Venetoclax exposure-efficacy and exposure-safety relationships in patients with treatment-naïve acute myeloid leukemia who are ineligible for intensive chemotherapy

Abstract

This study evaluated venetoclax population pharmacokinetics (popPK) in patients with treatment-naïve acute myeloid leukemia and assessed the relationship between venetoclax exposure and clinical response for venetoclax in combination with either a hypomethylating agent (HMA) or low-dose cytarabine (LDAC). A total of 771 patients who received venetoclax from 5 Phase 1-3 studies were included in the popPK model. Exposure-response analyses included data from 575 patients for venetoclax/placebo plus HMA and 279 patients for venetoclax/placebo plus LDAC. The popPK model successfully characterized venetoclax plasma concentrations over time and confirmed venetoclax exposure did not vary significantly with age, weight, sex, mild to moderate hepatic impairment, or mild to severe renal impairment. Asian patients had 67% higher mean relative bioavailability than non-Asian patients, however the range of exposures in Asian patients was similar to non-Asian patients. For all efficacy endpoints with both treatment combinations, efficacy was higher in the venetoclax treatment groups compared with the respective control arm of placebo plus azacitidine or LDAC. Within patients who received venetoclax, no significant exposure-efficacy relationships were identified for either treatment combination, indicating that the beneficial effects of venetoclax were already maximized in the dose ranges studied. There was no apparent effect of venetoclax exposure on treatment-emergent Grade ≥3 thrombocytopenia or infections for either combination. Rates of treatment-emergent Grade ≥3 neutropenia were higher in the venetoclax treatment arms compared with the respective control arms; however, within patients who received venetoclax, there was only a shallow relationship or no apparent relationship with venetoclax exposure for venetoclax plus HMA or LDAC, respectively. Along with the efficacy and safety data previously published, the exposure-response analyses support the venetoclax dose regimens of 400 mg once daily (QD) plus HMA and 600 mg QD plus LDAC in treatment-naïve AML patients who are ineligible for intensive chemotherapy.

Keywords: acute myeloid leukemia; dose selection; exposure-response; hypomethylating agents; low-dose cytarabine; venetoclax.