Molecular pathological approaches to human tumor immunology

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.

Fundamental and Essential Knowledge for Pathologists Engaged in the Research and Practice of Immune Checkpoint Inhibitor-Based Cancer Immunotherapy

Extensive research over 100 years has demonstrated that tumors can be eliminated by the autologous immune system. Without doubt, immunotherapy is now a standard treatment along with surgery, chemotherapy, and radiotherapy; however, the field of cancer immunotherapy is continuing to develop. The current challenges for the use of immunotherapy are to enhance its clinical efficacy, reduce side effects, and develop predictive biomarkers. Given that histopathological analysis provides molecular and morphological information on humans in vivo, its importance will continue to grow. This review article outlines the basic knowledge that is essential for the research and daily practice of immune checkpoint inhibitor-based cancer immunotherapy from the perspective of histopathology.

Immune evasion by cancer stem cells

Tumor immunity represents a new avenue for cancer therapy. Immune checkpoint inhibitors have successfully improved outcomes in several tumor types. In addition, currently, immune cell-based therapy is also attracting significant attention. However, the clinical efficacy of these treatments requires further improvement. The mechanisms through which cancer cells escape the immune response must be identified and clarified. Cancer stem cells (CSCs) play a central role in multiple aspects of malignant tumors. CSCs can initiate tumors in partially immunocompromised mice, whereas non-CSCs fail to form tumors, suggesting that tumor initiation is a definitive function of CSCs. However, the fact that non-CSCs also initiate tumors in more highly immunocompromised mice suggests that the immune evasion property may be a more fundamental feature of CSCs rather than a tumor-initiating property. In this review, we summarize studies that have elucidated how CSCs evade tumor immunity and create an immunosuppressive milieu with a focus on CSC-specific characteristics and functions. These profound mechanisms provide important clues for the development of novel tumor immunotherapies.

Immunohistological analysis of pancreatic carcinoma after vaccination with survivin 2B peptide: Analysis of an autopsy series

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of cancer by providing new options in addition to existing therapies. However, peptide vaccination therapies still represent an attractive approach, because of the antigen specificity. We identified survivin 2B peptide (SVN-2B), a 9-mer antigenic peptide encoded by survivin, and an SVN-2B peptide vaccine-based phase II randomized clinical trial targeting unresectable and refractory pancreatic carcinoma was undertaken. The SVN-2B peptide vaccine did not have any statistically significant clinical benefits in that study. Therefore, we undertook an autopsy study to analyze the immune status of the pancreatic cancer lesions at the histological level. Autopsies were carried out in 13 patients who had died of pancreatic cancer, including 7 who had received SVN-2B peptide vaccination and 6 who had not, as negative controls. The expression of immune-related molecules was analyzed by immunohistochemical staining. Cytotoxic T lymphocytes were analyzed by tetramer staining and enzyme-linked immunospot assay. Histological analysis revealed dense infiltration of CD8+ T cells in some lesions in patients who had received the SVN-2B peptide vaccine. A high rate of programmed cell death ligand 1 expression in cancer cells was observed in these cases, indicating that CTLs were induced by SVN-2B peptide vaccination and had infiltrated the lesions. The lack of a significant antitumor effect was most likely attributable to the expression of immune checkpoint molecules. These findings suggest that the combination of a tumor-specific peptide vaccine and an ICI might be a promising approach to the treatment of pancreatic carcinoma in the future.

Immune responses to human cancer stem-like cells/cancer-initiating cells

Cancer stem‐like cells (CSC)/cancer‐initiating cells (CIC) are defined as minor subpopulations of cancer cells that are endowed with properties of higher tumor‐initiating ability, self‐renewal ability and differentiation ability. Accumulating results of recent studies have revealed that CSC/CIC are resistant to standard cancer therapies, including chemotherapy, radiotherapy and molecular targeting therapy, and eradiation of CSC/CIC is, thus, critical to cure cancer. Cancer immunotherapy is expected to become the “fourth” cancer therapy. Cytotoxic T lymphocytes (CTL) play an essential role in immune responses to cancers, and CTL can recognize CSC/CIC in an antigen‐specific manner. CSC/CIC express several tumor‐associated antigens (TAA), and cancer testis (CT) antigens are reasonable sources for CSC/CIC‐targeting immunotherapy. In this review article, we discuss CSC/CIC recognition by CTL, regulation of immune systems by CSC/CIC, TAA expression in CSC/CIC, and the advantages of CSC/CIC‐targeting immunotherapy.

