The commercial prophylactic vaccines for human papillomavirus (HPV) are subunit vaccines composed of spontaneously assembled virus-like particles formed from 360 copies of the L1 major virion protein. The vaccines have exceeded expectations in immunogenicity, clinical trials efficacy, and effectiveness in national immunisation programmes. Booster doses are not required to generate these outcomes. In this Review, we discuss the immunological and virological considerations that can help with explaining the high potency of HPV vaccines. These considerations provide biological plausibility for HPV vaccines being the first subunit vaccines to confer high-level, long-term protection after a single priming dose, support projections of eliminating vaccine-targeted types in populations with achievable coverage rates in adolescents, and offer insights for developing future antimicrobial vaccines.

Intratumoral (IT) immunotherapy can stimulate the tumor microenvironment and enhance anti-tumor immunity. We investigated IT delivery of three licensed viral vaccines—Shingrix (VZV shingles), Gardasil-9 (HPV), and Spikevax (SARS-CoV-2)—in prevaccinated mice using the murine tumor model TC-1, which expresses HPV16 oncogenes E6 and E7. Shingrix IT injection often induced tumor regression and resistance to secondary challenge. Injecting a VZV glycoprotein E (gE)-derived MHC-II-restricted peptide with polyI:C also led to durable remission, highlighting the role of gE-specific CD4+ T cells. While Gardasil-9 IT injection alone was ineffective, combining a HPV L1-derived MHC-I-restricted peptide with polyI:C or Shingrix enhanced tumor regression. Both approaches elicited CD8+ T cells against the E7 tumor viral oncoprotein. Tumor microenvironment analysis revealed remodeling of the myeloid compartment, significant induction of IFN-γ, TNF-α, and CXCL9 and broad gene expression reprograming. In a dual-flank model, IT injection of Shingrix with an MHC-I-restricted E7 tumor-specific peptide eliminated primary and non-injected tumors. Finally, Spikevax IT injection showed modest tumor growth delay, while improved control was observed with a SARS-CoV-2 spike-derived MHC-I-restricted peptide and polyI:C. These results demonstrate the potential of licensed vaccines as promising platforms for IT immunotherapy, either alone or combined with vaccine- or tumor-derived MHC-I-restricted peptide epitopes.

B cell responses to membrane-presented antigens appear to be strongly favored over soluble antigens in vivo suggesting that vaccines that mimic membrane-presented antigens may be highly efficacious. We recently demonstrated that human B cell responses to membrane-associated but not to soluble antigens in vitro depended on the expression and activity of the plasma membrane mechanosensitive ion channel, Piezo1. Here, we provide evidence that the efficacy of the current human papillomavirus virus-like particle (HPV VLP) vaccines may be due in part to their inherent ability to mimic Piezo1-dependent membrane presentation of antigens to B cells. We compared HPV-specific human B cell responses to HPV VLPs versus soluble HPV pentameric capsomeres and showed that although both induced calcium responses, only HPV VLP-induced responses were blocked by Piezo1 inhibitors. The kinetics of internalization of HPV-VLP and capsomeres into HPV-specific B cells were similar and neither required Piezo1 function as shown by small interfering RNA (siRNA)-mediated knockdown of Piezo. However, trafficking of HPV-VLPs into intracellular major histocompatibility complex (MHC) class II, lysosomal associated membrane protein 1 (LAMP1)+ antigen-processing compartments was Piezo1-dependent, whereas trafficking of capsomeres was not. In addition, a time course of intracellular trafficking suggested that colocalization of HPV-VLP with MHC classII was more stable over time as compared to capsomeres. Taken together these findings suggest that the ability of HPV-VLP vaccines to mimic Piezo1-dependent membrane antigen presentation may be exploited in the design of highly effective human vaccines.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) evades the innate immune machinery through multiple viral proteins, including nonstructural protein 1 (NSP1). While NSP1 is known to suppress translation of host mRNAs, the mechanisms underlying its immune evasion properties remain elusive. By integrating RNA-seq, ribosome footprinting, and ChIP-seq in A549 cells we found that NSP1 predominantly represses transcription of immune-related genes by favoring Histone 3 Lysine 9 dimethylation (H3K9me2). G9a/GLP H3K9 methyltransferase inhibitor UNC0638 restored expression of antiviral genes and restricted SARS-CoV-2 replication. Our multi-omics study unravels an epigenetic mechanism underlying host immune evasion by SARS-CoV-2 NSP1. Elucidating the factors involved in this phenomenon, may have implications for understanding and treating viral infections and other immunomodulatory diseases.

