Human Papillomavirus 16 E6-specific CD45RA+ CCR7+ High Avidity CD8+ T Cells Fail to Control Tumor Growth Despite Interferon-γ Production in Patients With Cervical Cancer

Dual T cell receptor/chimeric antigen receptor engineered NK-92 cells targeting the HPV16 E6 oncoprotein and the tumor-associated antigen L1CAM exhibit enhanced cytotoxicity and specificity against tumor cells

The human papillomavirus type 16 (HPV16) causes a large fraction of genital and oropharyngeal carcinomas. To maintain the transformed state, the tumor cells must continuously synthesize the E6 and E7 viral oncoproteins, which makes them tumor-specific antigens. Indeed, specific T cell responses against them have been well documented and CD8+ T cells engineered to express T cell receptors (TCRs) that recognize epitopes of E6 or E7 have been tested in clinical studies with promising results, yet with limited clinical success. Using CD8+ T cells from peripheral blood of healthy donors, we have identified two novel TCRs reactive to an unexplored E618-26 epitope. These TCRs showed limited standalone cytotoxicity against E618-26-HLA-A*02:01-presenting tumor cells. However, a single-signaling domain chimeric antigen receptor (ssdCAR) targeting L1CAM, a cell adhesion protein frequently overexpressed in HPV16-induced cancer, prompted a synergistic effect that significantly enhanced the cytotoxic capacity of NK-92/CD3/CD8 cells armored with both TCR and ssdCAR when both receptors simultaneously engaged their respective targets, as shown by live microscopy of 2-D and 3-D co-cultures. Thus, virus-specific TCRs from the CD8+ T cell repertoire of healthy donors can be combined with a suitable ssdCAR to enhance the cytotoxic capacity of the effector cells and, indirectly, their specificity.

Role of chemokines in HPV-induced cancers

Human papillomaviruses (HPVs) cause cancers of the uterine cervix, oropharynx, anus, and vulvovaginal tract. Low-risk HPVs, such as HPV6 and 11, can also cause benign mucosal lesions including genital warts, and in patients with recurrent respiratory papillomatosis, lesions in the larynx, and on occasion, in the lungs. However, both high and less tumorigenic HPVs share a striking commonality in manipulating both innate and adaptive immune responses in HPV- infected keratinocytes, the natural host for HPV infection. In addition, immune/inflammatory cell infiltration into the tumor microenvironment influences cancer growth and prognosis, and this process is tightly regulated by different chemokines. Chemokines are small proteins and exert their biological effects by binding with G protein-coupled chemokine receptors (GPCRs) that are found on the surfaces of select target cells. Chemokines are not only involved in the establishment of a pro-tumorigenic microenvironment and organ-directed metastases but also involved in disease progression through enhancing tumor cell growth and proliferation. Therefore, having a solid grasp on chemokines and immune checkpoint modulators can help in the treatment of these cancers. In this review, we discuss the recent advances on the expression patterns and regulation of the main chemokines found in HPV-induced cancers, and their effects on both immune and non-immune cells in these lesions. Importantly, we also present the current knowledge of therapeutic interventions on the expression of specific chemokine and their receptors that have been shown to influence the development and progression of HPV-induced cancers.

HPV-Positive and -Negative Cervical Cancers Are Immunologically Distinct

Although infection with human papillomavirus (HPV) is associated with nearly all cervical cancers (CC), a small proportion are HPV-negative. Recently, it has become clear that HPV-negative CC represent a distinct disease phenotype compared to HPV-positive disease and exhibit increased mortality. In addition, variations between different HPV types associated with CC have been linked to altered molecular pathology and prognosis. We compared the immune microenvironments of CC caused by HPV α9 species (HPV16-like), HPV α7 species (HPV18-like) and HPV-negative disease. HPV-negative CC appeared distinct from other subtypes, with greatly reduced levels of lymphocyte infiltration compared to either HPV α9 or α7 CC. Besides reduced levels of markers indicative of B, T, and NK lymphocytes, the expression of T-cell effector molecules, activation/exhaustion markers, and T-cell receptor diversity were also significantly lower in HPV-negative CC. Interestingly, HPV-negative CC expressed much higher levels of potential neoantigens than HPV-positive CC. These results identify profound differences between the immune landscape of HPV-positive and HPV-negative CC as well as modest differences between HPV α9 and α7 CC. These differences may contribute to altered patient outcomes between HPV-negative and HPV-positive CC and potentially between CC associated with different HPV types.

