Pharmacological properties : תכונות פרמקולוגיות

Pharmacodynamic Properties

12.2 Pharmacodynamics

Intravenous carfilzomib administration resulted in suppression of proteasome chymotrypsin-like (CT-L) activity when measured in blood 1 hour after the first dose. Doses of carfilzomib ≥ 15 mg/m2 with or without lenalidomide and dexamethasone induced a ≥ 80% inhibition of the CT-L activity of the proteasome. In addition, carfilzomib, 20 mg/m2 intravenously as a single agent, resulted in a mean inhibition of the low molecular mass polypeptide 2 (LMP2) and multicatalytic endopeptidase complex-like 1 (MECL1) subunits of the proteasome ranging from 26% to 32% and 41% to 49%, respectively. Proteasome inhibition was maintained for ≥ 48 hours following the first dose of carfilzomib for each week of dosing.

Pharmacokinetic Properties

12.3 Pharmacokinetics

Carfilzomib at doses between 20 mg/m2 and 70 mg/m2 administered as a 30-minute infusion resulted in dose-dependent increases in maximum plasma concentrations (Cmax) and area under the curve over time to infinity (AUC0-INF) in patients with multiple myeloma. A dose-dependent increase in Cmax and AUC0-INF was also observed between carfilzomib 20 mg/m2 and 56 mg/m2 as a 2- to 10-minute infusion in patients with relapsed or refractory
multiple myeloma. A 30-minute infusion resulted in a similar AUC0-INF, but 2- to 3-fold lower Cmax than that observed with a 2- to 10-minute infusion at the same dose. There was no evidence of carfilzomib accumulation following repeated administration of carfilzomib 70 mg/m2 as a 30-minute once weekly infusion or 15 and 20 mg/m2 as a 2- to 10-minute twice weekly infusion.

Table 20 lists the estimated mean average daily area under the curve in the first cycle (AUCC1,avg), average daily area under the curve at steady-state (AUCss) and Cmax at the highest dose in the first cycle (Cmax,C1) for the different dosing regimens.


Table 20: Carfilzomib Exposure Parameters for Different Dosing Regimens 
20/27 mg/m2 twice        20/56 mg/m2 twice       20/70 mg/m2 once
Estimated Parameters
weekly with 2- to 10-   weekly with 30-minute   weekly with 30-minute (%CV)
minute infusion              infusion                infusion
AUCC1,avg (ng•hr/mL)                   95 (40)                170 (35)                114 (36) AUCss (ng•hr/mL)                      111 (34)                228 (28)                150 (35) Cmax,C1 (ng/mL)                      1282 (17)                1166 (29)               1595 (36) CV = Coefficient of variation


Distribution

The mean steady-state volume of distribution of a 20 mg/m2 dose of carfilzomib was 28 L.
Carfilzomib is 97% bound to human plasma proteins over the concentration range of 0.4 to 4 micromolar in vitro.

Elimination

Carfilzomib has a half-life of ≤ 1 hour on Day 1 of Cycle 1 following intravenous doses ≥ 15 mg/m2. The half-life was similar when administered either as a 30-minute infusion or a 2- to 10-minute infusion. The systemic clearance ranged from 151 to 263 L/hour.

Metabolism

Carfilzomib is rapidly metabolized. Peptidase cleavage and epoxide hydrolysis were the principal pathways of metabolism. Cytochrome P450 (CYP)-mediated mechanisms contribute a minor role in overall carfilzomib metabolism.

Excretion

Approximately 25% of the administered dose of carfilzomib was excreted in urine as metabolites in 24 hours. Urinary and fecal excretion of the parent compound was negligible (0.3% of total dose).

Specific Populations

Age (35-89 years), sex, race or ethnicity (80% White, 11% Black, 6% Asians, 3% Hispanics), and mild to severe renal impairment (creatinine clearance 15-89 mL/min) did not have clinically meaningful effects on the pharmacokinetics of carfilzomib.

Patients with Hepatic Impairment

Compared to patients with normal hepatic function, patients with mild (total bilirubin 1 to 1.5 × ULN and any AST or total bilirubin ≤ ULN and AST > ULN) and moderate (total bilirubin > 1.5 to 3 × ULN and any AST) hepatic impairment had approximately 50% higher carfilzomib AUC. The pharmacokinetics of carfilzomib has not been evaluated in patients with severe hepatic impairment (total bilirubin > 3 × ULN and any AST).

Patients with Renal Impairment

Relative to patients with normal renal function, ESRD patients on hemodialysis showed 33% higher carfilzomib AUC. Since hemodialysis clearance of Kyprolis concentrations has not been studied, the drug should be administered after the hemodialysis procedure.

Drug Interaction Studies

Clinical Studies
Effect of Carfilzomib on Sensitive CYP3A Substrate: Midazolam (a sensitive CYP3A substrate) pharmacokinetics was not affected by concomitant administration of carfilzomib.

In Vitro Studies

Effect of Carfilzomib on Cytochrome P450 (CYP) Enzymes: Carfilzomib showed direct and time-dependent inhibition of CYP3A but did not induce CYP1A2 and CYP3A4 in vitro.

Effect of Transporters on Carfilzomib: Carfilzomib is a P-glycoprotein (P-gp) substrate in vitro.

Effect of Carfilzomib on Transporters: Carfilzomib inhibits P-gp in vitro. However, given that Kyprolis is administered intravenously and is extensively metabolized, the pharmacokinetics of Kyprolis is unlikely to be affected by P-gp inhibitors or inducers.