Keisuke Aoe

Presence of Epidermal Growth Factor Receptor Gene T790M Mutation as a Minor Clone in Non–Small Cell Lung Cancer

The threonine-to-methionine substitution at amino acid position 790 (T790M) of the epidermal growth factor receptor (EGFR) gene has been reported in progressing lesions after gefitinib treatment in non-small cell lung cancer (NSCLC) that causes sensitive tumors to become resistant to gefitinib. Alternatively, the EGFR T790M mutation might be present in small fractions of tumor cells before drug treatment, and the tumor cells harboring the T790M mutation might be enriched during the proliferation after drug treatment. We developed a mutant-enriched PCR assay to detect small fractions of cells with T790M mutation and used this technique to detect mutations in 280 NSCLCs, including gefitinib-treated 95 cases. Although the direct sequencing detected only 1 T790M mutant case, the mutant-enriched PCR (confirmed to enrich one mutant out of 1 x 10(3) wild-type alleles) detected 9 additional cases among 280 cases. As linkage to clinicopathologic factors, the T790M mutation showed no bias for sex, smoking status, or histology but was significantly more frequent in advanced tumors (9 of 111 cases) than in early-stage tumors (1 of 169 cases; P = 0.0013). Among gefitinib-treated cases, gefitinib-sensitive mutations were found in 30 cases. The T790M mutation was present in 3 of 7 no-responders with the gefitinib-sensitive mutation and was not present in 19 responders (P = 0.014). Our results indicate that the T790M mutation is sometimes present in a minor population of tumor cells during the development of NSCLC and suggest that the detection of small fractions of T790M mutant alleles may be useful for predicting gefitinib resistance of NSCLCs with sensitive EGFR mutations.

Lung cancers with acquired resistance to EGFR inhibitors occasionally harbor BRAF gene mutations but lack mutations in KRAS, NRAS, or MEK1

Acquired resistance to EGF receptor (EGFR) tyrosine kinase inhibitors (TKIs) is inevitable in metastatic EGFR-mutant lung cancers. Here, we modeled disease progression using EGFR-mutant human tumor cell lines. Although five of six models displayed alterations already found in humans, one harbored an unexpected secondary NRAS Q61K mutation; resistant cells were sensitive to concurrent EGFR and MEK inhibition but to neither alone. Prompted by this finding and because RAS/RAF/MEK mutations are known mediators of acquired resistance in other solid tumors (colon cancers, gastrointestinal stromal tumors, and melanomas) responsive to targeted therapies, we analyzed the frequency of secondary KRAS/NRAS/BRAF/MEK1 gene mutations in the largest collection to date of lung cancers with acquired resistance to EGFR TKIs. No recurrent NRAS, KRAS, or MEK1 mutations were found in 212, 195, or 146 patient samples, respectively, but 2 of 195 (1%) were found to have mutations in BRAF (G469A and V600E). Ectopic expression of mutant NRAS or BRAF in drug-sensitive EGFR-mutant cells conferred resistance to EGFR TKIs that was overcome by addition of a MEK inhibitor. Collectively, these positive and negative results provide deeper insight into mechanisms of acquired resistance to EGFR TKIs in lung cancer and inform ongoing clinical trials designed to overcome resistance. In the context of emerging knowledge about mechanisms of acquired resistance to targeted therapies in various cancers, our data highlight the notion that, even though solid tumors share common signaling cascades, mediators of acquired resistance must be elucidated for each disease separately in the context of treatment.

Detection of EGFR Gene Mutation in Lung Cancer by Mutant-Enriched Polymerase Chain Reaction Assay

Purpose: Mutations in the epidermal growth factor receptor (EGFR) gene have been reported to be present in non–small cell lung cancer (NSCLC) and related to the responsiveness of tumors to EGFR tyrosine kinase inhibitors, suggesting its usefulness as a biomarker. Because clinical samples contain tumor and normal cells or genes, a highly sensitive assay for detecting mutation is critical for clinical applications. Experimental Design: The mutant-enriched PCR is a rapid and sensitive assay with selective restriction enzyme digestion. We developed the mutant-enriched PCR assay targeting exons 19 and 21 of EGFR and applied the developed assay to detect mutations in 108 cases of surgically resected specimens of NSCLCs, 18 samples of computed tomography (CT)–guided needle lung biopsies, and 20 samples of pleural fluid. In addition, results were then compared with those from direct sequencing and a nonenriched PCR assay. Results: The mutant-enriched PCR that was proved to enrich one mutant of 2 × 103 normal genes detected mutations in 37 cases of 108 resected tumors, seven samples of CT-guided lung biopsies, and seven samples of pleural fluid. Among mutant cases, four resected tumors, two CT-guided lung biopsies, and two pleural fluid were identified as additional mutant cases by the mutant-enriched PCR, which were considered normal based on nonenriched assays. Conclusions: Our results indicate that EGFR mutations are readily detectable by mutant-enriched PCR in various clinical samples. Thus, mutant-enriched PCR may provide a valuable method of potentially detecting a small fraction of mutant genes in heterogeneous specimens, indicating its possible use in clinical application for NSCLC.

