Syndax Pharmaceuticals, Inc. announced that data from the Phase 1 portion of the ongoing Phase 1/2 AUGMENT-101 trial of revumenib in patients with nucleophosmin mutant (mNPM1) and KMT2A-rearranged (KMT2Ar) relapsed/refractory (R/R) acute leukemia and an analysis describing MEN1 mutations observed in the study have been published in the journal Nature. Revumenib is the Company's highly selective, oral menin inhibitor. The Phase 1 publication in Nature includes data from 68 patients evaluable for safety, 60 patients of whom were evaluable for efficacy, as of a March 2022 data cutoff.

Patients were heavily pretreated with a median of four prior therapies, and 46% (31/68) of the patients had at least one prior stem cell transplant. Within the efficacy evaluable population, the overall response rate was 53% (32/60) with a CR/CRh rate of 30% (18/60), and 78% (14/18) of patients with CR/CRh attaining measurable residual disease (MRD) negativity. The median time to CR/CRh response in the trial was 1.9 months, and the median duration of CR/CRh response was 9.1 months in the efficacy evaluable population as of data cutoff.

A total of 38% (12/32) of responders proceeded to transplant, with nine in remission at the time of the data cutoff, seven of whom have been in remission for greater than six months and four who have been in remission for greater than a year. Eleven (92%) patients who underwent a transplant were MRD negative prior to transplant. Revumenib was well-tolerated, and no new safety signals were identified in the trial, including in patients who proceeded to stem cell transplant.

There were no discontinuations due to treatment-related adverse events. The only dose limiting toxicity was asymptomatic Grade 3 QT prolongation, observed in 10% of patients treated at or below the RP2D and 13% of patients treated at all doses tested. No ventricular arrythmias or other clinical sequelae related to QTc prolongation were reported.

Differentiation syndrome occurred in 16% of patients, all which were Grade 2, and patients responded to standard management of steroids with or without hydroxyurea.