Detection of MAGE-4 protein in lung cancers

MAGE-A3: an immunogenic target used in clinical practice

Melanoma antigen family A, 3 (MAGE-A3) is a cancer-testis antigen whose expression has been demonstrated in a wide array of malignancies including melanoma, brain, breast, lung and ovarian cancer. In addition, its ability to elicit spontaneous humoral and cellular immune responses has been shown in cancer patients. As antigen-specific immune responses can be stimulated by immunization with MAGE-A3, several clinical trials have used MAGE-A3 vaccines to observe clinical responses. The frequent expressions of this antigen in various tumors and its immunogenicity in cancer patients have led to application of this antigen in cancer immunotherapy. However, the results of recent clinical trials indicate that there is a need for research in the vaccine design, adjuvant selection as well as patient selection criteria.

EGFR T790M mutation as a possible target for immunotherapy; identification of HLA-A*0201-restricted T cell epitopes derived from the EGFR T790M mutation

Treatment with epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs), such as gefitinib and erlotinib, has achieved high clinical response rates in patients with non–small cell lung cancers (NSCLCs). However, over time, most tumors develop acquired resistance to EGFR-TKIs, which is associated with the secondary EGFR T790M resistance mutation in about half the cases. Currently there are no effective treatment options for patients with this resistance mutation. Here we identified two novel HLA-A*0201 (A2)-restricted T cell epitopes containing the mutated methionine residue of the EGFR T790M mutation, T790M-5 (MQLMPFGCLL) and T790M-7 (LIMQLMPFGCL), as potential targets for EGFR-TKI-resistant patients. When peripheral blood cells were repeatedly stimulated in vitro with these two peptides and assessed by antigen-specific IFN-γ secretion, T cell lines responsive to T790M-5 and T790M-7 were established in 5 of 6 (83%) and 3 of 6 (50%) healthy donors, respectively. Additionally, the T790M-5- and T790M-7-specific T cell lines displayed an MHC class I-restricted reactivity against NSCLC cell lines expressing both HLA-A2 and the T790M mutation. Interestingly, the NSCLC patients with antigen-specific T cell responses to these epitopes showed a significantly less frequency of EGFR-T790M mutation than those without them [1 of 7 (14%) vs 9 of 15 (60%); chi-squared test, p  =  0.0449], indicating the negative correlation between the immune responses to the EGFR-T790M-derived epitopes and the presence of EGFR-T790M mutation in NSCLC patients. This finding could possibly be explained by the hypothesis that immune responses to the mutated neo-antigens derived from T790M might prevent the emergence of tumor cell variants with the T790M resistance mutation in NSCLC patients during EGFR-TKI treatment. Together, our results suggest that the identified T cell epitopes might provide a novel immunotherapeutic approach for prevention and/or treatment of EGFR-TKI resistance with the secondary EGFR T790M resistance mutation in NSCLC patients.

Proteomic profiling of triple-negative breast carcinomas in combination with a three-tier orthogonal technology approach identifies Mage-A4 as potential therapeutic target in estrogen receptor negative breast cancer

Breast cancer is a very heterogeneous disease, encompassing several intrinsic subtypes with various morphological and molecular features, natural history and response to therapy. Currently, molecular targeted therapies are available for estrogen receptor (ER)(-) and human epidermal growth factor receptor 2 (Her2)-positive breast tumors. However, a significant proportion of primary breast cancers are negative for ER, progesterone receptor (PgR), and Her2, comprising the triple negative breast cancer (TNBC) group. Women with TNBC have a poor prognosis because of the aggressive nature of these tumors and current lack of suitable targeted therapies. As a consequence, the identification of novel relevant protein targets for this group of patients is of great importance. Using a systematic two dimensional (2D) gel-based proteomic profiling strategy, applied to the analysis of fresh TNBC tissue biopsies, in combination with a three-tier orthogonal technology (two dimensional PAGE/silver staining coupled with MS, two dimensional Western blotting, and immunohistochemistry) approach, we aimed to identify targetable protein markers that were present in a significant fraction of samples and that could define therapy-amenable sub-groups of TNBCs. We present here our results, including a large cumulative database of proteins based on the analysis of 78 TNBCs, and the identification and validation of one specific protein, Mage-A4, which was expressed in a significant fraction of TNBC and Her2-positive/ER negative lesions. The high level expression of Mage-A4 in the tumors studied allowed the detection of the protein in the tumor interstitial fluids as well as in sera. The existence of immunotherapeutics approaches specifically targeting this protein, or Mage-A protein family members, and the fact that we were able to detect its presence in serum suggest novel management options for TNBC and human epidermal growth factor receptor 2 positive/estrogen receptor negative patients bearing Mage-A4 positive tumors.

