Previous cancer vaccination trials often aimed to activate CD8+ cytotoxic T-cell (CTL) responses with short (8–10mer) peptides and targeted CD4+ helper T cells (TH) with HLA class II–binding longer peptides (12–16 mer) that were derived from tumor antigens. Accordingly, a study of immunomonitoring focused on the detection of CTL responses to the short, and TH responses to the long, peptides. The possible induction of concurrent TH responses to short peptides was widely neglected. In a recent phase I vaccination trial, 53 patients with different solid cancers were vaccinated with EMD640744, a cocktail of five survivin-derived short (9- or 10-mer) peptides in Montanide ISA 51VG. We monitored 49 patients and found strong CD8+ T-cell responses in 63% of the patients. In addition, we unexpectedly found CD4+ TH cell responses against at least two of the five short peptides in 61% (23/38) of the patients analyzed. The two peptides were recognized by HLA-DP4– and HLA-DR–restricted TH1 cells. Some short peptide–reactive (sp)CD4 T cells showed high functional avidity. Here, we show that a short peptide vaccine is able to activate a specific CD4+ T-cell repertoire in many patients, facilitating a strong combined CD4+/CD8+ T-cell response. Cancer Immunol Res; 4(1); 1–8. ©2015 AACR.
Note: Supplementary data for this article are available at Cancer Immunology Research Online (http://cancerimmunolres.aacrjournals.org/).
Study number/Clinicaltrials.gov reference: EMR 200032-001/NCT01012102
- Received April 16, 2015.
- Revision received August 12, 2015.
- Accepted September 4, 2015.
- ©2015 American Association for Cancer Research.