New findings in cancer vaccines described by J. Zeng and co-researchers.

According to a study from Guangzhou, People's Republic of China, "The present study investigated an immunotherapeutic strategy for rearranged during transfection proto-oncogene (ret)associated carcinomas in a transgenic MT/ret 304/B6 mouse model in which spontaneous tumors develop due to overexpression of the ret gene. A Ret peptide vaccine comprising an extracellular fragment of Ret protein and Th1-polarized immunoregulator CpG oligonucleotide (1826) induced strong and specific cellular and Immoral immune responses in wildtype C57BL/6 mice, showing that the Ret peptide has a strong immunogenic potential as part of an antitumor vaccine."

"In MT/ret 304/B6 mice, however, the vaccine was only modestly effective as an inducer of the humoral immune response, and it failed to elicit a T-cell response. An immunohistochemical analysis revealed marked indoleamine 2,3-dioxygenase expression after immunization with Ret peptide vaccine in the lymph nodes and spleens of MT/ret 304/B6 mice. The systemic administration of the potent inhibitor of indoleamine 2,3-dioxygenase 1-methyl tryptophan (1MT) along with Ret vaccine produced a significant increase in tumor-specific cytotoxic activity. A delay in spontaneous tumor development was also observed in the MT/ret 304/B6 mice to which the Ret vaccine and 1MT were administered," wrote J. Zeng and colleagues (see also Cancer Vaccines).

The researchers concluded: "These results indicate that an improved Ret vaccine composed of Ret peptide plus CpG oligonucleotide plus 1MT is a potential ...