Identification of epidermal growth factor receptor-derived peptides recognised by both cellular and humoral immune responses in HLA-A24+ non-small cell lung cancer patients

Potential association factors for developing effective peptide-based cancer vaccines

Peptide-based cancer vaccines have been shown to boost immune systems to kill tumor cells in cancer patients. However, designing an effective T cell epitope peptide-based cancer vaccine still remains a challenge and is a major hurdle for the application of cancer vaccines. In this study, we constructed for the first time a library of peptide-based cancer vaccines and their clinical attributes, named CancerVaccine (https://peptidecancervaccine.weebly.com/). To investigate the association factors that influence the effectiveness of cancer vaccines, these peptide-based cancer vaccines were classified into high (HCR) and low (LCR) clinical responses based on their clinical efficacy. Our study highlights that modified peptides derived from artificially modified proteins are suitable as cancer vaccines, especially for melanoma. It may be possible to advance cancer vaccines by screening for HLA class II affinity peptides may be an effective therapeutic strategy. In addition, the treatment regimen has the potential to influence the clinical response of a cancer vaccine, and Montanide ISA-51 might be an effective adjuvant. Finally, we constructed a high sensitivity and specificity machine learning model to assist in designing peptide-based cancer vaccines capable of providing high clinical responses. Together, our findings illustrate that a high clinical response following peptide-based cancer vaccination is correlated with the right type of peptide, the appropriate adjuvant, and a matched HLA allele, as well as an appropriate treatment regimen. This study would allow for enhanced development of cancer vaccines.

First-in-human study of the cancer peptide vaccine TAS0313 in patients with advanced solid tumors

TAS0313, a novel cancer vaccine cocktail, was developed to overcome the disadvantages of previously developed short and long peptide vaccines; it comprises several long peptides targeting multiple cancer antigens. We evaluated TAS0313 monotherapy in Japanese patients with advanced solid tumors for which no other therapies were available. In the dose‐finding cohort, patients received TAS0313 (9 or 27 mg) on days 1, 8, and 15 of cycles 1 and 2, and then on day 1 of each subsequent 21‐day cycle. The primary objective was the evaluation of safety and tolerability. Secondary objectives were evaluation of efficacy, tumor responses, and immune activation (CTL, IgG, and tumor‐infiltrating lymphocyte [TIL] levels). The full analysis set contained 10 patients in the 9‐mg group and seven in the 27‐mg group. No dose‐limiting toxicities were reported in cycle 1. All adverse drug reactions (ADRs) were grade 1 or 2; the most common ADRs were injection site‐related events. The best response was stable disease in four of 17 patients. The median progression‐free survival (PFS) duration was 2.2 (95% confidence interval, 1.0‐2.3) months overall; patients with baseline low lymphocyte counts (≤750/μL) had shorter PFS. Compared with baseline, TILs were increased in five patients. Although CTLs, IgG, and TILs were induced, no correlative pattern with clinical outcomes was observed. The safety, tolerability, and induction of immune responses in patients with advanced solid tumors receiving TAS0313 were confirmed. Further evaluation of TAS0313’s efficacy as monotherapy or in combination with pembrolizumab is underway. The study is registered at www.clinicaltrials.jp (JapicCTI‐183824).

TAS0314, a novel multi-epitope long peptide vaccine, showed synergistic antitumor immunity with PD-1/PD-L1 blockade in HLA-A*2402 mice

Cancer peptide vaccines are a promising cancer immunotherapy that can induce cancer-specific cytotoxic T lymphocytes (CTLs) in tumors. However, recent clinical trials of cancer vaccines have revealed that the efficacy of the vaccines is limited. Targeting single antigens and vaccination with short peptides are partly the cause of the poor clinical outcomes. We synthesized a novel multi-epitope long peptide, TAS0314, which induced multiple epitope-specific CTLs in HLA knock-in mice. It also showed superior epitope-specific CTL induction and antitumor activity. We also established a combination treatment model of vaccination with PD-1/PD-L1 blockade in HLA-A*2402 knock-in mice, and it showed a synergistic antitumor effect with TAS0314. Thus, our data indicated that TAS0314 treatment, especially in combination with PD-1/PD-L1 blockade, is a promising therapeutic candidate for cancer immunotherapy.

