The coronavirus disease 2019 (COVID-19) outbreak, caused by SARS-CoV-2, has rapidly expanded to a global pandemic. However, numbers of infected cases, deaths, and mortality rates related to COVID-19 ...vary from country to country. Although many studies were conducted, the reasons of these differences have not been clarified. In this study, we comprehensively investigated 12,343 SARS-CoV-2 genome sequences isolated from patients/individuals in six geographic areas and identified a total of 1234 mutations by comparing with the reference SARS-CoV-2 sequence. Through a hierarchical clustering based on the mutant frequencies, we classified the 28 countries into three clusters showing different fatality rates of COVID-19. In correlation analyses, we identified that ORF1ab 4715L and S protein 614G variants, which are in a strong linkage disequilibrium, showed significant positive correlations with fatality rates (r = 0.41, P = 0.029 and r = 0.43, P = 0.022, respectively). We found that BCG-vaccination status significantly associated with the fatality rates as well as number of infected cases. In BCG-vaccinated countries, the frequency of the S 614G variant had a trend of association with the higher fatality rate. We also found that the frequency of several HLA alleles, including HLA-A*11:01, were significantly associated with the fatality rates, although these factors were associated with number of infected cases and not an independent factor to affect fatality rate in each country. Our findings suggest that SARS-CoV-2 mutations as well as BCG-vaccination status and a host genetic factor, HLA genotypes might affect the susceptibility to SARS-CoV-2 infection or severity of COVID-19.
To control and prevent the current COVID-19 pandemic, the development of novel vaccines is an emergent issue. In addition, we need to develop tools that can measure/monitor T-cell and B-cell ...responses to know how our immune system is responding to this deleterious virus. However, little information is currently available about the immune target epitopes of novel coronavirus (SARS-CoV-2) to induce host immune responses. Through a comprehensive bioinformatic screening of potential epitopes derived from the SARS-CoV-2 sequences for HLAs commonly present in the Japanese population, we identified 2013 and 1399 possible peptide epitopes that are likely to have the high affinity (<0.5%- and 2%-rank, respectively) to HLA class I and II molecules, respectively, that may induce CD8
and CD4
T-cell responses. These epitopes distributed across the structural (spike, envelope, membrane, and nucleocapsid proteins) and the nonstructural proteins (proteins corresponding to six open reading frames); however, we found several regions where high-affinity epitopes were significantly enriched. By comparing the sequences of these predicted T cell epitopes to the other coronaviruses, we identified 781 HLA-class I and 418 HLA-class II epitopes that have high homologies to SARS-CoV. To further select commonly-available epitopes that would be applicable to larger populations, we calculated population coverages based on the allele frequencies of HLA molecules, and found 2 HLA-class I epitopes covering 83.8% of the Japanese population. The findings in the current study provide us valuable information to design widely-available vaccine epitopes against SARS-CoV-2 and also provide the useful information for monitoring T-cell responses.
Recent advances in next-generation sequencing technologies have led to significant improvements in cancer genomic research and cancer treatment. Through the use of comprehensive cancer genome data, ...precision medicine has become more of a reality; albeit, at present, only ~10-15% of patients can benefit from current genomic testing practices. Improvements in cancer genome analyses have contributed to a better understanding of antitumor immunity and have provided solutions for targeting highly cancer-specific neoantigens generated from somatic mutations in individual patients. Since then, numerous studies have demonstrated the importance of neoantigens and neoantigen-reactive T cells in the tumor microenvironment and how their presence influences the beneficial responses associated with various cancer immunotherapies, including immune checkpoint inhibitor therapy. Indeed, cancer immunotherapies that explicitly target neoantigens specific to individual cancer patients would lead to the ultimate form of cancer precision medicine. For this to be realized, several issues would need to be overcome, including the accurate prediction and selection of neoantigens that can induce cytotoxic T cells in individual patients. The precise prediction of target neoantigens will likely accelerate the development of personalized immunotherapy including cancer vaccines and T-cell receptor-engineered T-cell therapy for patients with cancer.
