Autologous cytolytic T lymphocytes recognize a MAGE-1 nonapeptide on melanomas expressing HLA-Cw*1601

A microfluidics-enabled automated workflow of sample preparation for MS-based immunopeptidomics

Mass spectrometry (MS)-based immunopeptidomics is an attractive antigen discovery method with growing clinical implications. However, the current experimental approach to extract HLA-restricted peptides requires a bulky sample source, which remains a challenge for obtaining clinical specimens. We present an innovative workflow that requires a low sample volume, which streamlines the immunoaffinity purification (IP) and C18 peptide cleanup on a single microfluidics platform with automated liquid handling and minimal sample transfers, resulting in higher assay sensitivity. We also demonstrate how the state-of-the-art data-independent acquisition (DIA) method further enhances the depth of tandem MS spectra-based peptide sequencing. Consequently, over 4,000 and 5,000 HLA-I-restricted peptides were identified from as few as 0.2 million RA957 cells and a melanoma tissue of merely 5 mg, respectively. We also identified multiple immunogenic tumor-associated antigens and hundreds of peptides derived from non-canonical protein sources. This workflow represents a powerful tool for identifying the immunopeptidome of sparse samples.

Therapeutic Cancer Vaccines—Antigen Discovery and Adjuvant Delivery Platforms

For decades, vaccines have played a significant role in protecting public and personal health against infectious diseases and proved their great potential in battling cancers as well. This review focused on the current progress of therapeutic subunit vaccines for cancer immunotherapy. Antigens and adjuvants are key components of vaccine formulations. We summarized several classes of tumor antigens and bioinformatic approaches of identification of tumor neoantigens. Pattern recognition receptor (PRR)-targeting adjuvants and their targeted delivery platforms have been extensively discussed. In addition, we emphasized the interplay between multiple adjuvants and their combined delivery for cancer immunotherapy.

Cancer Testis Antigen, NOL4, Is an Immunogenic Antigen Specifically Expressed in Small-Cell Lung Cancer

To identify cancer/testis (CT) antigens and immunogenic proteins, immunoscreening of testicular and small-cell lung cancer cell line NCI-H889 cDNA libraries was performed using serum obtained from a small-cell lung cancer (SCLC) patient. We obtained 113 positive cDNA clones comprised of 74 different genes, designated KP-SCLC-1 through KP-SCLC-74. Of these genes, 59 genes were found to be related to cancers by EMBASE analysis. Three of these antigens, including KP-SCLC-29 (NOL4), KP-SCLC-59 (CCDC83), and KP-SCLC-69 (KIF20B), were CT antigens. RT-PCR and western blot analysis showed that NOL4 was frequently present in small-cell lung cancer cell lines (8/9, 8/9). In addition, NOL4 mRNA was weakly, or at a low frequency, or not detected in various cancer cell lines. Our results reveal that NOL4 was expressed at protein levels in small-cell lung cancer tissues (10/10) but not detected in lung adenocarcinoma and squamous cell carcinoma by immunohistochemical analysis. Serological response to NOL4 was also evaluated by western blot assay using NOL4 recombinant protein. A humoral response against NOL4 proteins was detected in 75% (33/44) of small-cell lung cancer patients and in 65% (13/20) of healthy donors by a serological western blot assay. These data suggest that NOL4 is a specific target that may be useful for diagnosis and immunotherapy in SCLC.

The ectopic expression of meiCT genes promotes meiomitosis and may facilitate carcinogenesis

Cancer meiomitosis is defined as the concurrent activation of both mitotic and meiotic machineries in neoplastic cells that confer a selective advantage together with increased genomic instability. MeiCT (meiosis-specific cancer/testis) genes that perform specialized functions in the germline events required for the first meiotic division are ectopically expressed in several cancers. Here we describe the expression profiles of meiCT genes and proteins across a number of cancers and review the proposed mechanisms that increase aneuploidy and elicit reduction division in polyploid cells. These mechanisms are centered on the overexpression and function of meiCT proteins in cancers under various conditions that includes a response to genotoxic stress. Since meiCT genes are transcriptionally repressed in somatic cells, their target offers a promising therapeutic approach with limited toxicity to healthy tissues. Throughout the review, we provide a detailed description of the roles for each gene in the context of meiosis and we discuss proposed functions and outcomes resulting from their ectopic reactivation in cancer.

Cellular immune responses against cancer-germline genes in cancers

BACKGROUND

Cancer-germline genes are a class of genes that are normally expressed in testis, trophoblast and few somatic tissues but abnormally expressed in tumor tissues. Their expression signature indicates that they can induce cellular immune responses, thus being applied as targets in cancer immunotherapy.

OBJECTIVES

To obtain the data of cellular immune responses against cancer-germline genes in cancer.

METHODS

We searched PubMed/Medline with the key words cancer-germline antigen, cancer-testis antigen, CD4+ T cell, CD8+ T cell and cancer.

RESULTS

About 40 cancer-germline genes have been shown to induce T cell specific responses in cancer patients. Melanoma, lung and breast cancer are among the mostly assessed cancer types. Several epitopes have been identified which can be used in immunotherapy of cancer.

CONCLUSION

Cellular immune responses against cancer-germline genes are indicative of appropriateness of these genes as therapeutic targets.

Molecular evolution of elements controlling HLA-C expression: Adaptation to a role as a killer-cell immunoglobulin-like receptor ligand regulating natural killer cell function

The regulatory elements controlling the transcription of the HLA-A, HLA-B, and HLA-C genes have been extensively studied and compared. However, few studies have considered regulatory differences in the HLA genes from the perspective of their role as ligands for the killer-cell immunoglobulin-like receptor (KIR) family of HLA receptors expressed by natural killer (NK) cells. HLA-C is the most recently evolved gene, and there is considerable evidence pointing to its emergence as a specialized KIR ligand playing a major role in the missing-self recognition system of NK cells. Here I evaluate gene-specific differences in regulatory elements of the HLA genes, showing alterations that are consistent with the adaptation of HLA-C to a role in NK cell regulation.

Update on Tumor Neoantigens and Their Utility: Why It Is Good to Be Different

Antitumor rejection by the immune system is a complex process that is regulated by several factors. Among these factors are the quality and quantity of mutational events that occur in cancer cells. Perhaps one of the most important types of mutations that influence antitumor immunity is the neoantigen, that is, a non-self-antigen that arises as a result of somatic mutation. Recent work has demonstrated that neoantigens hold significant promise for developing new diagnostic and therapeutic modalities. Therapeutic targeting of neoantigens is important for achieving benefit following therapy with immune checkpoint blockade agents or for cancer vaccines targeting mutations. Here, we review our understanding of neoantigens and discuss new developments in the quest to use them in cancer immunotherapy.

