4075 Background: In the ePHAS study we analyzed three eNOSpolymorphisms and at univariate analysis, patients with eNOS-786 -TTgenotype had significantly shorter median Progression Free Survival (PFS) and Overall Survival (OS) compared to those with other genotypes. On the basis of these preliminary results, our aim is to validate in a prospective study this data in patients with HCC treated with sorafenib. Methods: This is a prospective Italian multicenter study, that includes 141 HCC patients receiving sorafenib. We analyzed eNOS-786and itwas analyzed by Real Time PCR in relation to the primary end point (OS). Event-time distributions were estimated using the Kaplan-Meier method and survival curves were compared using the log-rank test. Results: 141 HCC patients (122 males and 19 females), prospectively treated with sorafenib from May 2015 to September 2018 were included. Median age was 69 years (range 28-88 years). 120 patients had Child-Pugh A and 21 had Child-Pugh B7. 43 had BCLC-B and 98 patients had BCLC-C. Atunivariate analysis, we confirmed that eNOS-786 TT genotype were significantly associated with a lower median OS than the other genotypes (8.8 vs 15.7 months, HR 1.69, 95% CI 1.02-2.83 p=0.0424). Following adjustment for clinical covariates (age, gender, etiology, BCLC stage, serum α-FP level, MELD score), multivariate analysis confirmed eNOS- 786 and BCLC stage as the independentsprognostic factors predicting OS (TTvsTC+CC; HR: 2.39, 95% CI 1.14-5.03 p=0.0211; C vs B;2.23, 95% CI 1.44-4.77 p=0.039). Conclusions: Our prospective study confirms the prognostic role of eNOS-786 in advanced HCC patients treated with sorafenib. Clinical trial information: NCT02786342.