Immunological evaluation of personalized peptide vaccination in refractory small cell lung cancer

Vaccination and personalized cancer vaccines focusing on common cancers in women: A narrative review

Immunotherapy has recently cast great attention on cancer vaccines in order to aim to decrease tumor growth, elicit persistent anti-tumor memory, and avert adverse reactions. Moreover, cancer vaccines employ tumor antigens to stimulate anti-tumor immunity using different platforms, for example, whole cells, nucleic acids, peptides, etc. Recent findings have classified cancer vaccines into cell-based, virus-based, peptide-based, and nucleic acid-based types. Personalized cancer vaccines, also known as neoantigens, have exhibited acceptable safety and efficacy in eliciting immune responses against melanoma and glioblastoma. Neoantigen-based vaccines, concentrating on tumor antigens present only in cancer cells, bring intriguing opportunities for different types of cancer, including melanoma, lung, bladder, breast, renal, head and neck, and colorectal cancers. Furthermore, breast cancer research underscores ongoing trials of vaccines targeting α-lactalbumin to prevent the recurrence of triple-negative breast cancer. Lung cancer studies have discovered interesting outcomes with liposomal vaccines and the potential of CIMAvax-EGF in the prevention of lung cancer. Studies on ovarian cancer highlight personalized cancer vaccines using dendritic cells and various tumor-associated antigens to elicit T-cell responses against cancer cells. Overall, such advancements suggest great promise for future clinical translation of cancer novel immunotherapy-based approaches to effectively counter various types of cancer.

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.

Immunotherapy in small cell lung cancer: one step at a time: a narrative review

Chemotherapy with or without radiotherapy has been the standard of care for many years for patients with small cell lung cancer (SCLC). Despite exceptionally high responses (up to 80%) with chemotherapy, the majority of patients relapse rapidly within weeks to months after treatment completion. Therefore, new and better treatment options are necessary. Recently, synergistic activity has been reported for the addition of immune checkpoint inhibitors (ICI) to standard platinum-based chemotherapy in the therapeutic strategy of advanced SCLC. For the first time after several decades, a significant survival improvement was achieved for this population. However, the overwhelming majority of patients do not respond to ICI, or relapse rapidly. There is need for better knowledge about the biology, histopathologic features, and molecular pathways of SCLC. This can probably help to identify the optimal predictive biomarkers, which are warranted to develop an individual therapeutic strategy including the rational use of a combination of immunotherapeutic agents. Here, we provide an overview of the rationale for and clinical results of the completed and ongoing trials using different strategies of immunotherapy in SCLC. In addition, opportunities for further improvement of therapies will be discussed, including the addition of radiotherapy, co-stimulatory antibodies, and other immune modifying agents.

Development of tumour peptide vaccines: From universalization to personalization

In recent years, relying on the human immune system to kill tumour cells has become an effective means of cancer treatment. The development of peptide vaccines, which not only break the immune tolerance of a tumour but also attack malignant cells via specific antitumour immunity, has received increased attention in tumour immunization therapy due to their safety and easy preparation. The use of large-scale sequencing technology enables the continuous discovery of new tumour antigens. With improved accuracy of epitope prediction by computer simulation and the usage of a tetramer assay, cytotoxic lymphocyte epitopes can be screened and identified more easily. Transmembrane peptide and nanoparticle technologies promote more effective intake and delivery of antigens. Consequently, considerable evolution from universal to personalized peptide vaccines has taken place, and such vaccines induce an efficient and specific immune response targeting tumour neoantigens. Recently, genomic analysis and bioinformatics approaches have greatly facilitated the breakthrough of personalized peptide vaccines targeting neoantigens, resulting in a renewed interest in this field. Further, the combination of tumour peptide vaccines with checkpoint blockades may improve patient outcomes. In this review, we discuss the development of tumour peptide vaccines and the new technological progress, from universalization to personalization, to highlight the substantial promise of tumour peptide vaccines in clinical cancer immunotherapy.

Computational study on the origin of the cancer immunotherapeutic potential of B and T cell epitope peptides

Immune therapy is generally seen as the future of cancer treatment. The discovery of tumor-associated antigens and cytotoxic T lymphocyte epitope peptides spurned intensive research into effective peptide-based cancer vaccines. One of the major obstacles hindering the development of peptide-based cancer vaccines is the lack of humoral response induction. As of now, very limited work has been performed to identify epitope peptides capable of inducing both cellular and humoral anticancer responses. In addition, no research has been carried out to analyze the structure and properties of peptides responsible for such immunological activities. This study utilizes a machine learning method together with interpretable descriptors in an attempt to identify parameters determining the immunotherapeutic activity of cancer epitope peptides.