Safety and efficacy study of nasopharyngeal cancer stem cell vaccine

In this trial, nasopharyngeal cancer stem cells (CSCs) were separated and cultured to produce a vaccine; its safety and efficacy were prospectively evaluated in low-, medium-, and high-dose groups. Between April and September 2014, we enrolled 90 patients who met the enrolment criteria, and assigned them to three groups (n=30). Throughout the trial, injection site reaction was the most common reaction (81%), and fever was least common (31%); however, there was no difference among the three groups. When the immune responses pre- and post-vaccination were compared, we found that the CSC-specific and -nonspecific response in the medium- and high-dose groups were both significantly enhanced. This study is the first clinical trial of a nasopharyngeal CSC vaccine and preliminarily proves its safety and efficacy.

Specific targeting of a naturally presented osteosarcoma antigen, papillomavirus binding factor peptide, using an artificial monoclonal antibody

Osteosarcoma is a rare but highly malignant tumor occurring most frequently in adolescents. The prognosis of non-responders to chemotherapy is still poor, and new treatment modalities are needed. To develop peptide-based immunotherapy, we previously identified autologous cytotoxic T lymphocyte-defined osteosarcoma antigen papillomavirus binding factor (PBF) in the context of HLA-B55 and the cytotoxic T lymphocyte epitope (PBF A2.2) presented by HLA-A2. PBF and HLA class I are expressed in ∼90 and 70% of various sarcomas, respectively. However, the expression status of peptide PBF A2.2 presented by HLA-A2 on osteosarcoma cells has remained unknown because it is difficult to generate a specific probe that reacts with the HLA·peptide complex. For detection and qualification of the HLA-A*02:01·PBF A2.2 peptide complex on osteosarcoma cells, we tried to isolate a single chain variable fragment (scFv) antibody directed to the HLA-*A0201·PBF A2.2 complex using a naïve scFv phage display library. As a result, scFv clone D12 with high affinity (KD = 1.53 × 10(-9) M) was isolated. D12 could react with PBF A2.2 peptide-pulsed T2 cells and HLA-A2+PBF+ osteosarcoma cell lines and simultaneously demonstrated that the HLA·peptide complex was expressed on osteosarcoma cells. In conclusion, scFv clone D12 might be useful to select candidate patients for PBF A2.2 peptide-based immunotherapy and develop antibody-based immunotherapy.

Prognostic significance of HLA EMR8-5 immunohistochemically analyzed expression in osteosarcoma

Background

Defects in Human Leukocyte Antigen (HLA) class I antigen expression and/or function in tumor cells have been extensively investigated, because of their potential role in the escape of tumor cells from T cell recognition and destruction. The researchers evaluated HLA class I expression in tumor tissue as a prognostic factor in osteosarcoma patients and as a predictor of their survival. This retrospective cohort study was conducted at the pathology laboratory of Ain Shams University Hospital, and Ain Shams University Specialized Hospital during the period between January 2009 and January 2012.

Methods

The researchers investigated HLA class I expression in primary osteosarcoma by immunohistochemistry using EMR8-5 mAbs. Furthermore, researchers evaluated the correlation between HLA class I expression and the clinicopathological status and outcome in formalin fixed paraffin embedded tissues from thirty six (36) patients with osteosarcoma.

Results

A high expression of HLA class I was detected in 18 (50) % of tumor samples examined; while tumors with low or negative expression represented 9 (25%) cases each. Data indicate that the overall survival rate of patients with tumors highly expressing HLA class I was significantly higher than those with low or negative expression.

Conclusion

Down-regulation of class I antigen expression is associated with features of aggressive disease and a poorer prognosis. Therefore, it is imperative to identify HLA as a prognostic factor at the time of diagnosis to detect chemotherapy-resistant tumors and to generate a modified treatment regimen.

Virtual slides

The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1159334857109547.

LOH in the HLA class I region at 6p21 is associated with shorter survival in newly diagnosed adult glioblastoma

PURPOSE

Glioblastoma (GBM) shows downregulated expression of human leukocyte antigen (HLA) class I, thereby escaping from cytotoxic T cells and limiting the efficacy of immunotherapy. Loss of heterozygosity (LOH) of HLA class I (6p21) and/or β-2 microglobulin (B2m) (15q21) regions represents irreversible downregulation. In this study, we examined the prevalence of these LOH events and their relations with overall survival in GBM.

EXPERIMENTAL DESIGN

In a cross-sectional analysis on 60 adult patients with GBM, DNA from formalin-fixed, paraffin-embedded specimens were evaluated for 10 microsatellite regions of HLA class I, B2m, HLA class II, HLA class III, and 6q by PCR as well as immunohistochemical evaluation of HLA class I expression and CD8(+) T-cell infiltration.

