Nagio Takigawa

Emergence of epidermal growth factor receptor T790M mutation during chronic exposure to gefitinib in a non-small cell lung cancer cell line

The epidermal growth factor receptor (EGFR)-specific tyrosine kinase inhibitor gefitinib may provide dramatic clinical responses in some patients with pulmonary adenocarcinoma carrying activating mutations of the EGFR. However, prolonged administration of gefitinib may eventually induce acquired resistance in such patients. To gain insight into the mechanisms of this phenomenon, we placed PC-9, a cell line derived from pulmonary adenocarcinoma that has a 15-bp deletion in EGFR exon 19, under the continuous selective pressure of low levels of gefitinib without any mutagen, and established a subline that was able to grow in the presence of 2 micromol/L of gefitinib (designated RPC-9). In this cell line, about half of the reverse transcription-PCR products from mutated EGFR also carried an additional mutation (T790M). In keeping with the proposed role of T790M in abrogating gefitinib binding with EGFR, gefitinib-treated RPC-9 hardly displayed any decrease in the constitutive phosphorylation of EGFR, Akt, or Erk1/2 unlike in PC-9 cells. Interestingly, transfection of the EGFR carrying only a 15-bp deletion reversed the resistance to gefitinib in RPC-9 cells. Thus, the balance of expression levels between gefitinib-sensitive or gefitinib-resistant EGFR may govern the response to gefitinib in lung cancer.

MET gene amplification or EGFR mutation activate MET in lung cancers untreated with EGFR tyrosine kinase inhibitors

We analyzed MET protein and copy number in NSCLC with or without EGFR mutations untreated with EGFR tyrosine kinase inhibitors (TKIs). MET copy number was examined in 28 NSCLC and 4 human bronchial epithelial cell lines (HBEC) and 100 primary tumors using quantitative real‐time PCR. Positive results were confirmed by array comparative genomic hybridization and fluorescence in‐situ hybridization. Total and phospho‐MET protein expression was determined in 24 NSCLC and 2 HBEC cell lines using Western blot. EGFR mutations were examined for exon 19 deletions, T790M, and L858R. Knockdown of EGFR with siRNA was performed to examine the relation between EGFR and MET activation. High‐level MET amplification was observed in 3 of 28 NSCLC cell lines and in 2 of 100 primary lung tumors that had not been treated with EGFR‐TKIs. MET protein was highly expressed and phosphorylated in all the 3 cell lines with high MET amplification. In contrast, 6 NSCLC cell lines showed phospho‐MET among 21 NSCLC cell lines without MET amplification (p = 0.042). Furthermore, those 6 cell lines harboring phospho‐MET expression without MET amplification were all EGFR mutant (p = 0.0039). siRNA‐mediated knockdown of EGFR abolished phospho‐MET expression in examined 3 EGFR mutant cell lines of which MET gene copy number was not amplified. By contrast, phospho‐MET expression in 2 cell lines with amplified MET gene was not down‐regulated by knockdown of EGFR. Our results indicated that MET amplification was present in untreated NSCLC and EGFR mutation or MET amplification activated MET protein in NSCLC.

Twenty-Seven Years of Phase III Trials for Patients with Extensive Disease Small-Cell Lung Cancer: Disappointing Results

Background Few studies have formally assessed whether treatment outcomes have improved substantially over the years for patients with extensive disease small-cell lung cancer (ED-SCLC) enrolled in phase III trials. The objective of the current investigation was to determine the time trends in outcomes for the patients in those trials. Methods and Findings We searched for trials that were reported between January 1981 and August 2008. Phase III randomized controlled trials were eligible if they compared first-line, systemic chemotherapy for ED-SCLC. Data were evaluated by using a linear regression analysis. Results: In total, 52 trials were identified that had been initiated between 1980 and 2006; these studies involved 10,262 patients with 110 chemotherapy arms. The number of randomized patients and the proportion of patients with good performance status (PS) increased over time. Cisplatin-based regimens, especially cisplatin and etoposide (PE) regimen, have increasingly been studied, whereas cyclophosphamide, doxorubicin, and vincristine–based regimens have been less investigated. Multiple regression analysis showed no significant improvement in survival over the years. Additionally, the use of a PE regimen did not affect survival, whereas the proportion of patients with good PS and the trial design of assigning prophylactic cranial irradiation were significantly associated with favorable outcome. Conclusions and Significance The survival of patients with ED-SCLC enrolled in phase III trials did not improve significantly over the years, suggesting the need for further development of novel targets, newer agents, and comprehensive patient care.

