A phase I study of milademetan in combination with quizartinib in patients (pts) with newly diagnosed (ND) or relapsed/refractory (R/R) FLT3-ITD acute myeloid leukemia (AML).

Abstract

TPS7067 Background: Fms -like tyrosine kinase 3 internal tandem duplication ( FLT3-ITD) mutations occur in ≈ 25% of pts with AML and are associated with poor prognosis. Quizartinib is a highly potent, selective, next-generation type II FLT3 inhibitor. In the phase 3 QuANTUM-R trial, quizartinib prolonged overall survival vs salvage chemotherapy in pts with R/R FLT3-ITD AML. MDM2 downregulates the p53 tumor suppressor and is upregulated in pts with AML. Targeting MDM2 may restore p53 activity in pts with wild-type p53 AML. Milademetan, a novel and specific MDM2 inhibitor, showed activity in an ongoing phase 1 trial in pts with AML or myelodysplastic syndromes (MDS). Preclinical studies have shown that quizartinib plus milademetan may act synergistically to target FLT3-ITD and restore p53 activity in FLT3-ITD/ TP53 wild-type AML [Andreeff et al. ASH 2018, abstract 2720]. Methods: This open-label phase 1 study (NCT03552029) has 2 parts: dose escalation (part 1) followed by dose expansion (part 2), with 2 planned cohorts. Key inclusion criteria include FLT3-ITD AML (primary or secondary to MDS) and adequate renal, hepatic, and clotting functions. Key exclusion criteria include acute promyelocytic leukemia, prior treatment with a MDM2 inhibitor, QTcF interval > 450 ms, significant cardiovascular disease, and unresolved toxicities from prior therapies. Dose escalation and expansion cohort 1 includes R/R pts. Expansion cohort 2 includes ND pts unfit for intensive chemotherapy. During dose escalation, quizartinib will be administered once daily in 28-day cycles, with 3 proposed levels (30, 40, and 60 mg). Milademetan will be administered on days 1-14 of each 28-day cycle, with 3 proposed levels (90, 120, and 160 mg). The quizartinib dose will be escalated first, followed by the milademetan dose with no simultaneous escalation, guided by modified continual reassessment with overdose control. Primary objectives are safety and tolerability, optimum dosing schedule, maximum tolerated dose, recommended dosing for the expansion cohort, and phase 2 dosing. Secondary objectives are pharmacokinetics and preliminary efficacy. This study is recruiting. Clinical trial information: NCT03552029.