Influence of BRAF and PIK3CA mutations on the efficacy of FOLFIRI plus bevacizumab or cetuximab as first-line therapy in patients with RAS wild-type metastatic colorectal carcinoma and <3 baseline circulating tumour cells: the randomised phase II VISNÚ-2 study

Abstract

Background We explored the influence of BRAF and PIK3CA mutational status on the efficacy of bevacizumab or cetuximab plus 5-fluorouracil/leucovorin and irinotecan (FOLFIRI) as first-line therapy in patients with RAS wild-type metastatic colorectal cancer (mCRC).

Patients and methods VISNÚ-2 was a multicentre, randomised, phase II study. Patients with RAS wild-type mCRC and <3 circulating tumour cells/7.5 ml blood were stratified by BRAF/PIK3CA status (wild-type versus mutated) and number of affected organs (1 versus >1), and allocated to bevacizumab (5 mg/kg every 2 weeks) or cetuximab (400 mg/m2 then 250 mg/m2 weekly) plus FOLFIRI [irinotecan 180 mg/m2, leucovorin 400 mg/m2, 5-fluorouracil 400 mg/m2 (bolus) then 2400 mg/m2 (46-h continuous infusion) every 2 weeks]. The primary endpoint was progression-free survival (PFS). All analyses were exploratory.

Results Two hundred and forty patients with BRAF/PIK3CA wild-type (n = 196) or BRAF- and/or PIK3CA-mutated tumours (n = 44) were enrolled. Median PFS was 12.7 and 8.8 months in patients with BRAF/PIK3CA wild-type and BRAF/PIK3CA-mutated tumours, respectively [hazard ratio (HR) = 1.22; 95% confidence interval (CI) 0.80-1.85; P = 0.3602]. In the BRAF- and/or PIK3CA-mutated cohort, median PFS was 2.8, 8.8 and 15.0 months in patients with BRAF/PI3KCA-mutated (n = 8), BRAF-mutated/PI3KCA wild-type (n = 16) and BRAF wild-type/PI3KCA-mutated (n = 20) tumours, respectively (P = 0.0002). PFS was similar with bevacizumab plus FOLFIRI versus cetuximab plus FOLFIRI in BRAF/PIK3CA wild-type (HR = 0.99; 95% CI 0.67-1.45; P = 0.9486) and BRAF/PIK3CA-mutated tumours (HR = 1.11; 95% CI 0.53-2.35; P = 0.7820). The most common grade 3/4 treatment-related adverse events were neutropenia, diarrhoea and asthenia in both treatment groups.

Conclusions BRAF/PIK3CA status influences outcomes in patients with RAS wild-type mCRC but does not appear to assist with the selection of first-line targeted therapy