Generation of tumor-specific cytotoxic T lymphocytes by stimulation with HPV type 16 E7 peptide-pulsed dendritic cells: an approach to immunotherapy of cervical cancer

Chemoprevention of Head and Neck Cancer: A Review of Current Approaches and Future Perspectives

Head and neck squamous cell carcinoma (HNSCC) is a spectrum of heterogeneous malignancies. A variety of genetic, environmental, and lifestyle factors contribute to the development of HNSCC. Carcinogenesis is a multistep process in which cell proliferation-associated oncogenes and cell-cycle regulation-associated tumor suppressor genes are dysregulated, resulting in premalignant lesions. Immune evasion is a critical step in the progression of benign lesions to advanced cancer. This review discusses the advances that have been made in chemoprevention strategies for HNSCC. The rationale for the use of chemopreventive agents to inhibit head and neck cancer development is highlighted by the positive outcomes of several clinical trials. We discuss the potential of some of the commonly studied agents including vitamin A analogs, EGFR inhibitors, COX-2 inhibitors, metabolic modulators, and natural compounds such as green tea, as well as immunotherapy and photodynamic therapy to prevent HNSCC. Our review provides insight into the potential benefits of these agents and the gaps that remain to be addressed. The published results reaffirm the promise of chemoprevention in head and neck cancer and suggest that continued exploration is needed to overcome the limitations. Because the current focus on chemopreventive agents is limited, major efforts in precision oncology approaches and substantial increase in funding will promote research into chemoprevention, which will eventually decrease the incidence of HNSCC.

Immune concept of human papillomaviruses and related antigens in local cancer milieu of human cervical neoplasia

It is presently the right time for clarifying human papillomavirus (HPV)-associated cellular immunity and clinical implications before global HPV vaccination programs begin. Infection with oncogenic HPV associates with the progression of cervical neoplasia. Both cellular and humoral immune responses are essential for the clearance of HPV-associated cervical lesions. There is increasing evidence that the immune system plays a pivotal role in determining the outcome of HPV infection. Viruses and associated neoplastic cells are proposed to have evolved mechanisms to avoid immune attack. T-cell-mediated immune responses against oncogenic HPV are believed to play a central role in cervical carcinogenesis. The presence of HPV-specific cytotoxic T lymphocytes (CTL) in a majority of human cervical cancer patients provides an approach for further study of their functional role in modulating this malignancy. Tumor-infiltrating lymphocytes (TIL) develop as manifestations of the recognition and defense against malignant cells by the host immune system. Cancer cells may overcome immune surveillance, either by downregulating the proliferation of HPV-specific CTL, or altering the effector compositions of immune cells against HPV infections. TIL in the tumor microenvironment can be functionally inhibited and lose the ability of clonal proliferation as a result of depressed expression of IL-2Ralpha. The upregulation of inhibitory signaling relates to the modulation of the virus- and/or tumor-specific immune responses. Alteration of host genetic susceptibility may also lead to abnormal immune response as a general genomic instability resulting from virus persistence. Induction of HPV-specific immune responses is anticipated as an intimate point for the treatment of cervical neoplasia.

Sensitive detection of human papillomavirus type 16 E7-specific T cells by ELISPOT after multiple in vitro stimulations of CD8+ T cells with peptide-pulsed autologous dendritic cells

BACKGROUND

Cervical cancer is the second most common gynecological cancer amongst women world-wide. Despite optimized protocols, standard treatments still face several disadvantages. Therefore, research aims at the development of immune-based strategies using tumor antigen-loaded dendritic cells for the induction of cellular anti-tumor immunity.

RESULTS

In this study, we used dendritic cells loaded with the HLA-A2-restricted HPV type 16 E711-20 peptide in order to induce an in vitro CD8+ T cell response. For this purpose, peptide-pulsed dendritic cells were co-cultured with autologous CD8+ T cells. After 5 weekly stimulations with peptide-pulsed mature dendritic cells, cultured T cells were analyzed for antigen specificity by an IFN-gamma ELISPOT assay. Using this ELISPOT assay, we were able to detect E7-specific IFN-gamma-secreting CD8+ T cells in 5/5 healthy donors.

CONCLUSION

We show that peptide-pulsed mature dendritic cells are able to stimulate a HPV type 16 E7 peptide-specific immune response in vitro. These experiments describe an efficient culture protocol for antigen-specific T cells for use in pre-clinical vaccination research and confirm the need for sensitive T cell assays for detection of tumor-specific immune responses in vitro.

Deficiencies in myeloid antigen-presenting cells in women with cervical squamous intraepithelial lesions

BACKGROUND

There is little information on the function of dendritic cells in women with human papillomavirus (HPV)-related cervical squamous intraepithelial lesions (SILs). In the current study the functions of dendritic cells in the development of T-cell immunity in women with cervical SILs were assessed.