RESULTS

LOH in HLA class I, B2m, HLA class II, HLA class III, and 6q regions was present in 41.4%, 18.2%, 9.4%, 77.8%, and 36.0% of informative cases, respectively. LOH of HLA class I was associated with shorter overall survival (HR = 4.89, P = 0.0078). HLA class I was downregulated in 22% to 43% of cases based on immunohistochemistry. Cases that displayed negative staining were significantly younger. HLA class I expression correlated with intratumoral CD8(+) T-cell infiltration.

CONCLUSION

LOH in the HLA class I region is frequent in adult GBMs. The association of shorter survival with LOH in this region suggests a crucial role for these genes in immunosurveillance.

Elevated circulating CD19+ lymphocytes predict survival advantage in patients with gastric cancer

BACKGROUND

Circulating lymphocyte subsets reflect the immunological status and might therefore be a prognostic indicator in cancer patients. Our aim was to evaluate the clinical significance of circulating lymphocyte subset in gastric cancer (GC) cases.

METHODS

A retrospective study on a prevalent cohort of 846 GC patients hospitalized at Hospital from Aug 2006 to Jul 2010 was conducted. We calculated the patient's disease free survival (DFS) after first hospital admission, and hazard ratios (HR) from the Cox proportional hazards model.

RESULTS

Our findings indicated a significantly decreased percentage of CD3+, and CD8+ cells, a significantly increased proportion of CD4+, CD19+, CD44+, CD25+, NK cells, and an increased CD4+/CD8+ ratio in GC patients as compared with healthy controls (all P<0.05). Alteration of lymphocyte subsets was positively correlated with sex, age, smoking, tumor stage and distant metastasis of GC patients (all P<0.05). Follow-up analysis indicated significantly higher DFS for patients with high circulating CD19+ lymphocytes compared to those with low CD19+ lymphocytes (P=0.037), with CD19+ showing an important cutoff of 7.91± 2.98%.

CONCLUSION

Circulating lymphocyte subsets in GC patients are significantly changed, and elevated CD19+ cells may predict a favorable survival.

FOXM1 (Forkhead box M1) in tumorigenesis: overexpression in human cancer, implication in tumorigenesis, oncogenic functions, tumor-suppressive properties, and target of anticancer therapy

FOXM1 (Forkhead box M1) is a typical proliferation-associated transcription factor and is also intimately involved in tumorigenesis. FOXM1 stimulates cell proliferation and cell cycle progression by promoting the entry into S-phase and M-phase. Additionally, FOXM1 is required for proper execution of mitosis. In accordance with its role in stimulation of cell proliferation, FOXM1 exhibits a proliferation-specific expression pattern and its expression is regulated by proliferation and anti-proliferation signals as well as by proto-oncoproteins and tumor suppressors. Since these factors are often mutated, overexpressed, or lost in human cancer, the normal control of the foxm1 expression by them provides the basis for deregulated FOXM1 expression in tumors. Accordingly, FOXM1 is overexpressed in many types of human cancer. FOXM1 is intimately involved in tumorigenesis, because it contributes to oncogenic transformation and participates in tumor initiation, growth, and progression, including positive effects on angiogenesis, migration, invasion, epithelial-mesenchymal transition, metastasis, recruitment of tumor-associated macrophages, tumor-associated lung inflammation, self-renewal capacity of cancer cells, prevention of premature cellular senescence, and chemotherapeutic drug resistance. However, in the context of urethane-induced lung tumorigenesis, FOXM1 has an unexpected tumor suppressor role in endothelial cells because it limits pulmonary inflammation and canonical Wnt signaling in epithelial lung cells, thereby restricting carcinogenesis. Accordingly, FOXM1 plays a role in homologous recombination repair of DNA double-strand breaks and maintenance of genomic stability, that is, prevention of polyploidy and aneuploidy. The implication of FOXM1 in tumorigenesis makes it an attractive target for anticancer therapy, and several antitumor drugs have been reported to decrease FOXM1 expression.

