This is a multicenter, international, phase II study of post-radiotherapy (RT) administration of olutasidenib to treat pediatric and young adult patients newly diagnosed with an IDH1-mutant HGG. The trial will include a feasibility cohort to identify the dose of olutasidenib that is feasible when given in combination with temozolomide as maintenance therapy after completion of focal radiotherapy in this patient population. Efficacy will be defined by progression-free survival (PFS) distribution of these patients after completion of radiotherapy treated with maintenance olutasidenib and TMZ for 13 cycles followed by 13 cycles of single agent olutasidenib compared to molecularly-stratified and matched historical controls. Objective radiographic response rates, agent-specific toxicities as well as the pharmacokinetic and pharmacodynamic properties of olutasidenib will also be assessed.

BACKGROUND: Olutasidenib (FT-2102) is a potent, selective, oral, small-molecule inhibitor of mutant isocitrate dehydrogenase 1 (IDH1). The aims for phase 1 of this phase 1/2 study were to assess the safety, pharmacokinetics, pharmacodynamics, and clinical activity of olutasidenib, as monotherapy or in combination with azacitidine, in patients with acute myeloid leukaemia or myelodysplastic syndrome, harbouring mutant IDH1. METHODS: In this phase 1/2, multicentre, open-label clinical trial, we enrolled patients aged 18 years or older with acute myeloid leukaemia or intermediate, high, or very high risk myelodysplastic syndrome harbouring mutant IDH1 at 18 study sites in the USA, Australia, France, and Spain. Other key eligibility criteria included Eastern Cooperative Oncology Group performance status 0-2 with adequate liver and renal function. The primary outcomes were dose-limiting toxicities and the maximum tolerated dose, maximum evaluated dose, and the recommended phase 2 dose of olutasidenib. Olutasidenib was administered orally in doses of 150 mg once daily, 150 mg twice per day, and 300 mg once daily. Azacitidine (75 mg/m2) was administered subcutaneously or intravenously daily for 7 days on, 21 days off. The study was ongoing at the data cutoff (Oct 2, 2019) and is registered with ClinicalTrials.gov, NCT02719574. FINDINGS: Patients were enrolled between Aug 8, 2016, and Nov 14, 2018. 78 patients received olutasidenib as monotherapy (n=32) or in combination with azacitidine (n=46). The median follow-up was 8·3 months (IQR 3·1-13·3) for monotherapy and 10·1 months (4·2-15·3) for combination therapy. 16 (50%) of 32 patients in the monotherapy group and 24 (52%) of 46 patients in the combination therapy group were women. Most patients were White (26 [81%] for monotherapy and 31 [67%] for combination therapy). No dose-limiting toxicities were reported in the dose-escalation cohorts and 150 mg twice per day was declared the recommended phase 2 dose on the basis of safety, pharmacokinetics and pharmacodynamics, and clinical activity. The most common (≥20%) grade 3-4 treatment-emergent adverse events with monotherapy were thrombocytopenia (nine [28%] of 32 patients), febrile neutropenia (seven [22%] of 32), and anaemia (seven [22%] of 32); and with combination therapy were thrombocytopenia (19 [41%] of 46), febrile neutropenia (13 [28%] of 46), neutropenia (13 [28%] of 46), and anaemia (nine [20%] of 46). 11 (34%) of 32 patients in the monotherapy group and nine (20%) of 46 patients in the combination therapy group died (most commonly from disease progression [three (9%) of 32 and four (9%) of 46]). No deaths were considered study-drug related. For patients with relapsed or refractory acute myeloid leukaemia, 41% (95% CI 21-64; nine of 22) receiving monotherapy and 46% (27-67; 12 of 26) receiving combination therapy had an overall response. For treatment-naive patients with acute myeloid leukaemia, 25% (1-81; one of four) receiving monotherapy and 77% (46-95; ten of 13) receiving combination therapy had an overall response. INTERPRETATION: Olutasidenib, with or without azacitidine, was well tolerated and showed meaningful clinical activity in patients with IDH1-mutated acute myeloid leukaemia. The results of this phase 1 study provide rationale for the continued evaluation of olutasidenib in multiple patient populations with myeloid malignancies. FUNDING: Forma Therapeutics.

This Phase 1/2 study will evaluate the safety, efficacy, PK, and PD of FT-2102 (olutasidenib) as a single agent or in combination with azacitidine or cytarabine. The Phase 1 stage of the study is split into 2 distinct parts: a dose escalation part, which will utilize an open-label design of FT-2102 (olutasidenib) (single agent) and FT-2102 (olutasidenib) + azacitidine (combination agent) administered via one or more intermittent dosing schedules followed by a dose expansion part. The dose expansion part will enroll patients in up to 5 expansion cohorts, exploring single-agent FT-2102 (olutasidenib) activity as well as combination activity with azacitidine or cytarabine. Following the completion of the relevant Phase 1 cohorts, Phase 2 will begin enrollment. Patients will be enrolled across 8 different cohorts, examining the effect of FT-2102 (olutasidenib) (as a single agent) and FT-2102 (olutasidenib) + azacitidine (combination) on various AML/MDS disease states.