Immune-mediated antitumor effect by type 2 diabetes drug, metformin.

Metformin, a prescribed drug for type 2 diabetes, has been reported to have anti-cancer effects; however, the underlying mechanism is poorly understood. Here we show that this mechanism may be immune-mediated. Metformin enabled normal but not T-cell-deficient SCID mice to reject solid tumors. In addition, it increased the number of CD8(+) tumor-infiltrating lymphocytes (TILs) and protected them from apoptosis and exhaustion characterized by decreased production of IL-2, TNFα, and IFNγ. CD8(+) TILs capable of producing multiple cytokines were mainly PD-1(-)Tim-3(+), an effector memory subset responsible for tumor rejection. Combined use of metformin and cancer vaccine improved CD8(+) TIL multifunctionality. The adoptive transfer of antigen-specific CD8(+) T cells treated with metformin concentrations as low as 10 µM showed efficient migration into tumors while maintaining multifunctionality in a manner sensitive to the AMP-activated protein kinase (AMPK) inhibitor compound C. Therefore, a direct effect of metformin on CD8(+) T cells is critical for protection against the inevitable functional exhaustion in the tumor microenvironment.

Immunochromatography test for rapid diagnosis of Mycoplasma pneumoniae infection.

The sensitivity and specificity of a new rapid Mycoplasma pneumoniae antigen immunochromatography (IC) test, DK-MP-001, were determined using particle agglutination (PA) antibody response and loop-mediated isothermal amplification (LAMP) gene detection as the gold standard. Of 165 patients, 59 were diagnosed with M. pneumoniae infection based on a ≥fourfold rise of serum PA antibody during the course of the illness. Of the first visit swabs, 60 were positive for M. pneumoniae on LAMP, and 49 were positive for M. pneumoniae antigen on IC test. Compared with PA antibody and LAMP, the sensitivity/specificity of the IC test were 81.4% (48/59) and 99.1% (105/106); and 81.7% (49/60) and 100% (105/105), respectively. IC test detected antigen in pharyngeal swabs more sensitively than in nasal swabs for the same subjects (P < 0.05). The IC test performs well enough to be used with pharyngeal swabs at the first examination.

Sensitive Multiplexed Quantitative Analysis of Autoantibodies to Cancer Antigens with Chemically S-Cationized Full-Length and Water-Soluble Denatured Proteins.

Humoral immune responses against tumor-associated antigens (TAAs) or cancer/testis antigens (CTAs) aberrantly expressed in tumor cells are frequently observed in cancer patients. Recent clinical studies have elucidated that anticancer immune responses with increased levels of anti-TAA/CTA antibodies improve cancer survival rates. Thus, these antibody levels are promising biomarkers for diagnosing the efficiency of cancer immunotherapy. Full-length antigens are favored for detecting anti-TAA/CTA antibodies because candidate antigen proteins contain multiple epitopes throughout their structures. In this study, we developed a methodology to prepare purified water-soluble and full-length antigens by using cysteine sulfhydryl group cationization (S-cationization) chemistry. S-Cationized antigens can be prepared from bacterial inclusion bodies, and they exhibit improved protein solubility but preserved antigenicity. Anti-TAA/CTA antibodies detected in cancer patients appeared to recognize linear epitopes, as well as conformational epitopes, and because the frequency of cysteine side-residues on the epitope-paratope interface was low, any adverse effects of S-cationization were virtually negligible for antibody binding. Furthermore, S-cationized antigen-immobilized Luminex beads could be successfully used in highly sensitive quantitative-multiplexed assays. Indeed, patients with a more broadly induced serum anti-TAA/CTA antibody level showed improved progression-free survival after immunotherapy. The comprehensive anti-TAA/CTA assay system, which uses S-cationized full-length and water-soluble recombinant antigens, may be a useful diagnostic tool for assessing the efficiency of cancer immunotherapy.

Hepatitis C virus-specific T-cell response correlates with hepatitis activity and donor IL28B genotype early after liver transplantation.