Immunotherapeutic benefit of α-interferon (IFNα) in survivin2B-derived peptide vaccination for advanced pancreatic cancer patients

Survivin, a member of the inhibitor of apoptosis protein (IAP) family containing a single baculovirus IAP repeat domain, is highly expressed in cancerous tissues but not in normal counterparts. Our group identified an HLA-A24-restricted antigenic peptide, survivin-2B80-88 (AYACNTSTL), that is recognized by CD8 + CTLs and functions as an immunogenic molecule in patients with cancers of various histological origins such as colon, breast, lung, oral, and urogenital malignancies. Subsequent clinical trials with this epitope peptide alone resulted in clinical and immunological responses. However, these were not strong enough for routine clinical use as a therapeutic cancer vaccine, and our previous study of colon cancer patients indicated that treatment with a vaccination protocol of survivin-2B80-88 plus incomplete Freund's adjuvant (IFA) and α-interferon (IFNα) conferred overt clinical improvement and enhanced the immunological responses of patients. In the current study, we further investigated whether this vaccination protocol could efficiently provide not only improved immune responses but also better clinical outcomes for advanced pancreatic cancers. Tetramer and enzyme-linked immunosorbent spot analysis data indicated that more than 50% of the patients had positive clinical and immunological responses. In contrast, assessment of treatment with IFNα only to another group of cancer patients resulted in no obvious increase in the frequency of survivin-2B80-88 peptide-specific CTLs. Taken together, our data clearly indicate that a vaccination protocol of survivin-2B80-88 plus IFA and IFNα is very effective and useful in immunotherapy for this type of poor-prognosis neoplasm. This trial was registered with the UMIN Clinical Trials Registry, no. UMIN000000905.

Heat shock enhances the expression of cytotoxic granule proteins and augments the activities of tumor-associated antigen-specific cytotoxic T lymphocytes

Focal inflammation causes systemic fever. Cancer hyperthermia therapy results in shrinkage of tumors by various mechanisms, including induction of adaptive immune response. However, the physiological meaning of systemic fever and mechanisms of tumor shrinkage by hyperthermia have not been completely understood. In this study, we investigated how heat shock influences the adaptive immune system. We established a cytotoxic T lymphocyte (CTL) clone (#IM29) specific for survivin, one of the tumor-associated antigens (TAAs), from survivin peptide-immunized cancer patients' peripheral blood, and the CTL activities were investigated in several temperature conditions (37-41 °C). Cytotoxicity and IFN-γ secretion of CTL were greatest under 39 °C condition, whereas they were minimum under 41 °C. To address the molecular mechanisms of this phenomenon, we investigated the apoptosis status of CTLs, expression of CD3, CD8, and TCRαβ by flow cytometry, and expression of perforin, granzyme B, and Fas ligand by western blot analysis. The expression of perforin and granzyme B were upregulated under temperature conditions of 39 and 41 °C. On the other hand, CTL cell death was induced under 41 °C condition with highest Caspase-3 activity. Therefore, the greatest cytotoxicity activity at 39 °C might depend on upregulation of cytotoxic granule proteins including perforin and granzyme B. These results suggest that heat shock enhances effector phase of the adaptive immune system and promotes eradication of microbe and tumor cells.

HSP DNAJB8 controls tumor-initiating ability in renal cancer stem-like cells

Cancer stem-like cells (CSC) are a small population of cancer cells with superior tumor initiating, self-renewal, and differentiation properties. In this study, we show that the cancer-testis antigen and HSP40 family member DNAJB8 contributes to the CSC phenotype in renal cell carcinoma (RCC). DNAJB8 overexpression increased the percentage of side population (SP) cells representing CSCs in RCC cells, enhancing their tumor-initiating ability. Conversely, attenuation of DNAJB8 decreased SP cells and reduced tumor-initiating ability. The utility of DNAJB8 as an immunologic target was established in DNA vaccination experiments. Compared with immunization with the tumor-associated antigen survivin, which was expressed in both CSCs and non-CSCs in RCC, immunization with Dnajb8 expression plasmids yielded stronger antitumor effects. Together, our findings suggest that DNAJB8 plays a role in CSC maintenance and that it offers a candidate for CSC-targeting immunotherapy in RCC.

Clinical implication of HLA class I expression in breast cancer

BACKGROUND

Human leukocyte antigen (HLA)-class I molecules on tumor cells have been regarded as crucial sites where cytotoxic T lymphocytes (CTL) can recognize tumor-specific antigens and are strongly associated with anti-tumor activity. However, the clinical impact of HLA class I expression in breast cancer has not been clarified.

METHODS

A total of 212 breast cancer patients who received curative surgery from 1993 to 2003 were enrolled in the current study. HLA class I expression was examined immunohistochemically using an anti-HLA class I monoclonal antibody. The correlation between HLA class I positivity and clinical factors was analyzed.

RESULTS

The downregulation of HLA class I expression in breast cancer was observed in 69 patients (32.5%). HLA class I downregulation was significantly associated with nodal involvement (p < 0.05), TNM stage (p < 0.05), lymphatic invasion (p < 0.01), and venous invasion (p < 0.05). Patients with preserved HLA class I had significantly better disease-free interval (DFI) than those with loss of HLA class I (p < 0.05). However, in multivariable analysis, HLA class I was not selected as one of the independent prognostic factors of disease-free interval.

