Peptide vaccine with adjuvant and CTLA-4 blockade elicits antitumor response.

2003 SEP 3 - (NewsRx.com & NewsRx.net) -- A protective antitumor immune response was elicited by cytotoxic T lymphocyte epitope peptide vaccination combined with CpG-oligodeoxynucleotide adjuvant and a CTLA-4 blockade.

"Although peptide immunization often leads to the induction of strong T-cell responses, it is seldom effective against established tumors. One possibility is that these T-cell responses are not strong enough or do not last sufficiently long to have an effect in tumor eradication," researchers in the United States report.

"Here, we examined the role of synthetic oligodeoxynucleotide (ODN) adjuvants containing unmethylated cytosine-guanine motifs (CpG-ODN) and CTLA-4 blockade in enhancing the antitumor effectiveness of peptide vaccines intended to elicit CTL responses," stated Eduardo Davila and colleagues at the Mayo Clinic. "The results show that combination immunotherapy consisting of vaccination with a synthetic peptide corresponding to an immunodominant CTL epitope derived from tyrosinase-related protein-2 administered with CpG-ODN adjuvant and followed by systemic injection of anti-CTLA-4 antibodies increased the survival of mice against the poorly immunogenic B16 melanoma."

"Interestingly, whereas this combination therapy was effective when administered to tumor-bearing mice (therapeutic protocol), it had no significant effect when applied in the prophylactic mode (i.e., before the tumor challenge)," reported Davila and his ...