Phase II study evaluating the effect of concomitant ramucirumab (RAM) on the pharmacokinetics (PK) of irinotecan (IRI) and its metabolite SN-38 when coadministered with folinic acid (FA) and 5-fluorouracil (5-FU) (FOLFIRI) in patients (pts) with advanced malignant solid tumors.

Abstract

691 Background: The primary objective was to assess the effect of concomitant RAM on the PK of IRI and its metabolite SN-38 when coadministered with FA and 5-FU. Methods: Key eligibility criteria included pts aged ≥18 years with metastatic or locally advanced malignant solid tumors resistant to standard therapy or for which no standard therapy was available, and an Eastern Cooperative Oncology Group performance status of 0 to 2. Pts received intravenous infusions of FOLFIRI and RAM 8 mg/kg on day 1 of a 2-week cycle. FOLFIRI was administered alone in cycle 1; RAM was administered followed by FOLFIRI in all subsequent cycles. Blood for PK was collected at regular intervals after infusions in cycles 1 and 2 to determine IRI and SN-38 plasma concentrations. Pts who completed the first 2 cycles of study treatment were included in the drug-drug interaction (DDI) population. All pts who received at least 1 dose of RAM or FOLFIRI were included in the safety population. Results: The safety population comprised 29 pts, and the DDI population included 25 of these 29 pts. The dose-normalized area under the concentration versus time curve from zero to infinity [AUC(0-∞)] and the maximum observed drug concentration (Cmax) of IRI and SN-38 were comparable between cycle 1 (FOLFIRI alone) and cycle 2 (RAM+FOLFIRI). The ratios of geometric least-squares (LS) means for IRI were 0.93 (90% CI; 0.83, 1.05) for AUC(0-∞) and 1.04 (90% CI; 0.97, 1.12) for Cmax. 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 Cmax. The most prevalent treatment-emergent adverse events (TEAEs) were fatigue/asthenia (n=19, 65.5%), diarrhea (n=16, 55.2%), neutropenia (n=15, 51.7%), nausea (n=14, 48.3%), and decreased appetite and anemia (n=13 each, 44.8%). Grade ≥3 TEAEs were rare, except for neutropenia in 7 (24.1%) pts. Conclusions: The PKs of IRI and its metabolite, SN-38, were not affected when coadministered with RAM. RAM with FOLFIRI was well-tolerated in this study without new safety concerns. Clinical trial information: NCT01634555.