Single nucleotide polymorphisms of the haptoglobin gene in non-small cell lung cancer treated with personalized peptide vaccination

The present study analyzed polymorphisms of the 5' flanking region (from nt -840 to +151) of the haptoglobin gene in 120 patients with advanced non-small cell lung cancer (NSCLC) receiving personalized peptide vaccinations. In the region, six single nucleotide polymorphisms (SNPs) were confirmed, of which two, rs5472 and rs9927981, were completely linked to each other. The minor allele frequencies of rs5472/rs9927981 and rs4788458 were higher than those of the other three SNPs. The genotype frequencies of rs5472 or rs9927981 were A/A or C/C (42.5%, n=51), A/G or C/T (40.8%, n=49), and G/G or T/T (16.7%, n=20), respectively; and those of rs4788458 were T/T (34.2%, n=41), T/C (40.0%, n=48), and C/C (25.8%, n=31). The association between polymorphism rs5472/rs9927981 and prognosis, or between rs4788458 and prognosis, was analyzed further. However, no correlation was found between these SNPs and overall survival, regardless of subgroup analysis of gender, histology or concurrent therapy. These results suggest that the polymorphisms rs5472/rs9927981 and rs4788458 are not useful prognostic tools for patients with NSCLC treated with personalized peptide vaccination.

Feasibility Study of Personalized Peptide Vaccination for Advanced Small Cell Lung Cancer

INTRODUCTION

The prognosis of patients with small cell lung cancer (SCLC) remains very poor. Therefore, the development of new therapeutic approaches, including immunotherapies, is desirable.

PATIENTS AND METHODS

We conducted a phase II study of personalized peptide vaccination (PPV), in which a maximum of 4 human leukocyte antigen-matched peptides were selected from 31 pooled peptides according to the pre-existing peptide-specific IgG responses before vaccination. The PPV was subcutaneously administered.

RESULTS

Forty-six patients were enrolled (median age, 63 years; 40 patients were men). Grade 1 (n = 13), 2 (n = 10), or 3 (n = 1) skin reactions at the injection sites were observed; however, no other severe adverse events related to the PPV were observed. The median survival time was 466, 397, 401, and 107 days in the subgroups with 0 (n = 5), 1 (n = 15), 2 (n = 12), and ≥ 3 (n = 14) previous chemotherapy regimens, respectively. Peptide-specific IgG responses to the vaccinated peptides were augmented in 70% and 95% of patients after 1 and 2 vaccination cycles, respectively. The overall survival (OS) of patients with augmented IgG responses to a greater number of nonvaccinated peptides after the second cycle of vaccination was significantly longer (median survival time, 1237 days vs. 382 days; P = .010). In addition, augmentation of IgG responses specific to 6 peptides, including Lck-derived peptides, was significantly related to better OS (P < .05, in each peptide).

CONCLUSION

These results suggest the feasibility of PPV for SCLC patients from the viewpoints of safety, immune boosting, and possible prolongation of OS. Therefore, further evaluation of PPV for advanced SCLC in prospective randomized trials is warranted.

Prospect and progress of personalized peptide vaccinations for advanced cancers

INTRODUCTION

The field of cancer immunotherapy has made dramatic progress in the past 20 years, in part due to the identification of numerous tumor-associated antigens (TAAs). We have developed a novel immunotherapeutic approach called the personalized peptide vaccine (PPV), in which a maximum of four human leukocyte antigen (HLA)-matched vaccine peptides are selected based on the pre-existing host immunity before vaccination.

AREAS COVERED

This review describes recent progress in the use of PPV for various types of advanced cancer.

EXPERT OPINION

Although various approaches for therapeutic cancer immunotherapies, including peptide-based vaccines, have been developed and clinically examined, the diverse and heterogeneous characteristics of tumor cells and host immunity seem to limit their therapeutic efficacy. Selection of suitable peptide vaccines for individual patients based on the pre-existing host immunity before vaccination could resolve this limitation and could be a rational approach for developing effective cancer vaccines.