It is not known how the immune system targets hepatitis C virus (HCV)-infected HLA-mismatched hepatocytes under immune-suppressed conditions after orthotopic liver transplantation (OLT). In addition, the relationship between the HCV-specific immune response and IL28B variants as predictors of HCV clearance has not been well-characterized. We determined the IL28B polymorphisms for 57 post-OLT HCV carriers, and we assessed the HCV-specific immune responses by measuring the peripheral blood mononuclear cell-derived HCV-specific interferon-gamma (IFN-γ) response using an enzyme-linked immunospot assay. At 1-3 years after OLT, patients with no active hepatitis showed higher total spots on the immunospot assay. At＞3 years after OLT, patients with resolved HCV showed higher levels of core, NS3, NS5A, and total spots compared to the chronic hepatitis patients. The IL28B major genotype in the donors correlated with higher spot counts for NS5A and NS5B proteins at 1-3 years after OLT. In the post-OLT setting, the HCV-specific immune response could be strongly induced in patients with no active hepatitis with an IL28B major donor or sustained virological response. Strong immune responses in the patients with no active hepatitis could only be maintained for 3 years and diminished later. It may be beneficial to administer IFN treatment starting 3 years after OLT, to induce the maximum immunological effect.

Induction of CD8 T-cell responses restricted to multiple HLA class I alleles in a cancer patient by immunization with a 20-mer NY-ESO-1f (NY-ESO-1 91-110) peptide.

Immunogenicity of a long 20-mer NY-ESO-1f peptide vaccine was evaluated in a lung cancer patient TK-f01, immunized with the peptide with Picibanil OK-432 and Montanide ISA-51. We showed that internalization of the peptide was necessary to present CD8 T-cell epitopes on APC, contrasting with the direct presentation of the short epitope. CD8 T-cell responses restricted to all five HLA class I alleles were induced in the patient after the peptide vaccination. Clonal analysis showed that B*35:01 and B*52:01-restricted CD8 T-cell responses were the two dominant responses. The minimal epitopes recognized by A*24:02, B*35:01, B*52:01 and C*12:02-restricted CD8 T-cell clones were defined and peptide/HLA tetramers were produced. NY-ESO-1 91-101 on A*24:02, NY-ESO-1 92-102 on B*35:01, NY-ESO-1 96-104 on B*52:01 and NY-ESO-1 96-104 on C*12:02 were new epitopes first defined in this study. Identification of the A*24:02 epitope is highly relevant for studying the Japanese population because of its high expression frequency (60%). High affinity CD8 T-cells recognizing tumor cells naturally expressing the epitopes and matched HLA were induced at a significant level. The findings suggest the usefulness of a long 20-mer NY-ESO-1f peptide harboring multiple CD8 T-cell epitopes as an NY-ESO-1 vaccine. Characterization of CD8 T-cell responses in immunomonitoring using peptide/HLA tetramers revealed that multiple CD8 T-cell responses comprised the dominant response.

Spontaneous antibody, and CD4 and CD8 T-cell responses against XAGE-1b (GAGED2a) in non-small cell lung cancer patients.

The spontaneous immune responses against XAGE-1b (GAGED2a) were analyzed in non-small cell lung cancer (NSCLC) patients. An antibody response against XAGE-1b (GAGED2a) was observed in 10% (20/200) of NSCLC patients and in 19% (13/69) of stage IIIB/IV lung adenocarcinoma patients. A CD4 T-cell response was detected in 88% (14/16) and a CD8 T-cell response in 67% (6/9) in the XAGE-1b (GAGED2a) antibody-positive patients examined. Frequent antibody responses and CD4 and CD8 T-cell responses in XAGE-1b (GAGED2a) antibody-positive patients indicate the strong immunogenicity of the XAGE-1b (GAGED2a) antigen in NSCLC patients. We established T-cell clones from PBMCs of antibody-positive patients and determined the DRB1*04:05-restricted XAGE-1b (GAGED2a) 18-31 peptide (14-mer) as a CD4 T cell epitope and the A*02:06-restricted XAGE-1b (GAGED2a) 21-29 peptide (9-mer) as a CD8 T cell epitope. As for peptide recognition, CD4 and CD8 T-cell clones responded to naturally processed antigen. The CD4 T-cell clone recognized DCs pulsed with the synthetic protein or a lysate from XAGE-1b-transfected 293T cells. The CD8 T-cell clone showed cytotoxicity against a tumor expressing XAGE-1b (GAGED2a) and the appropriate HLA class I allele. These findings establish XAGE-1b (GAGED2a) as a promising target for a lung cancer vaccine.