CONCLUSION

The examination of HLA class I expression is useful for the prediction of tumor progression and recurrent risk of breast cancer via the antitumor immune system.

Oral administration of immunopotentiator from Pantoea agglomerans 1 (IP-PA1) improves the survival of B16 melanoma-inoculated model mice

To investigate the usefulness of the immunopotentiator from Pantoea agglomerans 1 (IP-PA1) as a supportive drug in melanoma therapy, we analyzed the immunological effects of IP-PA1 on melanoma-inoculated model mice. Oral administration of IP-PA1 increased the serum levels of tumor necrosis factor (TNF)-α at 2 h after the administration and interferon (IFN)-γ and IL-12 at 12 h after the administration in naïve BALB/cCrSlc mice as evaluated by ELISA. IP-PA1 did not affect the proliferation of melanoma cells directly determined by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. Combinatory treatment of IP-PA1 with doxorubicin for 9 days increased the serum levels of IFN-γ and IL-12 by 71.0 and 15.3%, respectively, compared to the treatment of doxorubicin alone in melanoma-bearing C57BL/6NCrSlc mice as evaluated by ELISA. It also increased the proportion of natural killer (NK) cells and the ratio of CD4(+) to CD8(+) T cells in the spleen from 6.1 ± 0.3 to 7.4 ± 0.5% and from 1.25 ± 0.03 to 1.38 ± 0.04, respectively, compared to the treatment of doxorubicin alone as analyzed by flow cytometry. The mean survival period of melanoma-bearing, doxorubicin treated mice was prolonged from 31.4 ± 7.1 to 35.3 ± 8.4, 51.1 ± 5.4, and 45.0 ± 8.4 days by combinatory treatment of IP-PA1 at the daily doses of 0.1, 0.5, and 1 mg/kg, respectively. In conclusion, the results of the present study suggest the usefulness of IP-PA1 as a supportive drug in melanoma therapy.

Chimeric DNA Vaccines against ErbB2+ Carcinomas: From Mice to Humans

DNA vaccination exploits a relatively simple and flexible technique to generate an immune response against microbial and tumor-associated antigens (TAAs). Its effectiveness is enhanced by the application of an electrical shock in the area of plasmid injection (electroporation). In our studies we exploited a sophisticated electroporation device approved for clinical use (Cliniporator, IGEA, Carpi, Italy). As the target antigen is an additional factor that dramatically modulates the efficacy of a vaccine, we selected ErbB2 receptor as a target since it is an ideal oncoantigen. It is overexpressed on the cell membrane by several carcinomas for which it plays an essential role in driving their progression. Most oncoantigens are self-tolerated molecules. To circumvent immune tolerance we generated two plasmids (RHuT and HuRT) coding for chimeric rat/human ErbB2 proteins. Their immunogenicity was compared in wild type mice naturally tolerant for mouse ErbB2, and in transgenic mice that are also tolerant for rat or human ErbB2. In several of these mice, RHuT and HuRT elicited a stronger anti-tumor response than plasmids coding for fully human or fully rat ErbB2. The ability of heterologous moiety to blunt immune tolerance could be exploited to elicit a significant immune response in patients. A clinical trial to delay the recurrence of ErbB2+ carcinomas of the oral cavity, oropharynx and hypopharynx is awaiting the approval of the Italian authorities.

Cytotoxic T lymphocytes efficiently recognize human colon cancer stem-like cells

Cancer stem-like cells (CSCs) and tumor-initiating cells (TICs) are a small population of cancer cells that share three properties: tumor initiating ability, self-renewal, and differentiation. These properties suggest that CSCs/TICs are essential for tumor maintenance, recurrence, and distant metastasis. Here, we show that cytotoxic T lymphocytes (CTLs) specific for the tumor-associated antigen CEP55 can efficiently recognize colon CSCs/TICs both in vitro and in vivo. Using Hoechst 33342 dye staining, we isolated CSCs/TICs as side population (SP) cells from colon cancer cell lines SW480, HT29, and HCT15. The SP cells expressed high levels of the stem cell markers SOX2, POU5F1, LGR5, and ALDH1A1 and showed resistance to chemotherapeutic agents such as irinotecan or etoposide.To evaluate the susceptibility of SP cells to CTLs, we used CTL clone 41, which is specific for the CEP55-derived antigenic peptide Cep55/c10orf3_193 (10) (VYVKGLLAKI). The SP cells expressed HLA class I and CEP55 at the same level as the main population cells. The SP cells were susceptible to CTL clone 41 at the same level as main population cells. Furthermore, adoptive transfer of CTL clone 41 inhibited tumor growth of SW480 SP cells in vivo. These observations suggest that Cep55/c10orf3_193(10) peptide-based cancer vaccine therapy or adoptive cell transfer of the CTL clone is a possible approach for targeting chemotherapy-resistant colon CSCs/TICs.

