Lack of pharmacokinetic drug–drug interaction between ramucirumab and irinotecan in patients with advanced solid tumors

The objective of this phase II study was to evaluate the potential of pharmacokinetic (PK) drug–drug interactions between ramucirumab and irinotecan or its metabolite, SN-38, when administered with folinic acid and 5-fluorouracil (FOLFIRI). Patients received intravenous infusions of FOLFIRI and ramucirumab 8 mg/kg on Day 1 of a 2-week cycle. FOLFIRI was administered alone in Cycle 1; ramucirumab followed by FOLFIRI was administered in all subsequent cycles. Blood was collected at regular intervals after infusions in Cycles 1 and 2 to determine irinotecan, SN-38, and ramucirumab concentrations. PK parameters were derived by noncompartmental analysis. Twenty-nine patients received treatment. The dose-normalized area under the concentration versus time curve from zero to infinity [AUC(0–∞)] and the maximum observed concentration (C max) of irinotecan and SN-38 were comparable between Cycle 1 (FOLFIRI alone) and Cycle 2 (ramucirumab + FOLFIRI). The ratios of geometric least squares (LS) means for irinotecan were 0.93 (90 % CI 0.83–1.05) for AUC(0–∞) and 1.04 (90 % CI 0.97–1.12) for C max. The ratios of geometric LS means for SN-38 were 0.95 (90 % CI 0.88–1.04) for AUC(0–∞) and 0.97 (90 % CI 0.85–1.12) for C max. The most common treatment-emergent adverse events, regardless of grade, were fatigue (19 patients, 65.5 %), diarrhea, (16 patients, 55.2 %), and neutropenia (15 patients, 51.7 %). Grade ≥3 neutropenia was reported in 7 (24.1 %) patients. There was no PK drug–drug interaction between ramucirumab and irinotecan or its metabolite, SN-38. Ramucirumab with FOLFIRI was well tolerated in this study, with no new safety concerns.