Identification of novel immunogenic human leukocyte antigen-A 2402-binding epitopes of human papillomavirus type 16 E7 for immunotherapy against human cervical cancer

Identification of HPV-E7 specific TCRs for tumor immunotherapy

The oncogenic protein E7 of the Human Papillomavirus (HPV) is constitutionally expressed in HPV-associated tumors and has the potential to be targeted in T cell receptor (TCR)-based immunotherapy. Adoptive transfer of TCR-engineered T (TCR-T) cells has shown promise as a therapeutic approach for HPV-induced tumors. This study aimed to identify HPV-E7 specific TCRs from HLA-A11:01 transgenic mice through single-cell sorting and sequencing facilitated by E789-97/HLA-A11:01 tetramer. Two dominant TCRs were identified, which exhibited specific binding to E789-97 presented in the context of HLA-A*11:01. TCR-T cells were prepared by infecting primary T cells with lentiviruses containing the TCR genes, and the two TCRs demonstrated substantial responsiveness and showed CD8+ dependent cytokine secretion characteristics. Further analyses of the cytokine profiles revealed that the two TCRs were capable of exerting polyfunctional responses upon specific stimulation. These findings suggest that the two TCRs represent promising candidates for the development of future therapeutic drugs targeting HPV-E7 in the context of HLA-A*11:01 for tumor immunotherapy.

The common HLA class I-restricted tumor-infiltrating T cell response in HPV16-induced cancer

Immunotherapies targeting truly tumor-specific targets focus on the expansion and activation of T cells against neoantigens or oncogenic viruses. One target is the human papilloma virus type 16 (HPV16), responsible for several anogenital cancers and oropharyngeal carcinomas. Spontaneous and vaccine-induced HPV-specific T cells have been associated with better clinical outcome. However, the epitopes and restriction elements to which these T cells respond remained elusive. To identify CD8+ T cell epitopes in cultures of tumor infiltrating lymphocytes, we here used multimers and/or a functional screening platform exploiting single HLA class I allele-engineered antigen presenting cells. This resulted in the detection of 20 CD8+ T cell responses to 11 different endogenously processed HLA-peptide combinations within 12 HPV16-induced tumors. Specific HLA-peptide combinations dominated the response in patients expressing these HLA alleles. T cell receptors (TCRs) reactive to seven different HLA class I-restricted peptides could be isolated and analysis revealed tumor reactivity for five of the six TCRs analyzed. The tumor reactive TCRs to these dominant HLA class I peptide combinations can potentially be used to engineer tumor-specific T cells for adoptive cell transfer approaches to treat HPV16-induced cancers.

Therapeutic DNA Vaccines against HPV-Related Malignancies: Promising Leads from Clinical Trials

In 2014 and 2021, two nucleic-acid vaccine candidates named MAV E2 and VGX-3100 completed phase III clinical trials in Mexico and U.S., respectively, for patients with human papillomavirus (HPV)-related, high-grade squamous intraepithelial lesions (HSIL). These well-tolerated but still unlicensed vaccines encode distinct HPV antigens (E2 versus E6+E7) to elicit cell-mediated immune responses; their clinical efficacy, as measured by HSIL regression or cure, was modest when compared with placebo or surgery (conization), but both proved highly effective in clearing HPV infection, which should help further optimize strategies for enhancing vaccine immunogenicity, toward an ultimate goal of preventing malignancies in millions of patients who are living with persistent, oncogenic HPV infection but are not expected to benefit from current, prophylactic vaccines. The major roadblocks to a highly efficacious and practical product remain challenging and can be classified into five categories: (i) getting the vaccines into the right cells for efficient expression and presentation of HPV antigens (fusion proteins or epitopes); (ii) having adequate coverage of oncogenic HPV types, beyond the current focus on HPV-16 and -18; (iii) directing immune protection to various epithelial niches, especially anogenital mucosa and upper aerodigestive tract where HPV-transformed cells wreak havoc; (iv) establishing the time window and vaccination regimen, including dosage, interval and even combination therapy, for achieving maximum efficacy; and (v) validating therapeutic efficacy in patients with poor prognosis because of advanced, recurrent or non-resectable malignancies. Overall, the room for improvements is still large enough that continuing efforts for research and development will very likely extend into the next decade.