Local immunotherapy against solid tumors is considered a viable approach to stimulate the tumor immune microenvironment and anti-tumor immunity. Here, we interrogate whether preexisting anti-vaccine immunity induced by licensed subunit vaccines could be leveraged for local cancer immunotherapy in the syngeneic murine tumor models. We selected Shingrix, a VZV vaccine containing the glycoprotein E (gE) antigen and adjuvant AS01B, and Gardasil-9, a HPV vaccine containing the L1 virus-like particles and alum because of the CD4 and CD8 T cell responses they respectively induce. Intratumoral injection of Shingrix alone or with immune checkpoint blockade (CTLA-4), in prevaccinated mice delayed tumor growth and often led to complete regression. These responses were associated with the induction of CD8+ T cell responses against tumor associated antigen, to tumor immune activation and alteration of the myeloid compartment. The injection of selected MHC-II-restricted gE minimal peptide epitopes combined with polyI:C also led to durable remission suggesting a contribution of gE-specific CD4 T cells. In contrast, Gardasil-9 i.t. injection did not delay tumor growth or cause tumor rejection which suggests inefficient class I cross-presentation of native VLP in the tumor cells. However, the injection of MHC-I-restricted L1 minimal peptide epitopes led to complete and durable remissions suggesting efficient tumor control by L1-specific CD8 T cells. Our results suggest that anti-viral licensed vaccines can be leverage as a new class of immunotherapeutics for local cancer therapy and intrinsic immunogenicity properties of vaccines should be considered as these effects appeared to be vaccine specific. NIH Intramural program.

Abstract Local immunotherapy against solid tumors is considered a viable approach to stimulate the tumor microenvironment (TME) and anti-tumor immunity. We assessed in situ vaccination with licensed subunit vaccines to leverage preexisting anti-vaccine immunity in a tumor model expressing HPV16 viral oncogenes E6 and E7. We chose Shingrix, a VZV vaccine containing the glycoprotein E (gE), and Gardasil-9, an HPV vaccine containing the L1 virus-like particles (VLP) to preferentially induce CD4 and CD8 T cell responses, respectively. Intratumoral (IT) injection of Shingrix in prevaccinated mice often led to complete regression and elicited CD8 T cell responses against E7. IT injection of an MHC-II-restricted gE peptide with polyI:C also led to durable remission, suggesting a role for gE-specific CD4 T cells. In contrast, IT injection of Gardasil-9 did not delay tumor growth, but IT injection of an MHC-I-restricted L1 peptide with Shingrix led to complete remissions hence overcoming preexisting antibodies against native HPV VLP. TME analysis showed that IT injection of Shingrix with Gardasil-derived peptide induced IFN-g, TNF-a and CXCL9 and reshaped the myeloid cell infiltrate. Finally, IT injection of Shingrix and the E7 viral neoantigen peptide led to the eradication of all primary injected and abscopal tumors. Our results indicate that Shingrix is a versatile component for in-situ vaccination which can be combined with peptides derived from licensed vaccines or tumor antigens.

EDITORIAL article Front. Immunol., 24 May 2022Sec. Vaccines and Molecular Therapeutics Volume 13 - 2022 | https://doi.org/10.3389/fimmu.2022.924099

Tumor infiltration by T cells profoundly affects cancer progression and responses to immunotherapy. However, the tumor immunosuppressive microenvironment can impair the induction, trafficking, and local activity of antitumor T cells. Here, we investigated whether intratumoral injection of virus-derived peptide epitopes could activate preexisting antiviral T cell responses locally and promote antitumor responses or antigen spreading. We focused on a mouse model of cytomegalovirus (CMV), a highly prevalent human infection that induces vigorous and durable T cell responses. Mice persistently infected with murine CMV (MCMV) were challenged with lung (TC-1), colon (MC-38), or melanoma (B16-F10) tumor cells. Intratumoral injection of MCMV-derived T cell epitopes triggered in situ and systemic expansion of their cognate, MCMV-specific CD4+ or CD8+ T cells. The MCMV CD8+ T cell epitopes injected alone provoked arrest of tumor growth and some durable remissions. Intratumoral injection of MCMV CD4+ T cell epitopes with polyinosinic acid:polycytidylic acid (pI:C) preferentially elicited tumor antigen-specific CD8+ T cells, promoted tumor clearance, and conferred long-term protection against tumor rechallenge. Notably, secondary proliferation of MCMV-specific CD8+ T cells correlated with better tumor control. Importantly, intratumoral injection of MCMV-derived CD8+ T cell-peptide epitopes alone or CD4+ T cell-peptide epitopes with pI:C induced potent adaptive and innate immune activation of the tumor microenvironment. Thus, CMV-derived peptide epitopes, delivered intratumorally, act as cytotoxic and immunotherapeutic agents to promote immediate tumor control and long-term antitumor immunity that could be used as a stand-alone therapy. The tumor antigen-agnostic nature of this approach makes it applicable across a broad range of solid tumors regardless of their origin.