Immunological evaluation of peptide vaccination for cancer patients with the HLA-A26 allele

To develop a peptide vaccine for cancer patients with the HLA-A26 allele, which is a minor population worldwide, we investigated the immunological responses of HLA-A26(+) /A26(+) cancer patients to four different CTL epitope peptides under personalized peptide vaccine regimens. In personalized peptide vaccine regimens, two to four peptides showing positive peptide-specific IgG responses in pre-vaccination plasma were selected from the four peptide candidates applicable for HLA-A26(+) /A26(+) cancer patients and administered s.c. Peptide-specific CTL and IgG responses along with cytokine levels were measured before and after vaccination. Cell surface markers in PBMCs and plasma cytokine levels were also measured. In this study, 21 advanced cancer patients, including seven lung, three breast, two pancreas, and two colon cancer patients, were enrolled. Their HLA-A26 genotypes were HLA-A26:01 (n = 24), HLA-A26:03 (n = 10), and HLA-A26:02 (n = 8). One, 14, and 6 patients received two, three, and four peptides, respectively. Grade 1 or 2 skin reactions at the injection sites were observed in the majority of patients, but no severe adverse events related to the vaccination were observed. Peptide-specific CTL responses were augmented in 39% or 22% of patients after one or two cycles of vaccination, respectively. Notably, peptide-specific IgG were augmented in 63% or 100% of patients after one or two cycles of vaccination, respectively. Personalized peptide vaccines with these four CTL epitope peptides could be feasible for HLA-A26(+) advanced cancer patients because of their safety and higher rates of immunological responses.

Feasibility study of personalized peptide vaccination for advanced non-small cell lung cancer patients who failed two or more treatment regimens

The prognosis of non-small cell lung cancer (NSCLC) patients who failed two or more treatment regimens remains very poor. We conducted a phase II study to explore the feasibility of personalized peptide vaccination (PPV), in which peptides are selected and administered based on the pre-existing host immunity before vaccination, as a third or more line treatment in advanced NSCLC patients who failed two or more regimens. Among 57 patients enrolled, 23 or 16 patients received PPV with chemotherapy or targeted therapy, respectively, whereas 18 patients received PPV alone. A maximum of four HLA-matched peptides showing higher peptide-specific IgG responses in pre-vaccination plasma were selected from 31 pooled peptide candidates applicable for patients with HLA-A2, -A24, -A3 supertypes, and/or -A26, followed by subcutaneous administration. No severe adverse events related to PPV were observed. Median survival time was 692, 468, or 226 days in the group of PPV/chemotherapy, PPV/targeted therapy, or PPV alone, respectively. CTL responses to the vaccinated peptides became detectable after vaccination in 58, 50, or 42% of patients in each of these three groups, respectively. In contrast, peptide-specific IgG responses after vaccination augmented in 55, 75, or 62% of patients in each of these groups, respectively. These results suggest the feasibility of PPV for heavily treated advanced NSCLC patients from the view of both immunological responses and safety. Therefore, further evaluation of PPV by prospective randomized trial is warranted for a third or fourth line treatment of advanced NSCLC.

PD-1 expression on peripheral blood T-cell subsets correlates with prognosis in non-small cell lung cancer

PD-1 expression in peripheral blood T-cells has been reported in several kinds of cancers, including lung cancer. However, the relationship between PD-1 expression in peripheral blood T-cells and prognosis after treatment with a cancer vaccine has not been reported. To elucidate this relationship, we analyzed PD-1 expression in the peripheral blood T-cells of patients with non-small cell lung cancer. The blood samples used in this study were obtained from patients enrolled in phase II clinical trials of a personalized peptide vaccine. Seventy-eight samples obtained before and after a single vaccination cycle (consisting of six or eight doses) were subjected to the analysis. PD-1 was expressed on lymphocytes in the majority of samples. The relative contents of PD1(+) CD4(+) T-cells against total lymphocytes before and after the vaccination cycle correlated with overall survival (OS) with a high degree of statistical significance (P < 0.0001 and P = 0.0014). A decrease in PD-1(+) CD8(+) T-cells after one cycle of vaccination also correlated with longer OS (P = 0.032). The IgG response to the non-vaccinated peptides suggested that the epitope spreading seemed to occur more frequently in high-PD-1(+) CD4(+) T-cell groups. Enrichment of CD45RA(-) CCR7(-) effector-memory phenotype cells in PD-1(+) T-cells in PBMCs was also shown. These results suggest that PD-1 expression on the peripheral blood T-cell subsets can become a new prognostic marker in non-small cell lung cancer patients treated with personalized peptide vaccination.

Immunotherapy treatments for small-cell lung cancer: past, present and future

Small-cell lung cancer remains a considerable cause of morbidity and mortality. To this day, first-line therapy continues to be a platinum agent with etoposide, combined with radiation therapy in cases of limited stage disease. Numerous, largely unsuccessful, attempts at controlling the disease have included different chemotherapy strategies, the utilization of antiangiogenic agents, tyrosine kinase inhibitors, mammalian target of rapamycin inhibitors and other treatment modalities. Immunotherapy, including vaccines, immune response modifiers, inhibitors of check point blockades and immunologic-targeted toxins may well be the future of treatment, not only to enhance the proven chemotherapy effects, but to improve the control of minimal residual disease and the response with salvage chemotherapy. This article reviews the current advances in immunotherapeutic strategies against small-cell lung cancer.

