Pharmacokinetics and safety of carfilzomib in patients with relapsed multiple myeloma and end-stage renal disease (ESRD): an open-label, single-arm, phase I study

Purpose: The pharmacokinetics (PK) of carfilzomib have been previously studied in multiple myeloma patients with varying degrees of renal impairment (normal, mild, moderate, severe, and end-stage renal disease [ESRD]) at doses of 15 and 20 mg/m². This study evaluated carfilzomib PK at higher doses of 27 and 56 mg/m² in normal renal function and ESRD patients. Methods: Patients received carfilzomib on two consecutive days/week for 3 weeks every 28-day cycle: 20 mg/m² (cycle 1 day 1–2), escalated to 27 mg/m² on cycle 1 day 8; if tolerated, 56 mg/m² starting cycle 2 day 1. The primary objective was PK assessment with safety/tolerability and response rate as secondary and exploratory objectives, respectively. Results: 26 patients were enrolled (15 normal, 11 ESRD). There was a trend toward higher area under the concentration time curve (AUC) and maximum concentration in ESRD versus normal renal function patients; however, high interpatient PK variability was discerned. Relative to patients with normal renal function, ESRD patients showed 33% higher AUC. Overall response rate was 43% for the normal renal function and 60% for the ESRD groups. Safety findings were generally similar between the two groups and consistent with the known safety profile of carfilzomib in multiple myeloma patients. Conclusion: There were no meaningful differences in PK between patients with normal renal function and ESRD in light of carfilzomib exposure–response relationships. These results continue to support dosing recommendation that no starting dose adjustment of carfilzomib appears warranted in patients with baseline renal impairment.