The significance of MAGED4 expression in non-small cell lung cancer as analyzed by real-time fluorescence quantitative PCR

The aim of this study was to detect differences in the expression levels of melanoma-associated antigen D4 (MAGED4) mRNA between non-small cell lung cancer (NSCLC) tissues and normal tissues, and to compare differences in the expression levels of MAGED4 in tumor patients. Patients were grouped according to age, gender, smoking history, tumor size, pathological classification, degree of lung cancer cell differentiation and presence of lymph node metastasis. The expression levels of MAGED4 were detected using real-time fluorescence quantitative PCR. MAGED4 expression was higher in squamous cell carcinomas compared to adenocarcinomas (P<0.05), in poorly differentiated tissues compared to well-differentiated tissues (P<0.05), and in patients with lymph node metastasis compared to patients without lymph node metastasis (P<0.05). MAGED4 may be used as a specific antigen for NSCLC to influence the improvement of diagnosis, prognosis and immunological therapy outcomes in lung cancer patients.

HM1.24 (CD317) is a novel target against lung cancer for immunotherapy using anti-HM1.24 antibody

HM1.24 antigen (CD317) was originally identified as a cell surface protein that is preferentially overexpressed on multiple myeloma cells. Immunotherapy using anti-HM1.24 antibody has been performed in patients with multiple myeloma as a phase I study. We examined the expression of HM1.24 antigen in lung cancer cells and the possibility of immunotherapy with anti-HM1.24 antibody which can induce antibody-dependent cellular cytotoxicity (ADCC). The expression of HM1.24 antigen in lung cancer cells was examined by flow cytometry as well as immunohistochemistry using anti-HM1.24 antibody. ADCC was evaluated using a 6-h (51)Cr release assay. Effects of various cytokines on the expression of HM1.24 and the ADCC were examined. The antitumor activity of anti-HM1.24 antibody in vivo was examined in SCID mice. HM1.24 antigen was detected in 11 of 26 non-small cell lung cancer cell lines (42%) and four of seven (57%) of small cell lung cancer cells, and also expressed in the tissues of lung cancer. Anti-HM1.24 antibody effectively induced ADCC in HM1.24-positive lung cancer cells. Interferon-beta and -gamma increased the levels of HM1.24 antigen and the susceptibility of lung cancer cells to ADCC. Treatment with anti-HM1.24 antibody inhibited the growth of lung cancer cells expressing HM1.24 antigen in SCID mice. The combined therapy with IFN-beta and anti-HM1.24 antibody showed the enhanced antitumor effects even in the delayed treatment schedule. HM1.24 antigen is a novel immunological target for the treatment of lung cancer with anti-HM1.24 antibody.

The detection of peripheral lung cancer by MAGE A1-6 RT-nested PCR in bronchial washing specimens

BACKGROUND

With expansion of lung cancer screening by computed tomography (CT) and increased incidence of adenocarcinoma, we encountered more peripheral nodules to be identified. We evaluated detection rates of the melanoma antigen genes (MAGE) RT-nested PCR using a common MAGE A1-6 primer in bronchoscopic washing samples from patients with bronchoscopically invisible peripheral nodules, and compared with those of conventional cytology and percutaneous needle aspiration biopsy (PCNB).

MATERIALS AND METHODS

Forty-two patients with bronchoscopically invisible peripheral lung nodules were studied. Bronchoscopic washing specimens were collected by instilling 20ml of normal saline into a tumor bearing segment and retrieving samples. Samples were split and analyzed by MAGE RT-PCR and conventional cytology. A PCNB was performed in all but two patients. Twenty-eight lesions were diagnosed as lung cancers and 14 as benign lung diseases. We evaluated MAGE A1-6 RT-nested PCR, cytology, and PCNB results and analyzed them according to histologic cell types and tumor sizes.

RESULTS

In bronchial washing samples, the detection rates of MAGE A1-6 RT-nested PCR (67.9%) were higher than that of conventional cytology (21.4%, p=.04) and similar to that of PCNB (73.1%, p=.45) in 28 cancer patients. In terms of histologic types, the detection rates of MAGE A1-6 RT-nested PCR, conventional cytology, and PCNB were 78.6%, 21.4% and 64.3% in adenocarcinoma, 70%, 20% and 77.8% in squamous cell carcinoma, respectively. The sensitivity of conventional cytology was significantly lower than that of MAGE RT-nested PCR or PCNB regardless of tumor histology p=.04, p=.025, respectively, in adenocarcinoma; p=.035, p=.04, respectively, in squamous cell carcinoma). In terms of tumor size, the corresponding detection rates were 73.3%, 6.7% and 73.3% for tumors smaller than 3cm (N=15), and 61.5%, 38.5% and 72.7% for tumors larger than 3cm (N=13).

