In ePHAS study a training cohort of 41 HCC patients and a validation cohort of 87 patients receiving sorafenib was analyzed. At univariate analysis, patients homozygous for an endothelial nitric oxide synthase (eNOS) haplotype (HT1: T-4b at eNOS-786/eNOS VNTR) had a lower median PFS (2.6 vs. 5.8 months, p <0.0001) and OS (3.2 vs.14.6 months, p = 0.024) than those with other haplotypes. These data were confirmed in the validation set in which patients homozygous for HT1 had a lower median PFS (2.0 vs. 6.7 months, p <0.0001) and OS (6.4 vs.18.0 months, p < 0.0001).