Immune targets and neoantigens for cancer immunotherapy and precision medicine

Harnessing the immune system to eradicate malignant cells is becoming a most powerful new approach to cancer therapy. FDA approval of the immunotherapy-based drugs, sipuleucel-T (Provenge), ipilimumab (Yervoy, anti-CTLA-4), and more recently, the programmed cell death (PD)-1 antibody (pembrolizumab, Keytruda), for the treatment of multiple types of cancer has greatly advanced research and clinical studies in the field of cancer immunotherapy. Furthermore, recent clinical trials, using NY-ESO-1-specific T cell receptor (TCR) or CD19-chimeric antigen receptor (CAR), have shown promising clinical results for patients with metastatic cancer. Current success of cancer immunotherapy is built upon the work of cancer antigens and co-inhibitory signaling molecules identified 20 years ago. Among the large numbers of target antigens, CD19 is the best target for CAR T cell therapy for blood cancer, but CAR-engineered T cell immunotherapy does not yet work in solid cancer. NY-ESO-1 is one of the best targets for TCR-based immunotherapy in solid cancer. Despite the great success of checkpoint blockade therapy, more than 50% of cancer patients fail to respond to blockade therapy. The advent of new technologies such as next-generation sequencing has enhanced our ability to search for new immune targets in onco-immunology and accelerated the development of immunotherapy with potentially broader coverage of cancer patients. In this review, we will discuss the recent progresses of cancer immunotherapy and novel strategies in the identification of new immune targets and mutation-derived antigens (neoantigens) for cancer immunotherapy and immunoprecision medicine.

Molecular cancer vaccines: Tumor therapy using antigen-specific immunizations

Vaccination against tumors promises selective destruction of malignant cells by the host's immune system. Molecular cancer vaccines rely on recently identified tumor antigens as immunogens. Tumor antigens can be applied in many forms, as genes in recombinant vectors, as proteins or peptides representing T cell epitopes.Analysis of various aspects indicates some advantage for peptide-based vaccines over the other modalities. Further refinements and extensively monitored clinical trials are necessary to advance molecular cancer vaccines from concepts into powerful therapy.

Enhancing cancer immunotherapy by intracellular delivery of cell-penetrating peptides and stimulation of pattern-recognition receptor signaling

The importance of T-cell-mediated antitumor immunity has been demonstrated in both animal models and human cancer immunotherapy. In the past 30 years, T-cell-based immunotherapy has been improved with an objective clinical response rate of up to 72%. Identification of MHC class I- and II-restricted tumor antigens recognized by tumor-reactive T cells has generated a resurgence of interest in cancer vaccines. Although clinical trials with cancer peptide/protein vaccines have only met a limited success, several phase II/III clinical trials are either completed or ongoing with encouraging results. Recent advances in immunotherapy have led to the approval of two anticancer drugs (sipuleucel-T vaccine and anti-CTLA-4 antibody) by the US FDA for the treatment of metastatic castration-resistant prostate cancer and melanoma, respectively. Intracellular delivery of antigenic peptides into dendritic cells (DCs) prolongs antigen presentation of antigen-presenting cells to T cells, thus further improving clinical efficacy of peptide/protein cancer vaccines. Because innate immune responses are critically important to provide sensing and initiating of adaptive immunity, combined use of cell-penetrating peptide vaccines with stimulation of innate immune signaling may produce potent antitumor immune responses. We will discuss the recent progress and novel strategies in cancer immunotherapy.

Use of dentritic cells pulsed with HLA-A2-restricted MAGE-A1 peptide to generate cytotoxic T lymphocytes against malignant glioma

This study developed a novel approach of targeting malignant glioma with pMAGE-A1(278-286)-specific cytotoxic T lymphocytes (CTLs) induced from the peripheral blood mononuclear cells of healthy donors by multiple stimulations with human leukocyte antigen (HLA)-A2-restricted pMAGE-A1(278-286) peptide-pulsed dentritic cells. Cytotoxic assays were performed by the colorimetric CytoTox 96 assay to analyze cytotoxic activity of the induced CTLs against various target cells. The induced CTLs showed approximately 45% specific lysis against T2pMAGE-A1(278-286) (pMAGE-A1(278-286) peptide pulsed T2 cells) and U251 (HLA-A2(+), MAGE-A1(+)) at an effector:target ratio of 40:1, and approximately 5% cytolysis against T2pHIV, A172 (HLA-A2(-), MAGE-A1(+)), K562 and T2 cells without being pulsed with peptide at any effector:target ratio. The specific killing activity of the induced CTLs against T2pMAGE-A1(278-286) and U251 was much more obvious than in any other control group (P<0.05). The cytotoxic activity against the T2pMAGE-A1(278-286) and U251 was significantly eliminated by anti-HLA class I mAb W6/32. These results suggest that pMAGE-A1(278-286) epitope may serve as a surrogate tumor antigen target of specific immunotherapy for treating HLA-A2 patients with malignant glioma.

A new MAGE-4 antigenic peptide recognized by cytolytic T lymphocytes on HLA-A24 carcinoma cells

"Cancer-germline" genes such as those of the MAGE family are expressed in many tumors and in male germline cells, but are silent in other normal tissues. They encode tumor specific antigens that are used in cancer immunotherapy trials. MAGE-4 antigens represent promising targets for cancer immunotherapy because gene MAGE-4 is expressed in more than 50% of carcinomas of the esophagus, lung, bladder, and head and neck. To identify new MAGE-4 antigenic peptides, we have folded HLA-A*2402 soluble molecules with candidate peptide NYKRCFPVI, which corresponds to amino acids 143 to151 of the MAGE-4 protein. A24/MAGE-4 multimers were used to isolate a cytolytic T cell clone that recognized the MAGE-4 peptide from the blood cells of a donor without cancer. This clone lysed specifically A24 carcinoma cells expressing MAGE-4. The antigenic peptide is processed more efficiently in tumor cells pre-treated with IFN-gamma. This MAGE-4 peptide could represent an interesting target for immunotherapy because it is presented by HLA-A24 molecules, which are widely expressed in different ethnic groups.

Expression of MAGE tumor-associated antigen in thyroid carcinomas

The 12 members of the MAGE gene family encode tumor-specific antigens that are recognized by autologous cytotoxic T lymphocytes. The MAGE genes are expressed not only in melanoma but in other malignant tumors as well. There is, however, little information on their expression in thyroid carcinomas. We studied the expression of the MAGE-3 antigen in human thyroid carcinomas to explore the possibility of specific immunotherapy using MAGE peptides. Tumor tissue samples of thyroid carcinomas were obtained from 60 patients. Standard pathohistologic analysis followed by immunohistochemistry analysis of MAGE-3 expression was performed in all patients. The overall expression rate of MAGE-3 antigen in thyroid carcinomas was 65%. According to histological types of thyroid carcinomas, expression rate of MAGE-3 antigen was as follows: 0% in anaplastic, 20% in medullary, 29% in follicular, and 80% in papillary thyroid carcinomas (p < 0.01). On the other hand, significantly higher expression of MAGE-3 antigen was observed in classical subtypes of papillary thyroid carcinomas and in small papillary tumors sized to 1 cm in diameter. These findings demonstrated that MAGE-3 antigen expression seems to be particularly high in the small, typical papillary carcinomas, thus suggesting that MAGE-3 gene abnormality is an early step in thyroid cancer progression.