CONCLUSIONS

MAGE A1-6 RT-nested PCR showed higher detection rates in the bronchial washes of peripheral lung cancer patients than conventional cytology testing. This method is simple and robust, and it could be effectively utilized as a peripheral lung cancer detection tool in clinical laboratories.

A phase I study of dexosome immunotherapy in patients with advanced non-small cell lung cancer

Background

There is a continued need to develop more effective cancer immunotherapy strategies. Exosomes, cell-derived lipid vesicles that express high levels of a narrow spectrum of cell proteins represent a novel platform for delivering high levels of antigen in conjunction with costimulatory molecules. We performed this study to test the safety, feasibility and efficacy of autologous dendritic cell (DC)-derived exosomes (DEX) loaded with the MAGE tumor antigens in patients with non-small cell lung cancer (NSCLC).

Methods

This Phase I study enrolled HLA A2+ patients with pre-treated Stage IIIb (N = 4) and IV (N = 9) NSCLC with tumor expression of MAGE-A3 or A4. Patients underwent leukapheresis to generate DC from which DEX were produced and loaded with MAGE-A3, -A4, -A10, and MAGE-3DPO4 peptides. Patients received 4 doses of DEX at weekly intervals.

Results

Thirteen patients were enrolled and 9 completed therapy. Three formulations of DEX were evaluated; all were well tolerated with only grade 1–2 adverse events related to the use of DEX (injection site reactions (N = 8), flu like illness (N = 1), and peripheral arm pain (N = 1)). The time from the first dose of DEX until disease progression was 30 to 429+ days. Three patients had disease progression before the first DEX dose. Survival of patients after the first DEX dose was 52–665+ days. DTH reactivity against MAGE peptides was detected in 3/9 patients. Immune responses were detected in patients as follows: MAGE-specific T cell responses in 1/3, increased NK lytic activity in 2/4.

Conclusion

Production of the DEX vaccine was feasible and DEX therapy was well tolerated in patients with advanced NSCLC. Some patients experienced long term stability of disease and activation of immune effectors

Lung cancer detection by a RT-nested PCR using MAGE A1--6 common primers

BACKGROUND

Since the mortality of lung cancer patients remains very high, the development of a sensitive detection method remains an urgent task. The authors have designed common melanoma antigen gene (MAGE) primers that enable the detection of MAGE A1 to A6 subtypes simultaneously. These primers were applied to the detection of lung cancer using sputum specimens.

METHODS

The study involved, 53 cancer patients and three non-cancer groups (193 healthy people, 235 lung cancer screening group and 140 patients with benign lung diseases) were investigated. One hundred and thirty-six respiratory specimens (55 random sputa, 33 induced sputa, 40 broncho-alveolar lavage (BAL) fluids, and 8 pleural fluids) from different lung cancer patients were blindly tested. The MAGE assay was performed by RT-nested PCR, and the results obtained from sputum were compared with those obtained by telomerase assay and conventional cytology.

RESULTS

In the sputum of the non-cancer groups, the positive rates were less than 2.1%, while the detection rates were 83.3% in the cancer tissues and 54.3% in the sputa of lung cancer patients. For the random sputum samples of lung cancer patients, the detection rate was 47.5%, but in the induced sputum, BAL and pleural fluids, the detection rate was up to over 70.0%. The MAGE assay produced a higher detection rate than the telomerase assay and conventional cytology.

CONCLUSIONS

MAGE A1-6 RT-PCR, which showed high sensitivity and specificity, provides an effective means for the lung cancer detection in sputum.

Cancer/testis tumour-associated antigens: immunohistochemical detection with monoclonal antibodies

Cancer/testis tumour-associated antigens (C/T TAA) were the first human tumour-associated antigens to be characterised at the molecular level. Specific genes are expressed in the testis and in tumours of varying histological origin. The tissue expression pattern supports the notion that these antigens could be targets for active specific immunotherapy. Specific serological reagents have been developed and have helped to clarify biochemical characteristics of C/T TAA and to assess their distribution within clinical tumour samples. We review immunohistochemical evidence of the expression of C/T TAA known to be recognised by specific cytotoxic T lymphocytes. The emerging picture is consistent with a mostly heterogeneous expression in human cancers. These findings support the concept of multiantigenic tumour vaccine preparations. Moreover, the wide range of tumours in which C/T TAA have been detected urges further efforts to develop effective specific immunotherapeutic procedures.

