Clinical Study on the Medical Value of Combination Therapy Involving Adoptive Immunotherapy and Chemotherapy for Stage IV Colorectal Cancer (COMVI Study)

BACKGROUND

Adoptive immunotherapy for cancer has evolved through development of novel technologies for generating a large number of activated killer cells, such as αβ T-cells, γδ T-cells, and natural killer cells. There has been no prospective trial of combination therapy involving adoptive immunotherapy and first-line chemotherapy for stage IV colorectal cancer. The present pilot study aimed to evaluate the safety and feasibility of combination therapy involving adoptive immunotherapy and chemotherapy for stage IV colorectal cancer (COMVI study).

PATIENTS AND METHODS

The COMVI study was a prospective, single-arm pilot trial. Therapy in each 21-day treatment cycle involved XELOX (130 mg/m² of oxaliplatin on day 1 plus 1,000 mg/m² of capecitabine twice daily on days 1-14), bevacizumab (7.5 mg/kg on day 1), and αβ T-lymphocytes (over 5×10⁹ on day 18) cultured ex vivo with an immobilized antibody to CD3 and interleukin-2.

RESULTS

The study included six patients (two men and four women) between June 2013 and September 2014. The median patient age was 68 years (range=55-75 years). The overall response rate was 83.3% [complete response in two (33.3%); partial response in three (50.0%); stable disease in one (16.7%); no cases of progressive disease]. The tumor volume reduction rate was 53% (range=38.0-100%). The median progression-free and overall survival durations were 567 and 966 days, respectively. Most adverse events were mild-to-moderate in intensity, and no grade 4 adverse events occurred in the six patients. Only one patient experienced grade 3 hypertension and ileus. Immunotherapy-associated toxicity was minimal in this study.

CONCLUSION

Combination therapy involving adoptive immunotherapy and chemotherapy for stage IV colorectal cancer is feasible and safe. Phase II prospective studies are needed to confirm the safety and efficacy of such chemoimmunotherapy.

Hepatectomy for Liver Metastases of Colorectal Cancer After Adoptive Chemoimmunotherapy Using Activated αβ T-cells

BACKGROUND/AIM

Various types of chemoimmunotherapies for malignant tumors have been reported. However, there are few reports on hepatectomy after chemoimmunotherapy. We evaluated the safety and efficacy of hepatectomy for patients with stage IV colorectal liver metastases (CLM) after chemoimmunotherapy using activated αβ T-cells.

PATIENTS AND METHODS

From June 2012 to December 2016, five patients who underwent hepatectomy after receiving capecitabine and oxaliplatin (XELOX) plus bevacizumab and ex vivo-expanded αβ T-lymphocytes as first-line chemoimmunotherapy were included.

RESULTS

The median age of the five patients (two men, three women) was 61.4 (range=56-75) years. The surgical procedure was partial hepatectomy in two, laparoscopic partial hepatectomy in two, and one case of partial hepatectomy with subsegmentectomy. There was no postoperative complication of Clavien-Dindo grade 3A or higher. One patient had multiple lung metastases.

CONCLUSION

Hepatectomy after chemoimmunotherapy using activated αβ T-cells for CLM can be performed safely.

Immunotherapy using activated T cells with chemotherapy for metastatic colorectal cancer

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Background: The programmed death-1 (PD-1), an inhibitory receptor expressed on activated T cells, is demonstrated to induce an immune-mediated response and play a critical role in tumor initiation and development. T cell activation induces effective antitumor immune response in cancer patients. Adoptive immunotherapy of cancer is evolving with the development of novel technologies that generate proliferation of large number of T cells. We evaluated the safety and efficacy of the combination of adoptive immunotherapy using αβ T cells with chemotherapy for metastatic colorectal cancer (mCRC). Methods: Seventeen patients with mCRC received XELOX + bevacizumab + ex vivo expanded αβ T lymphocytes as a first-line chemoimmunotherapy. Results: Median age of the 17 patients (6 men, 11 women) was 64 years (range:38–80). The T cell number was more than 5.0×109 for each infusion. Median progression-free survival was 15.2 months. Response rate was 80% (complete response (CR) = 23.5%, partial response (PR) = 47.1%, stable disease (SD) = 29.4% and progressive disease (PD) = 0%). Most adverse events were mild to moderate in intensity and immunotherapy-associated toxicity was minimal. Conclusions: Combination of adoptive αβ T cell immunotherapy with chemotherapy for mCRC is safe and effective.

