Yoshinobu Ichiki

Mutations within the tyrosine kinase domain of EGFR gene specifically occur in lung adenocarcinoma patients with a low exposure of tobacco smoking.

Somatically acquired mutations in the epidermal growth factor receptor (EGFR) gene in lung cancer are associated with significant clinical responses to gefitinib, a tyrosine kinase inhibitor that targets EGFR. We screened the EGFR in 469 resected tumours of patients with lung cancer, which included 322 adenocarcinomas, 102 squamous cell carcinomas, 27 large cell carcinomas, 13 small cell carcinomas, and five other cell types. PCR with a specific condition was performed to identify any deletion in exon 19, while mutant-allele-specific amplification was performed to identify a mutation in codon 858 of exon 21. EGFR mutations were found in 136 cases (42.2%) with adenocarcinoma, in one case with large cell carcinoma, and in one case with pleomorphic carcinoma. An in-frame deletion in exon 19 was found in 62 cases while an L858R mutation was found in 77 cases. In the 322 cases with adenocarcinoma, these mutations were more frequently found in women than in men (P=0.0004), in well differentiated tumours than in poorly differentiated tumours (P=0.0014), and in patients who were never smokers than in patients who were current/former smokers (P<0.0001). The mutation was more frequently observed in patients who smoked ⩽20 pack-year, and in patients who quit at least 20 years before the date of diagnosis for lung cancer. The K-ras mutations were more frequently found in smokers than in never smokers, and in high-dose smokers than in low-dose smokers. In conclusion, the mutations within the tyrosine kinase domain of EGFR were found to specifically occur in lung adenocarcinoma patients with a low exposure of tobacco smoking.

Prospective phase II study of gefitinib in non-small cell lung cancer with epidermal growth factor receptor gene mutations.

BACKGROUND This study prospectively assessed the efficacy of gefitinib and the survival benefit for non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutations. METHOD Patients with either recurrent disease after undergoing surgery or advanced NSCLC disease (IIIB or IV) which demonstrated EGFR mutations were eligible for this study. EGFR mutations in exons 19-21 were examined. The patients with EGFR mutations were enrolled in this study after obtaining their informed consent a second time, and they were thereafter treated with gefitinib. RESULTS EGFR mutations were detected in 20 of 48 patients with NSCLC, and 19 patients were enrolled onto this study and treated with gefitinib. Seven patients had an exon 19 deletion, 10 had L858R, 1 had both, and 1 had an exon 19 deletion and G796A. The overall response rate was 63.2%, and the disease control rate was 89.5%. In patients with an exon 19 del and L858R, the response rates were 71.4% and 60.0%, respectively. The median progression-free survival time was 7.1 months, and the median survival time was 20.0 months. No life-threatening toxicity was observed. Four of five acquired resistant tumors showed an acquired T790M mutation. CONCLUSIONS EGFR mutations in exons 19 or 21 are considered to be a good predictor of the efficacy of gefitinib.

Haplotype loss of HLA class I antigen as an escape mechanism from immune attack in lung cancer.

One of tumor escape mechanisms from the hosts immunosurveillance system (i.e., a haplotype loss of HLA class I antigens) has been detected in various tumor cells. We hypothesize that the majority of tumor cells with normal HLA class I expression were attacked and eradicated by CTLs, and only a minority with an abnormal expression of HLA class I antigens could escape the hosts immunosurveillance system. Using HLA class I-transfected tumor variants as stimulators in A904L lung cancer cell line, which has a haplotype loss of HLA class I antigens, both the transfected HLA-A26 and HLA-B39-restricted CTL lines were induced from autologous lymphocytes. However, only one HLA-B39-restricted CTL clone (CTL G3b) was established, and it was then used to identify the antigen. SGT1B [suppressor of G2 allele of SKP1 (SGT1), suppressor of kinetochore protein (SKP1)] was identified as the antigen recognized by CTL G3b. Further experiments using 13 subclones from a primary culture of A904L were found to confirm our above-mentioned hypothesis. Tumor cells with a normal HLA class I expression may thus be killed by CTL at an early stage of carcinogenesis, and only tumor cells with a haplotype loss of HLA class I antigens can escape an immune attack and develop into clinical cancer.

