LOGY
12.1 Mechanism of Action
Bosutinib is a tyrosine kinase inhibitor. Bosutinib inhibits the Bcr-Abl kinase that promotes CML; it is also an inhibitor of Src-family kinases including Src, Lyn, and Hck. Bosutinib inhibited 16 of 18 imatinib-resistant forms of Bcr-Abl expressed in murine myeloid cell lines. Bosutinib did not inhibit the T315I and V299L mutant cells. In mice, treatment with bosutinib reduced the size of CML tumors relative to controls and inhibited growth of murine myeloid tumors expressing several imatinib-resistant forms of Bcr-Abl.
12.3 Pharmacokinetics
Absorption
Following administration of a single dose of BOSULIF (500 mg) with food in patients with cancer, the median time-to-peak concentration (tmax) was 4–6 hours. Bosutinib exhibits dose proportional increases in AUC and Cmax, over the dose range of 200 to 800 mg. After 15 daily doses of BOSULIF (500 mg) with food in patients with CML, the mean (SD) Cmax value was 200 (12) ng/mL, and the mean (SD) AUC was 3650 (425) ng∙h/mL. When given with a high fat meal, the Cmax and AUC of bosutinib increased 1.8- and 1.7-fold, respectively.
Distribution
After administration of a single dose of BOSULIF (500mg) with food in patients with CML, bosutinib had a mean apparent volume of distribution ± standard deviation of 6080 ± 1230 L.
Bosutinib was highly bound to human plasma proteins in vitro (94%) and ex vivo in healthy subjects (96%), and binding was not concentration-dependent. Bosutinib is a P-gp substrate and inhibitor in vitro. No studies have been conducted with other transporters.
Metabolism
Bosutinib is primarily metabolized by CYP3A4. The major circulating metabolites identified in plasma are oxydechlorinated (M2) bosutinib (19% of parent exposure) and N-desmethylated (M5) bosutinib (25% of parent exposure), with bosutinib N-oxide (M6) as a minor circulating metabolite. All the metabolites were deemed inactive.
Elimination
In patients with CML given single-oral doses of BOSULIF (500mg) with food, the mean terminal phase elimination half-life (t1/2) was 22.5 (1.7) hours, and the mean (SD) clearance (Cl/F) was 189 (48) L/h. In six healthy male subjects given a single oral dose of [14C] radiolabeled bosutinib, 91.3% of the dose was recovered in feces and 3% of the dose recovered in urine.
Hepatic Impairment
In a dedicated hepatic impairment trial, a single dose of BOSULIF 200 mg was administered with food to 18 hepatically impaired volunteers (Child-Pugh classes A, B, and C) and 9 matched healthy volunteers. Cmax of bosutinib increased 2.4-fold, 2-fold, and 1.5-fold, respectively, in Child-Pugh classes A, B, and C, and bosutinib AUC increased 2.3-fold, 2-fold, and 1.9-fold, respectively.
Drug Interactions
CYP3A Inhibitors
In a cross-over trial of 24 healthy volunteers, a single dose of 100 mg of BOSULIF was either administered alone or in combination with five daily doses of 400 mg of ketoconazole under fasting conditions. Ketoconazole increased bosutinib Cmax and AUC 5.2-fold and 8.6-fold, respectively.
CYP3A Inducers
In a cross-over trial of 24 healthy volunteers, a single dose of 500 mg of BOSULIF was either administered alone or in combination with six daily doses of 600 mg of rifampin under fed conditions. Rifampin decreased bosutinib Cmax and AUC by 86% and 94%, respectively.
P-gp Substrates
An in vitro study suggests that BOSULIF has the potential to increase the plasma concentrations of drugs that are P-gp substra |