Immunogenic enhancement and clinical effect by type-I interferon of anti-apoptotic protein, survivin-derived peptide vaccine, in advanced colorectal cancer patients

We previously identified a human leukocyte antigen (HLA)-A24-restricted antigenic peptide, survivin-2B80-88, recognized by CD8+ cytotoxic T lymphocytes (CTL). Subsequently, we attempted clinical trials with this epitope peptide alone for some malignancies, resulting in clinical and immunological responses, although their potential was not strong enough for routine clinical use as a cancer vaccine. In the current study, to assess whether immunogenicity of the survivin-2B80-88 peptide could be enhanced with other vaccination protocols, we performed clinical trials in advanced colon cancer patients with two vaccination protocols: (i) survivin-2B80-88 plus incomplete Freund's adjuvant (IFA); and (ii) survivin-2B80-88 plus IFA and a type-I interferon (IFN), IFNα. Our data clearly indicated that, although the effect of survivin-2B80-88 plus IFA was not significantly different from that with survivin-2B80-88 alone, treatment with the vaccination protocol of survivin-2B80-88 plus IFA and IFNα resulted in clinical improvement and enhanced immunological responses of patients. Tetramer analysis of survivin-2B80-88 peptide-specific CTL demonstrated that such CTL were increased at least twofold after vaccination with this protocol in four of eight patients. In these patients, enzyme-linked immunosorbent spot (ELISPOT) results were also enhanced. Subsequent study of single-cell clone separation by cell sorting of peptide-specific CTL showed that each CTL clone was indeed not only peptide-specific but also cytotoxic against human cancer cells in the context of the expression of both HLA-A24 and survivin molecules. Taken together, these results indicate that vaccination of colon cancer patients with survivin-2B80-88 plus IFA and IFNα can be considered to be a very potent immunotherapeutic regimen, and that this protocol might work for other cancers.

Hepatitis C virus-specific CD8+ T cell frequencies are associated with the responses of pegylated interferon-α and ribavirin combination therapy in patients with chronic hepatitis C virus infection

AIM

  Hepatitis C virus (HCV)-specific cytotoxic T lymphocytes (CTLs) play critical roles in elimination of the HCV-infected hepatocytes. However, the mechanism of HCV elimination by pegylated interferon-α (peg-IFNα) plus ribavirin is not fully understood. We examined HCV-specific CTL responses during this combination therapy.

METHODS

  CD8+ T cells were isolated from 16 HCV infected patients treated by this combination therapy and were subjected to IFN-γ enzyme-linked immunospot (ELISPOT) assay.

RESULTS

  The numbers of IFN-γ spots against HCV Core or NS3 protein-derived peptides in HCV patients before treatment were similar to those in healthy donors, and those in HCV patients significantly increased 4 weeks after the initiation of combination therapy. All HCV Core or NS3 proteins-derived peptides specific CD8+ T cells responses in pre-treated patients were not associated with ALT levels and HCV viral loads of HCV patients before treatment. And those in pre-treated patients were similar between sustained virologic responder (SVR) patients and non-SVR patients. Significant increase of HCV Core or NS3 proteins-derived peptides specific CD8+ T cells responses between before and 4 weeks after this combination therapy were observed in SVR patients, but not in non-SVR patients.

CONCLUSIONS

  These results demonstrated that significant increase of HCV-specific CD8+ T cells at 4 weeks after the initiation of IFN treatment might be associated with the elimination of HCV. Our findings suggest that the reactivity against HCV Core and NS3 proteins-derived peptides might be useful in predicting the clinical outcome of the combination therapy of peg-IFNα and ribavirin.

Prognostic significance of HLA class I expression in Ewing's sarcoma family of tumors

BACKGROUND

Ewing's sarcoma family of tumors (ESFT) is one of the most malignant groups of tumors in young people. Human leukocyte antigen (HLA) class I displays endogenously processed peptides to CD8+ T lymphocytes and has a key role for host immune surveillance. In ESFT, the investigation concerning both HLA class I expression and T-cell infiltration has yet to be reported.

METHODS

Biopsy specimens from 28 ESFT patients were evaluated by immunohistochemistry with the anti-HLA class I monoclonal antibody (mAb) EMR8-5 and anti-CD8 mAb, respectively.

