摘要
Unmethylated cytosine‐phosphorothioate‐guanine containing oligodeoxynucleotides (CpG‐ODN) is known as a ligand of toll‐like receptor 9 (TLR9), which selectively activates type‐1 immunity. We have already reported that the vaccination of tumor‐bearing mice with liposome‐CpG coencapsulated with model‐tumor antigen, ovalbumin (OVA) (CpG + OVA‐liposome) caused complete cure of the mice bearing OVA‐expressing EG‐7 lymphoma cells. However, the same therapy was not effective to eradicate Lewis lung carcinoma (LLC)‐OVA‐carcinoma. To overcome the refractoriness of LLC‐OVA, we tried the combination therapy of radiation with CpG‐based tumor vaccination. When LLC‐OVA‐carcinoma intradermally (i.d.) injected into C57BL/6 became palpable (7–8 mm), the mice were irradiated twice with a dose of 14 Gy at intervals of 24 h. After the second radiation, CpG + OVA‐liposome was i.d. administered near the draining lymph node (DLN) of the tumor mass. The tumor growth of mice treated with radiation plus CpG + OVA‐liposome was greatly inhibited and approximately 60% of mice treated were completely cured. Moreover, the combined therapy with radiation and CpG + OVA‐liposome allowed the augmented induction of OVA‐tetramer+ LLC‐OVA‐specific cytotoxic T lymphocyte (CTL) in DLN of tumor‐bearing mice. These results indicate that the combined therapy of radiation with CpG‐based tumor vaccine is a useful strategy to eradicate intractable carcinoma. (Cancer Sci 2009; 100: 934–939)