Results of the Phase 1 Trial of RG7112, a Small-molecule MDM2 Antagonist in Leukemia
Mené sur 116 patients atteints d'un cancer hématologique, cet essai de phase I évalue la dose maximale tolérée et l'activité antitumorale d'un composé appelé RG7112, une petite molécule antagoniste de MDM2
Purpose: RG7112 is a small-molecule MDM2 antagonist. MDM2 is a negative regulator of the tumor suppressor p53 and frequently overexpressed in leukemias. Thus, a Phase I study of RG7112 in patients with hematologic malignancies was conducted. Experimental Design: Primary study objectives included determination of the dose and safety profile of RG7112. Secondary objectives included evaluation of pharmacokinetics, pharmacodynamics, such as TP53-mutation status and MDM2 expression, and preliminary clinical activity. Patients were divided into 2 cohorts: Stratum A (relapsed/refractory AML (except APL), ALL, and CML) and Stratum B (relapsed/refractory CLL/sCLL). Some Stratum A patients were treated at the MTD to assess clinical activity. Results: RG7112 was administered to 116 patients (96 patients in Stratum A and 20 patients in Stratum B). All patients experienced at least 1 adverse event, and 3 DLTs were reported. PK analysis indicated that twice-daily dosing enhanced daily exposure. Anti-leukemia activity was observed in the 30 patients with AML assessed at the MTD included 5 patients who met IWG criteria for response. Exploratory analysis revealed TP53 mutations in 14% of Stratum A patients and in 40% of Stratum B patients. Two patients with TP53 mutations exhibited clinical activity. p53 target genes were induced only in TP53 wild-type leukemic cells. Baseline expression levels of MDM2 correlated positively with clinical response. Conclusions: RG7112 demonstrated clinical activity against relapsed/refractory AML and CLL/sCLL. MDM2 inhibition resulted in p53 stabilization and transcriptional activation of p53-target genes. We provide proof-of-concept that MDM2 inhibition restores p53 function and generates clinical responses in hematologic malignancies.