Protocol of the EFFORT study: a prospective study of FOLFIRI plus aflibercept as second-line treatment after progression on FOLFOXIRI plus bevacizumab or during maintenance treatment in patients with unresectable/metastatic colorectal cancer

Background FOLFOXIRI plus bevacizumab is used as a first-line therapy for patients with unresectable or metastatic colorectal cancer. However, there are no clear recommendations for second-line therapy after FOLFOXIRI plus bevacizumab combination. Here, we describe our planning for the EFFORT study to investigate whether FOLFIRI plus aflibercept has efficacy following FOLFOXIRI plus bevacizumab for mCRC. Methods EFFORT is an open-label, multicenter, single arm phase II study to evaluate whether a FOLFIRI plus aflibercept has efficacy following FOLFOXIRI plus bevacizumab for mCRC. Patients with unresectable or metastatic colorectal cancer who received FOLFOXIRI plus bevacizumab as a first-line therapy will receive aflibercept and FOLFIRI (aflibercept 4 mg/kg, irinotecan 150 mg/m2 IV over 90 min, with levofolinate 200 mg/m2 IV over 2 h, followed by fluorouracil 400 mg/m2 bolus and fluorouracil 2400 mg/m2 continuous infusion over 46 h) every 2 weeks on day 1 of each cycle. The primary endpoint is progression-free survival (PFS). To achieve 80% power to show a significant response benefit with a one-sided alpha level of 0.10, assuming a threshold progression-free survival of 3 months and an expected value of at least 5.4 months, we estimated that 32 patients are necessary. Secondary endpoints include overall survival, overall response rate, safety, and exploratory biomarker analysis for differentiating anti-VEGF drug in 2nd-line chemotherapy for unresectable or metastatic colorectal cancer. Discussion This is the first study to investigate whether FOLFIRI plus aflibercept has efficacy following FOLFOXIRI plus bevacizumab for unresectable or metastatic colorectal cancer. Switching to a different type of anti-VEGF drug in second-line therapy after FOLFOXIRI plus bevacizumab appears to be an attractive treatment strategy when considering survival benefit. It is expected that this phase II study will prove the efficacy of this strategy and that a biomarker for drug selection will be discovered. Trial registration Japan Registry of Clinical Trials jRCTs071190003. Registered April 18, 2019.