Identification of a broad coverage HLA-DR degenerate epitope pool derived from carcinoembryonic antigen

Comparison of replicating and nonreplicating vaccines against SARS-CoV-2

Most gene-based severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines are nonreplicating vectors. They deliver the gene or messenger RNA to the cell to express the spike protein but do not replicate to amplify antigen production. This study tested the utility of replication in a vaccine by comparing replication-defective adenovirus (RD-Ad) and replicating single-cycle adenovirus (SC-Ad) vaccines that express the SARS-CoV-2 spike protein. SC-Ad produced 100 times more spike protein than RD-Ad and generated significantly higher antibodies against the spike protein than RD-Ad after single immunization of Ad-permissive hamsters. SC-Ad-generated antibodies climbed over 14 weeks after single immunization and persisted for more than 10 months. When the hamsters were challenged 10.5 months after single immunization, a single intranasal or intramuscular immunization with SC-Ad-Spike reduced SARS-CoV-2 viral loads and damage in the lungs and preserved body weight better than vaccination with RD-Ad-Spike. This demonstrates the utility of harnessing replication in vaccines to amplify protection against infectious diseases.

Identification of HLA-A2 restricted epitopes of glypican-3 and induction of CTL responses in HLA-A2 transgenic mice

Hepatocellular carcinoma (HCC) is a malignant tumor with high mortality, but lacks effective treatments. Carcinoembryonic antigen glypican-3 (GPC3) is a tumor-associated antigen overexpressed in HCC but rarely expressed in healthy individuals and thus is one of the most promising therapeutic targets. T cell epitope-based vaccines may bring light to HCC patients, especially to the patients at a late stage. However, few epitopes from GPC3 were identified to date, which limited the application of GPC3-derived epitopes in immunotherapy and T cell function detection. In this study, a total of 25 HLA-A0201 restricted GPC3 epitopes were in silico predicted and selected as candidate epitopes. Then, HLA-A0201⁺/GPC3⁺ HCC patients' PBMCs were collected and co-stimulated with the candidate epitope peptides in ex vivo IFN-γ Elispot assay, by which five epitopes were identified as real-world epitopes. Their capacity to elicit specific CD8⁺ T cells activation and proliferation was further confirmed by in vitro co-cultures of patients' PBMCs with peptide, in vitro co-cultures of healthy donors' PBLs with DCs and peptide, T2 cell binding assay as well as HLA-A2 molecule stability assay. Moreover, the in vivo immunogenicity of the five validated epitopes was confirmed by peptides cocktail/poly(I:C) vaccination in HLA-A0201/DR1 transgenic mice. Robust epitope-specific CD8⁺ T cell responses and cytotoxicity targeting HepG2 cells were observed as detected by IFN-γ Elispot, intracellular IFN-γ staining and cytolysis assay. This study provided novel GPC3 CTL epitopes for the development of T cell epitope vaccines and evaluation of GPC3 specific T cell responses.

Th17-inducing autologous dendritic cell vaccination promotes antigen-specific cellular and humoral immunity in ovarian cancer patients

In ovarian cancer (OC), IL-17-producing T cells (Th17s) predict improved survival, whereas regulatory T cells predict poorer survival. We previously developed a vaccine whereby patient-derived dendritic cells (DCs) are programmed to induce Th17 responses to the OC antigen folate receptor alpha (FRα). Here we report the results of a single-arm open-label phase I clinical trial designed to determine vaccine safety and tolerability (primary outcomes) and recurrence-free survival (secondary outcome). Immunogenicity is also evaluated. Recruitment is complete with a total of 19 Stage IIIC-IV OC patients in first remission after conventional therapy. DCs are generated using our Th17-inducing protocol and are pulsed with HLA class II epitopes from FRα. Mature antigen-loaded DCs are injected intradermally. All patients have completed study-related interventions. No grade 3 or higher adverse events are seen. Vaccination results in the development of Th1, Th17, and antibody responses to FRα in the majority of patients. Th1 and antibody responses are associated with prolonged recurrence-free survival. Antibody-dependent cell-mediated cytotoxic activity against FRα is also associated with prolonged RFS. Of 18 patients evaluable for efficacy, 39% (7/18) remain recurrence-free at the time of data censoring, with a median follow-up of 49.2 months. Thus, vaccination with Th17-inducing FRα-loaded DCs is safe, induces antigen-specific immunity, and is associated with prolonged remission.