Expression spectrum and methylation-dependent regulation of melanoma antigen-encoding gene family members in pancreatic cancer cells

Human MAGE and GAGE genes encode tumor-specific antigens presented by HLA I molecules recognized on tumor cells by cytolytic T lymphocytes. To determine if pancreatic cancer patients would be suitable for MAGE- or GAGE-based immunotherapy, the expression frequency of MAGE-A1, -A2, -A3, -A4, -A6 and GAGE1-8 genes was assessed in 15 pancreatic tumor cell lines and 23 pancreatic tumor specimens using reverse transcription-polymerase chain reaction (RT-PCR). In 67% of the cell lines at least one of the MAGE-A genes was detected, 53% revealed concomitant expression of two or more genes. GAGE1-8 expression was detected in 47% of the cell lines. In the primary pancreatic tumors, MAGE-A analysis revealed exclusive MAGE-A1 and MAGE-A2 gene expression in 26 and 30% of the specimens, respectively, independent from clinicopathologic factors. Treatment of MAGE-A expression-negative pancreatic tumor cells with the demethylating agent 5-aza-2'-deoxycytidine could activate MAGE-A1, MAGE-A2, MAGE-A3, MAGE-A4 and GAGE transcription suggesting silencing due to promoter methylation. Interestingly, a metastatic lesion to the liver revealed concomittant expression of MAGE-A1, -A2, -A3 and -A6 consistent with a more pronounced genome-wide hypomethylation in metastases. Therefore, a subset of pancreatic cancer patients could be eligible for active, specific immunotherapy directed against MAGE-A antigens and demethylating agents could increase the number of candidate patients.

MAGE, BAGE, and GAGE gene expression in patients with esophageal squamous cell carcinoma and adenocarcinoma of the gastric cardia

BACKGROUND

The MAGE, BAGE, and GAGE gene families code for distinct, tumor specific antigens that are recognized by cytotoxic T lymphocytes in the context of HLA molecules. The purpose of this study was to analyze MAGE, BAGE, and GAGE gene expression in the two major histologic types of esophageal carcinoma, squamous carcinoma (ESCc) and adenocarcinoma (CAc), and to correlate their expression patterns with the principal prognostic parameters and long term survival.

METHODS

Gene expression was analyzed in surgical samples from 24 patients with ESCc and 24 patients with CAc by reverse transcriptase-polymerase chain reaction amplification (RT-PCR). None of the patients had received preoperative chemotherapy or radiotherapy, and all were followed until death or for a minimum of 4 years.

RESULTS

Sixteen ESCc samples (67%) and 9 CAc samples (37.5%) expressed at least one of the genes under study. The expression of each MAGE gene in the two histologic types was not significantly different, with the exception of MAGE-4, which was expressed more in ESCc samples than in CAc samples. BAGE and GAGE expression was rather low and, in every case, was associated with the expression of at least one MAGE gene.

CONCLUSIONS

In the group as a whole, and in both ESCc and CAc subgroups, no significant correlation emerged between the expression of any gene and prognostic parameters, such as pathologic tumor, lymph node, or disease stage. Nevertheless, BAGE or GAGE expression was related significantly to a poor prognosis, whereas the expression of MAGE genes (in the absence of BAGE and GAGE expression) was related significantly to a good prognosis.

Cancer Vaccines for the Treatment and Prevention of Non–Small-Cell Lung Cancer

Cancer vaccines targeting non small-cell lung cancer (NSCLC) have been studied for decades; clinical trials, for the most part, have focused on the use of autologous and allogeneic whole-tumor cell vaccines. Recent advances in molecular biology and immunology, however, have allowed the identification of many tumor antigens involved in the generation of immunity to NSCLC. Although small-cell lung cancer (SCLC) is commonly thought of as an immunogenic tumor, it is now clear that NSCLC is also capable of eliciting an endogenous immune response in patients with the disease and, in fact, has a natural history that may make NSCLC more amenable to vaccine therapy as an adjuvant treatment strategy. This review will high-light the major components of the immune system that may potentially interact with tumor-associated proteins as well as outline the immunologic similarities and differences between SCLC and NSCLC. Tumor antigens that elicit immune responses in patients with NSCLC will be discussed. Finally, clinical trials of whole-tumor cell vaccines, both autologous and allogeneic, and tumor antigen-specific vaccines will also be discussed.

A MAGE-A4 peptide presented by HLA-A2 is recognized by cytolytic T lymphocytes

The MAGE-encoded antigens that are recognized by cytolytic T lymphocytes (CTL) are shared by many tumors and are strictly tumor specific. Clinical trials involving therapeutic vaccination of cancer patients with MAGE antigenic peptides or proteins are in progress. To increase the range of patients eligible for therapy with peptides, it is important to identify additional MAGE epitopes. We have used a method to identify CTL epitopes, which selects naturally processed peptides. CD8(+) T cells, obtained from individuals without cancer, were stimulated with autologous dendritic cells infected with a recombinant adenovirus containing the MAGE-A4 coding sequence. Responder cell microcultures that specifically lysed autologous EBV-transformed B cells infected with vaccinia-MAGE-A4 were cloned using autologous stimulator cells infected with a Yersinia enterocolitica carrying the MAGE-A4 sequence. An anti-MAGE-A4 CTL clone was obtained and the epitope was found to be decapeptide GVYDGREHTV (amino acids 230-239) presented by HLA-A2 molecules. The CTL clone lysed HLA-A2 tumor cells expressing MAGE-A4. This is the first reported antigenic peptide encoded by MAGE-A4. It may be valuable for cancer immunotherapy because MAGE-A4 is expressed in 51% of lung carcinomas and 63% of esophageal carcinomas, whereas about 50% of Caucasians and Asians express HLA-A2.