The Role of Chemokines in Cervical Cancers

Both clinical-pathological and experimental studies have shown that chemokines play a key role in activating the immune checkpoint modulator in cervical cancer progression and are associated with prognosis in tumor cell proliferation, invasion, angiogenesis, chemoresistance, and immunosuppression. Therefore, a clear understanding of chemokines and immune checkpoint modulators is essential for the treatment of this disease. This review discusses the origins and categories of chemokines and the mechanisms that are responsible for activating immune checkpoints in cervical dysplasia and cancer, chemokines as biomarkers, and therapy development that targets immune checkpoints in cervical cancer research.

Prognostic and therapeutic TILs of cervical cancer-Current advances and future perspectives

Cervical cancer is a top lethal cancer for women worldwide. Although screening and vaccination programs are available in many countries, resulting in the decline of new cases, this is not true for developing countries where there are many new cases and related deaths. Cancer immunotherapy through adaptive cell therapy (ACT) has been applied in clinics, but now much attention is focused on autogenic tumor-infiltrating lymphocyte (TIL)-based therapy, which has shown more specificity and better ability to inhibit tumor growth. Data from melanoma and cervical cancers confirm that tumor-specific T cells in TILs can be expanded for more specific and effective ACT. Moreover, TILs are derived from individual patients and are ready to home back to kill tumor cells after patient infusion, aligning well with personalized and precision medicine. In addition to therapy, TIL cell types and numbers are good indicators of host immune response to the tumor, and thus they have significant values in prognosis. Because of the special relationship with human papillomavirus (HPV) infection, cervical cancer has some specialties in TIL-based prognosis and therapy. In this review, we summarize the recent advances in the prognostic significance of TILs and TIL-based therapy for cervical cancer and discuss related perspectives.

A comprehensive in silico analysis for identification of therapeutic epitopes in HPV16, 18, 31 and 45 oncoproteins

Human papillomaviruses (HPVs) are a group of circular double-stranded DNA viruses, showing severe tropism to mucosal tissues. A subset of HPVs, especially HPV16 and 18, are the primary etiological cause for several epithelial cell malignancies, causing about 5.2% of all cancers worldwide. Due to the high prevalence and mortality, HPV-associated cancers have remained as a significant health problem in human society, making an urgent need to develop an effective therapeutic vaccine against them. Achieving this goal is primarily dependent on the identification of efficient tumor-associated epitopes, inducing a robust cell-mediated immune response. Previous information has shown that E5, E6, and E7 early proteins are responsible for the induction and maintenance of HPV-associated cancers. Therefore, the prediction of major histocompatibility complex (MHC) class I T cell epitopes of HPV16, 18, 31 and 45 oncoproteins was targeted in this study. For this purpose, a two-step plan was designed to identify the most probable CD8+ T cell epitopes. In the first step, MHC-I and II binding, MHC-I processing, MHC-I population coverage and MHC-I immunogenicity prediction analyses, and in the second step, MHC-I and II protein-peptide docking, epitope conservation, and cross-reactivity with host antigens’ analyses were carried out successively by different tools. Finally, we introduced five probable CD8+ T cell epitopes for each oncoprotein of the HPV genotypes (60 epitopes in total), which obtained better scores by an integrated approach. These predicted epitopes are valuable candidates for in vitro or in vivo therapeutic vaccine studies against the HPV-associated cancers. Additionally, this two-step plan that each step includes several analyses to find appropriate epitopes provides a rational basis for DNA- or peptide-based vaccine development.