Rapid Generation of Sustainable HER2-specific T-cell Immunity in Patients with HER2 Breast Cancer using a Degenerate HLA Class II Epitope Vaccine

PURPOSE

Patients with HER2⁺ breast cancer benefit from trastuzumab-containing regimens with improved survival. Adaptive immunity, including cytotoxic T-cell and antibody immunity, is critical to clinical efficacy of trastuzumab. Because Th cells are central to the activation of these antitumor effectors, we reason that HER2 patients treated with trastuzumab may benefit by administering vaccines that are designed to stimulate Th-cell immunity.

PATIENTS AND METHODS

We developed a degenerate HER2 epitope-based vaccine consisting of four HLA class II-restricted epitopes mixed with GM-CSF that should immunize most (≥84%) patients. The vaccine was tested in a phase I trial. Eligible women had resectable HER2⁺ breast cancer and had completed standard treatment prior to enrollment and were disease free. Patients were vaccinated monthly for six doses and monitored for safety and immunogenicity.

RESULTS

Twenty-two subjects were enrolled and 20 completed all six vaccines. The vaccine was well tolerated. All patients were alive at analysis with a median follow-up of 2.3 years and only two experienced disease recurrence. The percent of patients that responded with augmented T-cell immunity was high for each peptide ranging from 68% to 88%, which led to 90% of the patients generating T cells that recognized naturally processed HER2 antigen. The vaccine also augmented HER2-specific antibody. Immunity was sustained in patients with little sign of diminishing at 2 years following the vaccination.

CONCLUSIONS

Degenerate HLA-DR-based HER2 vaccines induce sustainable HER2-specific T cells and antibodies. Future studies, could evaluate whether vaccination during adjuvant treatment with trastuzumab-containing regimens improves patient outcomes.

High-throughput Screening of Human Tumor Antigen-specific CD4 T Cells, Including Neoantigen-reactive T Cells

PURPOSE

Characterization of tumor antigen-specific CD4 T-cell responses in healthy donors and malignant melanoma patients using an in vitro amplified T-cell library screening procedure.

PATIENTS AND METHODS

A high-throughput, human leukocyte antigen (HLA)-independent approach was used to estimate at unprecedented high sensitivity level precursor frequencies of tumor antigen- and neoantigen-specific CD4 T cells in healthy donors and patients with cancer. Frequency estimation was combined with isolation and functional characterization of identified tumor-reactive CD4 T-cell clones.

RESULTS

In healthy donors, we report frequencies of naïve tumor-associated antigen (TAA)-specific CD4 T cells comparable with those of CD4 T cells specific for infectious agents (Tetanus toxoid). Interestingly, we also identified low, but consistent numbers of memory CD4 T cells specific for several TAAs. In patients with melanoma, low frequencies of circulating TAA-specific CD4 T cells were detected that increased after peptide-based immunotherapy. Such antitumor TAA-specific CD4 T-cell responses were also detectable within the tumor-infiltrated tissues. TAA-specific CD4 T cells in patients displayed a highly polyfunctional state, with partial skewing to Type-2 polarization. Finally, we report the applicability of this approach to the detection and amplification of neoantigen-specific CD4 T cells.

CONCLUSIONS

This simple, noninvasive, high-throughput screening of tumor- and neoantigen-specific CD4 T cells requires little biologic material, is HLA class II independent and allows the concomitant screening for a large number of tumor antigens of interest, including neoantigens. This approach will facilitate the immunomonitoring of preexisting and therapy-induced CD4 T-cell responses, and accelerate the development of CD4 T-cell-based therapies.