METHODS

The percentage of myeloid dendritic cells (MDCs) and plasmacytoid dendritic cells (PDCs) in peripheral blood were enumerated of 44 patients with SIL (low-grade, 19; high-grade, 25), 19 patients with atypical squamous cells of undetermined significance (ASCUS), and 18 controls. The expression of costimulatory receptors was assessed and the ability of monocyte-derived dendritic cells (MDDC) to present HPV16-E6 and HPV16-E7 antigens to autologous T cells.

RESULTS

Patients with either low (L)-grade or high (H)-grade SIL had significantly lower median plasma levels of interferon-gamma than did the controls (P = .038 and .031, respectively). Compared with the controls, patients with ASCUS or LSILs had significantly lower median percentages of MDCs (P = .002 and P < .001, respectively), and significantly lower median percentages of MDDCs that expressed CD86 (P < .001 and P = .003, respectively) and major histocompatability complex class-II antigen human leukocyte antigen DR (HLA-DR) (P = .012 and P < .001, respectively). T cells of patients with ASCUS or LSILs proliferated less than those of the controls in response to HPV16-E7 (P = .002 and .046, respectively).

CONCLUSIONS

Low levels of peripheral blood MDCs and of MDDCs expressing CD86 and HLA-DR suggest that deficiencies in the ability of MDDC to present antigen to autologous T cells may lead to persistent infection with HPV and the development of cervical SILs in HPV-infected women.

Inverse correlation of cellular immune responses specific to synthetic peptides from the E6 and E7 oncoproteins of HPV-16 with recurrence of cervical intraepithelial neoplasia in a cross-sectional study

BACKGROUND

Epidemiological studies have clearly established that human papillomavirus (HPV) infection is the major risk factor for cervical cancer. Most cervical cancers and pre-cancers are HPV-positive. Not all pre-cancers progress to cancer; a significant number regress. The immunological basis for either spontaneous or treatment-mediated recovery from HPV-associated CIN is not clear. Currently, prophylactic vaccines are successfully inducing antibody responses in HPV negative patients. Therapeutic vaccines for HPV-positive patients with disease are needed. There is a need to understand the immunologic basis for the Cell-Mediated Immune (CMI) response and for histological regression to help the formulation of therapeutic vaccines.

MATERIAL AND METHODS

Four groups of women were identified for this cross-sectional study of CMI. Group 1 consisted of six women without cytological or histological diagnosis of CIN and with an HPV negative test (CIN((-))/HPV((-))). Group 2 included 31 women with a new histological diagnosis of CIN and HPV positive test (CIN((+))/HPV((+))). Groups 3 and 4 were selected from women who had undergone ablative or excisional treatment for CIN at the colposcopy clinic at least 6 months before the study. The women in groups 3 and 4 were (CIN((+))/HPV((+))) before CIN treatment. Group 3 consisted of 22 women without evidence of recurrence of CIN (Recur((-))), and group 4 included 10 with histological diagnosis of recurrent CIN (Recur((+))). In particular, we investigated CMI responses to synthetic peptides from the E6 and E7 oncoproteins of HPV-16.

RESULTS

Compared to patients with disease recurrence (Recur((+)), n = 10), the majority of individuals who remained recurrence-free post-treatment (Recur((-)), n = 22) exhibited significant proliferative responses to synthetic peptides from the E6 (P = 0.001) and the E7 (P = <0.001). In particular, significant responses were observed with the E6 peptide Q15L (aa 43-57, P = 0.006) and the E7 peptide Q19D (aa 44-62, P = 0.002) in Recur((-)) patients but not Recur((+)) individuals. Additionally, PBMC from women in the Recur((-)) group, but not the Recur((+)) group, produced predominantly TH1 cytokines upon stimulation with the peptides Q15L or Q19D.

CONCLUSIONS

These results indicate an association between significant cellular immune responses specific to synthetic peptides from the E6 and E7 oncoproteins of HPV-16 and recurrence-free survival in HPV patients treated for CIN. We predict that these peptides may be useful as indicators of protective immunity for recovery from CIN and also for potential inclusion in designing immunotherapeutic and immunoprophylactic reagents for HPV-associated CIN.