Heteroclitic serological response in esophageal and prostate cancer patients after NY-ESO-1 protein vaccination.

NY-ESO-1 is a prototypic cancer/testis antigen. In a recent phase I clinical trial, we vaccinated 13 patients bearing NY-ESO-1-expressing tumors with a complex of cholesterol-bearing hydrophobized pullulan (CHP) and NY-ESO-1 protein (CHP-NY-ESO-1) and showed efficient induction of NY-ESO-1 antibody, and CD4 and CD8 T cell responses using peripheral blood from the patients. In our study, we analyzed heteroclitic serological responses in those patients after vaccination. Serological response against 11 tumor antigens including MAGE-A1, MAGE-A3, MAGE-A4, CT7/MAGEC1, CT10/MAGEC2, CT45, CT46/HORMAD1, SOX2, SSX2, XAGE1B and p53 was examined by enzyme-linked immunosorbent assay (ELISA) using sera from ten vaccinated patients. Expression of tumor antigens was determined by reverse transcription-polymerase chain reaction or immunohistochemistry. Eight of nine patients who showed antibody responses against NY-ESO-1 also showed an antibody response against at least 1 of these 11 tumor antigens after vaccination. In one patient, seven tumor antigens were recognized. Specificity analysis of the antibody response by ELISA using control recombinant proteins and synthetic peptides and by Western blot showed that the response was not against His6-tag and/or bacterial products included in a preparation of CHP-NY-ESO-1 used for vaccination. Thus, heteroclitic serological responses appear to be indicative of the overall immune response against the tumor, and their analysis could be useful for immune monitoring in cancer vaccine.

Serological identification of Tektin5 as a cancer/testis antigen and its immunogenicity.

BACKGROUND: Identification of new cancer antigens is necessary for the efficient diagnosis and immunotherapy. A variety of tumor antigens have been identified by several methodologies. Among those antigens, cancer/testis (CT) antigens have became promising targets. METHODS: The serological identification of antigens by the recombinant expression cloning (SEREX) methodology has been successfully used for the identification of cancer/testis (CT) antigens. We performed the SEREX analysis of colon cancer. RESULTS: We isolated a total of 60 positive cDNA clones comprising 38 different genes. They included 2 genes with testis-specific expression profiles in the UniGene database, such as TEKT5 and a CT-like gene, A kinase anchoring protein 3 (AKAP3). Quantitative real-time RT-PCR analysis showed that the expression of TEKT5 was restricted to the testis in normal adult tissues. In malignant tissues, TEKT5 was aberrantly expressed in a variety of cancers, including colon cancer. A serological survey of 101 cancer patients with different cancers by ELISA revealed antibodies to TEKT5 in 13 patients, including colon cancer. None of the 16 healthy donor serum samples were reactive in the same test. CONCLUSION: We identified candidate new CT antigen of colon cancer, TEKT5. The findings indicate that TEKT5 is immunogenic in humans, and suggest its potential use as diagnostic as well as an immunotherapeutic reagent for cancer patients.

Enrichment of Foxp3+ CD4 regulatory T cells in migrated T cells to IL-6- and IL-8-expressing tumors through predominant induction of CXCR1 by IL-6.

Analysis of cytokine and chemokine production by tumor cell lines including five lung cancers, a malignant mesothelioma, and a malignant melanoma recently established in our laboratory showed rather high production of IL-8 in all tumors and IL-6 in one lung cancer, the malignant mesothelioma, and the malignant melanoma. We investigated the migration of PBMCs to these tumor cells using Transwell plates and showed enrichment of Foxp3(+) CD4 regulatory T cells (Tregs) in migrated T cells to both IL-6- and IL-8-producing tumors. Marked induction of CXCR1 expression on Foxp3(+) CD4 Tregs by IL-6 followed by IL-8-mediated migration appeared to be responsible for enriched migration. Frequent production of IL-8 by the tumors and Treg migration to those tumors through induction of IL-8R expression by IL-6 is one of the mechanisms for tumor escape.

