Exposure–response relationship of ramucirumab in patients with advanced second-line colorectal cancer: exploratory analysis of the RAISE trial

Purpose To characterize ramucirumab exposure–response relationships for efficacy and safety in patients with metastatic colorectal cancer (mCRC) using data from the RAISE study. Methods Sparse pharmacokinetic samples were collected; a population pharmacokinetic analysis was conducted. Univariate and multivariate Cox proportional hazards models analyzed the relationship between predicted ramucirumab minimum trough concentration at steady state ( C min,ss ) and survival. Kaplan–Meier analysis was used to evaluate survival from patients in the ramucirumab plus folinic acid, 5-fluorouracil, and irinotecan (FOLFIRI) treatment arm stratified by C min,ss quartiles (Q). An ordered categorical model analyzed the relationship between C min,ss and safety outcomes. Results Pharmacokinetic samples from 906 patients were included in exposure–efficacy analyses; samples from 905 patients were included in exposure–safety analyses. A significant association was identified between C min,ss and overall survival (OS) and progression-free survival (PFS) ( p < 0.0001 for both). This association remained significant after adjusting for baseline factors associated with OS or PFS ( p < 0.0001 for both). Median OS was 11.5, 12.9, 16.4, and 16.7, and 12.4 months for ramucirumab C min,ss Q1, Q2, Q3, Q4, and placebo group, respectively. Median PFS was 5.4, 4.6, 6.8, 8.5, and 5.2 months for ramucirumab C min,ss Q1, Q2, Q3, Q4, and placebo group, respectively. The risk of Grade ≥3 neutropenia was associated with an increase in ramucirumab exposure. Conclusions Exploratory exposure–response analyses suggested a positive relationship between efficacy and ramucirumab exposure with manageable toxicities in patients from the RAISE study with mCRC over the ranges of exposures achieved by a dose of 8 mg/kg every 2 weeks in combination with FOLFIRI.