was 29 percent. Across all evaluable patients, 48 percent saw a response and 67 percent reached MRD-negative status.

"Data reported today further support the potential for SNDX-5613 to induce clinically meaningful responses in patients with genetically defined acute leukemias," Syndax CEO Briggs Morrison said in a statement. "Notably, robust clinical activity, including multiple complete responses with no evidence of minimal residual disease, were observed in heavily pretreated MLLr and NPM1c patients. We have identified a candidate recommended Phase II dose and expect to commence the pivotal Phase II portion of the trial by the end of the second quarter."

In the Phase II portion of the trial, researchers will enroll patients into three indication-specific cohorts: patients with MLL-rearranged acute lymphoblastic leukemia or mixed phenotype acute leukemia, patients with MLL-rearranged acute myeloid leukemia, and patients with NPM1c-mutated acute myeloid leukemia.

Daiichi Sankyo is also developing a menin inhibitor to treat leukemias with a MLL rearrangement or NPM1 mutation, currently in a Phase I/II trial. Kronos Bio is studying its drug, entospletinib, in a Phase III trial of patients with NPM1-mutated acute myeloid leukemia.