mFOLFOXIRI with or without bevacizumab for conversion therapy of RAS/BRAF/PIK3CA mutant unresectable colorectal liver metastases: the FORBES non-randomized phase II trial

Background: The aim of this non-randomized single-center phase II trial was to prospectively assess the clinical efficacy of triplet chemotherapy with modified 5-fluorouracil, folinic acid, oxaliplatin, and irinotecan (mFOLFOXIRI) plus bevacizumab as conversion therapy for initially unresectable rat sarcoma viral oncogene homolog (RAS)/v-raf murine sarcoma viral oncogene homolog B1 (BRAF)/phosphatidylinositol-3 kinase catalytic alpha (PIK3CA) mutant colorectal liver-limited metastases (CRLMs).

Methods: Patients with RAS/BRAF/PIK3CA mutant initially unresectable CRLMs were recruited at a ratio of 2:1 to receive mFOLFOXIRI plus bevacizumab (experimental group) or mFOLFOXIRI alone (control group). The rate of patients attaining no evidence of disease (NED) was the primary endpoint. The secondary endpoints included objective response rate (ORR), depth of tumor response (DpR), secondary resection rate, progression-free survival (PFS), overall survival (OS), and safety.

Results: The rate of NED achieved was 40.7% and 30.8%, respectively, in the experimental (n=54) and control groups (n=26); the adjusted odds ratio was 4.519 [95% confidence interval (CI): 1.247-16.375, P=0.022]. The ORR was 77.4% in the experimental group and 60.0% in the control group (P=0.112). The median DpR was significantly greater in the experimental group (45.6% vs. 34.9%, P=0.041). The median PFS was 12.6 months in the experimental group and 9.1 months in the control group [adjusted hazard ratio (HR): 0.584, 95% CI: 0.304-1.121, P=0.106]. Median OS was prolonged in the experimental group compared with the control group (42.6 vs. 35.3 months, adjusted HR: 0.443, 95% CI: 0.195-1.006, P=0.052). Thirty patients (55.6%) in the experimental group and 16 (61.5%) in the control group experienced grade 3/4 adverse events.

Conclusions: We observed that the combination of mFOLFOXIRI and bevacizumab increased the rate of clinical NED and showed a trend toward improved survival compared with mFOLFOXIRI alone. This could represent a conversion therapy option for fit patients with initially unresectable RAS/BRAF/PIK3CA mutant CRLMs.