Folate Receptor Alpha Peptide Vaccine Generates Immunity in Breast and Ovarian Cancer Patients

Purpose: Folate receptor alpha (FR) is overexpressed in several cancers. Endogenous immunity to the FR has been demonstrated in patients and suggests the feasibility of targeting FR with vaccine or other immune therapies. CD4 helper T cells are central to the development of coordinated immunity, and prior work shows their importance in protecting against relapse. Our previous identification of degenerate HLA-class II epitopes from human FR led to the development of a broad coverage epitope pool potentially useful in augmenting antigen-specific immune responses in most patients.Patients and Methods: We conducted a phase I clinical trial testing safety and immunogenicity of this vaccine, enrolling patients with ovarian cancer or breast cancer who completed conventional treatment and who showed no evidence of disease. Patients were initially treated with low-dose cyclophosphamide and then vaccinated 6 times, monthly. Immunity and safety were examined during the vaccine period and up to 1 year later.Results: Vaccination was well tolerated in all patients. Vaccine elicited or augmented immunity in more than 90% of patients examined. Unlike recall immunity to tetanus toxoid (TT), FR T-cell responses developed slowly over the course of vaccination with a median time to maximal immunity in 5 months. Despite slow development of immunity, responsiveness appeared to persist for at least 12 months.Conclusions: The results demonstrate that it is safe to augment immunity to the FR tumor antigen, and the developed vaccine is testable for therapeutic activity in most patients whose tumors express FR, regardless of HLA genotype. Clin Cancer Res; 24(13); 3014-25. ©2018 AACR.

Folate Receptor Alpha Peptide Vaccine Generates Immunity in Breast and Ovarian Cancer Patients

Purpose: Folate receptor alpha (FR) is overexpressed in several cancers. Endogenous immunity to the FR has been demonstrated in patients and suggests the feasibility of targeting FR with vaccine or other immune therapies. CD4 helper T cells are central to the development of coordinated immunity, and prior work shows their importance in protecting against relapse. Our previous identification of degenerate HLA-class II epitopes from human FR led to the development of a broad coverage epitope pool potentially useful in augmenting antigen-specific immune responses in most patients.Patients and Methods: We conducted a phase I clinical trial testing safety and immunogenicity of this vaccine, enrolling patients with ovarian cancer or breast cancer who completed conventional treatment and who showed no evidence of disease. Patients were initially treated with low-dose cyclophosphamide and then vaccinated 6 times, monthly. Immunity and safety were examined during the vaccine period and up to 1 year later.Results: Vaccination was well tolerated in all patients. Vaccine elicited or augmented immunity in more than 90% of patients examined. Unlike recall immunity to tetanus toxoid (TT), FR T-cell responses developed slowly over the course of vaccination with a median time to maximal immunity in 5 months. Despite slow development of immunity, responsiveness appeared to persist for at least 12 months.Conclusions: The results demonstrate that it is safe to augment immunity to the FR tumor antigen, and the developed vaccine is testable for therapeutic activity in most patients whose tumors express FR, regardless of HLA genotype. Clin Cancer Res; 24(13); 3014-25. ©2018 AACR.

Immunotherapy of breast cancer

INTRODUCTION

Immunotherapy of breast cancer has been shown to prevent recurrence, improve survival and eliminate breast cancer in humans.

AREAS COVERED

The reason for this review is to present the current information and the prospects for the future of immunotherapy of breast cancer in humans to include tumor antigens for vaccines and targets for monoclonal antibodies and adoptive T-cell therapy, and immune modulatory agents, such as adjuvants to stimulate the immune response and inhibitors of checkpoint blockade to prevent downmodulation of activated lymphocytes, to enhance these modalities. The research discussed and the literature search undertaken is of the clinical immunotherapy of breast cancer in humans, from 2000 to September, 2011.