Immune Responses to Epidermal Growth Factor Receptor (EGFR) and Their Application for Cancer Treatment

Epidermal growth factor receptor (EGFR) is a prototypic cell-surface receptor belonging to the ErbB/HER onocogene family. Overexpression or somatic mutations of EGFR have been reported to play an important role in tumorigenesis in various types of epithelial cancers. Therefore, targeting of EGFR with specific blocking antibodies or inhibitors have been developing for treatment for EGFR-associated tumors. Immune responses to HER2, another molecule of the ErbB/HER onocogene family, have been well studied, but only limited information on the immune responses to EGFR in cancer has been currently available. In this review, we have summarized the available data and discussed potential clinical importance of the anti-EGFR immune responses and EGFR-mediated immune regulation in cancer. Several lines of evidence suggest that cellular and humoral immune responses to EGFR might be useful as a marker and/or target for cancer therapy against EGFR-associated tumors. In addition, recent studies suggest the critical roles of EGFR-mediated signaling in regulation of expression of an immune checkpoint molecule, programmed death-ligand 1 (PD-L1) in tumor cells. Further studies are warranted to clarify the impact of the anti-EGFR immune responses and EGFR-mediated immunomodulation for clinical application for cancer treatment.

A peptide antigen derived from EGFR T790M is immunogenic in non‑small cell lung cancer

Lung cancer is the leading cause of cancer-related deaths worldwide. Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs), such as gefitinib and erlotinib, have demonstrated marked clinical activity against non-small cell lung cancer (NSCLC) harboring activating epidermal growth factor receptor (EGFR) mutations. However, in most cases, patients develop acquired resistance to EGFR-TKI therapy. The threonine to methionine change at codon 790 of EGFR (EGFR T790M) mutation is the most common acquired resistance mutation, and is present in ~50% cases of TKI resistance. New treatment strategies for NSCLC patients harboring the EGFR T790M mutation are required. We evaluated the immunogenicity of an antigen derived from EGFR with the T790M mutation. Using BIMAS we selected several EGFR T790M-derived peptides bound to human leukocyte antigen (HLA)-A^*02:01. T790M-A peptide (789–797) (IMQLMPFGC)-specific cytotoxic T lymphocytes (CTLs) were induced from peripheral blood mononuclear cells (PBMCs) of HLA-A2⁺ healthy donors. An established T790M-A-specific CTL line showed reactivity against the NCSLC cell line, H1975-A2 (HLA-A2⁺, T790M⁺), but not H1975 (HLA-A2⁻, T790M⁺), and the corresponding wild-type peptide (ITQLMPFGC)-pulsed T2 cells using an interferon-γ (IFN-γ) enzyme-linked immuno spot (ELISPOT) assay. This CTL line also demonstrated peptide-specific cytotoxicity against H1975-A2 cells. This finding suggests that the EGFR T790M mutation-derived antigen could be a new target for cancer immunotherapy.

Humoral immune responses to CTL epitope peptides from tumor-associated antigens are widely detectable in humans: a new biomarker for overall survival of patients with malignant diseases

Both cellular and humoral immune responses are crucial to induce potent anti-tumor immunity, but most of currently conducted peptide-based cancer vaccines paid attention to cellular responses alone, and none of them are yet approved as a therapeutic modality against cancer patients. We investigated humoral immune responses to CTL epitope peptides derived from tumor-associated antigens in healthy donors and patients with various diseases to facilitate better understanding of their distribution patterns and potential roles. Bead-based multiplex assay, ELISA, and Western blotting were used to measure immunoglobulins reactive to each of 31 different CTL epitope peptides. Importantly, the sums of anti-peptide IgG levels specific to 31 CTL epitope peptides were well correlated with better overall survival (OS) in patients with malignant diseases. Our results suggested that humoral immune responses to CTL epitope peptides were widely detectable in humans. Measurement of immunoglobulins specific to CTL epitope peptides may provide a new biomarker for OS of patients with malignant diseases, although it still remains to be determined whether the correlations between humoral immune responses to epitope peptides and OS are observed only for the CTL epitopes used, or also for other panels of peptides. Quantity of circulating IgG reactive to these peptides was also discussed.

Personalized peptide vaccination: a new approach for advanced cancer as therapeutic cancer vaccine

Since both tumor cells and host immune cell repertoires are diverse and heterogeneous, immune responses against tumor-associated antigens should differ substantially among individual cancer patients. Selection of suitable peptide vaccines for individual patients based on the preexisting host immunity before vaccination could induce potent anti-tumor responses that provide clinical benefit to cancer patients. We have developed a novel immunotherapeutic approach of personalized peptide vaccination (PPV) in which a maximum of four human leukocyte antigen (HLA) class IA-matched peptides are selected for vaccination among pooled peptides on the basis of both HLA class IA type and the preexisting host immunity before vaccination. In this review, we discuss our recent results of preclinical and clinical studies of PPV for various types of advanced cancer.