A Phase II Trial of Erlotinib Monotherapy in Pretreated Patients with Advanced Non-small Cell Lung Cancer Who Do Not Possess Active EGFR Mutations: Okayama Lung Cancer Study Group Trial 0705

Backgrounds: Efficacy of gefitinib therapy strongly depends on epidermal growth factor receptor (EGFR)-mutation status in Asian patients with non-small cell lung cancer. Recently, the survival advantage of erlotinib, another tyrosine kinase inhibitor, was not affected by EGFR mutation status in a phase III trial, indicating that patients with EGFR-wild-type (EGFR-wt) tumors might also benefit from this tyrosine kinase inhibitor. The aim of this trial was to evaluate the efficacy and toxicity of erlotinib in Japanese patients with EGFR-wt tumors. Methods: The primary end point was an objective response. Patients with EGFR-wt tumors previously receiving one to three chemotherapy regimens were enrolled in this trial. The mutation status was assessed using the peptide nucleic acid-locked nucleic acid polymerase chain reaction clamp method. Erlotinib was administered (150 mg/d) until disease progression or unacceptable toxicities occurred. Results: Thirty patients were enrolled between January and December 2008. Objective response was observed in one patient (3.3%), and the disease became stable in 18 patients (60.0%). Skin rash was the most common side effect. Grades 3–4 adverse events included pulmonary embolism, keratitis, and anemia. Two other patients developed interstitial lung disease (grades 1 and 2). Nevertheless, all these events were reversible, resulting in no treatment-related deaths. With a median follow-up time of 10.7 months, the median survival time and median progression-free survival times were 9.2 and 2.1 months, respectively. Conclusion: This is the first prospective biomarker study showing that erlotinib therapy for pretreated patients with EGFR-wt tumors seems to have a modest activity with no irreversible toxicity.

Clinical Significance of Epidermal Growth Factor Receptor Gene Mutations on Treatment Outcome after First-line Cytotoxic Chemotherapy in Japanese Patients with Non-small Cell Lung Cancer

Introduction: The relationship between the EGFR gene mutation status and clinical outcome has not fully been assessed in patients with non-small cell lung cancer (NSCLC) who received cytotoxic agents. The aim of this study was to clarify its association. We also examined whether this association could be affected by previous gefitinib treatment. Methods: Patients with advanced or postoperative recurrent NSCLC who received both cytotoxic chemotherapy and gefitinib monotherapy in their treatment course were included in this study. An EGFR mutation was determined in exons 19 and 21 by direct sequencing. Results: Of 194 Japanese patients with advanced or relapsed NSCLC assessable for mutation analysis, 60 received both cytotoxic chemotherapy and gefitinib monotherapy through their treatment courses. EGFR mutations significantly affected progression-free survival (PFS) in the first-line cytotoxic chemotherapy regimens in the multivariate analysis (hazard ratio for PFS = 0.422; p = 0.0422). In contrast, in 28 (47%) of the 60 patients who also received cytotoxic chemotherapy after the relapse to gefitinib monotherapy, there were no differences in PFS stratified by EGFR mutation status. The sensitivity to gefitinib was, however, correlated with EGFR mutation status, and its sensitivity was retained even in the second-line treatment setting in patients with EGFR mutations. Conclusions: EGFR mutations were therefore significantly associated with a better PFS in the first-line cytotoxic chemotherapy regimens. However, its association was not observed in the cytotoxic regimens administered after the relapse to gefitinib monotherapy, whereas gefitinib sensitivity was associated with an EGFR mutation even in the second-line or later treatment settings.

Phase I/II study of docetaxel and cisplatin with concurrent thoracic radiation therapy for locally advanced non-small-cell lung cancer.

