We identified novel cancer testis antigens (CTAs) including CDCA1, LY6K (URLC10) and KIF20A that are overexpressed in lung cancer, head and neck cancer (HNC), and other various malignancies, but not expressed in many adult normal tissues except for testis and fetal organs by using genome-wide cDNA microarray analyses. We identified CTAs-derived peptides that can activate tumor-reactive and HLA-A2 or -A24-restricted CTLs in both in vitro preclinical and in vivo clinical studies of peptide vaccine. It is well known that IL-2 and IFN-γ produced by Th1 cells have pivotal roles in efficient induction of memory CTLs and efficient infiltration of CTLs into the tumor. We identified these CTAs-derived promiscuous 20∼26-mer long peptides (LPs) that can induce both Th1 cells restricted by several frequent HLA class II and tumor-reactive CTLs restricted by HLA-A2 or -A24. The LPs were naturally processed from CTAs and presented by dendritic cells. In addition, these LPs induced propagation of CTA-specific CTLs by cross presentation in both human in vitro and HLA-class I transgenic mice in vivo. Furthermore, these LPs and Th1-cell clone enhanced induction of CTA-specific CTLs in vitro. Significant frequencies of CTA-specific Th1 cells were detected after short-term in vitro stimulation with LPs in HNC patients vaccinated with CTA-derived CTL-epitope peptides and cancer patients before vaccination but not in healthy donors; responses were augmented by repeated vaccinations. These results show for the first time the presence of novel CTAs-specific Th1 cell responses in cancer patients and suggest the potential utility of these LPs for propagation of CTAs-specific Th1 cells and CTLs.

Citation Format: Yusuke Tomita, Akira Yuno, Yoshihiro Yoshitake, Hirotake Tsukamoto, Atsushi Irie, Satoru Senju, Koji Yoshida, Takuya Tsunoda, Yusuke Nakamura, Masanori Shinohara, Yasuharu Nishimura. Cancer testis antigens-specific CD4+ T-cell immunity augmented by CTL-epitopes vaccination in cancer patients. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2834. doi:10.1158/1538-7445.AM2013-2834