Population pharmacokinetic modeling of asciminib in support of exposure-response and ethnic sensitivity analyses in patients with chronic myeloid leukemia

BackgroundThe original population pharmacokinetics (popPK) model for asciminib in patients with chronic myeloid leukemia in chronic phase (CML-CP) was refined to address drug development needs in support of drug submission, namely, attainment of target drug exposure in specific patient populations, populating individual daily exposures for exposure-response analyses of key efficacy and safety endpoints, confirmation of comparability in exposure between 40 mg b.i.d. and 80 mg q.d., and assessment of ethnic insensitivity.MethodsParticipants from two organ dysfunction studies, patients with CML in blast and acute phases and acute lymphoblastic leukemia and patients from a phase III efficacy study in newly diagnosed Ph + CML-CP, and data from a dedicated phase II study in the Chinese patients previously treated with at least two prior tyrosine kinase inhibitors, and a phase IIIb study comparing two dose regimens of asciminib (40 mg b.i.d. and 80 mg q.d.) were included in the revised popPK model. Covariates evaluated were line of therapy, baseline renal and hepatic functions, Chinese or Japanese ethnicity.ResultsThe apparent clearance and steady-state volume of distribution of asciminib were 6.84 L/h and 110 L, respectively, for a typical individual of 70 kg weight and 90 mL/min absolute glomerular filtration rate. Both the 40 mg b.i.d. and 80 mg q.d. resulted in a steady-state daily AUC of 12,600 ng.h/mL, and there was no difference between lines of therapy. Effects of renal or hepatic impairment on clearance were not clinically relevant. Chinese and Japanese exhibited similar PK as that of the global population.ConclusionsThe 40 mg b.i.d. and 80 mg q.d. regimens are comparable in their daily exposure, supporting the use of the two dosing regimens in newly diagnosed and previously treated CML-CP patients. The PK of asciminib is insensitive to ethnic differences and no dose adjustment is required for severe renal and hepatic impaired patients.