Immunogenicity of intradermal vaccination of Japanese rabies vaccine for preexposure immunization following WHO recommendation.

In the present study, we evaluated the immunogenicity of intradermal vaccination of Japanese purified chick embryo cell rabies vaccine (PCEC-K) for preexposure immunization (PEI). A total of 39 healthy subjects were administered a single 0.1-ml dose of PCEC-K intradermally at the antebrachial region on days 0, 7, and 28. To assess immunogenicity, rabies neutralizing antibody (NA) titers were measured on days 7, 28, and 42 post vaccination. By day 42, all subjects developed NA titers ≥0.5 IU/ml (geometric mean titer, 2.7 IU/ml), a level that is considered protective. The vaccine was well tolerated; vaccinated subjects displayed minimal redness and pruritus. Although a 1.0-ml dose of PCEC-K administered subcutaneously is considered the standard method, the intradermal regimen using a 0.1-ml dose of PCEC-K is immunogenic, safe, and highly recommended for situations of vaccine shortage.

[Immune monitoring and cancer vaccine].

NY-ESO-1 antigen is a prototype of a class of cancer/testis antigens. We carried out three serial clinical trials using NY-ESO-1 whole protein, NY-ESO-1f long peptide and overlapping peptides as a cancer vaccine for advanced cancer patients. Although vaccines elicited NY-ESO-1 humoral and cellular immune responses in most patients, results of immune monitoring using peripheral blood was not consistent with clinical responses. Analysis of immunohistochemistry revealed possible involvement of regulatory mechanisms in local antitumor immunity. Immune checkpoint molecules, e.g., CTLA-4 and PD-1, on immune effector cells, and regulatory T cells are known to regulate the induced immune responses and minimize local tissue damage. We should take these factors into consideration for further strategy of cancer vaccine and its monitoring.

Pandemic (H1N1) 2009-associated pneumonia in children, Japan.

To describe clinical aspects of pandemic (H1N1) 2009 virus-associated pneumonia in children, we studied 80 such children, including 17 (21%) with complications, who were admitted to 5 hospitals in Japan during August-November 2009 after a mean of 2.9 symptomatic days. All enrolled patients recovered (median hospitalization 6 days). Timely access to hospitals may have contributed to favorable outcomes.

A phase I study of vaccination with NY-ESO-1f peptide mixed with Picibanil OK-432 and Montanide ISA-51 in patients with cancers expressing the NY-ESO-1 antigen.

We conducted a phase I clinical trial of a cancer vaccine using a 20-mer NY-ESO-1f peptide (NY-ESO-1 91-110) that includes multiple epitopes recognized by antibodies, and CD4 and CD8 T cells. Ten patients were immunized with 600 µg of NY-ESO-1f peptide mixed with 0.2 KE Picibanil OK-432 and 1.25 ml Montanide ISA-51. Primary end points of the study were safety and immune response. Subcutaneous injection of the NY-ESO-1f peptide vaccine was well tolerated. Vaccine-related adverse events observed were fever (Grade 1), injection-site reaction (Grade 1 or 2) and induration (Grade 2). Vaccination with the NY-ESO-1f peptide resulted in an increase or induction of NY-ESO-1 antibody responses in nine of ten patients. The sera reacted with recombinant NY-ESO-1 whole protein as well as the NY-ESO-1f peptide. An increase in CD4 and CD8 T cell responses was observed in nine of ten patients. Vaccine-induced CD4 and CD8 T cells responded to NY-ESO-1 91-108 in all patients with various HLA types with a less frequent response to neighboring peptides. The findings indicate that the 20-mer NY-ESO-1f peptide includes multiple epitopes recognized by CD4 and CD8 T cells with distinct specificity. Of ten patients, two with lung cancer and one with esophageal cancer showed stable disease. Our study shows that the NY-ESO-1f peptide vaccine was well tolerated and elicited humoral, CD4 and CD8 T cell responses in immunized patients.