The potential of melanoma antigen expression in cancer therapy

A potential new therapy for cancer is active specific immunotherapy with melanoma antigen (MAGE) gene products. The MAGE gene family comprizes a series of 12 closely related genes, some of which have been shown to be expressed in a variety of tumours of different histological origin. Peptides encoded by the MAGE genes are targets for specific immunotherapy as they are presented in association with human leucocyte antigen class I molecules and are recognised by cytotoxic T lymphocytes. This article reviews the discovery, development, role and therapeutic potential of MAGE tumour-associated antigens. Knowledge in this field of study is in its early stages. Future advances can be anticipated in term of defining therapeutic relevance, antigen detection and discovery of related genes.

Expression of the SART-1 tumor rejection antigen in breast cancer

We investigated in breast cancers the expression of the SART-1 gene encoding tumor rejection antigens. SART-1 mRNA was expressed in all of the samples tested. The SART-1(800) antigen was detectable in 20 of 50 (40%) breast cancer tissues and all breast cancer cell lines tested, but not in normal breast tissues. The SART-1(800)+ breast cancer cells transfected with HLA-A2601 or HLA-A2402 cDNA were recognized by the HLA-A26-restricted and SART-1-specific cytotoxic T lymphocytes (CTLs) or the HLA-A24-restricted and SART-1-specific CTLs, respectively. Among the 20 SART-1(800)+ tumors, 9 or 8 tumors expressed estrogen receptor or progesterone receptor, respectively. Therefore, the patients with HLA-A26 or -A24 haplotype might be appropriate candidates for specific immunotherapy with the SART-1 peptides independently or in combination with hormone therapy.

Isolation and characterization of PAGE-1 and GAGE-7. New genes expressed in the LNCaP prostate cancer progression model that share homology with melanoma-associated antigens

The LNCaP progression model of human prostate cancer consists of lineage-related sublines that differ in their androgen sensitivity and metastatic potential. A differential display polymerase chain reaction was employed to evaluate mRNA expression differences between the LNCaP sublines in order to define the differences in gene expression between the androgen-sensitive, nontumorigenic LNCaP cell line and the androgen-insensitive, metastatic LNCaP sublines, C4-2 and C4-2B. An amplicon, BG16.21, was isolated that showed increased expression in the androgen-independent and metastatic LNCaP sublines, C4-2 and C4-2B. Hybridization screening of a lambda gt11 expression library with BG16.21 revealed two transcripts, both homologous to BG16.21 at the 3' end. A GenBankTM data base search using the GCG Wisconsin software package revealed the shorter approximately 600-bp transcript (designated GAGE-7) to be a new member of the GAGE family. The second approximately 700-bp transcript was a novel gene (designated PAGE-1, "prostate associated gene") with only 45% homology to GAGE gene family members. RNA blot analysis demonstrated that GAGE-7 mRNA was expressed at equal levels in all lineage related prostate cancer cell sublines, while PAGE-1 mRNA levels were elevated 5-fold in C4-2 and C4-2B as compared with LNCaP cells. Neither GAGE-7 nor PAGE-1 demonstrated any regulation by androgens in the prostate cancer cell lines used in this study. PAGE-1 and GAGE-7 expression was found to be restricted to testes (high) and placenta (low) on human multiple tissue Northern blots. As GAGE/MAGE antigens were reported previously to be targets for tumor-specific cytotoxic lymphocytes in melanoma, these results suggest that PAGE-1 and GAGE-7 may be related to prostate cancer progression and may serve as potential targets for novel therapies.

Frequency of MAGE-3 gene expression in HLA-A2 positive patients with non-small cell lung cancer

