Molecular Profiling By Circulating Tumor Dna (Ctdna) And Benefit From Anti-Pd-1 In Hcc.

e15679 Background: Molecular profiling has defined actionable mutations in HCC, and has the potential to be used for selection of targeted therapies, as well as for the characterization of predictive biomarkers from approved treatments. Noninvasive strategies are critical to HCC given the challenge of obtaining liver biopsies. We investigated whether profiling by ctDNA could provide predictive and/or prognostic information for HCC patients (pt) treated with immune checkpoint inhibitors. Methods: We analyzed blood samples from 22 HCC pt who underwent treatment with anti-PD-1 using comprehensive genomic testing of ctDNA with a commercially-available platform (Guardant Health, CA). Demographic and treatment data were retrospectively collected with the goal of correlating treatment outcomes and drug response (by imaging and/or AFP) with molecular abnormalities. Results: 17/22 (77.3%) were men; median age was 66 years. 21 patients received nivolumab and 1 received pembrolizumab. 9 were HCV positive and 5 were HBV positive. 15/22 patients had > 1 alteration identified. The median number of alterations/pt was 3 (range, 1-8). TP53 was the common altered gene (n = 11) followed by CTNBB1 (n = 8) , TERT (n = 5) KRAS (n = 3) , GNAS (n = 2). Mutations were also seen (n = 1) in KIT, PIK3CA, PTEN, EGFR, NTRK, FGFR2 among others. 6 pt (27.3%) had AFP response and 8 (36.4%) achieved disease control > 12 weeks. Mutations involving KIT, PIK3CA and PTEN were associated with shorter progression-free (PFS) (p < .001 for all) and overall survival (OS) (p = .028 for all), whereas GNAS mutation was associated with shorter PFS (p = 0.019) but not OS. No differences in OS or PFS was observed for other alterations, including the presence of CTNNB1 mutation. There were no correlations between specific alterations and objective tumor response (either by imaging or AFP). 32% of pt were progression-free at 6 months. Median OS was not reached, and 62% were alive after 1 year. Conclusions: Identifying non-invasive predictive biomarkers of benefit to immunotherapy is a priority in HCC. Our data suggest that specific ctDNA alterations can provide predictive information for survival (OS and PFS) on immune checkpoint inhibitors. Further larger studies are warranted for confirmation.