Forma Therapeutics Holdings, Inc. announced positive top-line data from a planned interim analysis of a registrational Phase 2 clinical trial of olutasidenib, Forma’s selective inhibitor for hematological malignancy cancers with mutations in isocitrate dehydrogenase 1 (IDH1m). Olutasidenib demonstrated a favorable tolerability profile as a monotherapy in patients with IDH1m relapsed/refractory acute myeloid leukemia (R/R AML), and achieved a composite complete remission (CR+CRh, or complete remission plus complete remission with partial hematologic recovery) rate of 33.3% (30% CR and 3% CRh), the primary efficacy endpoint. While a median duration of CR/CRh has not been reached, a sensitivity analysis (with a hematopoietic stem cell transplant or HCST as the end of a response) indicates the median duration of CR/CRh to be 13.8 months. Safety results are consistent with previously reported Phase 1 clinical trial results . The most common adverse events (AEs) observed were nausea, constipation, increased white blood cell count, decreased red blood cell count, fever, febrile neutropenia and fatigue. Additional analyses and other outcome measures will be presented at an upcoming medical meeting. The Phase 1/2 study is a multicenter, open-label, multi-cohort evaluation of the safety, efficacy and pharmacokinetics/pharmacodynamics (PK/PD) of olutasidenib for patients with AML or myelodysplastic syndrome (MDS) with an IDH1 mutation. Phase 1 of the trial, FT2102-HEM-101, was an open-label, dose-escalation and expansion study of olutasidenib alone and in combination with azacitidine (AZA). The pivotal Phase 2 study is an open-label, fixed-dose study of olutasidenib as a monotherapy in IDH1m AML patients. The Phase 2 study includes other cohorts of olutasidenib in combination with AZA in IDH1m AML/MDS populations. The primary efficacy-evaluable population of the pivotal phase 2 study is comprised of 123 R/R AML patients, who received olutasidenib 150 mg BID at least six months prior to the interim analysis cutoff date of June 18, 2020. The primary endpoint is a composite of a complete remission (CR) plus a complete remission with partial hematological recovery (CRh), defined as less than 5% blasts in the bone marrow, no evidence of disease and partial recovery of peripheral blood counts (platelets >50,000/microliter and ANC >500/microliter). Olutasidenib is an oral, potent and small molecule investigational agent designed to selectively bind to and inhibit mutated IDH1 enzymes. This targeted treatment has the potential to provide therapeutic benefit by reducing 2-HG levels and restoring normal cellular differentiation. Forma is currently evaluating olutasidenib in a registrational Phase 2 trial for relapsed/refractory AML and in an exploratory Phase 1 trial for glioma and other solid tumors. IDH1 is a natural enzyme that is part of the normal metabolism of all cells; when mutated, its activity can promote blood malignancies and solid tumors. IDH1 mutations are present in 6-8% of patients with AML and as many as 70 to 80% of patients with grade II/III gliomas and secondary glioblastoma. In gliomas, IDH1 mutations occur early in the tumor pathogenesis and persist throughout progression from a neural stem or progenitor cell. Gliomas are the most common, aggressive and difficult-to-treat primary brain tumors, and high-grade gliomas are associated with poor long-term prognosis. Treatment options for relapsed glioma are limited.