Research Posters
R086 Cancer Immunotherapy for HLA-A2, HPVⴙ Head and Neck Cancer Duane Sewell, MD (presenter) Cheltenham PA
Problem: Recent studies indicate that the majority of oropharyngeal squamous cell carcinomas are associated with human papilloma virus (HPV) infection. Two HPV-transforming proteins, E6 and E7, are expressed in these tumors and they provide attractive targets for cancer immunotherapy. Listeria monocytogenes-based vaccines have been developed that cause regression of HPV-associated tumors in animal models. We have developed a new vaccine, Lm-ActA-E7, that is effective in treating HPV⫹ tumors in mice. While this vaccine works well in the context of the murine immune system, we decided to investigate whether it would work in the context of the human immune system. Methods: Mice that carry a human gene critical for presentation of foreign antigens were obtained. This gene encodes a major histocompatibility complex (MHC) molecule, HLA-A2, which is instrumental in directing lymphocytes to eliminate cancerous cells. The recombinant bacterial vaccine Lm-ActA-E7 was administered to these mice. Lymphocytes were harvested from the vaccinated mice, and then transferred to a group of mice with severe combined immunodeficiency. Human HPV⫹ head and neck cancers had been established in these mice prior to vaccination. Another group of miceharboring tumors were left untreated as a control. We then observed the growth of the tumors in each group for 39 days. Results: When compared to the untreated mice, tumor growth was slowed in the mice treated with vaccinated lymphocytes. Both groups started with tumor sizes of 4 mm in diameter. The untreated tumors grew to 10 mm, while the size of the treated tumors remained stable for the duration of the experiment. Conclusion: Our recombinant bacterial vaccine slows tumor growth in the context of a human gene critical for antigen presentation. Significance: These results indicate that our recombinant bacterial vaccine strategy has the potential to treat head and neck cancers that are associated with HPV infection. Support: None reported. R087 The In Vitro Effect of Cidofovir on HPV16 versus HPVHNSCC Cell Lines Mark W El-Deiry, MD; John H Lee, MD; William C Spanos, MD Coralville IA; Iowa City IA; Iowa City IA
Problem: Previous studies have suggested that cidofovir selectively inhibits cell proliferation in cervical cancer cell lines that contain human papillomavirus 16 (HPV16), possibly due to inhibition of viral oncogenes. We hypothesize that cidofovir may
also selectively alter viral gene expression and cellular proliferation in head and neck cancer cells that contain HPV16. Methods: To test this hypothesis we studied 2 HPVcontaining HNSCC cell lines (SCC 47, SCC 90) and 2 nonHPV-containing HNSCC cell lines (SCC 19, SCC 84). We created standard logarithmic dose response curves using the MTT assay. In addition, we examined the expression of viral oncogenes (E6, E7) and their cellular targets (P53, Rb) by quantitative RT-PCR to determine whether any notable response was due to selective cidofovir-induced changes in viral gene expression. Results: Dose response curves demonstrate decreased cell viability at increasing concentrations of cidofovir for all cell lines. There was no apparent difference in the dose response curves between cell lines containing HPV16 and cell lines without HPV16. Selective inhibition of viral oncogenes was not seen. Changes in the expression of P53 and Rb were also similar between cells regardless of HPV16 status. Conclusion: This study demonstrates that nonspecific cellular toxicity of cidofovir in vitro on HNSCC cell lines is independent of HPV16 status. Significance: HPV has recently been implicated in head and neck squamous cell carcinoma. If a chemotherapeutic agent could be used to affect the HPV virus, perhaps this could be used to treat HNSCC. Alternatively, if no effect is found attention could be turned elsewhere. Support: None reported. R088 Dendritic Cells Pulsed with Tumor-Derived Lysate Augment T Cell Mediated Tumor Cell Lysis Silke Gronau, MD (presenter); Michael Schmitt, Riechelmann, MD Ulm Germany; Ulm Germany; Ulm Germany
MD;
Herbert
Problem: Immunotherapy of malignant diseases mediated by dendritic cells (DC) pulsed with tumor antigens is a promising new tool in the individual treatment of malignant diseases. Tumor-specific T cells should be generated by coincubation with DC pulsed with tumor-derived lysate (TL), and their cytolytic activity should be assessed in an autologous ex vivo system. Methods: DC were generated from peripheral blood monocytes using standard techniques and pulsed with autologous TL from patients with head and neck squamous cell carcinoma (HNSCC). Pulsed DC are able to induce the generation of cytotoxic T cells (CTL). CTL were then coincubated with autologous tumor cells on a chorioallantois membrane. Tumor cells coincubated with 200l (0.5 mg/mL) Cisplatin; native T cells or cell culture medium served as controls. Results: Coincubation of HNSCC cells with CTL resulted in a decrease of viable cells at T24 and T48 when compared with the control containing only medium or native T cells.
POSTERS
P176
Otolaryngology– Head and Neck Surgery August 2004