RESULTS

Expression of HLA class I was negative in 10 tumors and down-regulated in 22 tumors. The status of CD8+ T cell infiltration was closely associated with the expression levels of HLA class I. ESFT patients with down-regulated or negative expression of HLA class I showed significantly poorer survival than the rest of the patients.

CONCLUSIONS

Our results suggested that CD8+ T cell-mediated immune response restricted by HLA class I might play an important role in immune surveillance of ESFT, and we revealed for the first time that the status of HLA class I expression affects the survival of the patients with ESFT.

Immune response against tumor antigens expressed on human cancer stem-like cells/tumor-initiating cells

Cancer stem-like cells (CSCs)/tumor-initiating cells (TICs) are a small population of cancer cells that have the properties of tumor-initiating ability, self-renewal and differentiation. These properties suggest that CSCs/TICs are essential for tumor maintenance, recurrence and distant metastasis. Thus, elimination of CSCs/TICs is essential to cure malignant diseases. However, there are several studies reporting that CSCs/TICs are more resistant to standard cancer therapies, including chemotherapy and radiotherapy, than non-CSC/TIC populations. How then, can we eliminate CSCs/TICs? Immunotherapy might be the possible answer. In recent analysis, innate immunity (natural killer cells and gammadeltaT cells) and also adaptive immunity (cytotoxic T lymphocyte-based cellular immunity and antibody-based humoral immunity) can recognize CSCs/TICs in vitro efficiently. Furthermore, CSC/TIC-specific monoclonal antibody therapies are also efficient in vivo. In this article, we describe the potency, possibilities and problems of CSC/TIC-targeting immunotherapy.

Immunity to stemness genes in human cancer

A growing body of data points to not only intraclonal heterogeneity and hierarchy of growth potential, but also plasticity of cellular differentiation within human tumors. Recent studies have also identified surprising overlap between pathways that regulate pluripotency in embryonal stem (ES) cells and oncogenesis. While there is a long history of targeting embryonal tissues toward cancer vaccines, recent identification of crucial stemness pathways in ES cells as well as putative cancer stem cells (CSCs) provides novel opportunities for antigen-specific targeted therapy. Here we discuss recent insights into the capacity of the immune system to target these pathways. Immunologic targeting of pathways associated with stemness has implications for both immune regulation of tumor growth as well as regenerative therapies with embryonal stem cells.

HLA class I molecules reflect an altered host proteome after influenza virus infection

Class I HLA sample and display peptides from thousands of endogenous proteins at the cell surface. During infection, the influenza virus modifies the host cell proteome by triggering host antiviral responses, hijacking host processes, and inhibiting host mRNA processing. In turn, the catalog of HLA class I peptides that decorate the surface of an infected cell is positioned to reflect an altered host cell proteome. To understand the host-encoded peptides presented by class I molecules after influenza infection, we compared by mass spectrometry (MS) the peptides eluted from the HLA of naive and infected cells. We identified 20 peptide ligands unique to infected cells and 347 peptides with increased presentation after infection. Infection with different influenza strains demonstrated that proteome changes are predominantly strain-specific, with few individual cellular interactions observed for multiple viral strains. Modeling by pathway analysis, however, revealed that strain specific host peptide changes represent different routes to the same destination; host changes mediated by influenza are found predominantly clustered around HLA-B, ACTB, HSP90AB1, CDK2, and ANXA2. The class I HLA proteome scanning of influenza-infected cells therefore indicates how divergent strains of influenza pursue alternate routes to access the same host cell processes.

Human leukocyte antigen class I down-regulation in muscle-invasive bladder cancer: its association with clinical characteristics and survival after cystectomy

Using a novel monoclonal anti-pan human leukocyte antigen (HLA) class I heavy chain antibody (EMR 8-5) reacting with paraffin-embedded sections, we examined the prognostic significance of HLA class I molecules in muscle-invasive bladder cancer patients who underwent radical cystectomy. Immunohistochemical staining for HLA class I molecules with monoclonal antibody EMR 8-5 was performed on specimens from 65 clinically muscle-invasive bladder cancer patients who underwent radical cystectomy and pelvic lymph node dissection without neoadjuvant chemotherapy. We analyzed the clinicopathological and prognostic significance of HLA class I expression. Immunohistochemical analysis revealed HLA class I down-regulation in 22 (33.8%) invasive bladder cancers. This down-regulation had no correlation with clinicopathological parameters such as pathologic stage, nodal status, and grade. The recurrence-free survival of patients with HLA class I-positive tumors was significantly better than that of those with down-regulation (log rank, P = 0.0337). Multivariate analysis revealed that HLA class I expression was a significant factor influencing the recurrence-free survival of bladder cancer patients after cystectomy (P = 0.0155). Our data demonstrate that HLA class I down-regulation in tumor cells was clearly observed in about one-third of the patients. HLA class I expression could be a prognostic marker for muscle-invasive bladder cancer patients after cystectomy.