Utilizing the host immune system to eradicate cancer cells has been the most investigated subject in the cancer research field in recent years. However, most of the studies have focused on highly ...variable responses from immunotherapies such as immune checkpoint inhibitors, from which the majority of patients experienced no or minimum clinical benefit. Advances in genomic sequencing technologies have improved our understanding of immunopharmacogenomics and allowed us to identify novel cancer‐specific immune targets. Highly tumor‐specific antigens, neoantigens, are generated by somatic mutations that are not present in normal cells. It is plausible that by targeting antigens with high tumor‐specificity, such as neoantigens, the likelihood of toxic effects is very limited. However, understanding the interaction between neoantigens and the host immune system remains a significant challenge. This review focuses on the potential use of neoantigen‐targeted immunotherapies in cancer treatment and the recent progress of different strategies in predicting, identifying, and validating neoantigens. Successful identification of highly tumor‐specific antigens accelerates the development of personalized immunotherapy with no or minimum adverse effects and with a broader coverage of patients.
Advances in genomic sequencing technologies have improved our understanding of immunopharmacogenomics and allowed us to identify novel cancer‐specific immune targets, including highly tumor‐specific neoantigens, which are generated by somatic mutations. However, understanding the interaction between neoantigens and the host immune system has remained to be a big challenge. This review focuses on the potential use of neoantigen‐targeted immunotherapies in cancer treatment and the recent progresses of the different strategies in predicting, identifying and validating neoantigens to develop personalized cancer immunotherapy.
Immune checkpoint blockade against programmed cell death 1 (PD-1) and its ligand PD-L1 often induces durable tumor responses in various cancers, including non-small cell lung cancer (NSCLC). However, ...therapeutic resistance is increasingly observed, and the mechanisms underlying anti-PD-L1 (aPD-L1) antibody treatment have not been clarified yet. Here, we identified two unique secreted PD-L1 splicing variants, which lacked the transmembrane domain, from aPD-L1-resistant NSCLC patients. These secreted PD-L1 variants worked as "decoys" of aPD-L1 antibody in the HLA-matched coculture system of iPSC-derived CD8 T cells and cancer cells. Importantly, mixing only 1% MC38 cells with secreted PD-L1 variants and 99% of cells that expressed wild-type PD-L1 induced resistance to PD-L1 blockade in the MC38 syngeneic xenograft model. Moreover, anti-PD-1 (aPD-1) antibody treatment overcame the resistance mediated by the secreted PD-L1 variants. Collectively, our results elucidated a novel resistant mechanism of PD-L1 blockade antibody mediated by secreted PD-L1 variants.
An 80‐year‐old man, who developed multiple lymph node and skin metastasis of malignant melanoma, received nivolumab monotherapy. Two weeks after the first dose, he experienced anorexia and fatigue, ...and suffered from progressive, severe dyspnea and muscle weakness. We diagnosed him with myocarditis, myositis, and myasthenic crisis induced by nivolumab. We commenced steroid therapy, immune absorption therapy, plasma exchange therapy, and i.v. immunoglobulin therapy, and succeeded in saving his life. Because his serum level of anti‐acetylcholine receptor antibodies in a sample collected before nivolumab treatment were positive and were elevated significantly after nivolumab, we suspected that nivolumab triggered a severe autoimmune response, which progressed subclinical myasthenia gravis to myasthenic crisis. We carried out T cell receptor repertoire analysis using next‐generation sequencing technologies and identified infiltration of clonally expanded T cell populations in the skeletal muscle after nivolumab treatment, implying a very strong T cell immune response against muscular cells. To avoid severe immune‐related adverse events, the exclusion of patients with subclinical autoimmune disease is very important for treatment with immune checkpoint inhibitors.
Myasthenic crisis and polymyositis were induced by one dose of nivolumab. We performed T cell receptor repertoire analysis using the next‐generation sequencing technologies and identified infiltration of clonally expanded T cell populations in the skeletal muscle tissue after the nivolumab treatment, implying the very strong T cell immune response against muscular cells
There are numerous histological subtypes (histotypes) of gynecological malignancies, with each histotype considered to largely reflect a feature of the "cell of origin," and to be tightly linked with ...the clinical behavior and biological phenotype of the tumor. The recent advances in massive parallel sequencing technologies have provided a more complete picture of the range of the genomic alterations that can persist within individual tumors, and have highlighted the types and frequencies of driver-gene mutations and molecular subtypes often associated with these histotypes. Several large-scale genomic cohorts, including the Cancer Genome Atlas (TCGA), have been used to characterize the genomic features of a range of gynecological malignancies, including high-grade serous ovarian carcinoma, uterine corpus endometrial carcinoma, uterine cervical carcinoma, and uterine carcinosarcoma. These datasets have also been pivotal in identifying clinically relevant molecular targets and biomarkers, and in the construction of molecular subtyping schemes. In addition, the recent widespread use of clinical sequencing for the more ubiquitous types of gynecological cancer has manifested in a series of large genomic datasets that have allowed the characterization of the genomes, driver mutations, and histotypes of even rare cancer types, with sufficient statistical power. Here, we review the field of gynecological cancer, and seek to describe the genomic features by histotype. We also will demonstrate how these are linked with clinicopathological attributes and highlight the potential tumorigenic mechanisms.