Tumor-associated antigens for specific immunotherapy of prostate cancer

Prostate cancer (PCa) is the most common noncutaneous cancer diagnosis and the second leading cause of cancer-related deaths among men in the United States. Effective treatment modalities for advanced metastatic PCa are limited. Immunotherapeutic strategies based on T cells and antibodies represent interesting approaches to prevent progression from localized to advanced PCa and to improve survival outcomes for patients with advanced disease. CD8⁺ cytotoxic T lymphocytes (CTLs) efficiently recognize and destroy tumor cells. CD4⁺ T cells augment the antigen-presenting capacity of dendritic cells and promote the expansion of tumor-reactive CTLs. Antibodies mediate their antitumor effects via antibody-dependent cellular cytotoxicity, activation of the complement system, improving the uptake of coated tumor cells by phagocytes, and the functional interference of biological pathways essential for tumor growth. Consequently, several tumor-associated antigens (TAAs) have been identified that represent promising targets for T cell- or antibody-based immunotherapy. These TAAs comprise proteins preferentially expressed in normal and malignant prostate tissues and molecules which are not predominantly restricted to the prostate, but are overexpressed in various tumor entities including PCa. Clinical trials provide evidence that specific immunotherapeutic strategies using such TAAs represent safe and feasible concepts for the induction of immunological and clinical responses in PCa patients. However, further improvement of the current approaches is required which may be achieved by combining T cell- and/or antibody-based strategies with radio-, hormone-, chemo- or antiangiogenic therapy.

Phase I trial of a personalized peptide vaccine for patients positive for human leukocyte antigen--A24 with recurrent or progressive glioblastoma multiforme

PURPOSE

Personalized selection of suitable peptides for patients could offer a novel approach to developing cancer vaccines that boost anticancer immunity. We present the results of a phase I trial of 14 kinds of vaccine candidates (ITK-1) in patients with recurrent or progressive glioblastoma multiforme (GBM).

PATIENTS AND METHODS

From January 2006 to January 2008, 12 patients from eight Japanese hospitals who were positive for human leukocyte antigen-A24, including 10 patients refractory to temozolomide (TMZ), were enrolled. The dose escalation trial included three dose groups (1, 3, and 5 mg) to determine the safety and tolerability of ITK-1 peptides. Immunologic response was monitored by measuring levels of cytotoxic T-lymphocyte precursors and peptide-specific immunoglobulin G. In another ITK-1 phase I trial for advanced prostate cancer, the vaccination schedule was skipped or discontinued in all three patients receiving the highest dose (5 mg/peptide) because of injection site reactions. This trial was therefore ended without enrollment for the highest dose, and data were analyzed by intention to treat.

RESULTS

No serious adverse drug reactions were encountered, and treatment was well tolerated. The vaccine induced dose-dependent immune boosting. The recommended dose of ITK-1 peptides is 3 mg/peptide.

CONCLUSION

Personalized vaccination with ITK-1 peptides could be recommended in further stages of clinical trials. The safety and increased frequency of immune boosting offers potential clinical benefits in cases of recurrent or progressive GBM, even in TMZ-refractory settings.

The functioning antigens: beyond just as the immunological targets

Antigenic peptides derived from tumor-associated antigens (TAAs) facilitate peptide cancer vaccine therapies. With the recent progress in cancer immunity research, huge amounts of antigenic peptides have already been reported. Clinical trials using such peptides are underway now all over the world. Some reports have shown the efficacy of peptide vaccine therapies. However, others ended with unfavorable results, suggesting fundamental underlying problems. One major mechanism that negates the peptide vaccine therapy is tumor escape from immunological systems caused by loss of antigens. TAAs that are used in cancer vaccine therapies may be divided into two major groups: functioning antigens and nonfunctioning antigens. A 'functioning antigen' could be defined as a TAA that is essential for tumor growth, is expressed in several kinds of malignancies and shows homogenous expression in cancerous tissues. It is not difficult to imagine that antigen loss will occur easily with non-functioning antigens as a target of cancer vaccine therapy. Thus, it is essential to use functioning antigens for successful cancer vaccine therapy. In this review, we discuss the functioning antigens and their categorization in detail.