Adoptive Chemoimmunotherapy Using Activated αβ T Cells for Stage IV Colorectal Cancer

BACKGROUND/AIM

Adoptive immunotherapy of cancer is evolving with the development of novel technologies that generate proliferation of large numbers of αβ and γδ T cells. We evaluated the safety and efficacy of the combination of adoptive immunotherapy using αβ T cells with chemotherapy for stage IV colorectal cancer (CRC).

PATIENTS AND METHODS

Fifteen patients with advanced or recurrent CRC received XELOX + bevacizumab + ex vivo expanded αβ T lymphocytes as a first-line chemoimmunotherapy.

RESULTS

Median age of the 15 patients (4 men, 11 women) was 65 years (range=49-80). Median progression-free survival was 21.3 months. Response rate was 80% (complete response (CR)=26.7%, partial response (PR)=53.3%, stable disease (SD)=20% and progressive disease (PD)=0%). Most adverse events were mild to moderate regarding their intensity and immunotherapy-associated toxicity was minimal.

CONCLUSION

Combination of adoptive αβ T cell immunotherapy with chemotherapy for stage IV CRC is feasible and safe.

Clinical study on medical value of adoptive immunotherapy with chemotherapy for stage IV colorectal cancer (COMVI study)

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Background: Adoptive immunotherapy of cancer is evolving with the development of novel technologies for generating a large number of activated killer cells such as αβ T cells, γδ T cells, and natural killer (NK) cells. We conducted a pilot study to evaluate the safety and feasibility of the combination treatment of adoptive immunotherapy with chemotherapy for stage IV colorectal cancer. Methods: The COMVI study was a prospective and single-arm pilot trial. Therapy in each 21-day treatment cycle consisted of XELOX (130 mg/m2 of oxaliplatin on day 1 plus 1,000 mg/m2 of capecitabine twice daily on days 1–14), bevacizumab (7.5 mg/kg on day 1) and αβ T lymphocytes (over 5 ×109 on day 18) cultured ex vivo with an immobilized anti-CD3 antibody and interleukin-2. Results: A total of 6 patients were enrolled from June 2013 to September 2014. Baseline characteristics included a median age of 66 years (range: 55-75) for 2 men and 4women. Median PFS was 567 days. Overall response rate was 100 % (CR 33.3%, PR 66.7%, SD 0%, PD 0%). The tumor reduction rate was 53% (38.0–100%). The majority of adverse events were mild to moderate in intensity, and no grade 4 adverse events occurred in the 6 patients. Only one patient experienced grade 3 hypertension and ileus. Immunotherapy-associated toxicity was minimal in this study. Conclusions: The combination treatment of adoptive immunotherapy with chemotherapy for stage IV colorectal cancer is feasible and safe. Phase II prospective studies are warranted to confirm the safety and efficacy of this chemoimmunotherapy. Clinical trial information: UMIN000010908.

Pulmonary dirofilariasis in a 59-year-old man

We present a case of a human pulmonary dirofilariasis in a 59-year-old man. At the medical examination, a chest computed tomography (CT) revealed a mass, measuring 18 × 15 mm in diameter, with an irregular margin on the bottom of the right lower lobe. We could not neglect the possibility of a primary lung cancer, and therefore, a lung partial resection was performed under video-assisted thoracoscopic surgery. The intra-operative pathological findings revealed inflammatory granuloma with coagulation necrosis and no malignant cells. The permanent pathological examination showed occlusion of the peripheral pulmonary artery by worms and formation of a necrotic mass surrounded by reactive inflammation and hemorrhage. Human pulmonary dirofilariasis is an extremely rare zoonotic infection, and sometimes it is difficult to distinguish it from a primary lung cancer on radiographic findings.