Depletion of central memory CD8+ T cells might impede the antitumor therapeutic effect of Mogamulizumab.

Regulatory T (Treg) cells are important negative regulators of immune homeostasis, but in cancers they tone down the anti-tumor immune response. They are distinguished by high expression levels of the chemokine receptor CCR4, hence their targeting by the anti-CCR4 monoclonal antibody mogamulizumab holds therapeutic promise. Here we show that despite a significant reduction in peripheral effector Treg cells, clinical responses are minimal in a cohort of patients with advanced CCR4-negative solid cancer in a phase Ib study (NCT01929486). Comprehensive immune-monitoring reveals that the abundance of CCR4-expressing central memory CD8+ T cells that are known to play roles in the antitumor immune response is reduced. In long survivors, characterised by lower CCR4 expression in their central memory CD8+ T cells possessed and/or NK cells with an exhausted phenotype, cell numbers are eventually maintained. Our study thus shows that mogamulizumab doses that are currently administered to patients in clinical studies may not differentiate between targeting effector Treg cells and central memory CD8+ T cells, and dosage refinement might be necessary to avoid depletion of effector components during immune therapy.

Pre-exposure immunization against rabies using Japanese rabies vaccine following the WHO recommended schedule.

We examined the efficacy and safety of the Japanese purified chick embryo cell rabies vaccine (PCEC-K) when administered on days 0, 7, and 28, as recommended by the WHO. Post-vaccination serum samples were obtained from 53 human subjects, and rabies antibody titers were determined by a combination of enzyme-linked immunosorbent assay (ELISA) and neutralizing antibody (NA) assay. By day 42 of the experiment, which was 2 weeks after the third dose, all subjects had developed NA titers of 0.5 IU/ml or higher. The geometric mean titers of ELISA antibody and NA were 3.8 EU/ml and 5.7 IU/ml, respectively. Overall, the vaccine was well tolerated by all subjects. These results suggest that PCEC-K used for pre-exposure immunization according to the WHO schedule is as immunogenic and effective as the current pre-exposure immunization regimen in Japan, which consists of vaccines administered on days 0, 28, and 180. An accelerated schedule would be of great advantage to Japanese travelers, who could complete the required three doses for primary immunization in 1 month.

Identification of CCDC62-2 as a novel cancer/testis antigen and its immunogenicity.

Cancer/testis (CT) antigens are expressed in normal germ line tissues and various cancers. They are considered promising target molecules for immunotherapy for patients with various cancers. To identify CT antigens, we performed serological identification of antigens by recombinant expression cloning. The humoral immune response of cancer patients against a newly defined antigen was analyzed. A testicular cDNA library was immunoscreened with serum obtained from a gastric adenocarcinoma patient whose primary cancer had regressed once and most liver metastases had disappeared transiently. We isolated 55 positive cDNA clones comprising 23 different genes. They included 4 genes with testis-specific expression profiles in the Unigene database, including coiled-coil domain containing 62 (CCDC62). RT-PCR analysis showed that the expression of 2 splice variants of CCDC62 was restricted to the testis in normal adult tissues. In malignant tissues, CCDC62 variant 2 (CCDC62-2) was aberrantly expressed in a variety of cancers, including stomach cancer. A serological survey of 191 cancer patients with a range of different cancers by ELISA revealed antibodies to CCDC62-2 in 13 patients, including stomach cancer. None of the 41 healthy donor serum samples were reactive in the same test. The serum reaction against CCDC62-2 was confirmed by western blot. CCDC62-2 is a CT antigen that is immunogenic in cancer patients.

Capsular type and antibiotic resistance in Streptococcus agalactiae isolates from patients, ranging from newborns to the elderly, with invasive infections.

Streptococcus agalactiae isolates (n = 189) from patients with invasive infections were analyzed for capsular type by PCR, for antimicrobial susceptibility, and for the presence of resistance genes. In contrast to the predominance of capsular type III in children, types Ib and V were most common among adults. All 45 levofloxacin-resistant strains had two amino acid substitutions, Ser(81)Leu in the gyrA gene and Ser(79)Phe in the parC gene, and showed similar pulsed-field gel electrophoresis patterns.

