Email: [email protected]

  Research Area:

Immunology, molecular biology, vaccine development, gynecologic oncology

  Research Summary:

We have focused on the development of vaccines for the treatment of cervical cancer. Over 90% of invasive cervical tumors harbor HPV DNA, and genotype 16 can be detected in approximately 50% of squamous cell carcinomas of the cervix. Recent research has shown that the E6 and E7 genes of HPV-16 encode for oncoproteins which can immortalize human keratinocytes. Because oncoproteins E6 and E7 are selectively retained and expressed in cervical tumors associated with HPV-16, they are attractive targets for novel immunotherapies. Presentation to T cells of endogenously synthesized viral antigens involves degradation of the viral protein into small epitope peptides that are transported via the endoplasmic reticulum to the cell surface in association with class I MHC molecules. Cytolytic T-cells (CTL) recognize antigens by the binding of their clonotypic T cell receptors to the processed endogenous peptides associated with class I molecules. major histoccompatibility (MHC) class I restricted CTL epitope peptides of HPV-16 E6 and E7 have been identified for both human and mouse model systems. The peptides have been used to stimulate CTL to recognize and kill cancer cells infected with the virus. Using leukapheresis specimens for HLA-A*0201-positive normal donors and patients with cervical cancer, we have assessed the vaccine potential of certain peptide epitopes of E7. Epitope-specific CTL were generated in vitro stimulation using autologous dendritic cells co-incubated with the HPV-16, HLA-A*0201 restricted, synthetic peptide E7. We found that cellular immune responses occured in all subjects and that the frequency of CTL response to the E7 epitope is similar for both healthy women and those with cervical cancer. Therefore, the ability to generate specific cellular immune responses is retained in patients with advanced cervical cancer. Furthermore, immunologic deficits other than insufficient CTL precursor frequencies, sich as defects in T-cell signaling or differences in the mechanisms HPV-infected cells use to escape immunologic recognition, may have important roles in the pathogenesis of HPV-associated cervical cancer. These studies form part of the scientific basis for a clinical phase I protocol to test the effects of a lipidated E7 peptide to treat patients with advanced servical cancer. In this study, 12 women with refractory cervical cancer received four E7 lipopeptide innoculations at 3-week intervals. HPV typing was assessed on tumor specimens and HLA-A2 subtyping was also performed. Peripheral blood leukapheresis specimens obtained before and after vaccination were analyzed for induction of epitope specific CD8* T-lymphocyte (CTL) responses in vitro stimulation using autologous dendritic cells coincubated with the HPV-16 E7, HLA-A*0201 restricted, synthetic peptide E7. Results clearly indicate that vaccination with the lipopeptide appears capable of safely augmenting CTL reactivity. Although enchancements of cellular immune responses are needed in order to achieve therapeutic utility in advanced cervical cancer, this approach might prove useful in treating patients with less extensive disease, such as pre-invasive cervical intra-epithelial neoplasia.