T-cell responses to human papillomavirus type 16 among women with different grades of cervical neoplasia

Infection with high-risk genital human papillomavirus (HPV) types is a major risk factor for the development of cervical intraepithelial neoplasia (CIN) and invasive cervical carcinoma. The design of effective immunotherapies requires a greater understanding of how HPV-specific T-cell responses are involved in disease clearance and/or progression. Here, we have investigated T-cell responses to five HPV16 proteins (E6, E7, E4, L1 and L2) in women with CIN or cervical carcinoma directly ex vivo. T-cell responses were observed in the majority (78%) of samples. The frequency of CD4+ responders was far lower among those with progressive disease, indicating that the CD4+ T-cell response might be important in HPV clearance. CD8+ reactivity to E6 peptides was dominant across all disease grades, inferring that E6-specific CD8+ T cells are not vitally involved in disease clearance. T-cell responses were demonstrated in the majority (80%) of cervical cancer patients, but are obviously ineffective. Our study reveals significant differences in HPV16 immunity during progressive CIN. We conclude that the HPV-specific CD4+ T-cell response should be an important consideration in immunotherapy design, which should aim to target preinvasive disease.

Induction of human papillomavirus type 16-specific immunologic responses in a normal and an human papillomavirus-infected populations

Human papillomavirus (HPV) infection, especially with the oncogenic genotypes, is the most important risk factor for developing cervical cancer. We focused on generating HPV16 E7-specific cytotoxic CD8(+) T lymphocytes and evaluating HPV16 E7-specific immune responses in HPV16-infected and uninfected populations. Peripheral blood mononuclear cells (PBMCs) were first collected from an uninfected group with an human lymphocyte antigen (HLA) A2 haplotype (four volunteers). Mature monocyte-derived dendritic cells (DCs) were generated from the PBMCs and pulsed with one of two HLA-A2-restricted E7 peptides, aa 11-20 [YMLDLQPETT] and aa 86-93 [TLGIVCPI], as antigen presenting cells. The autologous naive or cultured PBMCs were then cultured with peptide-pulsed DCs to detect the HPV16 E7-specific immune responses by a variety of techniques such as enzyme-linked immunosorbent assay (ELISA), enzyme-linked immunospot (ELISPOT) assay and cytotoxic T lymphocyte assay. Interferon-gamma (IFN-gamma) from E7-specific cytotoxic CD8(+) T lymphocytes stimulated with the respective peptide was detected by ELISA. Using ELISPOT analysis, a marked increase in the number of IFN-gamma-secreting CD8(+) E7-specific lymphocytes was observed following peptide stimulation. Cultured CD8(+) T lymphocytes were highly cytotoxic against the CaSki cells. PBMCs were then collected from an HPV16-infected population of the HLA-A2 haplotype, including four persons of HPV16 infection only, four with cervical intraepithelial neoplasia (CIN) lesions, and four cervical cancer patients. We then compared the immunologic responses to E7 between HPV16-infected and uninfected populations by ELISA and ELISPOT assay. The E7-specific immunologic responses of the HPV16-infected populations were significantly higher than those of the uninfected population. In addition, persons with an HPV16 infection only or those with CIN lesions generated higher E7-specific immunologic responses than cervical cancer patients. Our results demonstrate methods for evaluating E7-specific immunologic responses and reflect the biological responses of HPV16-infected people during different periods of cervical disease.

HPV16-specific cytotoxic T lymphocyte responses are detected in all HPV16-positive cervical cancer patients

OBJECTIVES

The specific CTL response against human papillomavirus (HPV) antigens in women with cervical cancer has been poorly studied. Immunological monitoring of this response is central for understanding the principles that underlie successful immunotherapeutic strategies. The aim of the study was to investigate the HPV16 E6/E7-specific CTL immune response in a group of untreated HPV16-positive cervical cancer patients.

METHODS

Peripheral blood mononuclear cells from 21 untreated cervical cancer patients and 4 healthy controls were isolated prior to any therapy. Autologous monocyte-derived dendritic cells (MDDCs) were transiently transfected with HPV16 E6 or E7 expression vectors and used for one round of in vitro restimulation and as target cells in chromium release assays with restimulated peripheral blood lymphocytes.

RESULTS

Transfected monocyte-derived dendritic cells were differentiated to exhibit a fully mature phenotype. HPV16 E6 and E7 transgenes were expressed and translated as measured by RT-PCR and intracellular flow cytometry, respectively. All HPV16-associated cervical cancer patients showed evidence of specific CTLs. Lytic activity for HPV16 E6 (11/12) and/or E7 (8/9) was above 30% at the 100:1 effector to target ratio. None of the HPV16-negative cervical cancer patients or healthy controls were above 15% of lysis.

CONCLUSIONS

These data suggest that HPV-specific cytolytic immune responses can be detected in all untreated cervical cancer patients. Our approach, using dendritic cells for restimulation and as target cells, may enhance immunomonitoring of cervical cancer patients.

Dendritic cell-based tumor vaccine for cervical cancer II: results of a clinical pilot study in 15 individual patients

PURPOSE

Human papillomavirus (HPV) type 16 and 18 are the most prevalent genotypes in cervical cancer. The viral oncoproteins E6 and E7 are considered to be tumor-specific targets for immunotherapy. HPV E7 antigen-loaded autologous dendritic cells (DC) were evaluated as cellular tumor vaccine in a case series of cervical cancer patients.