Variations in the structure and transcription of the mitochondrial atp and cox genes in wild Solanum species that induce male sterility in eggplant (S. melongena)

In order to determine the molecular basis of cytoplasmic male sterility (CMS) in alloplasmic lines of eggplant, the genomic structures and transcription patterns of mitochondrial ATP synthase subunit (atp) and cytochrome oxidase subunit (cox) genes were studied for wild and cultivated eggplants. Alloplasmic eggplant lines with cytoplasms of wild Solanum species showing either anther indehiscent type of CMS or non-pollen production type of CMS were studied with the cultivated eggplant Solanum melongena, used as a control. Southern hybridization of the mitochondrial genes indicated the difference between the two types of CMS and showed complete identity within each type. The cytoplasmic patterns of all wild species differed from that of the cultivated eggplant. Thus, the cytoplasm of the six wild eggplants and the one cultivated eggplant was classified into three groups. Male sterile plants of both types of CMS showed novel transcription patterns of atp1, whereas a different transcription pattern of cox2 was observed only in the anther indehiscent type. Based on these differences, we determined the DNA sequences of about a 4 kbp segment in the atp1 region. Although the coding and 3' flanking regions were almost identical among the cytoplasms, the 5' flanking region was completely different and novel open reading frames (orfs) were found for each of the CMS types and the cultivated eggplant. The cytoplasm of Solanum kurzii inducing the anther indehiscent type CMS had orf312, and those of Solanum aethiopicum and Solanum grandifolium of non-pollen production type CMS had orf218. The correspondence between the transcription patterns of these orfs and phenotypic expression of male sterility strongly suggests that these orfs are causal genes for each type of CMS.

[Clinical significance of micrometastases in the lymph nodes of patients with resectable lung cancer]

Clinical evaluation of micrometastases in the lymph nodes of lung cancer patients is not currently recommended in guidelines because of several different results concerning their prevalence and prognostic implications. However, a recent large, prospective, multicenter clinical study has shown a significant prognostic impact of micrometasteses in the lymph nodes of patients with resectable lung cancer; therefore, the clinical significance of micrometastases as predictive markers of recurrence and prognosis has begun to be clarified. From the viewpoint of surgery for lung cancer, sentinel node navigation surgery, segmentectomy, and individualized therapies such as adjuvant chemotherapy are expected to be developed. In the near future, standardization and improvement of the efficiency of diagnostic procedures will be necessary in common clinical practice. Recently, minimal residual cancer cell research, such as circulating tumor cells in the peripheral blood and disseminated tumor cells in the bone marrow, has made good progress. As research in this field continues, it is expected that the mechanism of metastasis and novel therapeutic strategies targeting minimal residual cancer cells will become better understood.

Immunosuppressive effect of regulatory T lymphocytes in lung cancer, with special reference to their effects on the induction of autologous tumor-specific cytotoxic T lymphocytes

It is not easy to induce cytotoxic T lymphocytes (CTLs) against cancer in in vitro culture. Regulatory T cells (Tregs) are considered to play a pivotal role in tumor immune escape. In this study, we analyzed the distribution of Tregs among tumor-infiltrating lymphocytes (TILs), regional lymph node lymphocytes (RLNLs) and peripheral blood lymphocytes (PBLs) in patients with lung cancer, and analyzed the effect of Tregs on the induction of CTLs in vitro. A total of 84 patients with non-small cell lung cancer underwent surgery between January 2003 and December 2004. The TILs, RLNLs and PBLs from these patients were subjected to a comparison analysis. The proportion of CD4(+)CD25(+)Foxp3(+) cells in these lymphocytes was determined by flow cytometry. The effects of Tregs on the induction of CTLs was analyzed by the depletion of Tregs in mixed lymphocyte-tumor cell culture (MLTC). The average proportions of Tregs in the TILs, RLNLs and PBLs were 10.4±9.5, 4.4±2.4 and 2.8±2.1%, respectively. The proportion of Tregs in the RLNLs was significantly higher than that in the PBLs (P<0.001); furthermore, TILs contained a larger number of Tregs than RLNLs (P=0.034). These Tregs substantially suppressed the induction of CTLs against autologous tumor cells. The depletion of Tregs in the MLTC resulted in the successful induction of CTLs. Tregs were found at a higher frequency in the TILs and RLNLs than in the PBLs in lung cancer patients. Since Tregs inhibited the induction of CTLs, the depletion of Tregs may represent a new therapeutic strategy for lung cancer patients.

