Background-Cervical cancer is the second largest cause of cancer deaths in women worldwide. It is now evident that persistent infection with high-risk human papillomavirus (HPV) is necessary for the development and maintenance of cervical cancer. Thus, effective vaccination against HPV represents an opportunity to restrain cervical cancer and other important cancers. The FDA recently approved the HPV vaccine Gardasil for the preventive control of HPV, using HPV virus-like particles (VLP) to generate neutralizing antibodies against major capsid protein, L1. However, prophylactic HPV vaccines do not have therapeutic effects against pre-existing HPV infections and HPV-associated lesions. Furthermore, due to the considerable burden of HPV infections worldwide, it would take decades for preventive vaccines to affect the prevalence of cervical cancer. Thus, in order to speed up the control of cervical cancer and treat current infections, the continued development of therapeutic vaccines against HPV is critical. Therapeutic HPV vaccines can potentially eliminate pre-existing lesions and malignant tumors by generating cellular immunity against HPV-infected cells that express early viral proteins such as E6 and E7. Objective-This review discusses the future directions of therapeutic HPV vaccine approaches for the treatment of established HPV-associated malignancies, with emphasis on current progress of HPV vaccine clinical trials. Methods-Relevant literature is discussed. Results/conclusion-Though their development has been challenging, many therapeutic HPV vaccines have been shown to induce HPV-specific antitumor immune responses in preclinical animal models and several promising strategies have been applied in clinical trials. With continued progress in the field of vaccine development, HPV therapeutic vaccines may provide a potentially promising approach for the control of lethal HPV-associated malignancies.

Purpose: Because the combination of multiple modalities for cancer treatment is more likely to generate more potent therapeutic effects for the control of cancer, we have explored the combination of chemotherapy using cisplatin, which is routinely used in chemotherapy for advanced cervical cancer, with immunotherapy using DNA vaccines encoding calreticulin (CRT) linked to human papillomavirus type 16 E7 antigen (CRT/E7) in a preclinical model. Experimental Design: We characterized the combination of cisplatin with CRT/E7 DNA vaccine using different regimen for its potential ability to generate E7-specific CD8 + T-cell immune responses as well as antitumor effects against E7-expressing tumors. Results: Our results indicate that treatment of tumor-bearing mice with chemoimmunotherapy combining cisplatin followed by CRT/E7 DNA generated the highest E7-specific CD8 + T-cell immune response and produced the greatest antitumor effects and long-term survival as well as significant levels of E7-specific tumor-infiltrating lymphocytes compared with all the other treatment regimens. Furthermore, we found that treatment with cisplatin leads to the cellmediated lysis of E7-expressing tumor cells in vitro and increased number of E7-specific CD8 + T-cell precursors in tumor-bearing mice. In addition, we observed that E7-specific CD8 + T cells migrate to and proliferate in the location of TC-1tumors in mice treated with cisplatin. Conclusions: Thus, our data suggest that chemoimmunotherapy using cisplatin followed by CRT/E7 DNA vaccine is an effective treatment against E7-expressing tumors and may potentially be translated into the clinical arena.Multimodality treatments that combine conventional cancer therapies with antigen-specific immunotherapy have emerged as promising approaches for the control of cancer (see refs. 1, 2 for reviews). Antigen-specific immunotherapy is an attractive approach for the treatment of cancers because it has the potency to specifically eradicate systemic tumors and control metastases without damaging normal cells. A favorable approach to antigen-specific immunotherapy is the use of DNA vaccines based on their safety, stability, and ease of preparation (see refs. 3, 4 for review). However, DNA vaccines are poorly immunogenic. Thus, the potency of DNA vaccines needs to be enhanced by using methods to target DNA to the professional antigen-presenting cells and by modifying the properties of antigen-expressing antigen-presenting cells to boost vaccine-elicited immune responses. Several approaches have been developed to enhance DNA vaccine potency (see refs. 5, 6 for review).One particular approach to enhance DNA vaccine potency involves the use of intracellular targeting strategies to enhance MHC class I and class II antigen presentation in dendritic cells. Our previous studies have explored the linkage of calreticulin (CRT), a Ca 2+ -binding protein located in the endoplasmic reticulum (see ref. 7 for review) to a model tumor antigen, human papillomavirus type 16 (HPV-16) E7, for the develo...

BackgroundEffective vaccination against human papillomavirus (HPV) represents an opportunity to control cervical cancer. Peptide-based vaccines targeting HPV E6 and/or E7 antigens while safe, will most likely require additional strategies to enhance the vaccine potency.MethodsWe tested the HPV-16 E7 peptide-based vaccine in combination with a strategy to enhance CD4+ T help using a Pan HLA-DR epitope (PADRE) peptide and a strategy to enhance dendritic cell activation using the toll-like receptor 3 ligand, poly(I:C).ResultsWe observed that mice vaccinated with E7 peptide-based vaccine in combination with PADRE peptide and poly(I:C) generated better E7-specific CD8+ T cell immune responses as well as significantly improved therapeutic anti-tumor effects against TC-1 tumors compared to E7 peptide-based vaccine with either PADRE peptide or poly(I:C) alone. Furthermore, we found that intratumoral vaccination with the E7 peptide in conjunction with PADRE peptide and poly(I:C) generates a significantly higher frequency of E7-specific CD8+ T cells as well as better survival compared to subcutaneous vaccination with the same regimen in treated mice.ConclusionsThe combination of PADRE peptide and poly(I:C) with antigenic peptide is capable of generating potent antigen-specific CD8+ T cell immune responses and antitumor effects in vaccinated mice. Our study has significant clinical implications for peptide-based vaccination.

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