A low-molecular-weight compound exerts anticancer activity against breast and lung cancers by disrupting EGFR/Eps8 complex formation

BACKGROUND

Epidermal growth factor receptor (EGFR) and epidermal growth factor receptor pathway substrate 8 (Eps8) have been widely reported to be expressed in various tumors. Eps8 is an important active kinase substrate of EGFR that directly binds to the juxtamembrane (JXM) domain of EGFR to form an EGFR/Eps8 complex. The EGFR/Eps8 complex is involved in regulating cancer progression and might be an ideal target for antitumor therapy. This study focused on the screening of small-molecule inhibitors that target the EGFR/Eps8 complex in breast cancer and non-small cell lung cancer (NSCLC).

METHODS

In silico virtual screening was used to identify small-molecule EGFR/Eps8 complex inhibitors. These compounds were screened for the inhibition of A549 and BT549 cell viability. The direct interaction between EGFR and Eps8 was measured using coimmunoprecipitation (CoIP) and JXM domain replacement assays. The antitumor effects of the inhibitors were analyzed in cancer cells and xenograft models. An acute toxicity study of EE02 was performed in a mouse model. In addition, the effect of the EE02 inhibitor on the protein expression of elements downstream of the EGFR/Eps8 complex was determined by western blotting and protein chip assays.

RESULTS

In this study of nearly 390,000 compounds screened by virtual database screening, the top 29 compounds were identified as candidate small-molecule EGFR/Eps8 complex inhibitors and evaluated by using cell-based assays. The compound EE02 was identified as the best match to our selection criteria. Further investigation demonstrated that EE02 directly bound to the JXM domain of EGFR and disrupted EGFR/Eps8 complex formation. EE02 selectively suppressed growth and induced apoptosis in EGFR-positive and Eps8-positive breast cancer and NSCLC cells. More importantly, the PI3K/Akt/mTOR and MAPK/Erk pathways downstream of the EGFR/Eps8 complex were suppressed by EE02. In addition, the suppressive effect of EE02 on tumor growth in vivo was comparable to that of erlotinib at the same dose.

CONCLUSIONS

We identified EE02 as an EGFR/Eps8 complex inhibitor that demonstrated promising antitumor effects in breast cancer and NSCLC. Our data suggest that the EGFR/Eps8 complex offers a novel cancer drug target.

A dual-function epidermal growth factor receptor pathway substrate 8 (Eps8)-derived peptide exhibits a potent cytotoxic T lymphocyte-activating effect and a specific inhibitory activity

The identification and characterization of tumor-associated antigens (TAAs) that generate specific cytotoxic T lymphocytes (CTLs) are vital to the development of cancer immunotherapy. The epidermal growth factor receptor (EGFR) pathway substrate 8 gene (Eps8) is involved in regulating cancer progression and might be an ideal antigen. In this study, we searched for novel human leukocyte antigen (HLA)-A*2402-restricted epitopes derived from the Eps8 protein via the HLA-binding prediction algorithm. Among four candidates, peptides 327 (EFLDCFQKF), 534 (KYAKSKYDF) and 755 (LFSLNKDEL) induced peptide-specific CTLs to secrete higher levels of interferon-gamma (IFN-γ) and showed enhanced cytotoxic activity against malignant cancer cells. Our results demonstrated that peptide-specific CTLs showed effective antitumor responses, including upregulation of interleukin-2 (IL-2), tumor necrosis factor-alpha (TNF-α), granzyme B and perforin. Treatment with peptide-sensitized peripheral blood mononuclear cells (PBMCs) significantly reduced the tumor growth in vivo compared with the non-peptide-sensitized PBMC treatment. Importantly, our results indicated that peptide 327 may interfere with EGFR signaling by mechanistically disrupting Eps8/EGFR complex formation. We extended this observation that peptide 327 also suppressed the viability of cancer cells, blocked EGFR signal pathway and reduced the expression of downstream targets. Notably, conjugation of peptide 327 to the TAT sequence (TAT-327) resulted in potent antitumor activity and selective insertion into cancer cell membranes, where it adopted a punctate distribution. Furthermore, peptide 327 and TAT-327 displayed anticancer properties in xenograft models. Our results indicated that 327, 534 and 755 were novel HLA-A*2402-restricted epitopes from Eps8. By inhibiting the Eps8/EGFR interaction, peptide 327 and TAT-327 may serve as novel peptide inhibitors, which could provide an innovative approach for treating various cancers.

