The role of genetic variants involved with ferroptosis regulator genes in predicting outcomes in patients (pts) with RAS-mutant metastatic colorectal cancer (mCRC): Data from MAVERICC and TRIBE trials.

197 Background: Ferroptosis, an iron-dependent programmed cell death, is one of the anti-tumor mechanisms of anti-angiogenesis drugs. RAS mutation can confer ferroptosis in colorectal cancer (CRC). Previous studies suggested that polymorphisms of ferroptosis regulator genes are associated with the increased risk of CRC. Therefore, we hypothesized that genetic variants in the ferroptosis regulator genes may predict first-line treatment outcome in RAS-mutant mCRC pts treated with bevacizumab (bev)-based chemotherapy. Methods: Genomic DNA from blood samples of mCRC pts enrolled in two independent randomized trials, MAVERICC (FOLFIRI+bev arm: discovery cohort, RAS-mutant, n = 56; control-1: RAS-wildtype, n = 87) and TRIBE (FOLFOXIRI+bev arm: validation cohort, RAS-mutant, n = 57; control-2: RAS-wildtype, n = 34), was genotyped through the OncoArray, a customized array manufactured by Illumina including approximately 530K SNP markers. The impact on outcome of 13 selected SNPs in 5 main ferroptosis regulator genes (ACSL4, LPCAT3, SLC3A2, SLC7A11, ALOX15) was analyzed. Results: In the MAVERICC bev cohort, pts with RAS-mutant tumors carrying ALOX15 rs7217186 any C allele (n = 35) showed significant longer overall survival (OS) than carrier of T/T allele (n = 5) in both univariate (24.97 vs. 12.22 months, hazard ratio [HR] = 0.23; 95% confidence interval [CI]: 0.06-0.9; p = 0.02) and multivariate (HR = 0.06; 95%CI 0.007-0.5; p = 0.009) analysis. In the TRIBE bev cohort, RAS-mutant carriers of any C allele (n = 30) showed numerically longer progression-free survival (PFS), compared to carriers of T/T allele (n = 13) in both univariate (11.91 vs. 9.47 months, HR = 0.45; 95%CI 0.2-1.02; p = 0.05) and multivariate (HR = 0.42; 95%CI 0.16-1.1; p = 0.09) analysis. Conversely, RAS-wildtype carriers of any C allele (n = 17) showed significant shorter PFS than T/T carriers in the TRIBE bev cohort (8.91 vs. 15.59 months, univariate HR = 3.39, 95%CI: 1.03-11.18, p = 0.04). Conclusions: Our study demonstrated for the first time that ALOX15 polymorphisms may have different predictive values for the bev-based treatment in mCRC patients based on RAS mutational status. These findings may provide novel insights for the combination of ferroptosis inducers and anti-VEGF treatment.