Cytokine production of lung cancer cell lines: Correlation between their production and the inflammatory/immunological responses both in vivo and in vitro

Cytokines produced by tumor cells may have various effects on antitumor immune responses and tumor growth. In the present study, the cytokine production of 31 lung cancer cell lines was evaluated, while any correlation with the histological type, the induction of tumor‐specific cytotoxic T lymphocytes (CTL) in vitro, and angiogenesis and the infiltration of inflammatory cells in tumor tissues were also examined. Production of interleukin (IL)‐1α, IL‐1β, IL‐4, IL‐6, IL‐8, IL‐10, tumor necrosis factor (TNF)‐α, granulocyte macrophage colony stimulating factor (GM‐CSF), granulocyte colony stimulating factor, transforming growth factor (TGF)‐β and vascular endothelial growth factor (VEGF) in the culture supernatant was measured using enzyme‐linked immunosorbent assay. Each cytokine was produced in a substantial number of the tumor cell lines. In particular, IL‐6, IL‐8, TGF‐β and VEGF were produced in 18 (55%), 29 (94%), 31 (100%) and 28 (90%) of 31 cell lines, respectively. However, neither IL‐4 nor TNF‐α was produced at all by any tumor cell line. TGF‐β production was significantly higher in adenocarcinoma than in squamous cell carcinoma (P = 0.03). Immunohistochemical staining revealed the magnitude of macrophage infiltration, and angiogenesis in surgically resected tumor tissue specimens correlated well with GM‐CSF and IL‐8 production from the corresponding cell lines. Among six lung cancer cell lines, CTL were induced in the three lung cancer cell lines that produced a lower amount of TGF‐β (<100 pg/mL). These findings suggested that TGF‐β produced by tumor cells could inhibit the induction of CTL in vitro. The present results suggest that the production of various cytokines from tumor cells might exert various paracrine effects both in vivo and in vitro. (Cancer Sci 2007; 98: 1048–1054)

Clinical significance of cancer/testis antigens expression in patients with non-small cell lung cancer

Cancer/testis antigens (CT antigens) are thought to be suitable targets for antigen-specific immunotherapy, because of the cancer-specific expression except for the testis among various normal tissues and no-expression of HLA class I in the testis. In the present study, the expressions of CT antigens (MAGE-A3, MAGE-A4, NY-ESO-1 and KK-LC-1) in non-small cell lung cancer (NSCLC) were analyzed by RT-PCR. The subjects were 239 patients with NSCLC who underwent surgery from 2001 to 2005 in our department. The expression rates of MAGE-A3, MAGE-A4, NY-ESO-1 and KK-LC-1 were 23.8%, 20.1%, 10.5% and 32.6% in patients with NSCLC, respectively. MAGE-A4 was expressed more frequently in male (25.3%) than in female (10.6%) (p<0.01). The positive proportion of MAGE-A4 was higher in stages II-IV (30.6%) than in stage I (12.8%) (p<0.01). Both of MAGE-A3 and MAGE-A4 were expressed more frequently in squamous cell carcinoma than in adenocarcinoma (p<0.01). Such tendency was not observed among NY-ESO-1 and KK-LC-1 expression. KK-LC-1 was expressed in 32.1% of patients with adenocarcinoma and in 36.5% of patients with squamous cell carcinoma. Patients with positive MAGE-A4 expression showed significantly poorer overall survival than those without MAGE-A4 expression (p=0.013), and such effect on survival was also observed, when the analysis was limited to patients at stage I (p=0.0037). Expression of MAGE-A3, NY-ESO-1 or KK-LC-1 did not affect survival of patients with NSCLC significantly, however, expression of at least one of such CT antigens negatively affect survival of patients with NSCLC (p=0.045).