Recent progress in peptide vaccination in cancer with a focus on non-small-cell lung cancer

Active immunotherapy aimed at the stimulation of tumor-specific T cells has established itself within the clinic as a therapeutic option to treat cancer. One strategy is the use of so-called peptides that mimic genuine T-cell epitopes as vaccines to activate tumor-specific T cells. In various clinical trials, different types of vaccines, adjuvants and other immunomodulatory compounds were evaluated in patients with different types of tumors. Here, we review the trials published in the last 3 years focusing on the T-cell response, the effect of immunomodulation and potential relationships with clinical outcomes. Furthermore, we would like to make a case for the development of peptide vaccines aiming to treat non-small-cell lung cancer, the most common cause of cancer mortality.

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.

Phase II study of personalized peptide vaccination for refractory bone and soft tissue sarcoma patients

Refractory bone and soft tissue sarcomas are challenging diseases to treat because of their robustness to chemotherapy. Although cancer vaccines have the potential to become an attractive treatment modality, their progress has been hampered by the presence of many subtypes of sarcomas and different human leukocyte antigen (HLA)‐types. We investigated whether personalized peptide vaccination (PPV) would be feasible for the vast majority of sarcoma patients. Twenty refractory bone and soft tissue sarcoma patients with nine different subtypes and 11 different HLA‐class IA phenotypes were enrolled in this study. A maximum of four HLA‐matched peptides showing higher peptide‐specific IgG responses in pre‐vaccination plasma were selected from 31 pooled peptide candidates applicable for the HLA‐A2, ‐A3, ‐A11, ‐A24, ‐A26, ‐A31, and ‐A33 types, and were subcutaneously administered weekly for 6 weeks and bi‐weekly thereafter. Measurement of peptide‐specific CTL and IgG responses along with other laboratory analyses were conducted before and after vaccination. No patients were excluded by either sarcoma subtypes or different HLA‐types. No severe adverse events associated with PPV were observed in any patients. Peptide‐specific immunological boosting was observed in the post‐vaccination samples from the majority of patients. Tumor reduction of the lung metastasis and a long stable disease was observed in each case, and the median overall survival time of the 20 cases was 9.6 months. Taken together, PPV could be feasible for the vast majority of refractory sarcoma patients because of the safety and higher rates of immunological responses regardless of the presence of different sarcoma subtypes and various HLA‐types.

A phase II study of a personalized peptide vaccination for chemotherapy-resistant advanced pancreatic cancer patients

Pancreatic cancer is one of the most aggressive cancers with a median survival time (MST) of <6 months in chemotherapy-resistant patients. Therefore, the development of novel treatment modalities is needed. In the present study, a phase II study of personalized peptide vaccination (PPV) was conducted, in which vaccine antigens were selected and administered based on the pre-existing IgG responses to 31 different pooled peptides, for 41 chemotherapy-resistant advanced pancreatic cancer patients. No vaccine-related severe adverse events were observed. IgG responses specific to at least one of the vaccine peptides were augmented in 14 of 36 patients (39%) and in 18 of 19 patients (95%) tested after the 5th and 11th vaccination, respectively. MST from the first vaccination was 7.9 months with a 1-year survival rate of 26.8%. Higher serum amyloid A (SAA) and C-reactive protein (CRP) levels in pre-vaccination plasma were unfavorable factors for overall survival (OS). Due to the safety profile and the potential clinical efficacy, the conduction of additional clinical trials of PPV for chemotherapy-resistant advanced pancreatic cancer patients is warranted.

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.

Next-generation peptide vaccines for advanced cancer

Many clinical trials of peptide vaccines have been carried out since the first clinical trial of a melanoma antigen gene-1-derived peptide-based vaccine was reported in 1995. The earlier generations of peptide vaccines were composed of one to several human leukocyte antigen class I-restricted CTL-epitope peptides of a single human leukocyte antigen type. Currently, various types of next-generation peptide vaccines are under development. In this review, we focus on the clinical trials of the following categories of peptide vaccines mainly published from 2008 to 2012: (i) multivalent long peptide vaccines; (ii) multi-peptide vaccines consisting of CTL- and helper-epitopes; (iii) peptide cocktail vaccines; (iv) hybrid peptide vaccines; (v) personalized peptide vaccines; and (vi) peptide-pulsed dendritic cell vaccines.