Phase 1 Study of the IDH1m Inhibitor FT-2102 As a Single Agent in Patients with IDH1m Acute Myeloid Leukemia (AML) or Myelodysplastic Syndrome (MDS)

Background: Isocitrate dehydrogenase 1 mutations (IDH1m) occur in 7-14% of AML patients and 3% of MDS patients and produce 2-hydroxyglutarate (2-HG), an oncometabolite that impairs differentiation. FT-2102 is an oral, highly potent, selective small molecule inhibitor of mutated IDH1, with the therapeutic potential to restore normal cellular differentiation. Herein, we present preclinical and clinical data from an ongoing Phase 1/2 study of single-agent (SA) FT-2102 in patients with IDH1m AML and MDS (CT.gov: NCT02719574). Methods: Extensive pre-clinical evaluations were performed on FT-2102, including CYP interactions in-vivo in rat and in-vitro in human tissue and in-vivo QTc toxicology in monkeys. The clinical Phase 1 study was initiated to evaluate the safety, PK/PD, and antileukemic activity of FT-2102 in patients with IDH1m AML or MDS and included both dose escalation and expansion phases. FT-2102 was administered daily until disease progression or unacceptable toxicity. Eligibility criteria included: IDH1m AML/MDS [relapsed/refractory (R/R) or treatment naïve (TN) for whom standard therapy was contraindicated], adequate liver and renal function, no prior IDH1 inhibitors, and no restrictions for concomitant non-anticancer medications. Investigator-assessed responses were per modified IWG 2003/2006 criteria. Efficacy was assessed at Cycle 2 Day 1 and as clinically indicated thereafter. Adverse events (AEs) were assessed throughout the study per NCI CTCAE version 4.03. Results: Evaluation of FT-2102 in in-vivo rat and in-vitro human tissue indicated hepatic metabolism by CYP enzymes (CPY3A4, 2C9, 1A1) as the major route of excretion. Animal toxicology studies predicted the threshold for QTc risk occurred at exposures >5.5 fold higher than the murine exposure at which 90% 2-HG reduction was observed. In the clinical study, at the time of the data cutoff, 31 patients (pts) had been treated with SA FT-2102, with a median of 3 mo. on treatment (range: 0.2 to 20 mo.). Of the 31pts treated, 25 had AML (22 R/R; 3 TN) and 6 had MDS (4 R/R; 2 TN). The median number of prior anti-leukemia therapies was 2 (range: 0-9) for AML pts and 1 (range: 0-4) for MDS pts. FT-2102 doses were: 150 mg QD (n=8), 300 mg QD (n=4), 150 mg BID (n=16), and 100 mg QD with food (n=3). Eighteen pts discontinued treatment, most commonly due to death (n=5), progressive disease (n=5), HSCT (n=3), or lack of response (n=3). Severe (≥Grade 3) AEs occurring in >5% of pts included thrombocytop