Simultaneous Cellular and Humoral Immune Response against Mutated p53 in a Patient with Lung Cancer

We recently identified several Ags recognized by tumor-infiltrating B lymphocyte-derived Ab using SCID mice and a xenografted non-small cell lung cancer system. One of these identified Ags was mutated p53 with a point mutation resulting in the alteration of codon 158 from Arg to Leu. The aim of this study was to ascertain whether cellular immunity against mutated p53 exists in the same patient together with humoral immunity. Two different nona peptides (mutated p53150 and p53155 peptides), including a mutated amino acid derived from p53, were synthesized according to the binding motif of HLA class I of the established cancer cell line A904L from the patient. Mediastinal lymph node lymphocytes of the patient were stimulated weekly with the peptides. The mutated p53155 peptide-stimulated lymphocytes showed specific cytotoxicity against both autologous EBV-transformed B cells pulsed with mutated p53155 peptide and A904L. The mutated p53155 peptide-specific CTL clone in an HLA-Cw*0702 restriction was established and analyzed for its TCR usage. Clonotypic PCR using CDR3-specific primers was applied to the tumor tissue containing the tumor-infiltrating lymphocytes. The specific amplification of PCR was found in the tumor tissue. These results demonstrated that not only B lymphocytes producing specific Ab against the p53 protein, but also CTL against mutated p53, expressed in autologous lung cancer cells exist in the tumor tissue. This approach may allow us to better understand the mechanisms of T and B cell immunity against the same tumor Ag in cancer patients.

Acute lung injury following an esophagectomy for esophageal cancer, with special reference to the clinical factors and cytokine levels of peripheral blood and pleural drainage fluid

Acute lung injury (ALI) is one of most serious complications to occur after an esophagectomy for esophageal cancer. However, the pathogenesis of ALI is still unclear. The cytokine levels of pleural drainage fluid as well as peripheral blood were measured in 27 patients who had undergone an extended radical esophagectomy. Both the clinical factors and cytokine levels were compared between 11 patients with (group I) and 16 without ALI (group II). ALI occurred more frequently in patients who underwent colon interposition than in those who received a gastric tube reconstruction (86%vs 25%, P = 0.009). The operation time of group I was significantly longer than that of group II. A logistic regression analysis revealed colon interposition to be an independent factor associated with the ALI (P < 0.05). Postoperative anastomotic leakage and systemic inflammatory response syndrome (SIRS) occurred more frequently in group I than in group II (P < 0.01). Both the serum interleukin-6 (IL-6) and IL-8 levels of group I were significantly higher than those of group II. IL-1beta and tumor necrosis factor-alpha were undetectable in the peripheral blood, whereas they were detectable in the pleural effusion. The IL-1beta of pleural effusion was higher in group I than group II. In conclusion, greater surgical stress, such as a longer operative time, is thus considered to be associated with the first attack of ALI. The adverse events developing in the extra-thoracic site, such as necrosis and local infection around anastomosis may therefore be the second attack. Furthermore, ALI may cause not only SIRS but also other complications such as anastomotic leakage.

Identification of a New Cancer/Germline Gene, KK-LC-1, Encoding an Antigen Recognized by Autologous CTL Induced on Human Lung Adenocarcinoma

The purpose of our present study is to identify a tumor-specific antigen capable of inducing a specific cellular immune response in lung cancer patients. We established a lung adenocarcinoma cell line, designated as F1121L, and induced tumor-specific CTL clone H1 from regional lymph node lymphocytes of patient F1121. CTL clone H1 lysed autologous tumor cells in an HLA-B*1507-restricted manner, but not autologous EBV-B, phytohemagglutinin-blast cells, and K562. The CTL clone also recognized allogeneic HLA-B*1501- or 1507-positive lung cancer cell lines in the HLA-restricted manner. Using the CTL clone, we identified an antigen-coding gene by cDNA expression cloning technique. The gene consisted of 556 bp, including an open reading frame consisted of 113 amino acids, designated as Kita-kyushu lung cancer antigen 1 (KK-LC-1). A 9-mer peptide (KK-LC-1(76-84); RQKRILVNL) was identified as an epitope peptide. The genomic DNA of this antigen was located in chromosome Xq22. A reverse transcription-PCR analysis revealed that the mRNA of this gene was only expressed in the testis among normal tissues. It was expressed in 9 of 18 (50%) allogeneic non-small-cell lung cancer cell lines and in 40 of 100 (40%) non-small-cell lung cancer tissues. We thus identified a new tumor antigen-coding gene categorized as a cancer/germline gene by an autologous lung cancer and CTL system. The new cancer/germline gene was located in Xq22, which is apparently different from the locations of previously reported cancer/germline genes.