A MAGE-1 antigenic peptide recognized by human cytolytic T lymphocytes on HLA-A2 tumor cells

"Cancer-germline" genes such as those of the MAGE family are expressed in many tumors and in male germline cells, but are silent in normal tissues. They encode shared tumor-specific antigens that have been used in therapeutic vaccination trials of cancer patients. It was previously demonstrated that MAGE-1 peptide KVLEYVIKV was presented by HLA-A 0201 molecules on the surface of a human breast carcinoma cell line, but no human specific CTL had been isolated so far. Here, we have used HLA-A2/MAGE-1 fluorescent multimers to isolate from blood cells three human CTL clones that recognized the MAGE-1 peptide. These clones killed efficiently HLA-A2 tumor cells expressing MAGE-1, whether or not they were treated with IFN-gamma, suggesting that the MAGE-1 antigen is processed efficiently by both the standard proteasome and the immunoproteasome. These results indicate that the MAGE-1.A2 peptide can be used for antitumoral vaccination.

Identification of the HLA-Cw*0702-restricted tumor-associated antigen recognized by a CTL clone from a lung cancer patient

PURPOSE

A large number of tumor-associated antigens have been used in vaccination trials for mainly melanomas. Our purpose of this study is to identify a novel tumor antigen useful for immunotherapy of lung cancer patients.

EXPERIMENTAL DESIGN

Analysis of an autologous tumor-specific CTL clone F2a that was established from regional lymph node lymphocytes of a patient with lung cancer (A904) by a mixed lymphocyte-tumor cell culture.

RESULTS

F2a recognized and killed autologous tumor cells (A904L), whereas it did not respond to autologous EBV-transformed B cells, phytohemagglutinin-blastoid T cells, and K562 cells. cDNA clone 31.2 was isolated by using cDNA expression cloning method as a gene encoding antigen. This gene was identical to the reported gene whose function was unknown. The antigen encoded by the cDNA was recognized by the CTL in a HLA-Cw*0702-restricted manner. Furthermore, a 9-mer peptide at positions 659 to 685 in cDNA clone 31.2 was identified as a novel epitope peptide. The CTL recognized some allogeneic cancer cell lines with HLA-Cw*0702 as well as some HLA-Cw*0702-negative cell lines when transfected with HLA-Cw*0702, thus indicating that the identified antigen was a cross-reactive antigen.

CONCLUSIONS

Although exact mechanism to process the encoded protein and present the antigen in the context of HLA class I remains to be elucidated, the CTL recognized some of tumor cells in the context of HLA-Cw*0702 but did not recognize a variety of normal cells and also autologous EBV-transformed B cells. These results indicated that the antigen identified in this study may therefore be a possible target of tumor-specific immunotherapy for lung cancer patients.

Identification of a MAGE-1 peptide recognized by cytolytic T lymphocytes on HLA-B*5701 tumors

"Cancer germline" genes such as those of the MAGE family are expressed in many tumors and in male germline cells but are silent in normal tissues. They encode shared tumor-specific antigens that have been used in therapeutic vaccination trials of cancer patients. We report the identification of a new MAGE-1-encoded peptide that is recognized by a cytolytic T-lymphocyte (CTL) clone on human leukocyte antigen (HLA)-B*5701. The sequence of the peptide, corresponding to position 102-112 of the MAGE-1 protein sequence, is ITKKVADLVGF. When tumor cells expressing MAGE-1 were transfected with HLA-B*5701, they were lyzed by the CTL clone, indicating that the peptide is processed in tumor cells and can, therefore, be used as a target for anti-tumoral vaccination.

The expression of MAGE and GAGE genes in uterine cervical carcinoma of Korea by RT-PCR with common primers

BACKGROUND

Melanoma antigen genes (MAGE) and GAGE genes are encoded by genes that are silent in virtually all normal adult tissues but are expressed in tumors from various tissues. These gene products are targets for specific immunotherapy as they are presented by HLA I molecules and recognized by autologous cytotoxic T-lymphocytes. However, the characteristics of these genes, especially in uterine cervical cancer are relatively unknown.

PURPOSE

This study evaluated the prevalence of MAGE and GAGE by reverse transcription-polymerase chain reaction (RT-PCR) with common primers and discusses clinical implications in cervical carcinoma.

MATERIALS AND METHODS

Fresh tissue from 37 cases of primary squamous cell carcinoma and normal cervical mucosa were evaluated for clinicopathologic parameters including Human Papilloma Virus (HPV)-16,18 infection by PCR, tumor stage by FIGO classification and lymph node involvement. RT-nested PCR for the MAGE and GAGE genes was performed with common primers and DNA sequencing after subcloning was used for identification of PCR products of MAGE. Formalin-fixed paraffin embedded material from the same specimen was analyzed by in situ RT-PCR for MAGE.

RESULTS

Expression of MAGE and GAGE was not observed in normal tissues. Eleven out of 37 cases expressed MAGE mRNA (29.7%): analysis of subtypes identified one case of MAGE-1, two cases of MAGE-4b, six cases of MAGE-3, and two unknown subtypes. Thirteen out of 37 cases (35.1%) expressed GAGE mRNA. No significant relationships between expression of these genes and FIGO staging, lymph node metastasis or HPV infection were found.

CONCLUSION

Expression of MAGE and GAGE may be involved in the development of uterine cervical carcinoma from intraepithelial neoplasia, although without distinct prognostic significance. MAGE and GAGE genes have the potential to be used as targets for the treatment of uterine cervical carcinoma.

A listing of human tumor antigens recognized by T cells: March 2004 update

The technological advances occurred in the last few years have led to a great increase in the number of tumor associated antigens (TAA) that are currently available for clinical applications. In this review we provide a comprehensive list of human tumor antigens as reported in the literature updated at February 2004. The list includes all T cell-defined epitopes, while excluding analogs or artificially modified epitopes, as well as virus-encoded and antibodies-recognized antigens. TAAs are listed in alphabetical order along with the epitope sequence and the HLA allele which restricts recognition by T cells. Data on the tissue distribution of each antigen are also provided together with an extensive bibliography that allows a rapid search for any additional information may be needed on each single antigen or epitope. Overall, the updated list is a database tool for clinicians, scientists and students who have an interest in the field of tumor immunology and immunotherapy.

A Nonclassical MHC Class I Molecule Restricts CTL-Mediated Rejection of a Syngeneic Melanoma Tumor

Although CTL and polymorphic, classical MHC class I molecules have well defined roles in the immune response against tumors, little is currently known regarding the participation of nonpolymorphic, nonclassical MHC class I in antitumor immunity. Using an MHC class I-deficient melanoma as a model tumor, we demonstrate that Q9, a murine MHC class Ib molecule from the Qa-2 family, expressed on the surface of tumor cells, protects syngeneic hosts from melanoma outgrowth. Q9-mediated protective immunity is lost or greatly diminished in mice deficient in CTL, including beta(2)-microglobulin knockout (KO), CD8 KO, and SCID mice. In contrast, the Q9 antitumor effects are not detectably suppressed in CD4 KO mice with decreased Th cell activity. Killing by antitumor CTL in vitro is Q9 specific and can be blocked by anti-Q9 and anti-CD8 Abs. The adaptive Q9-restricted CTL response leads to immunological memory, because mice that resist the initial tumor challenge reject subsequent challenges with less immunogenic tumor variants and show expansion of CD8(+) T cell populations with an activated/memory CD44(high) phenotype. Collectively, these studies demonstrate that a MHC class Ib molecule can serve as a restriction element for antitumor CTL and mediate protective immune responses in a syngeneic setting.

