Identification of biomarkers for personalized peptide vaccination in 2,588 cancer patients

Peptidebased cancer vaccines have failed to provide sufficient clinical benefits in order to be approved in clinical trials since the 1990s. To understand the mechanisms underlying this failure, the present study investigated biomarkers associated with the lower overall survival (OS) among 2,588 patients receiving personalized peptide vaccination (PPV). Survival data were obtained from a database of 2,588 cancer patients including 399 patients with lung, 354 with prostate and 344 with colon cancer. They entered into phase II clinical trials of PPV in which 2 to 4 of 31 warehouse peptides were selected for vaccination on an individual patient basis based on human leukocyte antigen (HLA) class IAtypes and preexisting peptidespecific IgG levels. Higher prevaccination neutrophil, monocyte and platelet counts, and lower prevaccination lymphocyte and red blood cell counts were inversely associated with OS, with higher sensitivities in the proportions of neutrophils and lymphocytes, respectively. The most potent unfavorable and favorable factors for OS were the median percentage of neutrophils (>/=64.8%) or percentage of lymphocytes (>/=25.1%) with correlation coefficients (R2) of 0.98 and 0.92, respectively. Higher prevaccination levels of creactive protein and other inflammatory soluble factors were inversely associated with OS. Prevaccination peptidespecific immunity levels had no effect on OS, although lower immune boosting levels were inversely associated with OS. None of the 31 peptides was inversely associated with OS, although a few peptides were positively associated with it. On the whole, the findings of the present study suggested that prevaccination inflammatory signatures, but not those of postvaccination immune induction, were associated with lower clinical benefits of PPV.