Phase I and II Clinical Study of Cancer Vaccine Consisting of 5 Novel Epitope Peptides For Patients with Metastatic Colorectal Cancer (MCRC)

ABSTRACT Background We have reported a phase I (PI) study for patients (pts) with mCRC using 5 novel HLA-A24-restricted peptides, which were derived from 3 oncoantigens (RNF43, TOMM34, KOC1), and from VEGFR1 and VEGFR2 at 2011 ASCO (oral paper). At 2012 ESMO, we will present the biomarkers for the efficacy of PI study, and an interim report about PII study of cancer vaccine consisting of 5 novel epitope peptides and FOLFOX for chemo naive pts with mCRC. Methods In a PI study conducted for mCRC, biomarkers were searched for the efficacy of vaccination. Eighteen mCRC pts who failed to standard therapy were enrolled in this study. Five peptides were injected to the inguinal or axillal region weekly at 0.5 mg to 3 pts, 1 mg to 3 pts, and 3 mg to 12 pts. Vaccinations were continuing until the pts refusal. Blood cell counts, CRP, and ELISPOT were performed before and after vaccinations. PII study was conducted to evaluate the efficacy of vaccination added on the standard FOLFOX therapy for chemo naive pts with mCRC. All enrolled patients had received FOLFOX and vaccination without knowing HLA-A status double-blindly, and the HLA genotype will not key-opened until the final analysis point. The endpoints evaluate between HLA-A*2402 positive (24(+), n = 60) and HLA-A*2402 negative (24(-), n = 40) group, because the frequency of A*2402 in Japanese pts forecast about 60%. Results In PI study, the total numbers of peptide specific response were 2 in 3 pts at 0.5mg, 6 in 3 pts at 1.0 mg, and 37 in 12 pts at 3.0 mg. We decided that the RD was 3.0 mg. One patient experienced a CR and 6 pts revealed SD. The median OS was 15.2 months. The lymphocyte% (above 15%: p  Conclusions The PI study demonstrated that Lymphocyte%, CRP and CTL responses were predictive biomarkers for vaccination. The interim report about PII study will be presented at the meeting. Disclosure All authors have declared no conflicts of interest.