EXPERT OPINION

The key message of the paper is that one reason for the failure of the immune system to control macroscopic disease is that the immune escape mechanisms involving both tumor and the tumor stroma prevent the immune system from destroying the tumor. Changing the tumor microenvironment is necessary to eliminate macroscopic tumors. Prospects for improvement are proposals for combining current modalities of therapy with type 1 cellular immunity-inducing agents, all targeting multiple tumor antigens and in the context of minimal disease.

Identification of prostatic acid phosphatase (PAP) specific HLA-DR1-restricted T-cell epitopes

BACKGROUND

Prostatic acid phosphatase (PAP) is a prostate cancer tumor antigen and is an immunological target in several active immunotherapy clinical trials for the treatment of prostate cancer. We and others have demonstrated that PAP-specific T-cell responses can be elicited and augmented following antigen-specific immunization in both humans and animal models. We have previously reported that prostate cancer patients immunized with a DNA vaccine encoding PAP (pTVG-HP) developed both CD4+ and CD8+ T-cell responses. PAP-specific, CD4+ T-cell proliferative responses were generated in three out of four HLA-DRB1*0101 patients suggesting the possibility that DR1-restricted epitopes exist.

METHODS

To identify PAP-specific HLA-DRB1*0101 restricted epitopes, we immunized HLA-A2.01/HLA-DRB1*0101 (A2/DR1) transgenic mice with the pTVG-HP DNA vaccine. To map DRB1*0101-restricted epitopes, splenocytes from immunized mice were screened against a library of overlapping 15-residue, PAP-derived peptides using an IFNγ ELISPOT assay.

RESULTS

We identified four HLA-DRB1*0101 epitopes for PAP in A2/DR1 mice (PAP(161-175) , PAP(181-195) , PAP(191-205) , and PAP (351-365) ). T cells specific for one epitope (PAP(181-195) ) were found to be augmented after immunization in a HLA-DRB1*0101+ prostate cancer patient.

CONCLUSIONS

The identification of MHC class II epitopes may provide tools to directly monitor immune responses after vaccination and may be important for the design of future prostate cancer vaccines.

A degenerate HLA-DR epitope pool of HER-2/neu reveals a novel in vivo immunodominant epitope, HER-2/neu88-102

PURPOSE

Over the past two decades, there has been significant interest in targeting HER-2/neu in immune-based approaches for the treatment of HER-2/neu+ cancers. For example, peptide vaccination using a CD8 T cell-activating HER-2/neu epitope (amino acids 369-377) is an approach that is being considered in advanced phase clinical trials. Studies have suggested that the persistence of HER-2/neu-specific CD8 T cells could be improved by incorporating human leukocyte antigen (HLA) class II epitopes in the vaccine. Our goal in this study was to identify broad coverage HLA-DR epitopes of HER-2/neu, an antigen that is highly expressed in a variety of carcinomas.

EXPERIMENTAL DESIGN

A combination of algorithms and HLA-DR-binding assays was used to identify HLA-DR epitopes of HER-2/neu antigen. Evidence of preexistent immunity in cancer patients against the identified epitopes was determined using IFN-gamma enzyme-linked immunosorbent spot (ELIspot) assay.

RESULTS

Eighty-four HLA-DR epitopes of HER-2/neu were predicted, 15 of which had high binding affinity for > or =11 common HLA-DR molecules. A degenerate pool of four HLA-DR-restricted 15-amino acid epitopes (p59, p88, p422, and p885) was identified, against which >58% of breast and ovarian cancer patients had preexistent T-cell immunity. All four epitopes are naturally processed by antigen-presenting cells. Hardy-Weinberg analysis showed that the pool is useful in approximately 84% of population. Lastly, in this degenerate pool, we identified a novel in vivo immunodominant HLA-DR epitope, HER-2/neu(88-102) (p88).

CONCLUSION

The broad coverage and natural immunity to this epitope pool suggests potential usefulness in HER-2/neu-targeting, immune-based therapies such as vaccines.