Pathologic and imunohistochemical characterization of tumoral inflammatory cell infiltrate in invasive penile squamous cell carcinomas: Fox-P3 expression is an independent predictor of recurrence

Penile carcinomas (PeCa) are relatively rare, but devastating neoplasms, more frequent among people of underprivileged socioeconomic status. There is mounting evidence that immune cells may trigger various mechanisms that enhance tumor growth and metastasis, but no data on the peritumoral inflammation is available for PeCa. The objectives of the present study are to evaluate the immunohistomorphology of tumoral inflammation in PeCa, and to correlate it with clinicopathological parameters, which could contribute to the prognostic evaluation. One hundred and twenty-two patients with the diagnosis of usual-type squamous cell penile carcinoma were included. Paraffin-embedded tissue was submitted to immunohistochemical evaluation of p16 protein, CD3, CD4, CD8, CD20, CD68, CD138, granzyme B, and Fox-P3. The Fisher's exact test was employed for comparison between histological variables and parameters, and the Kaplan-Meier method for the analysis of survival. Improved 5-year overall survival was significantly associated to age ≤60 years, stage I + II, tumor size T1 + T2, lymph node status N0, and absent perineural invasion. In a multivariate analysis age ≥60 years, presence of lymph node metastasis, urethral invasion, and high histologic grade retained a significantly more unfavorable outcome. Improved 5-year failure free survival was associated to stage of the disease I + II, lymph node status N0, absence of perineural, vascular, and urethral invasion, and Fox-P3 expression. In a multivariate analysis, presence of lymph node metastasis, perineural and vascular invasion, and of Fox-P3-positive lymphocytes together with low inflammatory infiltrate retained a significantly more unfavorable outcome. These results support the prognostic value of determining the levels of Fox-P3-positive lymphocytes by immunohistochemistry in PeCa, as this parameter adds value to the traditional clinicopathological features.

Location and Density of Immune Cells in Precursor Lesions and Cervical Cancer

Only a small proportion of women infected with Human Papillomavirus (HPV) develop cervical cancer. Host immune response seems to play a role eliminating the viral infection and preventing progression to cancer. Characterization of tumor infiltrating lymphocytes (TILs) in cervical pre-neoplastic lesions and cervical cancer may be helpful to understand the mechanisms that mediate this protection. The aim of this study was to determine if there are differences in the localization and density (cells/mm(2)) of CD8+ T-cells, CD4+ T-cells and Tregs (CD25 + Foxp3+) in cervical pre-neoplastic lesions and cervical cancer. Immunohistochemical analysis of sections of 96 (26 CIN1, 21 CIN2, 25 CIN3, and 24 SCC) samples revealed that regardless of CIN grades, CD8+ T-cells are more abundant than CD4+, CD25+ and Foxp3+ cells in both the stroma and epithelium. There was a higher density of CD8+ cells in the stroma of cervical cancer compared to CIN3 (OR = 4.20, 95% CI 1.2-15), CIN2 (OR = 7.86, 95% CI 1.7-36.4) and CIN1 (OR = 4.25, 95% CI 1.1-17). Studies evaluating whether these cells are recruited before or after cancer progression will be helpful to understand the role of these cells in the natural history of HPV-induced lesions.