The HPV vaccine has shown sustained efficacy and consistent stabilization of antibody levels, even after a single dose. We defined the HPV16-VLP antibody avidity patterns over 11 years among women who received one- or three doses of the bivalent HPV vaccine in the Costa Rica HPV Vaccine Trial. Absolute HPV16 avidity was lower in women who received one compared to three doses, although the patterns were similar (increased in years 2 and 3 and remained stable over the remaining 8 years). HPV16 avidity among women who were HPV16-seropositive women at HPV vaccination, a marker of natural immune response to HPV16 infection, was significantly lower than those of HPV16-seronegative women, a difference that was more pronounced among one-dose recipients. No differences in HPV16 avidity were observed by HPV18 serostatus at vaccination, confirming the specificity of the findings. Importantly, point estimates for vaccine efficacy against incident, six-month persistent HPV16 infections was similar between women who were HPV16 seronegative and seropositive at the time of initial HPV vaccination for both one-dose and three-dose participants. It is therefore likely that this lower avidity level is still sufficient to enable antibody-mediated protection. It is encouraging for long-term HPV-vaccine protection that HPV16 antibody avidity was maintained for over a decade, even after a single dose.

Abstract The availability of high throughput DNA sequencing provides an opportunity to generate a potent immune stimulation against unique antigens expressed by tumors. Although such approaches have led to increased immune responses in certain individuals, it is often limited to a small patient population and is associated with high development and implementation costs. Therefore, there is an unmet need for an immunotherapy that is easy to manufacture at affordable cost and applicable across many different tumor types. Here, we propose a unique approach to leverage pre-existing anti-Human Cytomegalovirus (CMV) immunity using a defined cocktail of viral epitopes, to both directly kill the tumor cells and induce a secondary T cell response to tumor neoantigens. We chose to recruit CMV immunity because CMV infection is highly prevalent, reaching approximately 90% of the population by the age of 80 years, and because of the naturally-occurring inflation of anti-CMV T cell responses with age leads to high levels CMV-specific T cells. Consequently, in elderly individuals, CMV-specific T cells recognizing a limited number of viral epitopes constitute approximately 10% of all systemic CD4 and CD8 T cells, a level rarely achieved by conventional vaccination. Additionally, in contrast to other chronic viral infections, CMV-specific T cells remain highly functional. In our experimental model, mice persistently infected with Murine Cytomegalovirus (mCMV) were subcutaneously challenged with TC-1 tumor cells (expressing human papillomavirus E6 and E7 oncogenes) or colon adenocarcinoma MC38 tumor cells, followed by intratumoral injections of mCMV peptide antigens together with a Toll-like receptor 3 (TLR3) agonist poly(I:C). Intratumoral injection of mCMV MHC-I or MHC-II restricted epitopes alone led to local and systemic recall of mCMV-specific T cells, and a potent local immune activation resulting in complete rejection of TC-1 and MC38 tumors in a subset of animals. Coinjection of both MHC-I and MHC-II peptides resulted in complete tumor clearance is most animals. Clearance was associated with antigen spreading, as evidenced by protection from secondary tumor challenge and ex vivo IFN-gamma ELISPOT responses to tumor-specific epitopes. Our preclinical studies provide a proof of concept of a first-in-class tumor antigen-agnostic immunotherapy based on recruitment of pre-existing antiviral T cells. The approach induced rapid tumor regression, profound changes in the tumor immune environment, epitope spreading, and resulted in long-term tumor protection. We are currently investigating the contribution of other cell types including NK cells and B cells to the anti-tumor effect of our approach. Citation Format: Nicolas Cuburu, Lukas Bialkowski, Sergio M. Pontejo, Alexander Bell, Rina Kim, Cynthia D. Thompson, Douglas R. Lowy, John T. Schiller. Harnessing pre-existing viral immunity for development of a broadly applicable tumor immunotherapy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5563.