Differences in sensitivity to tumor-specific CTLs between primary and metastatic esophageal cancer cell lines derived from the same patient

PURPOSE

MHC antigens and adhesion molecules, such as the intracellular adhesion molecule (ICAM-I), play an important role in cellular immune response. We examined the expression patterns of these molecules in both primary and metastatic esophageal carcinoma cells from the same patient and evaluated the cellular immune responses against these cells.

MATERIALS AND METHODS

In the esophageal cancer patient (H122), tumor cell lines were established from primary and subcutaneous metastatic lesions. We compared the expression of cell surface molecules on the metastatic tumor cell line (H122SC) with that on the primary tumor cell line (H122ESO) using flow cytometry. Moreover, we analyzed the differences in cellular immune responses against these cell lines, which expressed similar levels of the Tara antigen, using the Tara antigen-specific CTL clone.

RESULTS

H122SC ICAM-1 expression was significantly lower in H122ESO, and the Tara antigen-specific CTL clone produced lower levels of TNF in response to H122SC than H122ESO. ICAM-1 transfection into the H122SC rendered these cells as sensitive to the CTL clone as the H122ESO.

CONCLUSION

The metastatic tumor cells displayed lower regulated ICAM-1 expression levels and were less sensitive to specific CTLs. ICAM-1 downregulation may be one mechanism by which tumor cells escape immunologic surveillance.

Successful treatment of lung adenocarcinoma in an 18-year-old man

Primary lung cancer is an extremely rare neoplasm in young adults. We report a case of a primary lung adenocarcinoma in an 18-year-old man who presented for examination of a solitary nodule located in the right lower lobe of the lung. A right lower lobectomy was performed with an incomplete resection because of pleural dissemination (pT4N2M0 stage IIIB adenocarcinoma). Intrathoracic chemotherapy (cisplatin, 50 mg/body) was administered initially, followed by systemic chemotherapy (carboplatin + paclitaxel). A bronchopleural fistula occurred 2 months postoperatively and was successfully treated with conservative therapy, including thoracic drainage, intrathoracic fibrin glue administration, and transbronchial superglue administration. Thereafter, a total of five courses of systemic chemotherapy with minor changes in the administration regimen were performed. The patient was alive and with no evidence of recurrence at his 5-year follow-up.

Results of a Surgical Resection for Patients with Thymic Carcinoma

Objectives:

This study investigated the clinical features of patients with complete resection of thymic carcinoma.

Patients and Methods:

The clinical records from 11 patients who underwent a complete resection of thymic carcinoma were retrospectively reviewed.

Results:

Twelve of 22 patients underwent a resection (a complete resection in 11 and an incomplete in 1). Six of the 11 patients with complete had confirmed recurrent tumors. The 5-year survival rate was 45.4%, and the median survival time was 50.6 months. The patients who underwent complete resection showed significantly better prognosis than cases with incomplete resection and inoperable cases ( p = 0.048). Three of the 6 patients had a recurrence within 1 year. Frequent sites of recurrence were the pleura, pericardium, and lung.

Conclusions:

A complete resection improved the prognosis of thymic carcinoma. Further prospective studies regarding postoperative adjuvant therapy are necessary to prevent local recurrence after a surgical resection for thymic carcinoma.