Peptide microarrays for the profiling of cytotoxic T-lymphocyte activity using minimum numbers of cells

The identification of epitopes that elicit cytotoxic T-lymphocyte activity is a prerequisite for the development of cancer-specific immunotherapies. However, especially the parallel characterization of several epitopes is limited by the availability of T cells. Microarrays have enabled an unprecedented miniaturization and parallelization in biological assays. Here, we developed peptide microarrays for the detection of CTL activity. MHC class I-binding peptide epitopes were pipetted onto polymer-coated glass slides. Target cells, loaded with the cell-impermeant dye calcein, were incubated on these arrays, followed by incubation with antigen-expanded CTLs. Cytotoxic activity was detected by release of calcein and detachment of target cells. With only 200,000 cells per microarray, CTLs could be detected at a frequency of 0.5% corresponding to 1,000 antigen-specific T cells. Target cells and CTLs only settled on peptide spots enabling a clear separation of individual epitopes. Even though no physical boundaries were present between the individual spots, peptide loading only occurred locally and cytolytic activity was confined to the spots carrying the specific epitope. The peptide microarrays provide a robust platform that implements the whole process from antigen presentation to the detection of CTL activity in a miniaturized format. The method surpasses all established methods in the minimum numbers of cells required. With antigen uptake occurring on the microarray, further applications are foreseen in the testing of antigen precursors that require uptake and processing prior to presentation.

A flow cytometry-based assay to assess minute frequencies of CD8+ T cells by their cytolytic function

Limited sample size and low sensitivity of currently used functional assays challenge direct analysis of cytotoxic CD8+ T lymphocyte activity to quantify antigen-specific immunity after infection or vaccination. Our flow cytometry-based assay reproducibly detects at least three epitope-specific CD8+ T lymphocytes by their cytolytic function. As exemplified for viral epitopes restricted to the human leukocyte antigen (HLA)-A2, the HLA-A2+ human somatic cell hybrid T2 provided an about 10-fold more sensitive readout as compared to autologous B-lymphoblastoid cells or the human erythroleukemia cell line K562 transfected to express HLA-A2 when used as target cells. We named our assay VITAL-FR assay, referring to Hermans et al. (2004) and indicating the modification of using Far Red (FR) dye instead of CMTMR. Under optimal conditions the VITAL-FR assay proved 30 times more sensitive than the 51chromium-release assay to assess epitope-specific target cell lysis. The high overall sensitivity of the VITAL-FR assay basically depended on the negligible spectral overlap of the emission of a stable Far Red fluorescent reporter with the green tracer for target cell labelling. It also profited from long co-incubation of effector and target cells of up to 72, from prior in-vitro culture increasing the frequency of epitope-specific CD8+ T cells and from generic, easily accessible standardized target cells that were used with only 10(3) specific and 10(3) control target cells per individual experimental reaction. Our functional approach with the VITAL-FR assay therefore ideally suits for monitoring CD8+ T cell-mediated cytotoxicity in e.g. vaccination studies with known MHC-restricted immunogenic peptides in scientific and diagnostic applications.

Cross-protective responses to human papillomavirus infection

Human papillomavirus (HPV) infections with oncogenic types account for approximately 500,000 deaths per year worldwide, predominantly in underdeveloped countries. The major cause of death is cervical cancer in women, but some additional cancers of the head and neck and anogenital sites also have an HPV etiology. Current virus-like particle-based vaccines are in clinical trials, and show very strong, long-lasting protection against vaccine-matched HPV types. These vaccines currently contain virus-like particles for the HPV types 6, 11, 16 and 18 (Gardasil®) and HPV16 and -18 (Cervarix®). Although type-specific neutralizing antibodies develop from immunizations with these virus-like particle vaccines, promising evidence for cross-protection against related but nonvaccine HPV types is emerging. Strategies to increase cross-protection to cover all oncogenic HPV types (currently approximately 20 types) are underway. These strategies include increasing the number of HPV types in the virus-like particle vaccine, and to the development of second-generation HPV vaccines that include the minor coat protein.

Host immune responses to cervical cancer

PURPOSE OF REVIEW

The purpose of this review is to understand the role of the host immune system in clearing the human papillomavirus (HPV) infection, strategies adopted by HPV to subvert the host immune responses and analyze the challenges to the future immunotherapeutic treatment modalities.