Identification of HLA-Cw6.02 and HLA-Cw7.01 allele-specific binding motifs by screening synthetic peptide libraries

Unlike HLA-A and HLA-B, few peptide epitope motifs have been reported for HLA-C molecules. However, a number of cytotoxic T-lymphocyte epitopes derived from tumor antigens that bind to HLA-C molecules have been described. Here we report peptide-binding motifs for both HLA-Cw6.02 and HLA-Cw7.01 molecules. Recombinant human HLA molecules were generated and used to screen combinatorial 9mer peptide libraries. Complexes of HLA molecules properly folded and associated with beta2-microglobulin and peptides were identified using a conformation-specific HLA class I antibody conjugated to alkaline phosphatase. In the presence of substrate, peptide beads can be readily isolated and microsequenced to determine peptide identity. Of the peptides that bound to HLA-Cw6.02 and HLA-Cw7.01, 19 and 18 peptides, respectively, were sequenced, allowing motif identification for each C allele. This is the first report of an HLA-Cw7.01 peptide motif and extends the findings of Falk et al. [(1993) Proc Natl Acad Sci USA 90:12005] for an HLA-Cw6.02 motif. Anchoring amino acids for the HLA-Cw6.02 motif were phenylalanine or tyrosine in position (P)1, arginine in P2, and an aliphatic/aromatic residue at P9. Anchoring residues for HLA-Cw7.01 were positively charged amino acids in P1 and P2. Unlike most other HLA molecules, we were unable to assign P9 an anchoring residue, and we suspect that HLA-Cw7.01 binds peptides in an unconventional manner. Additionally, preferred amino acids were identified for both molecules. Identification of HLA-Cw6.02 and HLA-Cw7.01 peptide-binding motifs makes a significant contribution to the C allele peptide-binding motifs and will allow investigators to predict, design, and test HLA-Cw6.02 and HLA-Cw7.01 engineered peptides for immunotherapy.

New MAGE-4 antigenic peptide recognized by cytolytic T lymphocytes on HLA-A1 tumor cells

'Cancer-germline' genes such as those of the MAGE family are expressed in many tumors and in male germline cells, but are silent in other normal tissues. They encode shared tumor-specific antigens, which have been used in small therapeutic vaccination trials of cancer patients. Gene MAGE-4, which is expressed in more than 50% of carcinomas of esophagus, head and neck, lung, and bladder, has two known alleles. Using PCR amplifications and digestions of the amplified product, we found that one third of the MAGE-4-positive samples expressed MAGE-4a. We folded HLA-A1 tetramers with peptide MAGE-4a169-177 EVDPASNTY, which is homologous to MAGE-1- and MAGE-3-encoded peptides recognized on HLA-A1 by cytolytic T lymphocytes. Blood lymphocytes from an individual without cancer were directly labelled with these A1/MAGE-4 tetramers. The very rare cells that were stained were sorted by flow cytometry and cloned. We isolated a cytolytic T-lymphocyte clone that lyzed specifically cells pulsed with this MAGE-4 peptide and HLA-A1 tumor cells expressing MAGE-4a, demonstrating that this antigenic peptide is processed efficiently in tumor cells. This peptide might therefore be useful for therapeutic antitumoral vaccination.

Immunopathogenic mechanisms in psoriasis

Psoriasis is a common autoimmune skin disease characterized by T cell-mediated hyperproliferation of keratinocytes. The disease has a strong but complex genetic background with a concordance of approximately 60% in monozygotic twins, and recent linkage and high resolution association studies indicate that HLA-Cw*0602 is itself a major susceptibility allele for psoriasis. Patients carrying this allele have been shown to have different clinical features and earlier age of disease onset, and patients homozygous for this allele have about 2.5 times higher disease risk than heterozygotes. Published data indicate that CD8+ T cells may play a major effector role in psoriasis. Epidermal infiltration of predominantly oligoclonal CD8+ T cells, and probably also of CD4+ T cells in the dermis, is a striking feature of chronic psoriasis lesions, indicating that these cells are responding to specific antigens. We argue that CD4+ T cells are essential for initiating and maintaining the pathogenic process of psoriasis but that cross-primed CD8+ T cells are the main effector cells responding to antigens in the HLA-Cw*0602 binding pocket of keratinocytes. It is further proposed that CD8+ T cells are involved in the control of the Th1 polarization, which is observed in psoriasis lesions, through a complex interplay between CD4+, CD8+ T cells and cross-presenting dendritic cells. It is also suggested that spontaneous remissions or fluctuations in disease activity may be determined by a balance within the lesions between effector and suppressor CD4+ and CD8+ T cells.

Clonal deletion of simian virus 40 large T antigen-specific T cells in the transgenic adenocarcinoma of mouse prostate mice: an important role for clonal deletion in shaping the repertoire of T cells specific for antigens overexpressed in solid tumors

In addition to their overexpression in cancer cells, most of the tumor-associated Ags are expressed at low but detectable levels in normal tissues. It is not clear whether the repertoire of T cells specific for unmutated tumor Ags is shaped by negative selection during T cell development. The transgenic adenocarcinoma of mouse prostate (TRAMP) model is transgenic for the SV40 large T Ag (Tag) under the control of the rat probasin regulatory elements. Although it has been established that T lymphocytes from TRAMP mice are tolerant to SV40 Tag, the mechanism of the tolerance is largely unknown. To examine whether the T cell clonal deletion is responsible for the tolerance, we crossed the TRAMP mice with mice transgenic for a rearranged TCR specific for SV40 Tag presented by the H-2K(k). Double transgenic TRAMP/TCR mice showed profound thymic deletion of SV40 Tag-reactive T cells, including a 6- to 10-fold reduction in the total thymocyte numbers and a >50-fold reduction in phenotypically mature T cells. Consistent with this finding, we observed that the SV40 Tag and endogenous mouse probasin genes are expressed at low levels in the thymus. These results demonstrate that clonal deletion is a major mechanism for tolerance to Ags previously regarded as prostate-specific, and provide direct evidence that the T cell repertoire specific for an unmutated tumor Ag can be shaped by clonal deletion in the thymus.

A MAGE-A4 peptide presented by HLA-B37 is recognized on human tumors by cytolytic T lymphocytes

'Cancer-germline' genes such as those of the MAGE family are expressed in many tumors and in male germline cells, but are silent in normal tissues. They encode shared tumor-specific antigens, which have been used in therapeutic vaccination trials of cancer patients. MAGE-A4 is expressed in more than 50% of carcinomas of esophagus, head and neck, lung, and bladder. We report here the identification of a new MAGE-A4 encoded peptide, which is recognized by a cytolytic T lymphocyte (CTL) clone on HLA-B*3701. The sequence of the peptide is SESLKMIF. It corresponds to the MAGE-A4156-163 protein sequence. When tumor cells expressing MAGE-A4 were transfected with HLA-B*3701, they were recognized by the CTL clone, demonstrating that the peptide ought to be processed in tumor cells and could therefore serve as a target for therapeutic antitumoral vaccination.

