Immune responses to a class II helper peptide epitope in patients with stage III/IV resected melanoma.

The importance of CD8(+) cytolytic T cells for protection from viral infection and in the generation of immune responses against tumors has been well established. In contrast, the role of CD4(+) T-helper cells in human infection and in cancer immunity has yet to be clearly defined. In this pilot study, we show that immunization of three resected, high-risk metastatic melanoma patients with a T-helper epitope derived from the melanoma differentiation antigen, melanoma antigen recognized by T cells-1, results in CD4(+) T-cell immune responses. Immune reactivity to that epitope was detected by DR4-peptide tetramer staining, and enzyme-linked immunospot assay of fresh and restimulated CD4(+) T cells from patients over the course of the 12-month vaccine regimen. The postvaccine CD4(+) T cells exhibited a mixed T-helper 1/T-helper 2 phenotype, proliferated in response to the antigen and promiscuously recognized the peptide epitope bound to different human leukocyte antigen-DRbeta alleles. For 1 DRbeta1*0401(+) patient, antigen-specific CD4(+) T cells recognized human leukocyte antigen-matched antigen-expressing tumor cells, secreted granzyme B, and also exhibited cytolysis that was MHC class II-restricted. These data establish the immunogenicity of a class II epitope derived from a melanoma-associated antigen and support the inclusion of class II peptides in future melanoma vaccine therapies.

Designing HER2 vaccines.

HER2/neu is a compelling cancer vaccine candidate because it is overexpressed on some cancer cells relative to normal tissues, it is known to be immunogenic in both animal models and in humans, and it is already known to be targetable by the antibody component of the immune system in the form of monoclonal antibody therapy with trastuzumab. Vaccines offer the theoretical advantage of being able to elicit T-cell responses in addition to antibody responses. HER2 vaccines have been shown to provide benefit in animal models and to be immunogenic in humans. However, the optimal vaccine formulation is not yet known and the therapeutic efficacy of the vaccines in humans has not yet been evaluated. HER2 vaccine approaches currently being tested include peptide-based, DNA plasmid-based, and protein-based vaccines. Our group has developed and started testing a protein-based vaccine composed of both the extracellular domain of HER2 and the carboxyl terminal autophosphorylation portion of the intracellular domain. The extracellular domain was retained to provide for antibody targeting. The kinase domain of the intracellular domain was excluded because of its high degree of homology to other human kinases. The carboxyl terminal autophosphorylation domain was retained because it is the most unique and possibly most immunogenic portion of the HER2 molecule with the least homology to other members of the HER family. The vaccine, termed dHER2, is immunogenic in mice and primates. In animal models it can elicit CD8 and CD4 T-cell responses as well as antibody responses that suppress the growth of HER2-positive cancer cells in vitro and in vivo. Vaccine trials are contemplated in patients with breast cancer that will determine whether the vaccine construct is similarly immunogenic in humans.

Prevention of disease induced by a partially heterologous AIDS virus in rhesus monkeys by using an adjuvanted multicomponent protein vaccine.

Recombinant protein subunit AIDS vaccines have been based predominantly on the virus envelope protein. Such vaccines elicit neutralizing antibody responses that can provide type-specific sterilizing immunity, but in most cases do not confer protection against divergent viruses. In this report we demonstrate that a multiantigen subunit protein vaccine was able to prevent the development of disease induced in rhesus monkeys by a partially heterologous AIDS virus. The vaccine was composed of recombinant human immunodeficiency virus type 1 (HIV-1) gp120, NefTat fusion protein, and simian immunodeficiency virus (SIV) Nef formulated in the clinically tested adjuvant AS02A. Upon challenge of genetically unselected rhesus monkeys with the highly pathogenic and partially heterologous SIV/HIV strain SHIV(89.6p) the vaccine was able to reduce virus load and protect the animals from a decline in CD4-positive cells. Furthermore, vaccination prevented the development of AIDS for more than 2.5 years. The combination of the regulatory proteins Nef and Tat together with the structural protein gp120 was required for vaccine efficacy.

Immunologic analysis of a phase I/II study of vaccination with MAGE-3 protein combined with the AS02B adjuvant in patients with MAGE-3-positive tumors.

In a phase I/II study, patients with solid metastatic MAGE-3-positive tumors, mainly melanoma, were vaccinated with recombinant MAGE-3 protein combined with the immunologic adjuvant AS02B comprised of MPL and QS21 in an oil-in-water emulsion. The recombinant MAGE-3 protein was made up of a partial sequence of the protein D (ProtD) antigen of Haemophilus influenzae fused to the MAGE-3 sequence. The vaccine was given intramuscularly at 3-week intervals. Patients whose tumors stabilized or regressed after 4 vaccinations received 2 additional vaccinations at 6-week intervals. MAGE-3 and ProtD antibody and cellular immune responses were monitored after vaccination. Ninety-six percent (23/24) of the patients vaccinated with MAGE-3 protein in AS02B adjuvant elicited a significant anti-MAGE-3 IgG antibody response after 4 vaccinations, and all developed anti-ProtD IgG antibodies. For the detection of T-cell activity, total peripheral blood mononuclear cells were restimulated in vitro with MAGE-3- or ProtD-loaded autologous mature dendritic cells. In 30% of the evaluable patients vaccinated with the adjuvanted recombinant protein, IFNgamma production was increased in response to MAGE-3, and 2 patients (14% of evaluable patients) had a concomitant increase in IL-5 production. In 37% and 43% of the patients, respectively, IFNgamma or IL-5 production was increased in response to ProtD. It is concluded that vaccination of advanced cancer patients with MAGE-3 self-antigen in AS02B adjuvant is able to elicit MAGE-3-specific antibody and a T-cell response.