Melanoma tumor antigens, MAGE-1 and -3 are presented on HLA-A1 and -Cw*1601, or -A1 and -A2, respectively, to the corresponding cytotoxic T lymphocytes (CTL). If CTL recognizing these antigens were generated in patients, clones of positive tumor cells should be eliminated. To ascertain whether such an immunological response is active in patients with lung cancer and to determine what fraction of lung cancer patients are candidates for MAGE oriented immunotherapy, we assessed the relationship between HLA-A1 or -A2 expression and MAGE-1 or -3 gene expression in their tumors. MAGE-1 and -3 were detected in 18/55 (33%) and 23/55 (42%), respectively, by reverse transcriptase (RT)-polymerase chain reaction (PCR). Allele specific PCR revealed HLA-A1 and -A2 alleles to be expressed in 0/55 (0%) and 22/55 (40%) of our cohort, respectively. Among the 22 patients with HLA-A2 genotype, expression of HLA class I antigens detectable by immunohistochemistry was lost in five (23%) cases. The frequency of MAGE-3 expression in HLA-A2 patients was 5/17 (29%), somewhat lower than that of patients without HLA-A2 expression, 18/38 (47%), although the difference was not statistically significant (P = 0.17). Neither was there a significant association between HLA-A2/MAGE-3 co-expression and survival (P = 0.15, logrank test). We conclude that there is no clear evidence for elimination of lung cancers co-expressing HLA-A2 and MAGE-3 in vivo. Approximately 10% (5/55) of Japanese lung cancer patients are potential candidates for MAGE-3-based immunotherapy.

A gene encoding antigenic peptides of human squamous cell carcinoma recognized by cytotoxic T lymphocytes

Except for melanomas, tumor antigens recognized by cytotoxic T lymphocytes (CTLs) are yet unidentified. We have identified a gene encoding antigenic peptides of human squamous cell carcinomas (SCCs) recognized by human histocompatibility leukocyte antigens (HLA)- A2601-restricted CTLs. This gene showed no similarity to known sequences, and encoded two (125- and 43-kilodalton [kD]) proteins. The 125-kD protein with the leucine zipper motif was expressed in the nucleus of the majority of proliferating cells tested, including normal and malignant cells. The 43-kD protein was expressed in the cytosol of most SCCs from various organs and half of lung adenocarcinomas, but was not expressed in other cancers nor in a panel of normal tissues. The three nonapeptides shared by the two proteins were recognized by the KE4 CTLs, and one of the peptides induced in vitro from peripheral blood mononuclear cells (PBMCs) the CTLs restricted to the autologous tumor cells. The 43-kD protein and this nonapeptide (KGSGKMKTE) may be useful for the specific immunotherapy of HLA-A2601(+) epithelial cancer patients.

CTL response and protection against P815 tumor challenge in mice immunized with DNA expressing the tumor-specific antigen P815A

A DNA immunization approach was used to induce an immune response against the tumor-specific antigen P815A in DBA/2 mice. The P1A gene, which encodes the P815A antigen, was modified by the addition of a short sequence coding for a tag epitope recognized by the monoclonal antibody AU1, and cloned into the eukaryotic expression vector pBKCMV, resulting in plasmid pBKCMV-P1A. L1210 cells stably transfected with pBKCMV-P1A expressed P1A mRNA and were lysed by the syngeneic P815A-specific cytotoxic clone CTL-P1:5, thus confirming that the tag-modified P1A protein underwent correct processing and presentation. A single intramuscular injection of 100 microg of pBKCMV-P1A induced the expression of P1A mRNA for at least 4 months. Eighty percent of DBA/2 mice injected three times with 100 microg of pBKCMV-P1A generated cytotoxic T lymphocytes (CTL) that lysed P815 tumor cells, whereas mock-inoculated animals failed to show any cytotoxicity. Moreover, experiments designed to evaluate the protection of pBKCMV-P1A-immunized mice against a lethal challenge with P815 tumor cells showed that 6 of 10 immunized mice rejected the tumor, and 2 mice showed prolonged survival compared to control animals.

Detection of MAGE-4 protein in sera of lung cancer patients

We investigated the level of MAGE-4 protein in sera of patients with primary lung cancer to understand better the biological roles of the MAGE proteins. MAGE-4 protein was detected as a non-degraded form in both the supernatant of a MAGE-4+ tumor cell line and in a patient's serum. Serum level of the MAGE-4 protein in lung cancer patients (n=100, mean=1.17 ng/ml) was significantly higher than that in either patients with benign pulmonary diseases (n=80, 0.33 ng/ml) or healthy donors (n=68, 0.32 ng/ml). It was higher than the cutoff level (1.15 ng/ml) in 34 of 100 cancer patients, but not in anyone in the other groups.

Detection of MAGE-4 protein in sera of patients with head-and-neck squamous-cell carcinoma

The MAGE-4 gene, a member of the MAGE gene family, is expressed in various cancers, including head-and-neck squamous-cell carcinomas (HN-SCC), but is not expressed in any normal tissues except for the testis and placenta. The aim of this study was to determine whether serum MAGE-4 protein is a useful tumor marker for detection of HN-SCC. An enzyme-linked immunosorbent assay was used to measure serum level of MAGE-4 protein. The serum level of MAGE-4 in pre-operative HN-SCC patients was significantly higher than that in patients with non-malignant diseases (NMD) of the head and neck, volunteers undergoing cancer screening (VOL), or healthy donors (HD). When the cut-off level was determined at 1.15 ng/ml (mean plus 3 SD of HD), sera from 28 of 96 patients with HN-SCC (p < 0.0001 vs. the other groups), 7 of 82 patients with NMD, 2 of 92 with VOL, and 0 of 68 HD were positive for MAGE-4. Serum levels of MAGE-4 protein in all 7 HN-SCC patients whose sera were positive for MAGE-4 before operation decreased after operation, and, in one patient, a renewed rise in serum level was followed by recurrence. These results indicate that MAGE-4 protein is detectable in sera of a significant number of HN-SCC patients, and that serum MAGE-4 protein might be a useful tumor marker to monitor the recurrence of MAGE-4-positive HN-SCC.