Recent insight into the mechanisms of induction of tissue-resident memory (TRM) CD8+ T cells (CD8+ TRM) enables the development of novel vaccine strategies against sexually transmitted infections. To maximize both systemic and genital intraepithelial CD8+ T cells against vaccine Ags, we assessed combinations of i.m. and intravaginal routes in heterologous prime-boost immunization regimens with unrelated viral vectors. Only i.m. prime followed by intravaginal boost induced concomitant strong systemic and intraepithelial genital-resident CD8+ T cell responses. Intravaginal boost with vectors expressing vaccine Ags was far superior to intravaginal instillation of CXCR3 chemokine receptor ligands or TLR 3, 7, and 9 agonists to recruit and increase the pool of cervicovaginal CD8+ TRM Transient Ag presentation increased trafficking of cognate and bystander circulating activated, but not naive, CD8+ T cells into the genital tract and induced in situ proliferation and differentiation of cognate CD8+ TRM Secondary genital CD8+ TRM were induced in the absence of CD4+ T cell help and shared a similar TCR repertoire with systemic CD8+ T cells. This prime-pull-amplify approach elicited systemic and genital CD8+ T cell responses against high-risk human papillomavirus type 16 E7 oncoprotein and conferred CD8-mediated protection to a vaccinia virus genital challenge. These results underscore the importance of the delivery route of nonreplicating vectors in prime-boost immunization to shape the tissue distribution of CD8+ T cell responses. In this context, the importance of local Ag presentation to elicit genital CD8+ TRM provides a rationale to develop novel vaccines against sexually transmitted infections and to treat human papillomavirus neoplasia.

Protein-based drugs are very active in treating cancer, but their efficacy can be limited by the formation of neutralizing antidrug antibodies (ADAs). Recombinant immunotoxins are proteins that are very effective in patients with leukemia, where immunity is suppressed, but induce ADAs, which compromise their activity, in patients with intact immunity. Here we induced a specific, durable, and transferable immune tolerance to recombinant immunotoxins by combining them with nanoparticles containing rapamycin (SVP-R). SVP-R mitigated the formation of inhibitory ADAs in naïve and sensitized mice, resulting in restoration of antitumor activity. The immune tolerance is mediated by colocalization of the SVP-R and immunotoxin to dendritic cells and macrophages in the spleen and is abrogated by depletion of regulatory T cells. Tolerance induced by SVPs was not blocked by checkpoint inhibitors or costimulatory agonist monoclonal antibodies that by themselves enhance ADA formation.

Recombinant immunotoxins (RITs) are chimeric proteins being developed for cancer treatment. They are composed of an Ab fragment that targets a cancer Ag and a cytotoxic portion of Pseudomonas exotoxin A. They are effective for patients with hematologic malignancies with defective immunity, but their efficacy against solid tumors is limited by anti-drug Ab (ADA) responses in immune-competent patients. Pre-existing Abs or immune memory owing to previous toxin exposure represent additional hurdles because they induce rapid and strong ADA responses. Here, we evaluated the efficacy of methotrexate (MTX) to prevent ADA formation against the mesothelin-targeting RIT LMB-100 in naive mice and in mice with pre-existing Abs. We found that low-dose MTX combined with LMB-100 completely suppressed the formation of ADAs in a dose- and frequency-dependent manner. Suppression of the immune response restored blood levels of LMB-100 and prevented its neutralization. Furthermore, combination of MTX with LMB-100 did not compromise the immune response against a second Ag given after stopping MTX, indicating specific immune tolerance. Adoptive transfer of splenocytes suppressed Ab responses to LMB-100 in recipient mice, indicating a durable immune tolerance. We conclude that combination of MTX and LMB-100 is effective at preventing immune responses in a durable, Ag-specific manner. We propose combining low-dose MTX in immune-competent cancer patients receiving RIT therapy to prevent immunogenicity. This approach could be applied to other immunogenic therapeutic agents and to proteins for which there is pre-existing immunity.

Recent advances in immunotherapy against cancer underscore the importance of T lymphocytes and tumor microenvironment, but few vaccines targeting cancer have been approved likely due in part to the dearth of common tumor antigens, insufficient immunogenicity and the evolution of immune evasion mechanisms during the progression to malignancy. Human papillomaviruses (HPVs) are the primary etiologic agents of cervical cancer and progression from persistent HPV-infection to cervical intraepithelial lesions and eventually cancer requires persistent expression of the oncoproteins E6 and E7. This offers the opportunity to specifically target these virus-specific antigens for vaccine-induced clearance of infected cells before cancers develop. Here we have evaluated the immunogenicity of Adenovirus Types 26 and 35 derived vectors expressing a fusion of HPV16 E6 and E7 oncoproteins after intramuscular (IM) and/or intravaginal (Ivag) immunization in mice. The adenovirus vectors were shown to transduce an intact cervicovaginal epithelium. IM prime followed by Ivag boost maximized the induction and trafficking of HPV-specific CD8+ T cells producing IFN-γ and TNF-α to the cervicovaginal tract. Importantly, the cervicovaginal CD8+ T cells expressed CD69 and CD103; hallmarks of intraepithelial tissue-resident memory CD8+ T cells. This prime-boost strategy targeting heterologous locations also induced circulating HPV-specific CD8+ T cell responses. Our study prompts further evaluation of Ivag immunization with adenoviral vectors expressing modified E6 and E7 antigens for therapeutic vaccination against persistent HPV infection and cervical intraepithelial neoplasia.