Detection of EGFR and K-ras mutations for diagnosis of multiple lung adenocarcinomas

The incidence of multiple primary lung adenocarcinoma (MPLA) is increasing, and it is important to distinguish MPLA from intrapulmonary metastasis (IPM) in order to determine the therapeutic strategy. However, there is no reliable method to differentiate between the two. The purpose of this study was to distinguish MPLA from IPM based on the gene status of EGFR and K-ras and the morphological Noguchi classification system. Sixty-eight tumors from 34 cases of clinical MPLA were evaluated. Of them, 11 cases (32.4%) were diagnosed as biological MPLA (bMPLA) by EGFR/K-ras mutation analyses, and 12 cases (35.3%) by morphological analysis. In all, 23 of the 34 cases (67.6%) were diagnosed as bMPLA. The remaining 11 cases were diagnosed as biological IPM (bIPM). The 5-year survival rates of bMPLA and bIPM were 90.9% and 63.6%, respectively (p=0.04). These findings suggest that the combination method including gene mutation and morphological analysis can guide treatment decisions and that there is a need for systemic chemotherapy, and surveillance monitoring.

Preoperative CYFRA 21-1 and CEA as prognostic factors in patients with stage I non-small cell lung cancer

PURPOSE

This study investigated the preoperative serum levels of CYFRA 21-1 and CEA as prognostic factors in patients with stage I non-small cell lung cancer.

SUBJECTS

This study evaluated 341 patients who had undergone a complete resection for stage I NSCLC between 2002 and 2008.

RESULTS

The patients included 193 males and 148 females. The mean age of the patients was 69.2 years (range: 19-88). The histological types included 264 adenocarcinomas, 56 squamous cell carcinomas, 11 large cell carcinomas, and 10 other types of carcinoma. A pneumonectomy was performed in 2 patients, a bilobectomy in 7, a lobectomy in 255, a segmentectomy in 46, and partial resection of the lung in 31 patients. The positive rates for CYFRA 21-1 in the adenocarcinoma and squamous cell carcinoma patients were 33.3% and 76.8%, respectively. The positive rates for CEA in adenocarcinoma and squamous cell carcinoma patients were 23.8% and 26.8%, respectively. The 5-year survival rate after surgery in the normal CYFRA 21-1 group and the high CYFRA 21-1 groups were 92.8% and 75.4%, respectively, in the patients with stage I NSCLC. There was a significant difference between the 2 groups (p<0.0001). The 5-year survival rate according to the serum level of CEA in the patients with stage I NSCLC were 88.3% for the normal group and 76.3% for the high group. In a multivariate analysis using the variables found to be significant prognostic factors in univariate analysis, a high CYFRA 21-1 level was found to be a significant independent prognostic factor (95% confidence interval 1.213-5.442, p=0.014).

CONCLUSION

A high preoperative CYFRA 21-1 level was a significant independent prognostic factor in patients with stage I NSCLC. The patients with a high CYFRA 21-1 level should carefully followed-up to rule out occult metastasis. Further clinical studies will be necessary to evaluate the efficacy of adjuvant therapy for the patients selected according to this criterion.

[Clinical analysis of esophageal cancer associated with other primary cancers]

This study aims to investigate the therapeutic and prognostic implications of esophageal cancer in patients with other primary cancer. Between April 1992 and December 2008, in 83 patients underwent surgery for esophageal cancer at our department. Among them, 24 patients (28.9%) had medical history of additional primary cancer. There were 16 metachronous cancers and 8 synchronous cancers. Six patients had antecedent other primary cancers, and subsequent primary cancers developed in 10 patients. The other primary cancers included head and neck cancer in 8 patients, gastric cancer in 8, lung cancer in 6, colorectal cancer in 3, and other cancer in 3. The patients with other primary cancers were both heavy smokers and heavy drinkers in comparison to those without other primary cancers. The post-operative 5-year survival rate in patients with subsequent cancers, antecedent cancers, and synchronous cancers were 100%, 70.0%, and 46.9%. The 5-year survival rate was 33.4% in patients without other primary cancers. A high incidence of multiple primary cancers was observed in patients with esophageal carcinoma but the prognosis of these patients with metachronous cancers are better than that of patient with synchronous cancers and patients without other primary cancers. Post-operative follow up is considered to be necessary for early detection of multiple occurrences of carcinoma, especially in the upper aerodigestive tract.