Identification of HLA-CW3, GNAS and IMPA as cytotoxic T-lymphocyte (CTL) target antigens using an allogeneic mixed lymphocyte tumor cell culture (MLTC) system and subsequent cDNA library screening

Allogeneic mixed lymphocyte tumor cell cultures (MLTCs) were established using lymphocytes from non-small-cell lung cancer (NSCLC) patient UKY-53 and HLA-A2+ NSCLC tumor cells (UKY-29). The tumor cells expressed the lymphocyte costimulatory molecule CD80 (UKY29.7). Cytolytic activity showed the cytotoxic T-lymphocytes (CTL) lysed UKY-29, but not K562 or Daudi. The CTL also lysed: HLA-A2+ and -A24+ tumor cell lines from a number of tumor histologies. The CTL also lysed Epstein Barr virus transformed (EBV) B-cells, UKY-29EBV, autologous to the stimulating cell line, UKY29TC. These data suggested the presence of both tumor-specific and allogeneic reactivities in the bulk CTL population. Subsequent cDNA cloning analysis and sequencing demonstrated that the bulk CTL population was recognizing: (i) allogeneic target HLA-CW3, and two minor histocompatibility antigens; (ii) guanine nucleotide-binding protein, G(S) (GNAS), and (iii) inositol myophosphatase (IMPA). All three antigens, we believe, were restricted by HLA-A2. Whereas the system described was initially intended to identify tumor-associated antigens recognized by CTL, the nature of the allogeneic system provides a unique opportunity for the identification of epitopes that confer both allo and minor antigen recognition.

Autologous neu DNA vaccine can be as effective as xenogenic neu DNA vaccine by altering administration route

We examined the therapeutic efficacy of xenogenic human N'-terminal neu DNA vaccine and autologous mouse N'-terminal neu DNA vaccine on MBT-2 tumor cells in C3H mice. Intramuscular injection of xenogenic and autologous neu DNA vaccines produced comparable therapeutic efficacies. Mouse and human N'-neu DNA vaccine induced tumor infiltration of CD8(+) T cells, while the human vaccine was less effective at stimulating natural killer cells. Depletion of CD8(+) T cells abolished the therapeutic efficacy of both types of DNA vaccines. On the other hand, xenogenic neu DNA vaccine showed significantly better therapeutic efficacy than autologous DNA vaccine with gene gun immunization. Increased infiltration of CD8(+) T cells was correlated with enhanced therapeutic efficacy in the human N'-neu group of mice. Therefore, intramuscular injection can enhance the therapeutic efficacy of autologous neu DNA vaccine.

Vaccination therapy in malignant disease

Improvement in survival among patients with early malignancy is well established in various cancers. However, long-term survival in those with advanced malignancy has changed little and this poses a major therapeutic challenge to clinicians. Anti-cancer immunotherapy is a novel approach, which is still experimental, but offers a new therapeutic strategy. In this review, we discuss the basic immunological interplay between the host immune system and the tumour, mechanisms of anti-tumour immune responses induced by immunotherapy and key in vivo pilot studies of active specific immunotherapy in various sold cancers, carried out during the last five years.

Immunologic Evaluation of Personalized Peptide Vaccination for Patients with Advanced Malignant Glioma

PURPOSE

The primary goal of this phase I study was to assess the safety and immunologic responses of personalized peptide vaccination for patients with advanced malignant glioma.

EXPERIMENTAL DESIGN

Twenty-five patients with advanced malignant glioma (8 grade 3 and 17 grade 4 gliomas) were evaluated in a phase I clinical study of a personalized peptide vaccination. For personalized peptide vaccination, prevaccination peripheral blood mononuclear cells and plasma were provided to examine cellular and humoral responses to 25 or 23 peptides in HLA-A24+ or HLA-A2+ patients, respectively; then, only the reactive peptides (maximum of four) were used for in vivo administration.

RESULTS

The protocols were well tolerated with local redness and swelling at the injection site in most cases. Twenty-one patients received more than six vaccinations and were evaluated for both immunologic and clinical responses. Increases in cellular or humoral responses specific to at least one of the vaccinated peptides were observed in the postvaccination (sixth) samples from 14 or 11 of 21 patients, respectively. More importantly, significant levels of peptide-specific IgG were detected in the postvaccination tumor cavity or spinal fluid of all of the tested patients who showed favorable clinical responses. Clinical responses were 5 partial responses, 8 cases of stable disease, and 8 cases of progressive disease. The median overall survival for patients with recurrent glioblastoma multiforme in this study (n = 17) was 622 days.

CONCLUSIONS

Personalized peptide vaccinations were recommended for the further clinical study to malignant glioma patients.