METHODS

Autologous monocyte-derived DCs were pulsed with recombinant HPV16 E7 or HPV18 E7 oncoprotein and administered to 15 stage IV cervical cancer patients. Safety, toxicity, and induction of serological and cellular immune responses were monitored.

RESULTS

The vaccine was well-tolerated and no local or systemic side effects or toxicity were recorded. A specific serologic response was seen in 3/11 evaluated patients. Specific cellular immune responses (4/11) were detected with 2/10 positive de novo reactions plus one boosted preexistent response in proliferation assays and 3/11 in IFN-gamma ELISpot assays. A transient drop in tumor marker SCC was observed in 5/9 evaluable patients but did not correlate with markers of the immune response. No objective clinical response was observed. Tumor biopsies available from four patients showed severe or complete loss of HLA expression in three of the advanced tumors.

CONCLUSION

Autologous dendritic cells pulsed with HPV E7 protein can induce T cell responses in a portion of late stage cervical cancer patients. Boosting of immune responses by adjuvants and vaccination of tumor HLA-positive patients will be mandatory in future trials.

Disparate functions of immature and mature human myeloid dendritic cells: implications for dendritic cell-based vaccines

Although antigen-loaded dendritic cells (DC) are being investigated as antitumor vaccines, which DC differentiation state is most effective is not clear. Three DC functions that may be critical for immunization potential are expression of CD80/86, cytokine production following CD40 engagement, and migration to chemokine receptor 7-binding chemokines. We therefore examined highly purified human monocyte-derived immature and mature DC for these properties from normal donors and cancer patients. Although high expression of CD80/86 and migration to 6Ckine + macrophage-inflammatory protein-3beta were properties of mature DC, cytokine production following CD40 ligation was superior by immature DC. Loss of cytokine secretion occurred with multiple maturation conditions, was not apparently reversible, and was also seen with lipopolysaccharide stimulation in correlation with down-regulated Toll-like receptor expression. Our results suggest that the functions thought to contribute to optimal T cell priming are not coexpressed by the same DC population and that immature and mature DC likely possess distinct CD40-mediated signaling events.

HPV16 L1E7 chimeric virus-like particles induce specific HLA-restricted T cells in humans after in vitro vaccination

Cervical cancer has been shown to be highly associated with human papillomavirus (HPV) infection. The viral oncogenes E6 and E7 are constantly expressed by the tumor cells and are therefore targets for immunotherapy. In the present study we investigated the potential of HPV16 L1E7 chimeric virus-like particles (CVLP) to activate specific cytotoxic T lymphocytes in human blood donors. CVLP were expressed by recombinant baculovirus and purified. Direct incubation of freshly isolated peripheral blood lymphocytes (PBL) with CVLP resulted in induction of proliferation and growth of T cell lines. To enhance antigen presentation we also loaded dendritic cells with CVLP and used them to activate naive T cells. Growing cell lines were mainly CD3 positive (>95%) with a predominant CD4-positive and a minor CD8-positive component. Analysis of Tcell specificity was carried out by an interferon-gamma ELISpot assay. Dendritic cells pseudoinfected with CVLP or pulsed with human leukocyte antigen (HLA)-A*0201-restricted peptide E7(11-20) or with a newly identified HPV16 peptide L1(323-331) were used as stimulator cells. T cells responsive to CVLP were found in the cultures with frequencies of 0.5%-0.7%. Frequencies to peptides were around 0.1%. These T cells had cytolytic activity toward autologous B-lymphoblastic cell lines either pseudoinfected with CVLP or pulsed with HLA-A*0201-restricted peptides. They also lysed the HPV16- and HLA-A*0201-positive cervical cancer cell line CaSki, whereas HLA-A*0201-negative SiHa cells were not lysed. We conclude from our data that CVLP show promise for a therapeutic vaccine in patients with HPV16-positive cervical intraepithelial neoplasia lesions or cervical cancer.

Autologous dendritic cells for treatment of advanced cancer--an update

Dendritic cells (DC) are commonly viewed as the professional antigen-presenting cell. They capture antigens, migrate to appropriate lymphoid organs and initiate an antigen-specific CD4 and CD8 T cell response. Much is known about DC physiology, and it is now possible to culture, maintain and expand DC from different human sources, including hematopoietic progenitors in bone marrow and peripheral blood. Combined with the detection of an increasing number of tumor-associated antigens and T cell-recognized peptide epitopes, this has led to a new enthusiasm in the field of tumor immunotherapy and to various clinical applications in phase I/II studies on the treatment of different malignancies. This chapter will review the latest developments and give a brief update of the results obtained in studies of advanced melanoma, as well as provide a short overview of published results for other tumors.