Dendritic cells in vaccination therapies of malignant diseases

Dendritic cells (DC) are the most potent APC with the unique capacity to initiate primary immune responses. For clinical use DC can be generated in vitro from CD34+ peripheral blood progenitor cells or monocytes. Vaccination of patients with cancer using DC was shown to be effective for B-cell lymphoma, renal cell carcinoma (RCC), prostate cancer and malignant melanoma. We provide evidence that patients with advanced breast and ovarian cancer can be efficiently vaccinated with autologous DC pulsed with HER-2/neu- or MUC1-derived peptides. In 5 of 10 patients, peptide-specific cytotoxic T lymphocytes (CTL) could be detected in the peripheral blood using both intracellular IFN-gamma staining and Cr-release assays. In addition, in one patient vaccinated with the MUC1-derived peptides, CEA- and MAGE-3 peptide-specific T-cell responses were detected after several vaccinations. In a second patient immunized with the HER-2/neu peptides, MUC1-specific T lymphocytes were induced after seven immunizations, suggesting that antigen spreading in vivo might occur after successful immunization with a single tumor antigen. Currently we are analyzing the effect of T-helper epitopes and IL-2 on the CTL induction using peptide pulsed DC. In this ongoing trial one patient with metastatic RCC developed a partial remission of the metastatic sites was induced after the first four vaccinations with MUC1 peptides pulsed DC, that was ongoing after the next cycles containing IL-2. Vaccine-induced peptide-specific T-cell responses in vivo were detected in the PBMNC of this patient and in peptide-specific DTH reactions. This studies demonstrate that peptide pulsed DC can be effective in cancer patients and induce significant clinical and immunological responses.

Tumor-specific shared antigenic peptides recognized by human T cells

The first tumor-specific shared antigens and the cancer-germline genes that code for these antigens were identified with antitumor cytolytic T lymphocytes obtained from cancer patients. A few HLA class I-restricted antigenic peptides were identified by this 'direct approach'. A large set of additional cancer-germline genes have now been identified by purely genetic approaches or by screening tumor cDNA expression libraries with the serum of cancer patients. As a result, a vast number of sequences are known that can code for tumor-specific shared antigens, but most of the encoded antigenic peptides have not yet been identified. We review here recent 'reverse immunology' approaches for the identification of new antigenic peptides. They are based on in vitro stimulation of naive T cells with dendritic cells that have either been loaded with a cancer-germline protein or that have been transduced with viruses carrying cancer-germline coding sequences. These approaches have led to the identification of many new antigenic peptides presented by class I or class II molecules. We also describe some aspects of the processing and presentation of these antigenic peptides.

A MAGE-3 peptide presented by HLA-B44 is also recognized by cytolytic T lymphocytes on HLA-B18

Antigens encoded by MAGE genes are of particular interest for cancer immunotherapy because of their tumoral specificity and because they are shared by many tumors. Antigenic peptide MEVDPIGHLY, which is encoded by MAGE-3 and is known to be presented by human leukocyte antigen (HLA)-B44, is currently being used in therapeutic vaccination trials. We report here that a cytolytic T lymphocyte (CTL) clone, which is restricted by HLA-B*1801, recognizes the same peptide and, importantly, lyzes HLA-B18 tumor cells expressing MAGE-3. These results imply that the use of peptide MEVDPIGHLY can now be extended to HLA-B18 patients. We also provide evidence that, under limiting amounts of protein MAGE-3, HLA B*1801 and B*4403 compete for binding to the peptide.

Cancer/testis antigens: structural and immunobiological properties

Characterization of tumor-associated antigens recognized by cytotoxic T lymphocytes which has evolved during recent years opens new possibilities for specific anti-cancer immunotherapy. Among different groups of tumor-associated antigens, cancer/testis (CT) antigens (expressed in many tumors and among normal tissues only in testes) represent the most perspective antigens for immunotherapy because of their broad tumor-specific expression. More than 50 CT antigens have been described so far and, for many of them, epitopes recognized by T lymphocytes have been identified. The most studied group of CT antigens is the MAGE proteins, which form the so-called MAGE superfamily, together with some MAGE-like proteins that have a different distribution than classical CT antigens. The MAGE superfamily includes five families: MAGE-A, MAGE-B, MAGE-C, MAGE-D, and necdin. Comparison of the structure of members of MAGE superfamily points to the existence of a domain organization of these proteins. The central, core domain (second domain) is highly conservative. The first domain is homologous among MAGE family members with a CT expression, but unique for each member of the MAGE-D and necdin families. In addition to the homology of the central domain, the third domain is also homologous among all members of MAGE superfamily, but to a much lesser extent. The MAGE-D proteins contain an additional, fourth domain, which in the case of MAGE-D3 coincides with trophinin, a separate molecule described previously as an adhesion molecule that participates in embryo implantation. The structural classification of the members of MAGE superfamily might help in the future to understand the biological function of MAGE proteins. One important property of the CT antigens is the up-regulation of their expression by DNA demethylating agents, indicating a possible mechanism for their re-expression in tumors. One of the implications of this particular property could be that a combination of immunotherapy targeting CT antigens with chemotherapy inducing up-regulation of CT antigens might result in more efficient tumor eradication.

Cytotoxic T lymphocyte mediated recognition of human pancreatic cancer cells

T lymphocytes play an important role in tumor rejection and their response to human malignant melanoma has been well documented. In contrast, the existence of cytotoxic T lymphocytes (CTL) to pancreatic cancer remains unclear. Tumor-associated lymphocytes (TAL) and peripheral blood monocytes (PBMC) were isolated from pancreatic cancer patients. Tumor-specific CTL were generated from TAL and PBMC using solid-phase anti-CD3, low-dose IL-2 (50 IU/ml) and repetitive autologous tumor stimulation. The specificity of CTL was tested in standard cytotoxicity assays using autologous tumor cells, autologous fibroblasts when available, several allogeneic pancreatic tumor cells and the NK-sensitive cell line K562. Anti-HLA-Class I MAb, W6/32, was used to demonstrate that tumor-specific CTL were HLA-Class I restricted. HLA-molecules of human pancreatic cancer cells were washed out using acid elution. Eight consecutive, histologically confirmed pancreatic cancer specimen as well as peripheral blood mononuclear cells were analyzed. CTL were capable of lysing autologous tumor cells significantly after 3 stimulations with autologous tumor cells. T cell mediated recognition was HLA-Class I restricted as shown by incubation with MAb anti-HLA-Class I. In case of HLA-A2 positivity, incubation of tumor cells in cytotoxicity assays resulted in significant inhibition. Autologous fibroblasts or K562 cells were lysed significantly less. HLA-Class I molecule elution resulted in significantly lower recognition of these cells by CTL. These results show for the first time in a larger series the possibility of generating CTL in human pancreatic cancer. The identification of new tumor associated antigens or tumor antigens will be crucial for establishing new treatment strategies.