With the significant advances in cancer genomics using next-generation sequencing technologies, genomic and molecular profiling-based precision medicine is used as a part of routine clinical test for ...guiding and selecting the most appropriate treatments for individual cancer patients. Although many molecular-targeted therapies for a number of actionable genomic alterations have been developed, the clinical application of such information is still limited to a small proportion of cancer patients. In this review, we summarize the current status of personalized drug selection based on genomic and molecular profiling and highlight the challenges how we can further utilize the individual genomic information. Cancer immunotherapies, including immune checkpoint inhibitors, would be one of the potential approaches to apply the results of genomic sequencing most effectively. Highly cancer-specific antigens derived from somatic mutations, the so-called neoantigens, occurring in individual cancers have been in focus recently. Cancer immunotherapies, which target neoantigens, could lead to a precise treatment for cancer patients, despite the challenge in accurately predicting neoantigens that can induce cytotoxic T cells in individual patients. Precise prediction of neoantigens should accelerate the development of personalized immunotherapy including cancer vaccines and T-cell receptor-engineered T-cell therapy for a broader range of cancer patients.
Accurate human leukocyte antigen (HLA) genotyping is critical in studies involving the immune system. Several algorithms to estimate HLA genotypes from whole-exome data were developed. We compared ...the accuracy of seven algorithms, including Optitype, Polysolver and PHLAT, as well as investigated patterns and possible causes of miscalls using 12 clinical samples and 961 individuals from the 1000 Genomes Project. Optitype showed the highest accuracy of 97.2% for HLA class I alleles at the second field resolution, followed by 94.0% in Polysolver and 85.6% in PHLAT. In Optitype, 34 (21.1%) of 161 miscalls were across different serological types, and common miscalls were HLA-A*26:01 to HLA-A*25:01, HLA-B*45:01 to HLA-B*44:15 and HLA-C*08:02 to HLA-C*05:01 with error rates of 4.1%, 10.0% and 4.1%, respectively. In Polysolver, 193 (55.9%) of 345 miscalls occurred across different serological alleles, and a specific pattern of genotyping error from HLA-A*25:01 to HLA-A*26:01 was observed in 93.3% of HLA-A*25:01 carriers, due to dropping of HLA-A*25:01 sequence reads during the extraction process of HLA reads. In PHLAT, 147 (59.8%) of 246 miscalls in HLA-A were due to erroneous assignment of multiple alleles to either HLA-A*01:22 or HLA-A*01:81. These results suggest that careful considerations needed to be taken when using exome-based HLA class I genotyping data and applying these results in clinical settings.
Abstract
Neoantigens are tumour-specific antigens that arise from non-synonymous mutations in tumour cells. However, their effect on immune responses in the tumour microenvironment remains unclear in ...breast cancer. We performed whole exome and RNA sequencing of 31 fresh breast cancer tissues and neoantigen prediction from non-synonymous single nucleotide variants (nsSNVs) among exonic mutations. Neoantigen profiles were determined by predictive HLA binding affinity (IC
50
< 500 nM) and mRNA expression with a read count of ≥ 1. We evaluated the association between neoantigen load and expression levels of immune-related genes. Moreover, using primary tumour cells established from pleural fluid of a breast cancer patient with carcinomatous pleurisy, we induced cytotoxic T lymphocytes (CTLs) by coculturing neoantigen peptide-pulsed dendritic cells (DCs) with autologous peripheral lymphocytes. The functions of CTLs were examined by cytotoxicity and IFN-γ ELISpot assays. Neoantigen load ranged from 6 to 440 (mean, 95) and was positively correlated to the total number of nsSNVs. Although no associations between neoantigen load and mRNA expression of T cell markers were observed, the coculture of neoantigen-pulsed DCs and lymphocytes successfully induced CTLs ex vivo. These results suggest that neoantigen analysis may have utility in developing strategies to elicit T cell responses.
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