DAA/TAA Peptide Vaccine(University of Pittsburgh)

Dendritic cells (DC) elicit immunity to pathogens and tumors while simultaneously preserving tolerance to self. Efficacious cancer vaccines have been a challenge because they are based on tumor Ags, some of which are self-Ags and thus subject to self-tolerance. One such Ag is the tumor-associated mucin MUC1. Preclinical testing of MUC1 vaccines revealed existence of peripheral tolerance to MUC1 that compromises their efficacy. To identify mechanisms that act early postvaccination and might predict vaccine outcome, we immunized human MUC1 transgenic mice (MUC1.Tg) i.v. with a MUC1 peptide vaccine against which they generate weak immunity and wild-type (WT) mice that respond strongly to the same peptide. We analyzed differences in splenic DC phenotype and function between the two mouse strains at 24 and 72 h postvaccination and also performed unbiased total gene expression analysis of the spleen. Compared to WT, MUC1.Tg spleens had significantly fewer DC, and they exhibited significantly lower expression of costimulatory molecules, decreased motility, and preferential priming of Ag-specific Foxp3+ regulatory T cells. This tolerogenic DC phenotype and function was marked by a new putative biomarker revealed by the microarray: a cohort of pancreatic enzymes (trypsin, carboxypeptidase, elastase, and others) not previously reported in DC. These enzymes were strongly upregulated in the splenic DC from vaccinated WT mice and suppressed in the splenic DC of vaccinated MUC1.Tg mice. Suppression of the enzymes was dependent on regulatory T cells and on signaling through the IL-10R and correlated with global downregulation of DC immunostimulatory phenotype and function.

Lung cancer is the most common cause of cancer mortality worldwide for both men and women, causing approximately 1.2 million deaths per year. With the existing therapeutic efforts, the long-term survival for lung cancer patients remains low with only 15% surviving for 5 years following diagnosis. Therefore, new therapeutic strategies are needed. One such approach is the development of immune therapy for lung cancer. Immune approaches for lung cancer remain attractive because although surgery, chemotherapy and radiotherapy alone or in combination have response rates in all histological types of lung cancer, relapse is frequent. Immunologic targeting of lung cancer has the potential for nontoxic and specific therapy. Strategies that harness the immune system to react against tumors can be integrated with existing forms of therapy for optimal responses toward this devastating disease.