HMPL-306 in relapsed or refractory IDH1- and/or IDH2-mutated acute myeloid leukemia: A phase 1 study.

Background: HMPL-306 has equally high inhibitory activity against mutated isocitrate dehydrogenases 1 and 2 (mIDH1/2).

Methods: This first-in-human, phase 1 dose-escalation/dose-expansion study (this study was registered at ClinicalTrials.gov: NCT04272957) enrolled patients with relapsed/refractory (R/R) acute myeloid leukemia (AML) harboring mIDH1 and/or mIDH2. Patients received 25-250 mg of HMPL-306 orally once daily (QD) in a 28-day treatment cycle. Primary objectives were safety, tolerability, and recommended phase 2 dose (RP2D), and the secondary objective was preliminary efficacy.

Findings: A total of 76 patients were enrolled. No dose-limiting toxicities were observed, and the maximum tolerated dose was not reached. RP2D was 250 mg QD for cycle 1 and 150 mg QD from cycle 2 onward. Common (≥10%) grade ≥3 treatment-related adverse events included platelet count decreased, anemia, neutrophil count decreased, and white blood cell count decreased. In patients who received 150 mg, 250 mg, or the RP2D (N = 59), rates of complete remission (CR)+CR with partial hematologic recovery were 34.6% and 36.4% in the mIDH1 (n = 26) and mIDH2 (n = 33) subgroups, respectively, and among these, CR with minimal residual disease negative rates were 77.8% and 50.0%, respectively. The median overall survival was 13.4 months in patients with mIDH1 and 13.1 months in patients with mIDH2.

Conclusions: HMPL-306 showed an acceptable safety profile and promising preliminary efficacy. A phase 3, randomized study of HMPL-306 in R/R AML (this study was registered at ClinicalTrials.gov: NCT06387069) has been initiated.

Funding: HUTCHMED Limited, National Key Research and Development Program of China, National Natural Science Foundation of China, and Peking University Medicine Fund for world's leading discipline or discipline cluster development.