In an effort to understand whether the immune response exerts a role in controlling ovarian cancer, we isolated the HO8910 CD44+CD117+ CSCs from the human EOC HO8910 cell line [7, 9, 16] and selected the ID8 suspension sphere cells, which were presumed as cancer stem-like cells, from murine EOC ID8 cell line [17, 18], and used them as prophylactic CSC vaccines to investigate the antitumor immunity efficacy and mechanisms. The gene discussed is CD44; the disease is ovarian carcinoma.