Background: Glypican 3 (GPC3), WD-Repeat-containing Protein Up-regulated in HCC (WDRPUH), and Nei Endonuclease VIII-Like 3 (NEIL3) are tumor antigens in HCC. We conducted two phase 1 multicenter open-label studies for advanced HCC: one to evaluate the HLA-A*24-restricted 3-epitope peptide vaccine cocktail named ONO-7268MX1 (MX1); the other to evaluate the HLA-A*24 and -A*02-restricted 6-epitope peptide vaccine cocktail named ONO-7268MX2 (MX2). Both vaccines contain epitope peptides derived from GPC3, WDRPUH, and NEIL3. MX1 and MX2 cover most of Japanese HCC patients (pts). Safety is the primary, and efficacy and immunological response are the exploratory objectives. Methods: Pts received SC MX1 or MX2 once weekly. In MX1 study, pts received each of 3 peptides at 0.3 mg (cohort 1), 1 mg (cohort 2), and 3 mg of GPC3, 1.1 mg of WDRPUH and 3 mg of NEIL3 (cohort 3). In MX2 study, pts received each of 6 peptides at 1 mg. Results: In MX1 study, 3, 8, and 7 pts with HLA-A*24 were enrolled to cohort 1, 2, and 3, respectively. In MX2 study, 14 pts (7 with HLA-A*24, 6 with HLA-A*02, and 1 with HLA-A*24/A*02) were enrolled. No dose limiting toxicities were observed in both studies. The most commonly related AEs were Grade 1/2 injection site reaction (erythema, induration, pain, and pruritus), 44.4% (8/18) in MX1 and 78.6% (11/14) in MX2. Grade 3-related AEs occurred only in MX2 study; neutrophil count decreased, white blood cell count decreased, and decreased appetite (each 1 patient). No grade 4-related AEs occurred in both studies. No response (CR or PR) were seen in both studies. In MX1 study, median and mean of PFS [range], median duration of SD were 2.8, 3.4 [0.5-16.8], 3.7 months respectively, in MX2 study those were 1.9 and 2.8 [0.4-8.3], 5.7 respectively. In both studies, some pts showed long disease control (≥6 months). For those pts, each peptide-specific Cytotoxic T Lymphocyte (CTL) responses were shown by the ELISPOT assay. Conclusions: MX1 and MX2 showed good tolerability. Both vaccines induced CTL responses which may be related to antitumor effect. In addition, some pts showed long disease control. These results implied the potential usefulness of these vaccines for the treatment of HCC. Clinical trial information: JapicCTI-121933 and JapicCTI-142477.