Adjuvant immunotherapy of resected, intermediate-thickness, node-negative melanoma with an allogeneic tumor vaccine: impact of HLA class I antigen expression on outcome

PURPOSE

An association between expression of > or = two of five HLA class I antigens (HLA-A2, HLA-A28, HLA-B44, HLA-B45, and HLA-C3; collectively called M5) and response to an allogeneic melanoma vaccine (Melacine; Corixa Corporation, Seattle, WA) has been described in stage IV melanoma. This study investigated whether class I antigen expression impacted relapse-free survival (RFS) after adjuvant therapy with this vaccine.

PATIENTS AND METHODS

We performed class I (HLA-A, HLA-B, and HLA-C) serotyping on patients enrolled onto Southwest Oncology Group Trial 9035, a randomized, observation-controlled, phase III trial of adjuvant Melacine. All patients had clinically node-negative cutaneous melanoma (1.5 to 4.0 mm). Interactions between treatment and class I antigen expression were tested. Analyses involved all serotyped patients and were adjusted for tumor thickness, method of nodal staging, sex, ulceration, and primary tumor site.

RESULTS

HLA typing was performed on 553 (80%) of the 689 enrolled patients (294 vaccinated and 259 observed). Expression of > or = two M5 antigens was associated with a superior vaccine treatment effect. Among patients who matched > or = two of the M5, the 97 vaccine-treated patients had improved RFS compared with the 78 observation patients (5-year relapse-free survival, 83% v 59%; P =.0002). The major components of this effect were contributed by HLA-A2 and HLA-C3. Among those who were HLA-A2-positive and/or HLA-C3-positive, the 5-year RFS for vaccinated patients was 77%, compared with 64% for observation (P =.004). There was no impact of HLA-A2 and/or HLA-C3 expression among observation patients.

CONCLUSION

This prospective analysis indicates a highly significant benefit of adjuvant therapy with Melacine among patients expressing > or = two of the M5 class I antigens, validating a prior observation in stage IV disease. HLA-A2 and HLA-C3 contributed most to this effect. Processed melanoma peptides found in Melacine may be presented by HLA-A2 and HLA-C3 and play a role in preventing relapse in vaccinated patients.

Electrospray mass spectrometry for the identification of MHC class I-associated peptides expressed on cancer cells

Electrospray ionisation (ESI) mass spectrometry (MS) has been used extensively for the detection of peptides presented by major histocompatibility complex (MHC) molecules. This review focuses on the optimisation of electrospray mass spectrometry and the use of tandem mass spectrometry to sequence MHC class I peptides. We review the isolation of MHC class I peptides from the surface of cells with particular reference to tumour cells. In addition, we also discuss the advantages and disadvantages of the methods available to concentrate and fractionate the peptides prior to analysis by electrospray mass spectrometry.

The MAGE proteins: emerging roles in cell cycle progression, apoptosis, and neurogenetic disease

Since the identification of the first MAGE gene in 1991, the MAGE family has expanded dramatically, and over 25 MAGE genes have now been identified in humans. The focus of studies on the MAGE proteins has been their potential for cancer immunotherapy, as a result of the finding that peptides derived from MAGE gene products are bound by major histocompatibility complexes and presented on the cell surface of cancer cells. However, the normal physiological role of MAGE proteins has remained a mystery. Recent studies are now beginning to provide insights into MAGE gene function. Necdin acts as a cell cycle regulatory protein and plays a key role in the pathogenesis of Prader-Willi syndrome, a neurogenetic disorder. MAGE-D1, identified as a binding partner for the p75 neurotrophin receptor, the apoptosis inhibitory protein XIAP, and Dlx/MSX homeodomain proteins, blocks cell cycle progression and enhances apoptosis. This review provides an overview of the human MAGE genes and proteins, summarizes recent findings on their cellular roles, and provides a baseline for future studies on this intriguing gene family.

Immunotherapy for melanoma

BACKGROUND

Immunotherapy for cancers is based on the principle that the host's immune system is capable of generating immune responses against tumor cells. Currently available treatments for melanoma patients are limited by poor response rates. Interferon-a has been approved for adjuvant treatment of stage III melanoma with improved survival. New and more innovative approaches with improved efficacy are needed.

METHODS

We reviewed the various new approaches and strategies for immunotherapy for the treatment of melanoma.

RESULTS

Immunotherapy for melanoma includes a number of different strategies with vaccines utilizing whole cell tumors, peptides, cytokine-mediated dendritic cells, DNA and RNA, and antibodies.

CONCLUSIONS

A variety of approaches can be used to enhance immune reactivity in patients with melanoma. Preclinical studies and initial clinical trials have shown promising results. Additional clinical trials are currently ongoing to evaluate the clinical efficacy and the associated toxicities of these novel treatment strategies.

Dendritic cells in cancer vaccines

Dendritic cells (DC) are recognized as the most potent antigen-presenting cells with the ability to stimulate naive resting T cells and to initiate primary immune responses. Encouraging results in vaccination studies in animal models and the development of protocols to generate sufficient numbers of human DC for clinical application have led to attempts to verify the feasibility and efficacy of this approach in patients in the context of Phase I/II vaccination trials. This review aims to present a concise overview of the current knowledge in DC development and biology and describes the recent data of the first published DC-based vaccination studies. These preliminary trials indicate that immunotherapies utilizing DC-presenting tumor-associated antigens can safely be administered to patients with cancer and induce significant immunologic and clinical responses.

Structural characterization and chromosomal localization of the MAGE-E1 gene

Genes of the melanoma-associated antigen (MAGE) family are characterized by the expression of tumor antigens on a malignant melanoma recognized by autologous cytolytic T lymphocytes. We have previously identified novel members of the MAGE gene family expressed in human glioma and named them MAGE-E1a-c. In the present study, we have revealed the genomic structure of MAGE-E1 by sequence analysis of a human chromosome bacterial artificial chromosome clone containing the MAGE-E1 gene. The MAGE-E1 gene is composed of 13 exons, and three of these (exon 2, exon 3 and exon 12) are alternatively spliced in each variant (E1a-c). The open reading frame encoding the MAGE-E1 peptides initiates in exon 2 and ends in exon 13. We have also demonstrated that the MAGE-E1 gene is located in Xp11 through the analysis of radiation hybrid panels. The genomic structure of MAGE-E1 is markedly similar to that of MAGE-D and its chromosomal locus is also identical to that of MAGE-D, but these features contrast with those of other MAGEs. These results suggest that MAGE-D and -E1 may be evolutionarily distant from other members of the MAGE family, and the two may be ancestral genes for the others.

GD2 synthase: a new molecular marker for detecting neuroblastoma

BACKGROUND

Neuroblastomas (NBs) almost ubiquitously express the ganglioside GD2. GD2 synthesis is dependent on the key enzyme GD2 synthase. Thus, GD2 synthase transcript may prove to be a potential molecular marker of NB.

METHODS

Seventy-seven NB tumor tissues of all stages, 5 NB cell lines, and 26 normal bone marrows (BMs) and peripheral blood (PBL) samples, as well as 26 non-NB remission-BMs were analyzed for the expression of GD2 synthase by a highly sensitive reverse transcriptase-polymerase chain reaction (RT-PCR) and chemiluminescence detection. One hundred fifty-two NB BMs were tested and comparisons were made among three independent detection techniques, namely GD2 synthase RT-PCR, immunofluorescence (IF), and histology (HIST).