Expression of MAGE genes in osteosarcoma

Expression of MAGE genes that encode tumor-rejection antigens recognized by cytotoxic T lymphocytes with major histocompatibility complex class-I antigens was investigated in human osteosarcomas (20 cell lines and eight fresh tumor tissues). MAGE-1, 2, 3, 4, and 6 genes were expressed at the mRNA level in 11 (52.4%), 10 (47.6%), 10 (47.6%) one (4.8%), and 10 (47.6%) of 21 tumor cell lines, respectively, and in five (62.5%), six (75%), five (62.5%), one (12.5%), and five (62.5%) of eight fresh tumor tissues as determined by the reverse transcription-polymerase chain reaction method. MAGE-1 or 4 protein was detected by immunoblot analysis in eight of 11 or one of one tumor cell lines, respectively, where it was expressed at the mRNA level. Major histocompatibility complex class-I antigens were expressed in 19 of 21 tumor cell lines. These results suggest that MAGE tumor-rejection antigens are expressed in substantial numbers of osteosarcomas in a major histocompatibility class-I-restricted manner.

Development of cancer vaccine by tumor rejection antigens

Identification of the MAGE genes allowed us the molecular approach to identify genes encoding tumor rejection antigens expressed on human cancer cells. MAGE-1 proteins are normal tissue antigens compartmentalized in the particular testicular cells playing an important role in the early phase of the spermatogenesis. The MAGE-1, -2, -3, -4 and -6 genes are preferentially expressed in many different cancers at both the mRNA and protein levels. The MAGE genes, particularly MAGE-1, became positive in relatively advanced stages of cancers and recurrent cancers. Approximately one-third to half of human cancers except for myelo-monocytic leukemia expressed at least one of these MAGE genes. The MAGE gene products shall be appropriate target molecules for development of new cancer vaccine.

The tumour-associated antigen MAGE-1 is detectable in formalin-fixed paraffin sections of malignant melanoma

The MAGE-1 gene encodes a protein encompassing a HLA-A1-restricted target epitope for cytolytic T lymphocytes. Monoclonal antibodies directed against the MAGE-1 protein were tested for usage in immunohistology of routine pathology material. Seven formalin-fixed, paraffin-embedded malignant melanomas were studied by the Avidin-Biotin complex (ABC) method with or without different antigen retrieval methods. Native, frozen tissues from the same tumours were used to validate the results by immunohistochemistry on frozen sections, by PCR for mRNA and by protein demonstration in tissue extracts using western blotting. Of 4 monoclonal antibodies tested, mAB 34B and mAB 77B were highly efficient in detecting MAGE-1 protein in deparaffinised sections with the regular ABC method after microwave pretreatment. In a series of an additional 28 patients 75% expressed MAGE-1, 50% in a substantial proportion. Follow-up studies in 6 patients indicate that the expression pattern remains stable but may change substantially within a short range. Immunohistology is thus a rapid and well-established method that might be used to select and monitor HLA-A1 positive patients with malignant melanoma and other candidate tumours for MAGE-1-directed immuno-therapy.

Induction of MAGE genes in lymphoid cells by the demethylating agent 5-aza-2'-deoxycytidine

MAGE genes encoding tumor antigens recognized by cytotoxic T lymphocytes are appropriate target molecules for specific immunotherapy of cancer. We have investigated whether the demethylating agent 5-aza-2'-deoxycytidine (DAC) induces MAGE-1, -2, -3, and -6 in normal and malignant lymphoid cells. DAC induced these MAGE genes in both PHA/interleukin-2 (IL-2)-activated T cells from healthy donors and MAGE-negative T and B cell leukemias in most cases. It also induced MAGE-1 in IL-2-dependent T cell clones and all MAGE genes tested in Epstein-Barr virus-transformed B cell lines. Expression of MAGE-1 protein in the cells was confirmed by western blot analysis with anti-MAGE-1 polyclonal antibody. Therefore, demethylation is a potent stimulus to induce MAGE genes in both normal and malignant lymphoid cells.