Identificaiton of Novel Immunogenic Human Papillomavirus Type 16 E7-Specific Epitopes Restricted to HLA-A*33;03 for Cervical Cancer Immunotherapy

PURPOSE

To identify new immunogenic HLA-A*33;03-restricted epitopes from the human papillomavirus (HPV) 16 E7 protein for immunotherapy against cervical cancer.

MATERIALS AND METHODS

We synthesized fourteen overlapping 15-amino acid peptides and measured intracellular interferon-γ (IFN-γ) production in PBMC and CD8+ cytotoxic T lymphocytes (CTLs) after sensitization with these peptides using flow cytometry and ELISpot assay. The immunogenicity of epitopes was verified using a ⁵¹Cr release assay with SNU1299 cells.

RESULTS

Among the fourteen 15-amino acid peptides, E7₄₉₋₆₃ (RAHYNIVTFCCKCDS) demonstrated the highest IFN-γ production from peripheral blood mononuclear cells (PBMCs), and CD8+ CTLs sensitized with E7₄₉₋₆₃ showed higher cytotoxic effect against SNU1299 cells than did CD8+ CTLs sensitized with other peptides or a negative control group. Thirteen 9- or 10-amino acid overlapping peptides spanning E7₄₉₋₆₃, E7₅₀₋₅₉ (AHYNIVTFCC), and E7₅₂₋₆₁ (YNIVTFCCKC) induced significantly higher IFN-γ production and cytotoxic effects against SNU1299 cells than the other peptides and negative controls, and the cytotoxicity of E7₅₀₋₅₉- and E7₅₂₋₆₁-sensitized PBMCs was induced via the cytolytic effect of CD8+ CTLs.

CONCLUSION

We identified E7₅₀₋₅₉ and E7₅₂₋₆₁ as novel HPV 16 E7 epitopes for HLA-A*33;03. CD8+ CTL sensitized with these peptides result in an antitumor effect against cervical cancer cells. These epitopes could be useful for immune monitoring and immunotherapy for cervical cancer and HPV 16-related diseases including anal cancer and oropharyngeal cancer.

Current therapeutic vaccination and immunotherapy strategies for HPV-related diseases

Carcinomas of the anogenital tract, in particular cervical cancer, remains one of the most common cancers in women, and represent the most frequent gynecological malignancies and the fourth leading cause of cancer death in women worldwide. Human papillomavirus (HPV)-induced lesions are immunologically distinct in that they express viral antigens, which are necessary to maintain the cancerous phenotype. The causal relationship between HPV infection and anogenital cancer has prompted substantial interest in the development of therapeutic vaccines against high-risk HPV types targeting the viral oncoproteins E6 and E7. This review will focus on the most recent clinical trials for immunotherapies for mucosal HPV-induced lesions as well as emerging therapeutic strategies that have been tested in pre-clinical models for HPV-induced diseases. Progress in peptide- and protein-based vaccines, DNA-based vaccines, viral/bacterial vector-based vaccines, immune checkpoint inhibition, immune response modifiers, and adoptive cell therapy for HPV will be discussed.

Cross-Reactivity, Epitope Spreading, and De Novo Immune Stimulation Are Possible Mechanisms of Cross-Protection of Nonvaccine Human Papillomavirus (HPV) Types in Recipients of HPV Therapeutic Vaccines

Numerous versions of human papillomavirus (HPV) therapeutic vaccines designed to treat individuals with established HPV infection, including those with cervical intraepithelial neoplasia (CIN), are in development because approved prophylactic vaccines are not effective once HPV infection is established. As human papillomavirus 16 (HPV-16) is the most commonly detected type worldwide, all versions of HPV therapeutic vaccines contain HPV-16, and some also contain HPV-18. While these two HPV types are responsible for approximately 70% of cervical cancer cases, there are other high-risk HPV types known to cause malignancy. Therefore, it would be of interest to assess whether these HPV therapeutic vaccines may confer cross-protection against other high-risk HPV types. Data available from a few clinical trials that enrolled subjects with CINs regardless of the HPV type(s) present demonstrated clinical responses, as measured by CIN regression, in subjects with both vaccine-matched and nonvaccine HPV types. The currently available evidence demonstrating cross-reactivity, epitope spreading, and de novo immune stimulation as possible mechanisms of cross-protection conferred by investigational HPV therapeutic vaccines is discussed.