Recent studies have suggested the superiority of concomitant over sequential administration of chemotherapy and radiotherapy. Docetaxel and cisplatin have demonstrated efficacy in advanced non-small-cell lung cancer (NSCLC). This study evaluated the safety, toxicity, and antitumour activity of docetaxel/cisplatin with concurrent thoracic radiotherapy for patients with locally advanced NSCLC. Patients with locally advanced NSCLC (stage IIIA or IIIB), good performance status, age ⩽75 years, and adequate organ function were eligible. Both docetaxel and cisplatin were given on days 1, 8, 29, and 36. Doses of docetaxel/cisplatin (mg m−2) in the phase I study portion were escalated as follows: 20/30, 25/30, 30/30, 30/35, 30/40, 35/40, 40/40, and 45/40. Beginning on day 1 of chemotherapy, thoracic radiotherapy was given at a total dose of 60 Gy with 2 Gy per fraction over 6 weeks. In the phase I portion, the maximum tolerated doses (MTD) among 33 patients were docetaxel 45 mg m−2 and cisplatin 40 mg m−2. The major dose-limiting toxicity (DLT) was radiation oesophagitis. The recommended doses (RDs) for the phase II study were docetaxel 40 mg m−2 and cisplatin 40 mg m−2. A total of 42 patients were entered in the phase II portion. Common toxicities were leukopenia, granulocytopenia, anaemia, and radiation oesophagitis, with frequencies of grade ⩾3 toxicities of 71, 60, 24, and 19%, respectively. Toxicity was significant, but manageable according to the dose and schedule modifications. Dose intensities of docetaxel and cisplatin were 86 and 87%, respectively. Radiotherapy was completed without a delay in 67% of 42 patients. The overall response rate was 79% (95% confidence interval (CI), 66–91%). The median survival time was 23.4+ months with an overall survival rate of 76% at 1 year and 54% at 2 years. In conclusion, chemotherapy with cisplatin plus docetaxel given on days 1, 8, 29, and 36 and concurrent thoracic radiotherapy is efficacious and tolerated in patients with locally advanced NSCLC and should be evaluated in a phase III study.

Relationship between response and survival in more than 50,000 patients with advanced non-small cell lung cancer treated with systemic chemotherapy in 143 phase III trials.

Background: The association between the objective response to chemotherapy and survival has not yet been fully evaluated using large cohorts in advanced non-small cell lung cancer. Methods: We searched for phase III trials conducted between 1991 and 2006 to investigate the role of systemic chemotherapy for advanced non-small cell lung cancer. Associations were tested by multiple regression analysis. Results: Of the 1255 trials screened, 143 met our criteria, involving 50,569 patients with 309 chemotherapy regimens. In the first-line setting, the median intention-to-treat objective response rate (ORR) and disease control rate (DCR) were 26.4% and 62.5%, respectively (43,551 randomized patients; 290 trials). The median of the median survival time (MST) was 8.5 months in the first-line setting, and both the ORR and DCR were significantly associated with the MST in the multivariate analysis (regression coefficient = 0.0788 [p < 0.0001] and 0.0794 [p < 0.0001], respectively). Subgroup analysis showed no correlation between the ORR and MST in patients receiving chemotherapy containing molecular-targeted agents (p = 0.3817). In the second-line or later setting, the median ORR was only 6.8%, whereas the median DCR was 42.4% (4318 randomized patients; 19 trials). The median MST (6.6 months) was not associated with the ORR (p = 0.6992), but was associated with the DCR (p = 0.0129), despite the small sample size. Conclusions: We found that survival was associated with both the ORR and DCR in the first-line setting, although it should be interpreted cautiously because of the abstracted data–based analysis. Regarding chemotherapy regimens containing molecular-targeted agents and salvage chemotherapy regimens, further assessments are warranted to clarify the association between the parameters.

A phase I study of vaccination with NY-ESO-1f peptide mixed with Picibanil OK-432 and Montanide ISA-51 in patients with cancers expressing the NY-ESO-1 antigen.