Infrequent expression of the MAGE gene family in uveal melanomas

It has previously been reported that MAGE-1, -2, -3 and -4 genes are expressed in human cancers including cutaneous melanoma. MAGE-1 and MAGE-3 represent targets for specific immunotherapy because they encode peptide antigens which are recognised by cytotoxic T lymphocytes (CTL) when presented by HLA class I molecules, and pilot clinical trials with these peptides are currently in progress. It is likely that other members of the MAGE gene family may also encode antigens recognised by CTL. Uveal melanomas, like cutaneous melanomas, arise from melanocytes that are derived from the neural crest. To determine if uveal melanoma patients would be suitable for MAGE-peptide immunotherapy, the expression of MAGE-1, -2, -3 and -4 genes was assessed by reverse transcription followed by polymerase chain reaction (RT-PCR) amplification and ethidium bromide staining. Expression of MAGE genes was not detected in any of 27 primary tumours. Either MAGE-1 or MAGE-4 was expressed in only 2 of 26 metastatic samples, but expression of MAGE-2 or -3 was not detected. Our data suggest that, unlike cutaneous melanomas, uveal melanomas may not be suitable candidates for MAGE-peptide immunotherapy.

Expression of MAGE-1, MAGE-2, MAGE-3/-6 and MAGE-4a/-4b genes in ovarian tumors

MAGE genes encoding tumor-rejection antigens recognized by cytotoxic T lymphocytes are expressed at the mRNA level in various malignant tumors. We have investigated the expression of genes MAGE-1, -2, -3/-6 and -4a/-4b at the mRNA level in malignant and non-malignant ovarian tumors as well as in normal ovaries by reverse transcription-polymerase chain reaction. MAGE-1, -2, -3/-6 and -4a/-4b were expressed in 12, 5, 11 and 4 of 58 malignant tumors, respectively. The majority of these MAGE-mRNA-positive tumors were histologically surface-epithelial-stromal tumors, in particular serous adenocarcinomas. They mostly consisted of either advanced-stage or recurrent tumors. In contrast, neither benign tumors nor normal ovaries expressed any of the MAGE genes investigated. A 46-kDa MAGE-1 protein was identified in MAGE-1-mRNA-positive serous adenocarcinomas by immunoblot analysis with polyclonal anti-MAGE-1 antibody. These results provide important information for specific immunotherapy of ovarian serous adenocarcinomas with MAGE gene products.

Establishment of an enzyme-linked immunosorbent assay (ELISA) for measuring cellular MAGE-4 protein on human cancers

The MAGE genes encoding tumor-rejection antigens are expressed on various human cancers. An enzyme-linked immunosorbent assay (ELISA) was established for measuring cellular MAGE-4 protein (MAGE-4a and/or -4b) expressed on human tumor cells using a monoclonal antibody (mAb) and polyclonal Ab to recombinant MAGE-4b protein. Both the R5 mAb (IgG1) and the polyclonal Ab recognized a 45 kDa protein in extracts of MAGE-4 mRNA positive cancers, and showed no apparent cross-reactivity to the other MAGE gene products (MAGE-1, -2, -3, -6, and -12) by the immunoblot analyses. The R5 mAb and the polyclonal Ab primarily recognized one (the position 119-133) and two oligopeptides (the positions 119-133 and 259-273), respectively, among a series of 31 different MAGE-4b oligopeptides. The amino acid sequences of these two peptides were identical to those of MAGE-4a and -4b, but differed from those of all the other MAGE proteins (MAGE-1, -2, -3, -6, and -12). Substitution of glycine for amino acid in position 123 (arginine, R), 124 (lysine, K), 126 (R) or 128 (K) in a MAGE-4b oligopeptide of the position 119-132 severely decreased the reactivity of the R5 mAb to the oligopeptide. This ELISA also showed no apparent cross-reactivity with the other MAGE gene products (MAGE-1, -2, -3, -6, and -12). The minimum detectable level of MAGE-4 protein was determined to be 10 pg/well (100 pg/ml). The results suggest that this ELISA is a reliable and quantitative method to measure cellular MAGE-4 protein that is a potential target molecule for specific immunotherapy of human cancers.

Expression of MAGE-1 gene by esophageal carcinomas

Expression of the MAGE genes encoding tumor-rejection antigens on HLA-A1 and -Cw1601 recognized by cytotoxic T lymphocytes was investigated in esophageal carcinomas at the mRNA level by the semiquantitative reverse transcription-polymerase chain reaction method. MAGE-1 and -2 genes, but not MAGE-3, -3/-6 and -4a/-4b genes, were expressed in substantial proportions of the primary esophageal carcinomas and their metastatic lymph nodes. The proportion of MAGE-positive samples in the primary esophageal carcinomas correlated with the T factor of the TNM classification (pT1: 2 of 12 tumors, pT2: 1 of 6, pT3: 12 of 29, and pT4: 7 of 18). These results have important implications for specific immunotherapy of esophageal carcinomas using MAGE-1 gene product.