Pevonedistat in East Asian patients with acute myeloid leukemia or myelodysplastic syndromes: a phase 1/1b study to evaluate safety, pharmacokinetics and activity as a single agent and in combination with azacitidine

Pevonedistat, the first small-molecule inhibitor of NEDD8-activating enzyme, has demonstrated clinical activity in Western patients with acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). We report findings from a phase 1/1b study in East Asian patients with AML or MDS, conducted to evaluate the safety/tolerability and characterize the pharmacokinetics of pevonedistat, alone or in combination with azacitidine, in this population, and determine the recommended phase 2/3 dose for pevonedistat plus azacitidine. Twenty-three adult patients with very high/high/intermediate-risk AML or MDS were enrolled in Japan, South Korea and Taiwan. All 23 patients experienced at least one grade ≥ 3 treatment-emergent adverse event. One patient in the combination cohort reported a dose-limiting toxicity. Eighteen patients discontinued treatment; in nine patients, discontinuation was due to progressive disease. Three patients died on study of causes considered unrelated to study drugs. Pevonedistat exhibited linear pharmacokinetics over the dose range of 10–44 mg/m2, with minimal accumulation following multiple-dose administration. An objective response was achieved by 5/11 (45%) response-evaluable patients in the pevonedistat plus azacitidine arm (all with AML), and 0 in the single-agent pevonedistat arm. This study showed that the pharmacokinetic and safety profiles of pevonedistat plus azacitidine in East Asian patients were similar to those observed in Western patients as previously reported. The recommended Phase 2/3 dose (RP2/3D) of pevonedistat was determined to be 20 mg/m2 for co-administration with azacitidine 75 mg/m2 in Phase 2/3 studies, which was identical to the RP2/3D established in Western patients.