We conducted a phase I clinical trial of a cancer vaccine using a 20‐mer NY‐ESO‐1f peptide (NY‐ESO‐1 91–110) that includes multiple epitopes recognized by antibodies, and CD4 and CD8 T cells. Ten patients were immunized with 600 μg of NY‐ESO‐1f peptide mixed with 0.2 KE Picibanil OK‐432 and 1.25 ml Montanide ISA‐51. Primary end points of the study were safety and immune response. Subcutaneous injection of the NY‐ESO‐1f peptide vaccine was well tolerated. Vaccine‐related adverse events observed were fever (Grade 1), injection‐site reaction (Grade 1 or 2) and induration (Grade 2). Vaccination with the NY‐ESO‐1f peptide resulted in an increase or induction of NY‐ESO‐1 antibody responses in nine of ten patients. The sera reacted with recombinant NY‐ESO‐1 whole protein as well as the NY‐ESO‐1f peptide. An increase in CD4 and CD8 T cell responses was observed in nine of ten patients. Vaccine‐induced CD4 and CD8 T cells responded to NY‐ESO‐1 91–108 in all patients with various HLA types with a less frequent response to neighboring peptides. The findings indicate that the 20‐mer NY‐ESO‐1f peptide includes multiple epitopes recognized by CD4 and CD8 T cells with distinct specificity. Of ten patients, two with lung cancer and one with esophageal cancer showed stable disease. Our study shows that the NY‐ESO‐1f peptide vaccine was well tolerated and elicited humoral, CD4 and CD8 T cell responses in immunized patients.

Activation of downstream epidermal growth factor receptor (EGFR) signaling provides gefitinib-resistance in cells carrying EGFR mutation

Patients with pulmonary adenocarcinoma carrying the epidermal growth factor receptor (EGFR) mutation tend to display dramatic clinical response to treatment with the EGFR tyrosine kinase inhibitor gefitinib. Unfortunately, in many cases the cancer cells eventually acquire resistance, and this limits the duration of efficacy. To gain insight into these acquired resistance mechanisms, we first prepared HEK293T cell line stably transfected with either wild‐type (WT) or mutant (L858R) EGFR, and then expressed oncogenic K‐Ras12V mutant in the latter transfectant. Although 293T cells expressing wild‐type EGFR did not show any growth inhibition by gefitinib treatment similarly to the non‐transfected cells, the cells expressing the EGFR‐L858R were exquisitely sensitive. Consistently, phospho‐Akt levels were decreased in response to gefitinib in cells expressing EGFR‐L858R but not in cells with EGFR‐WT. In contrast, 293T cells expressing both EGFR‐L858R and oncogenic K‐Ras were able to proliferate even in the presence of high concentration of gefitinib probably by inducing Erk1/2 activation. We also expressed K‐Ras12V in the gefitinib‐sensitive pulmonary adenocarcinoma cell line PC‐9, which harbors an in‐frame deletion in the EGFR gene. The activated K‐Ras inhibited the effects of gefitinib treatment on cell growth, cell death induction and levels of phospho‐Akt, as well as phospho‐Erk. These data indicate that activated Ras could substitute most of the upstream EGFR signal, and are consistent with the hypothesis that mutational activation of targets immediately downstream from the EGFR could induce the secondary resistance to gefitinib in patients with lung cancer carrying EGFR mutation. (Cancer Sci 2007; 98: 357–363)

Clinical outcome in patients with leptomeningeal metastasis from non-small cell lung cancer: Okayama Lung Cancer Study Group

OBJECTIVE We examined the prognosis of patients with leptomeningeal metastasis (LM) from non-small cell lung cancer (NSCLC) and that stratified by epidermal growth factor receptor (EGFR) mutation status in LM patients receiving EGFR-tyrosine kinase inhibitors (TKIs). METHODS We retrospectively analyzed a series of 91 consecutive NSCLC patients with LM between 2001 and 2010. RESULTS Most of the LM patients had adenocarcinoma histology and a poor performance status (PS). The median survival time (MST) for all patients was 3.6 months. Adenocarcinoma and TKI treatment were associated with a better prognosis. Among the patients, 51 received EGFR-TKIs. Of these, the EGFR mutation status was assessed in 30 patients; 7 (23%) showed no mutation (group 1), 10 (33%) had a mutation in exon 21 (group 2), and 13 (43%) had deletions in exon 19 (group 3). Interestingly, PS was significantly improved in groups 2 and 3 but not in group 1. The MST in these subgroups was 1.4, 7.1, and 11.0 months in groups 1, 2, and 3, respectively (p<0.001). The median time to progression or symptom deterioration was 0.9, 2.0, and 7.8 months for groups 1, 2, and 3, respectively (p<0.001). A multivariate analysis showed that EGFR-mutant tumors were associated with a better prognosis in patients receiving EGFR-TKIs. CONCLUSIONS The prognosis for patients with LM from NSCLC was still poor. Survival after the initiation of EGFR-TKI treatment differed according to the type of EGFR mutation, suggesting the potential benefit of TKIs for patients with EGFR mutations, even though they suffered from LM.