Emerging concepts in biomarker discovery; the US-Japan Workshop on Immunological Molecular Markers in Oncology

Supported by the Office of International Affairs, National Cancer Institute (NCI), the "US-Japan Workshop on Immunological Biomarkers in Oncology" was held in March 2009. The workshop was related to a task force launched by the International Society for the Biological Therapy of Cancer (iSBTc) and the United States Food and Drug Administration (FDA) to identify strategies for biomarker discovery and validation in the field of biotherapy. The effort will culminate on October 28th 2009 in the "iSBTc-FDA-NCI Workshop on Prognostic and Predictive Immunologic Biomarkers in Cancer", which will be held in Washington DC in association with the Annual Meeting. The purposes of the US-Japan workshop were a) to discuss novel approaches to enhance the discovery of predictive and/or prognostic markers in cancer immunotherapy; b) to define the state of the science in biomarker discovery and validation. The participation of Japanese and US scientists provided the opportunity to identify shared or discordant themes across the distinct immune genetic background and the diverse prevalence of disease between the two Nations. Converging concepts were identified: enhanced knowledge of interferon-related pathways was found to be central to the understanding of immune-mediated tissue-specific destruction (TSD) of which tumor rejection is a representative facet. Although the expression of interferon-stimulated genes (ISGs) likely mediates the inflammatory process leading to tumor rejection, it is insufficient by itself and the associated mechanisms need to be identified. It is likely that adaptive immune responses play a broader role in tumor rejection than those strictly related to their antigen-specificity; likely, their primary role is to trigger an acute and tissue-specific inflammatory response at the tumor site that leads to rejection upon recruitment of additional innate and adaptive immune mechanisms. Other candidate systemic and/or tissue-specific biomarkers were recognized that might be added to the list of known entities applicable in immunotherapy trials. The need for a systematic approach to biomarker discovery that takes advantage of powerful high-throughput technologies was recognized; it was clear from the current state of the science that immunotherapy is still in a discovery phase and only a few of the current biomarkers warrant extensive validation. It was, finally, clear that, while current technologies have almost limitless potential, inadequate study design, limited standardization and cross-validation among laboratories and suboptimal comparability of data remain major road blocks. The institution of an interactive consortium for high throughput molecular monitoring of clinical trials with voluntary participation might provide cost-effective solutions.

HLA-A*0201-restricted CTL epitope of a novel osteosarcoma antigen, papillomavirus binding factor

Background

To develop peptide-based immunotherapy for osteosarcoma, we previously identified papillomavirus binding factor (PBF) as a CTL-defined osteosarcoma antigen in the context of HLA-B55. However, clinical application of PBF-based immunotherapy requires identification of naturally presented CTL epitopes in osteosarcoma cells in the context of more common HLA molecules such as HLA-A2.

Methods

Ten peptides with the HLA-A*0201 binding motif were synthesized from the amino acid sequence of PBF according to the BIMAS score and screened with an HLA class I stabilization assay. The frequency of CTLs recognizing the selected PBF-derived peptide was determined in peripheral blood of five HLA-A*0201⁺ patients with osteosarcoma using limiting dilution (LD)/mixed lymphocyte peptide culture (MLPC) followed by tetramer-based frequency analysis. Attempts were made to establish PBF-specific CTL clones from the tetramer-positive CTL pool by a combination of limiting dilution and single-cell sorting. The cytotoxicity of CTLs was assessed by ⁵¹Cr release assay.

Results

Peptide PBF A2.2 showed the highest affinity to HLA-A*0201. CD8+ T cells reacting with the PBF A2.2 peptide were detected in three of five patients at frequencies from 2 × 10^-7 to 5 × 10^-6. A tetramer-positive PBF A2.2-specific CTL line, 5A9, specifically lysed allogeneic osteosarcoma cell lines that expressed both PBF and either HLA-A*0201 or HLA-A*0206, autologous tumor cells, and T2 pulsed with PBF A2.2. Five of 12 tetramer-positive CTL clones also lysed allogeneic osteosarcoma cell lines expressing both PBF and either HLA-A*0201 or HLA-A*0206 and T2 pulsed with PBF A2.2.

Conclusion

These findings indicate that PBF A2.2 serves as a CTL epitope on osteosarcoma cells in the context of HLA-A*0201, and potentially, HLA-A*0206. This extends the availability of PBF-derived therapeutic peptide vaccines for patients with osteosarcoma.