Correlation of high and decreased NY-ESO-1 immunity to spontaneous regression and subsequent recurrence in a lung cancer patient.

We show correlation between strong and decreased NY-ESO-1-specific immunity with spontaneous regression and subsequent recurrence, respectively, in a long-surviving patient with an NY-ESO-1-expressing lung adenocarcinoma. An integrated immune response consisting of IgG antibody, as well as CD4 and CD8 T cells, against NY-ESO-1 was observed at the time of spontaneous regression of multiple pleural metastases. After tumor dormancy for 3 years, the tumor started to progress. IgG antibody levels and the number of CD4 and CD8 T cells against NY-ESO-1 decreased, but were still detectable. On the other hand, the number of Foxp3+ CD25 high T regulatory cells gradually increased. The findings suggest the relevance of the NY-ESO-1 immune response and its regulation by Foxp3+ CD25 high T regulatory cells in the clinical course of this lung cancer patient.

Analysis of peripheral and local anti-tumor immune response in esophageal cancer patients after NY-ESO-1 protein vaccination.

NY-ESO-1 antigen is a prototype of a class of cancer/testis antigens. We carried out a clinical trial using NY-ESO-1 whole protein as a cancer vaccine for 13 advanced cancer patients. We have recently reported that vaccine elicited humoral and cellular immune responses in 9 cancer patients including 4 esophageal cancer patients, and clinical responses were also observed in 4 of 5 evaluable patients. In this study, we analyzed the responses in 8 esophageal cancer patients including 4 newly enrolled patients. Patients were injected subcutaneously at biweekly intervals with NY-ESO-1 recombinant protein formulated with cholesterol-bearing hydrophobized pullulan. Induction of antibody, and CD4 and CD8 T-cell responses were observed in 7, 7 and 6 patients, respectively, out of 8 patients. 1 PR, 2 SD and 2 mixed clinical responses were observed in 6 evaluable patients. No significant adverse events were observed. Furthermore, we analyzed NY-ESO-1 and MHC class I expression and the infiltration of immune cells into tumor samples obtained before and after vaccination from 4 patients by immunohistochemistry. The results showed 2 patients with disappearance of CD4 and CD8 T-cell infiltration, 1 patient with increase in the number of CD68(+) macrophages and 1 patient with tumor antigen loss in the progressive tumors following vaccinations. The induction of NY-ESO-1 immunity and some preferable clinical outcomes were observed in esophageal cancer patients by vaccination with NY-ESO-1. However, the tumors grew eventually by various mechanisms after vaccination.

Identification of a CD4 T-cell epitope in tumor rejection antigen RLakt on BALB/c radiation-leukemia RL male 1.

We have previously shown that the RLakt antigen was predominantly recognized by CD8 cytotoxic T lymphocytes (CTL) in RL male 1-bearing or -rejected syngeneic BALB/c mice. CD8 CTL were directed to the octamer pRL1a peptide IPGLPLSL of which recognition was H-2L(d)-restricted. In this study, we identified a CD4 T-cell epitope peptide in the tumor rejection antigen RLakt on BALB/c radiation-leukemia RL male 1. Analyses of the recognition of a bulk CD4 T-cell line using several recombinant RLakt proteins suggested the presence of multiple CD4 T-cell epitopes in the molecule. However, cloning from a bulk CD4 T-cell line resulted in only two clones from 200 wells seeded at three cells per well, and those two CD4 T-cell clones recognized the same epitope peptide in RLakt. The epitope peptide was 14-mer p12-25, AYREETLSIIPGLP, and its recognition was H-2IA(d)-restricted. This sequence overlapped with the CD8 T-cell epitope pRL1a in its N-terminal 5 amino acid residues. The relationship of the epitope to the pRL1a peptide predominantly recognized by CD8 CTL suggests that the 14-mer epitope is predominantly recognized by CD4 T-cells.