RECENT FINDINGS

Cervical epithelium provides a protective niche to the virus to subvert the immune responses. The absence of an inflammatory milieu in the cervix makes the resident dendritic and langerhan cells tolerogenic to HPV antigens. CD4 cells predominated in regressing cervical intraepithelial neoplasia lesions, whereas CD8 cells were dominant in invasive carcinoma. A reduced expression of T cell signaling molecule T-cell receptor zeta chain was observed in CD8 lymphocytes. Decreased numbers of NKG2D expressing natural killer and T cells were present in patients with cervical cancer and cervical intraepithelial neoplasia. Increased frequencies of CD4 CD25+ FoxP3+ T regulatory cells were observed in patients with cervical cancer. The Nrp-1+Treg showed greater suppressive activity. A network of Treg and indoleamine 2, 3-dioxygenase expressed in tumor cells facilitates immune escape of tumor cells.

SUMMARY

The HPV uses different strategies to evade immune recognition. Understanding the immune evasion mechanisms used by HPV will help in designing newer therapeutic strategies for cervical cancer.

Memory T cells specific for novel human papillomavirus type 16 (HPV16) E6 epitopes in women whose HPV16 infection has become undetectable

Human papillomavirus (HPV)-specific T-cell response to the HPV type 16 (HPV16) E6 protein has been shown to be associated with successful viral clearance. The patterns of CD8 T-cell epitopes within HPV16 E6 protein were previously studied in two women with HPV16 clearance. The goal of this study was to characterize these epitopes in terms of their minimal and optimal amino acid sequences and the human leukocyte antigen (HLA) restriction molecules. The presence of the epitope-specific memory T cells after viral clearance was also examined. In subject A, the dominant epitope was characterized to be E6 75-83 (KFYSKISEY), restricted by the HLA-B62 molecule, while that of subject B was E6 133-142 (HNIRGRWTGR), restricted by the HLA-A6801 molecule. Homologous epitopes were identified in five other high-risk HPV types for both of these epitopes, but they were not recognized by respective T-cell clone cells. An enzyme-linked immunospot assay or tetramer analysis was performed on peripheral blood mononuclear cells from blood samples collected after viral clearance but prior to isolation of the T-cell clones. The presence of epitope-specific memory T cells was demonstrated. These data suggest that HPV-specific memory T cells were generated in vivo and that they may remain in circulation many months, if not years, after viral clearance. Our findings broaden the spectrum of the CD8 T-cell epitopes of the HPV16 E6 protein. The characterization of novel T-cell epitopes and long-lasting epitope-specific memory T cells may be useful for the development of a potential epitope-based vaccine.

Human papilloma virus specific T cells infiltrating cervical cancer and draining lymph nodes show remarkably frequent use of HLA-DQ and -DP as a restriction element

Human papillomavirus (HPV)-induced malignancies are frequently infiltrated by lymphocytes. To comprehend the contribution of HPV-specific T cells in this anti-tumor response we developed a method that allowed the analysis of the presence and specificity of cervix-infiltrating and draining lymph node resident T cells in a group of 74 patients with cervical malignancies, 54 of which were induced by HPV16 or HPV18. We detected the presence of HPV16 or HPV18-specific T cells in at least 23 of the 54 HPV-16 or -18 positive patients, and not in the 20 controls. Detailed studies resulted in the identification of 17 novel CD4+ and CD8+ T cell epitopes and their HLA-restriction elements, and also revealed that the HPV-specific immune response was aimed at both E6 and E7 and showed no preferential recognition of immunodominant regions. Unexpectedly, the vast majority of the CD4+ T cell epitopes were presented in the context of the less abundantly expressed HLA-DQ and HLA-DP molecules. Since the identified T cell epitopes constitute physiological targets in the immune response to HPV16 and HPV18 positive tumors they will be valuable for detailed studies on the interactions between the tumor and the immune system. This is crucial for the optimization of cancer immunotherapy in patients with pre-existing tumor-immunity.