Identification of novel epitopes from human papillomavirus type 18 E7 that can sensitize PBMCs of multiple HLA class I against human cervical cancer

Background

To identify the novel epitopes from the human papillomavirus type 18 E7 which can sensitize PBMCs of four different major HLA class I A allele.

Methods

Twenty-four synthetic overlapping 15-amino acid peptides were screened by measuring the frequency of CD8⁺ cytotoxic T lymphocytes (CTLs)-producing interferon-γ (IFN-γ) by using flow cytometry and ELISpot assays and selected peptides were validated for cytolytic activity by using the ⁵¹Cr release assay. Truncated peptides in the selected epitopes were tested to determine the important residues using ELISpot and ⁵¹Cr release assay.

Results

Among 24 peptides, E7_81-95DDLRAFQQLFLNTLS (#21) and E7_89-103LFLNTLSFVCPWCAS (#23) induced significantly higher Th 1 response including IFN-γ production and in vitro cytotoxicity of PBMCs of four different HLA-A alleles against cervical cancer cells than that of other peptides and the negative control (no peptide sensitization). In E7_81–95 (#21), amino acid position 81, 82 (N-terminus) and 92, 94, 95 (C-terminus) for HLA-A*02:02 and 24:02, and 81, 82 (N-terminus) and 92, 95 (C-terminus) for HLA-A*11:01 and 33:03 were important to elicit Th1 response of PBMCS. In E7_89–103 (#23), residue 100 and103 (C-terminus) were important to elicit the CD8⁺ CTL response in HLA-A*02:01, 11:01 and 33:03 and 100, 101, and 103 (C-terminus) were important to elicit the CD8⁺ CTL response in HLA-A*24:02.

Conclusions

E7_81–95 (#21) and E7_89–103 (#23) were identified as novel epitopes from HPV18 E7 which could sensitized PBMCs of four different HLA class I (HLA-A*02:01, 24:02, 11:01 and 33:03). These epitopes could be useful for immune monitoring and immunotherapy for HPV 18+ cervical cancer.

HPV-16 E6 and E7 protein T cell epitopes prediction analysis based on distributions of HLA-A loci across populations: an in silico approach

Human papillomavirus type 16 (HPV-16) is the most prevalent virus in human cervical cancers, as it is present in more than half of all cases. Many studies have found continued expression of E6 and E7 proteins in the majority of cervical cancer cases, but not in normal tissues. These results indicated that the E6 and E7 proteins could be ideal candidate therapeutic vaccines against HPV-16 infection and cervical cancer. Using the Immune Epitope Database Analysis Resource, cytotoxic T lymphocyte (CTL) epitopes of the HPV-16 E6 and E7 proteins were predicted according to worldwide frequency distributions of HLA-A alleles (HLA-A*01:01, -A*02:01, -A*02:06, -A*03:01, -A*11:01, -A*24:02, -A*26:01, -A*31:01 and -A*33:03). Our results predicted a total of 81 epitopes of HPV-16 E6 (n=59) and E7 (n=22). Epitope cluster analysis showed that among the 20 clusters of HPV-16 E6, cluster 3 contained the most epitopes (10 epitopes), which was represented by HLA-A*31:01 and -A*33:03. Of the 10 clusters of HPV-16 E7, cluster 3 contained the most epitopes (5 epitopes), which was represented by HLA-A*01:01 and -A*26:01. Our results indicated that the combination of epitopes FAFRDLCIVYR₅₂₋₆₂ of E6 (HLA-A*02:06, HLA-A*31:01, and HLA-A*33:03), PYAVCDKCLKF₆₆₋₇₆ of E6 (HLA-A*11:01 and HLA-A*24:02), HGDTPTLHEY₂₋₁₁ of E7 (HLA-A*01:01 and HLA-A*26:01), and YMLDLQPETT₁₁₋₂₀ of E7 (HLA-A*02:01) could vaccinate >50% of all individuals worldwide. Our results propose CTL epitopes or combinations of them predicted in current study for candidate therapeutic vaccines to effectively control HPV-16 infection and development of cervical cancer.