RESULTS

GD2 synthase transcript was present in 5 of 5 cell lines and in 77 of 77 tumors tested. Among 116 marrows that were positive by at least 1 of the 3 methods, 78% were detectable by GD2 synthase, 68% by IF, and 46% by HIST. Seventy-six percent of positive BMs that were obtained during treatment and follow-up had GD2 synthase expression, whereas only 29% were HIST positive. Correlation between RT-PCR and IF was high (P = 0.001), and positivity by 3 out of 3 methods was strongly correlated with poor survival (P < 0.01). Of note, marrows tested at the time of chemotherapy were positive by at least 2 out of 3 methods and were associated with adverse outcome (P = 0.01). Serial samples (n = 28) in 5 patients demonstrated close agreement between RT-PCR and patient disease status.

CONCLUSIONS

The current study found that molecular detection of GD2 synthase transcript in NB BMs may have potential value in detecting rare tumor cells.

Cancer vaccines

Attempts to generate an anticancer immune response in vivo in patients with cancer have taken several forms. Although to date there have been relatively few published studies describing the effects of the approach in hematologic malignancy, that circumstance is expected to change rapidly during the next few years. In solid tumors, it is not known which, if any, of the approaches being explored will be able to produce responses of sufficient effectiveness and duration to be of general clinical value. Despite the documented increase in survival of patients developing an immune response to tumor immunization, no randomized clinical trial has been entirely convincing. As knowledge of the molecular basis of the immune response and of the immune defenses used by cancer cells improves, it is reasonable to expect to see increasing benefits from tumor vaccines, which are likely to complement, long before they replace, conventional therapies.

Allele- and temperature-dependency of in vitro HLA class I assembly

Allelic variations of in vitro HLA class I assembly have been investigated in both the absence and the presence of binding peptides by flow cytometry using human leukocyte antigen (HLA) class I alpha chains isolated by alkali treatment from cultured HLA homozygous B cells and polystyrene beads coated with anti-HLA class I alpha chain antibodies specific to the C-terminal segment (anti-HLA class I beads). The specificity of assembly was temperature dependent, while the stability of the assembled complex depended on the bound peptide. The efficiency of assembly was allele dependent and primarily ruled by the binding affinity of alpha chains with beta(2)m. Thus, an allele hierarchy could be defined for the binding of HLA-B alpha chain with beta(2)-microglobulin: B7, B18 > B35, B62 > B27, B51. Allele and temperature dependency was found in HLA class I reassembly on acid treated B cells. The HLA class I proteins, reassembled with specific single peptides, could be efficiently transferred to anti-HLA class I beads. These findings would be used to produce microspheres coupled at high surface density with oriented single-peptide loaded HLA class I molecules and also to improve the preparation efficiency of HLA class I tetramers by the use of site-specific biotinylation.

A MAGE-1 peptide recognized on HLA-DR15 by CD4(+) T cells

Antigens encoded by MAGE genes and recognized by T cells are of interest for cancer immunotherapy because of their strict tumoral specificity and because they are shared by many tumors. Several MAGE-1 peptide that are recognized by CD8(+) cytolytic T lymphocytes have been used in therapeutic vaccination trials. To obtain anti-tumor immune response, vaccines combining peptides recognized by CD8(+) and peptides recognized by CD4(+) T cells might be optimal. We focused therefore on the identification of MAGE peptides recognized by CD4(+) T cells. We report here the identification of MAGE-1 epitope EYVIKVSARVRF, which is presented to CD4(+) T lymphocytes by HLA-DR15. This HLA allele is present in 29 % of Asians and 17 % of Caucasians.

A MAGE-3 peptide recognized on HLA-B35 and HLA-A1 by cytolytic T lymphocytes

Antigens encoded by MAGE genes are of particular interest for cancer immunotherapy because of their strict tumoral specificity and because they are shared by many tumors. Antigenic peptide EVDPIGHLY encoded by MAGE-3 and known to be presented by HLA-A*0101 is currently being used in therapeutic vaccination trials. We report here that a cytolytic T-lymphocyte (CTL) clone, which is restricted by HLA-B*3501, recognizes the same peptide and, importantly, lyses HLA-B*3501 tumor cells expressing MAGE-3. These results infer that the current clinical use of peptide EVDPIGHLY can now be extended to HLA-B*3501 patients.

Autologous dendritic cells for treatment of advanced cancer--an update

Dendritic cells (DC) are commonly viewed as the professional antigen-presenting cell. They capture antigens, migrate to appropriate lymphoid organs and initiate an antigen-specific CD4 and CD8 T cell response. Much is known about DC physiology, and it is now possible to culture, maintain and expand DC from different human sources, including hematopoietic progenitors in bone marrow and peripheral blood. Combined with the detection of an increasing number of tumor-associated antigens and T cell-recognized peptide epitopes, this has led to a new enthusiasm in the field of tumor immunotherapy and to various clinical applications in phase I/II studies on the treatment of different malignancies. This chapter will review the latest developments and give a brief update of the results obtained in studies of advanced melanoma, as well as provide a short overview of published results for other tumors.

Induction of primary NY-ESO-1 immunity: CD8+ T lymphocyte and antibody responses in peptide-vaccinated patients with NY-ESO-1+ cancers

Cancer-testis antigen NY-ESO-1 is one of the most immunogenic tumor antigens defined to date. Spontaneous humoral and CD8+ T-cell responses to NY-ESO-1 are detected in 40-50% of patients with advanced NY-ESO-1-expressing tumors. A clinical trial was initiated to study the immunological effects of intradermal vaccination with 3 HLA-A2-binding NY-ESO-1 peptides in 12 patients with metastatic NY-ESO-1-expressing cancers. Seven patients were NY-ESO-1 serum antibody negative, and five patients were NY-ESO-1 serum antibody positive at the outset of the study. Primary peptide-specific CD8+ T-cell reactions and delayed-type hypersensitivity responses were generated in four of seven NY-ESO-1 antibody-negative patients. Induction of a specific CD8+ T-cell response to NY-ESO-1 in immunized antibody-negative patients was associated with disease stabilization and objective regression of single metastases. NY-ESO-1 antibody-positive patients did not develop significant changes in baseline NY-ESO-1-specific T-cell reactivity. However, stabilization of disease and regression of individual metastases were observed in three of five immunized patients. These results demonstrate that primary NY-ESO-1-specific CD8+ T-cell responses can be induced by intradermal immunization with NY-ESO-1 peptides, and that immunization with NY-ESO-1 may have the potential to alter the natural course of NY-ESO-1-expressing tumors.