[Treatment recommendations for adrenal metastasis of non-small cell lung cancer]

To evaluate the optimum treatment strategy for metastatic adrenal tumors derived from non-small cell lung cancer (NSCLC), we retrospectively analyzed 17 consecutive cases (8 resection cases: 4 synchronous and 4 metachronous: 9 non-resection cases: 3 synchronous and 6 metachronous) who received surgical resection for NSCLC. The patients included 12 males and 5 females with a mean age of 63.9 years. Of these, 9, 3, 2, 2, and 1 patient (s) were diagnosed as having adenocarcinoma, squamous cell carcinoma, pleomorphic carcinoma, large cell carcinoma, and adenosquamous cell carcinoma, respectively. The mean interval after lung resection and treatment of metachronous adrenal metastasis was 9.9 months. The mean time to progression from treatment of metachronous adrenal metastasis to disease progression was 8.9 months. A survival analysis showed no significant prognostic difference between the patient age, gender, pathological stage, synchronous/metachronous classification, CEA, and site of metastases. However, patients who received an adrenalectomy had a more favorable prognosis. The 2-year survival of patients following resection versus those who did not undergo a resection for adrenal metastasis was 62.5 and 22.8%, respectively. These data indicate that metastatic adrenal tumors should be resected if the patient can tolerate surgery after appropriate selection.

Overexpression of MACC1 mRNA in lung adenocarcinoma is associated with postoperative recurrence

OBJECTIVE

The purpose of this study was to clarify the role and clinical significance of metastasis associated in colon cancer 1 in resected stage I non-small cell lung cancers.

METHODS

Tumor specimens were collected from 146 consecutive patients who underwent a complete resection for stage I lung adenocarcinoma from 1998 to 2007 at the University of Occupational and Environmental Health. We analyzed the expression of metastasis associated in colon cancer 1 mRNA of primary lung adenocarcinomas by real-time reverse transcriptase-polymerase chain reaction.

RESULTS

The average postoperative observation period was 49.4 months. Thirteen (8.9%) of 146 patients had recurrences after surgery. Overexpression of metastasis associated in colon cancer 1 mRNA was identified in 62 patients (42.5%). Metastasis associated in colon cancer 1 was overexpressed in 9 (69.2%) of 13 patients and 53 (39.9%) of 133 patients with and without recurrence, respectively (P = .004). The median metastasis associated in colon cancer 1 copy number was 3.0 and 1.4 in patients with and without tumor recurrence, respectively. Metastasis associated in colon cancer 1 overexpression was associated with poorer disease-free survival according to the survival analysis (P = .033).

CONCLUSIONS

Metastasis associated in colon cancer 1 gene overexpression may be a useful marker for predicting postoperative recurrence in patients with lung adenocarcinoma after surgery.

Limited pulmonary resection for peripheral small-sized adenocarcinoma of the lung

BACKGROUND

It was recently reported that a limited pulmonary resection (segmentectomy or wedge resection) was not inferior to a lobectomy in the management of peripheral small-sized adenocarcinoma (tumor ≦ 20 mm) of the lung.

METHODS

We retrospectively analyzed patients undergoing a lobectomy (n = 114) and a limited resection (n = 35) for peripheral small-sized adenocarcinoma of the lung during a 7-year period from April 2001 to March 2008. Our criteria for the limited resection of lung cancer were as follows: (1) adenocarcinoma of 10 mm or less in diameter and (2) adenocarcinoma of 11-20 mm in diameter, in which the ratio of the ground glass opacity is 50% or more, without pleural indentation on computed tomography. Additionally, the frozen sections of the tumors were intraoperatively diagnosed as Noguchi type A or B. The survival and clinical outcomes were analyzed.