Significance of Smoking as a Postoperative Prognostic Factor in Patients with Non-small Cell Lung Cancer

Introduction: In this study, we investigated the influence of smoking on the postoperative prognosis in patients with non-small cell lung cancer. Methods: The subjects consisted of 770 patients who underwent a resection of lung cancer in our department between 1994 and 2005. We compared the clinico-pathological findings between the smoking and never-smoking groups. The pack-year index (PYI) was used as a smoking index. Results: The smoking group consisted of 569 patients (74%), and the never-smoking group consisted of 201 patients (26%). The smokers were composed of 492 men and 77 women. Among the adenocarcinoma patients, there were 293 (61%) smokers and 185 (39%) never-smokers. The patients with squamous cell carcinoma included 204 (95%) smokers and 10 (5%) never-smokers. The proportion of patients with stage IA disease was significantly higher in the never-smokers than that of the smokers. The 5-year survival rate after surgery was 66% in the never-smoking group; however, the rates were 56% in patients with a PYI more than or equal to 20, and 55% in those with PYI more than 20. Seventy-nine (13.9%) patients in the smoking group and seven (3.5%) patients in the never-smoking group died of other diseases, with a significant difference (p < 0.01). Of these patients, 44 (56%) and 13 (16%) in the smoking group died of respiratory and cardiovascular disorders, respectively. In our series, excluding those who died of other diseases, there were no significant differences in the postoperative prognosis. Conclusions: In the smoking group, the prognosis was poorer than that in the never-smoking group. The higher proportion of early stage disease (stage IA) and female gender were major causes of the better prognosis of the never-smokers. Nevertheless, the high pulmonary/cardiovascular complication-related mortality was another cause of the poor prognosis of the smokers with lung cancer.

Lack and restoration of sensitivity of lung cancer cells to cellular attack with special reference to expression of human leukocyte antigen class I and/or major histocompatibility complex class I chain related molecules A/B

Both cytotoxic T lymphocytes (CTL) and natural killer (NK) cells may play major roles in the host defense against cancer. However, their relationship against the same tumor remains to be elucidated. Among 26 human lung cancer cell lines established in our laboratory, 10 (38%) exhibited human leukocyte antigen (HLA)‐class I haplotype loss and three (12%) lost HLA‐class I expression totally by flow cytometry analysis. The two cell lines (E522L and C831L) that lost their expression of HLA‐class I in vitro and in vivo were applied for further evaluations. Genetic abnormalities of β2‐microglobulin gene were observed in both E522L (loss of mRNA) and C831L (point mutation). Transduction of the wild‐type β2‐microglobulin gene rendered them positive for HLA‐class I expression. The CTL were induced from autologous peripheral blood mononuclear cells or regional lymph node lymphocytes by stimulation with wild‐type β2‐microglobulin transduced‐E522L or ‐C831L, and they showed tumor‐specific cytotoxicity against wild‐type β2‐microglobulin‐transductant, but not parental cells. In NK cell cytotoxicity, E522L showed high sensitivity to NK cells; however, C831L showed resistance despite loss of HLA‐class I expression. E522L expressed MHC class I chain related molecules A/B, but C831L did not. The transduction of the MHC class I chain related molecule A gene from E522L rendered C831L positive for expression and sensitive to NK cell cytotoxicity. Reconstruction of HLA‐class I and MHC class I chain related molecules A expression could abrogate evasion from cellular attack by CTL and NK cells, and it may lead to a breakthrough in the development of cancer immunotherapy. (Cancer Sci 2007; 98: 1795–1802)