Strategy for monitoring T cell responses to NY-ESO-1 in patients with any HLA class I allele

NY-ESO-1 elicits frequent antibody responses in cancer patients, accompanied by strong CD8(+) T cell responses against HLA-A2-restricted epitopes. To broaden the range of cancer patients who can be assessed for immunity to NY-ESO-1, a general method was devised to detect T cell reactivity independent of prior characterization of epitopes. A recombinant adenoviral vector encoding the full cDNA sequence of NY-ESO-1 was used to transduce CD8-depleted peripheral blood lymphocytes as antigen-presenting cells. These modified antigen-presenting cells were then used to restimulate memory effector cells against NY-ESO-1 from the peripheral blood of cancer patients. Specific CD8(+) T cells thus sensitized were assayed on autologous B cell targets infected with a recombinant vaccinia virus encoding NY-ESO-1. Strong polyclonal responses were observed against NY-ESO-1 in antibody-positive patients, regardless of their HLA profile. Because the vectors do not cross-react immunologically, only responses to NY-ESO-1 were detected. The approach described here allows monitoring of CD8(+) T cell responses to NY-ESO-1 in the context of various HLA alleles and has led to the definition of NY-ESO-1 peptides presented by HLA-Cw3 and HLA-Cw6 molecules.

A MAGE-A1 peptide presented to cytolytic T lymphocytes by both HLA-B35 and HLA-A1 molecules

Antigens encoded by melanoma antigen (MAGE) genes are of particular interest for cancer immunotherapy because of their strict tumoral specificity and because they are shared by many tumors. Antigenic peptide EADPTGHSY encoded by MAGE-A1 and known to be presented by HLA-A1 is currently being used in therapeutic vaccination trials. We report here that a cytotoxic T-lymphocyte (CTL) clone, which is restricted by HLA-B35, recognizes the same peptide and, importantly, lyses HLA-B35 tumor cells expressing MAGE-A1. This peptide can be presented to CTL by both HLA-B*3501 and HLA-B*3503 molecules, which are expressed by approximately 19% of Caucasians. These results infer that the current clinical use of peptide EADPTGHSY can now be extended to HLA-B35 patients.

Cytolytic T lymphocytes raised against a human bladder carcinoma recognize an antigen encoded by gene MAGE-A12

Human bladder carcinoma line LB831-BLC expresses several distinct Ags that are recognized by different autologous CTL. Here, we show that one of these Ags is presented by HLA-Cw7 and encoded by gene MAGE-A12. This is the first time that CTL directed against a MAGE-encoded Ag have been derived from the lymphocytes of a patient with cancer other than melanoma. This new Ag was found to be nonapeptide VRIGHLYIL, corresponding to position 170-178 of the MAGE-A12 protein. Gene MAGE-A12 is silent in normal tissues except in male germline cells, which do not express HLA molecules. It is expressed in 26-62% of melanomas, infiltrating bladder carcinomas, lung carcinomas, esophageal carcinomas, and head and neck carcinomas. Because HLA-Cw7 is present in 43% of Caucasians, this new Ag is shared by many tumors and should be a useful target for cancer immunotherapy.

A tumor-infiltrating lymphocyte from a melanoma metastasis with decreased expression of melanoma differentiation antigens recognizes MAGE-12

Twenty separate tumor infiltrating lymphocyte (TIL) bulk cultures and a tumor cell line were originated simultaneously from a fine needle aspiration biopsy of a metastasis in a patient with melanoma (F001) previously immunized with the HLA-A*0201-associated gp100:209-217(210 M) peptide. None of the TIL recognized gp100. However, 12 recognized autologous (F001-MEL) and allogeneic melanoma cells expressing the HLA haplotype A*0201, B*0702, Cw*0702. Further characterization of F001-MEL demonstrated loss of gp100/PMel17, severely decreased expression of other melanoma differentiation Ags and retained expression of tumor-specific Ags. Transfection of HLA class I alleles into B*0702/Cw*0702-negative melanoma cell lines identified HLA-Cw*0702 as the restriction element for F001-TIL. A cDNA library from F001-MEL was used to transfect IFN-alpha-stimulated 293 human embryonal kidney (293-HEK) cells expressing HLA-Cw*0702. A 100-gene pool was identified that induced recognition of 293-HEK cells by F001-TIL. Subsequent cloning of the pool identified a cDNA sequence homologous, except for one amino acid (aa 187 D-->A), to MAGE-12. Among 25 peptide sequences from MAGE-12 with the HLA-Cw*0702 binding motif, MAGE-12:170-178 (VRIGHLYIL) induced IFN-gamma release by F001-TIL when pulsed on F001-EBV-B cells at concentrations as low as 10 pg/ml. Peptide sequences from MAGE-1, 2, 3, 4a, and 6 aligned to MAGE-12:170-178 were not recognized by F001-TIL. In summary a TIL recognizing a MAGE protein was developed from an HLA-A*0201 expressing tumor with strongly reduced expression of melanoma differentiation Ags. Persisting tumor-specific Ag expression maintained tumor immune competence suggesting that tumor-specific Ags/melanoma differentiation Ags may complement each other in the context of melanoma Ag-specific vaccination.

Expression of MAGE, GAGE and BAGE genes in human liver diseases: utility as molecular markers for hepatocellular carcinoma

BACKGROUND/AIMS

The MAGE, GAGE and BAGE genes encode tumor antigens recognized by autologous cytotoxic T lymphocytes. The aim of this study was to evaluate the possibility of using these genes as molecular markers and as the targets of specific immunotherapy for human hepatocellular carcinoma (HCC).

METHODS

The expressions of MAGE-1, MAGE-3, GAGE1-6, GAGE1-2 and BAGE mRNA in 33 surgically resected HCC samples and 26 of their corresponding non-cancerous samples (11 liver cirrhosis and 15 chronic hepatitis) were studied by a reverse-transcription polymerase chain reaction, and were compared with clinicopathological parameters. The expression of MAGE-1 was also examined in 16 biopsied HCC samples.

RESULTS

MAGE-1, MAGE-3, GAGE1-6, GAGE1-2 and BAGE mRNA were expressed in 67%, 39%, 36%, 30%, and 21% of the HCC, respectively. At least one transcript was detected in 88% of the HCC, while no expression was observed in the non-cancerous livers. There was no significant correlation between the expression of any of the tumor antigens examined and the differentiation stage or size of the HCC. Especially, MAGE-1 was highly expressed in small HCC with a diameter of less than 2 cm and in well-differentiated HCC (81% and 70%, respectively), and was also expressed even in alpha-fetoprotein-negative and PIVKA-II-negative HCC (58% and 76%, respectively). The MAGE-1 expression was detected in 69% of biopsied HCC samples and the expression was high in both small and well-differentiated HCC.

CONCLUSIONS

These tumor-specific antigens can be useful as molecular markers and as the possible target molecules for the specific immunotherapy of human HCC.

Melanoma vaccines

Remarkable advances in tumor vaccination have been made since Coley first deliberately infected cancer patients with both live and heat-killed bacteria. Melanoma is the most immunogenic solid tumor and, as such, has served as the major model for tumor vaccine investigation in both the laboratory and the clinic. Many advances in the field of melanoma vaccination have been based on an improved understanding of the cellular interaction required to induce a specific antitumor immune response. As a result of this new knowledge, many clinical trials of melanoma vaccines are now under way, and vaccines for metastatic melanoma have shown evidence of clinical effectiveness. This paper outlines the current status of melanoma vaccination.