A phase two trial evaluating FOLFIRI plus aflibercept after failure of FOLFOXIRI plus bevacizumab in patients with unresectable metastatic colorectal cancer.

Background: FOLFOXIRI plus bevacizumab (BEV) is an option for first-line treatment of metastatic colorectal cancer (mCRC). However, there is no consensus on the optimal treatment strategy when disease progresses. The EFFORT open-label, multicenter, single-arm phase II study investigated whether FOLFIRI plus aflibercept retains activity after progression of FOLFOXIRI plus BEV treatment.

Methods: The patients with unresectable mCRC who failed first-line FOLFOXIRI plus BEV received FOLFIRI plus aflibercept. The primary endpoint was progression-free survival (PFS) in the full analysis set (FAS). Angiogenic biomarkers were measured before treatment initiation.

Results: From April 2019 to May 2021, 35 patients were enrolled and 34 were analysed in the FAS population (men, 18; median age, 63 years [range: 32-78]). The primary tumor was left-sided in most cases (23/34), 23 patients were RAS mutant, 3 patients had BRAF V600E mutation and 27 patients had liver metastases. The primary end-point was met with a median PFS of 4.3 months [80% confidence interval [CI] 3.7-5.1]. Median overall survival was 15.2 months [95% CI 8.9-22.7]. Per RECIST, there were 1 complete response, 4 partial responses, 21 stable diseases and 8 disease progressions. Overall response rate was 14.7% [95% CI 5.0-31.1], and disease control rate was 76.5% [95% CI 58.8-89.3]. Responses were more common in patients with high VEGF-C, low VEGF-D and low PlGF levels before treatment.

Conclusion: FOLFIRI plus aflibercept, administered after failure of FOLFOXIRI plus BEV, is effective and has a manageable safety profile. This regimen may be a useful second-line treatment option for these patients.