RESULTS

The 5-year survival rates of the lobectomy group and limited resection groups were 89.2% and 100%, respectively. No recurrence was seen in the limited resection group.

CONCLUSIONS

Our results suggest that our criteria for limited resection were adequate for the management of small-sized adenocarcinoma of the lung.

A randomized phase II trial of adjuvant chemotherapy with bi-weekly carboplatin plus paclitaxel versus carboplatin plus gemcitabine in patients with completely resected non-small cell lung cancer

BACKGROUND

The benefits of adjuvant chemotherapy for completely resected non-small cell lung cancer (NSCLC) have been demonstrated using mainly cisplatin (CDDP)-based chemotherapeutic regimens. However, treatment-related deaths sometimes occur. Therefore, the development of a safer regimen is necessary.

PATIENTS AND METHODS

The patients were randomized to either carboplatin (CBDCA) area under the curve (AUC) 3 and paclitaxel (PTX) 90 mg/m(2) (PCb arm) or CBDCA (AUC3) plus gemcitabine (GEM) (1000 mg/m(2)) (GCb arm) every 2 weeks for 8 cycles after surgery. The primary endpoint was the compliance with the regimen, while the secondary endpoints were safety and toxicity.

RESULTS

A total of 75 patients were enrolled in a multi-institutional study. Twenty-one out of 39 patients (54%) in the PCb arm and 25 of 36 patients (69%) in the GCb arm completed 8 cycles, and 59% in the PCb arm and 81% in the GCb arm completed ≥6 cycles. The predominant toxicity was neutropenia. Non-hematological adverse effects were infrequent and no treatment-related death was registered. The estimated disease-free survival and overall survival at 2 years were 70.8% and 66.3% in the PCb and 91.4% and 79.1% in the GCb arm, respectively.

CONCLUSION

This adjuvant bi-weekly scheduled chemotherapy resulted in good compliance in both arms, and the regimen was feasible, with acceptable levels of toxicity in completely resected Japanese NSCLC patients. Therefore, these regimens represent a new treatment option suitable for outpatients with completely resected NSCLC.

Loss of PTEN expression by blocking nuclear translocation of EGR1 in gefitinib-resistant lung cancer cells harboring epidermal growth factor receptor-activating mutations

Gefitinib (Iressa) and erlotinib (Tarceva), which target the epidermal growth factor receptor (EGFR), are approved for treatment of patients with advanced non-small cell lung cancer (NSCLC). Patients whose tumors harbor mutations in the EGFR gene, including delE746-A750 in exon 19 and L858R in exon 21, may benefit in particular from gefitinib treatment. However, acquired resistance to gefitinib has been a serious clinical problem, and further optimization is needed for application of EGFR-targeted drugs in lung cancer patients. In this study, we established gefitinib-resistant NSCLC cells from PC-9 cell line, which harbors the delE746-A750 mutation, by exposing the cell line to gefitinib for over 7 months. Gefitinib-resistant PC-9/GEFs cell lines showed a marked downregulation of PTEN expression and increased Akt phosphorylation. In revertant, gefitinib-sensitive clones (PC-9/Rev) derived from PC-9/GEF1-1 and PC-9/GEF2-1, PTEN expression, as well as sensitivity to gefitinib and erlotinib, was restored. Knockdown of PTEN expression using small interfering RNA specific for PTEN in PC-9 cells resulted in drug resistance to gefitinib and erlotinib. Nuclear translocation of the EGR1 transcription factor, which regulates PTEN expression, was shown to be suppressed in resistant clones and restored in their revertant clones. Reduced PTEN expression was also seen in tumor samples from a patient with gefitinib-refractory NSCLC. This study thus strongly suggests that loss of PTEN expression contributes to gefitinib and erlotinib resistance in NSCLC. Our findings reinforce the therapeutic importance of PTEN expression in the treatment of NSCLC with EGFR-targeted drugs.