Prognostic potential of FOXP3 expression in non-small cell lung cancer cells combined with tumor-infiltrating regulatory T cells

Expression of the transcription factor FOXP3 characterizes regulatory T cells (Tregs) that engage in the maintenance of immunological self-tolerance and immune homeostasis. Intra-tumoral accumulation of Tregs is associated with unfavorable prognosis in several kinds of cancers. Recently, expression of FOXP3 and its association with prognosis have also been shown in some cancer cells in clinical studies. For non-small cell lung cancer (NSCLC), however, prognostic significance of tumor FOXP3 expression and its relationship with Tregs remain unknown. FOXP3 expression in cancer cells and tumor-infiltrating lymphocytes was examined by immunohistochemical staining of surgical specimens from 87 patients with NSCLC. Prognostic values of the tumor-infiltrating Treg count and tumor FOXP3 expression status were evaluated retrospectively. FOXP3-positive cancer cells were observed in 27 of 87 (31.0%) patients. There was no significant relationship between Treg count and tumor FOXP3 status. Increased Treg counts were associated with worse overall and relapse-free survival whereas the influence of tumor FOXP3 status on survival was not significant. However, when FOXP3-positive cancer cells were present, the relationship between Treg accumulation and worse prognosis was attenuated. In contrast, patients without tumor FOXP3 expression and high Treg count had significantly worse overall and relapse-free survival (hazard ratio: 3.118 and 3.325, p=0.028 and 0.024, respectively) than other groups. These results suggest that tumor FOXP3 expression has a better prognostic potential in NSCLC and that in combination with tumor-infiltrating Treg count the absence of tumor FOXP3 allows the selection of high-risk patients.

The impact of epidermal growth factor receptor gene status on gefitinib-treated Japanese patients with non-small-cell lung cancer.

We investigated the relationships between genetic factors and clinical outcome in Japanese non‐small‐cell lung cancer (NSCLC) patients treated with gefitinib. Ninety‐eight NSCLC patients who had been treated with gefitinib, were screened for mutations in epidermal growth factor receptor (EGFR) exons 18–21, KRAS exon2, and polymorphisms including the CA simple sequence repeat in intron1 (CA‐SSR1) and single nucleotide polymorphisms in the promoter region (−216G/T and −191C/A), using a PCR‐based assay and direct sequencing. The EGFR copy number status was also evaluated using a fluorescence in situ hybridization assay. EGFR and KRAS mutations were found in 38 (38.8%) and 8 (8.2%) of the 98 patients, respectively. A high EGFR copy number status was identified in 31 (41.3%) of the 75 assessable patients. Drug‐sensitive EGFR mutations limited to exon19 deletions and L858R were independent predictive factors of a stronger sensitivity to gefitinib (p = 0.0002), the overall survival (OS) (p = 0.0036), and prolonged progression‐free survival (PFS) (p < 0.0001). The EGFR copy number status was not related to a sensitivity to gefitinib and prolonged OS and PFS. Regarding polymorphisms, patients with a short CA‐SSR1 showed a prolonged OS as compared with those with a long length in patients with a drug‐sensitive EGFR mutation, although this difference was not significant (p = 0.13). Thus, drug‐sensitive EGFR mutations predict a favorable clinical outcome and a high EGFR copy number may not be related to clinical benefits in gefitinib‐treated Japanese patients with NSCLC. Our findings also suggest that the CA‐SSR1 length may influence the clinical outcome in patients with a drug‐sensitive EGFR mutation.

Usefulness of EGFR mutation screening in pleural fluid to predict the clinical outcome of gefitinib treated patients with lung cancer

The importance of epidermal growth factor receptor (EGFR) gene mutation has been recognized in nonsmall cell lung cancer (NSCLC), requiring the standardization of mutation screening system including the kind of samples. Here, we examined the EGFR mutation status in 61 pleural fluid samples from NSCLC cases using direct sequencing, nonenriched PCR, mutant‐enriched PCR and peptide nucleic acid‐locked nucleic acid (PNA‐LNA) PCR clamp assay. The mutant‐enriched PCR assay detected 16 mutant cases. Among them, the nonenriched PCR assay failed to detect 3 mutant cases. Regarding the discrepancy between mutant‐enriched PCR and PNA‐LNA PCR clamp assays, 3 cases of exon19‐deletions were detected only by mutant‐enriched PCR assay and no difference at the L858R mutation. There was no difference in results between direct sequencing and nonenriched PCR assay. We also correlated the EGFR mutation with clinical outcome of gefitinib‐treated 29 cases. EGFR mutations were present in 10 cases, revealing 7 partial response and 3 no change (NC). In EGFR wild‐type cases, 10 revealed NC and 9 progressive disease. The responders were significantly more frequent among the EGFR mutant cases than among the wild‐type (p < 0.0001). Overall survival (p = 0.0092) and progression‐free survival (p = 0.018) were significantly longer among the EGFR mutant cases than among the wild‐type. In summary, we evaluated the utility of EGFR mutation screening in pleural fluid using 4 assays that showed some discrepancies arising from the designs of the assays. As clinical importance, the EGFR mutation status in pleural fluid can be a biomarker for the favorable outcome of gefitinib‐treated NSCLC cases.

Effect of nebulized furosemide in terminally ill cancer patients with dyspnea

We evaluated the effect of ultrasonically nebulized furosemide (20 mg) on dyspnea uncontrollable by standard therapy in patients with terminal cancer. Dyspnea was evaluated using the Cancer Dyspnea Scale (CDS) before and 60 min after inhalation. Changes in arterial blood gases, hemoglobin oxygen saturation (SpO2), heart rate (HR), and respiratory rate (RR) also were evaluated. In 12 of 15 patients (80%), total dyspnea scores by CDS improved significantly after inhalation of furosemide (P = 0.007), especially concerning a reduced sense of effort (P = 0.013) and reduced anxiety (P = 0.04). No significant changes were observed in the partial pressure of oxygen in arterial blood (PaO2), the partial pressure of carbon dioxide in arterial blood (PaCO2), SpO2, HR, or RR. Inhalation of nebulized furosemide appears to be effective against dyspnea in terminally ill cancer patients.

Thrombocytosis as a Useful Prognostic Indicator in Patients with Lung Cancer

Background: Thrombocytosis can accompany various cancers including lung cancer. This finding has recently been suggested to indicate poor prognosis. Objectives and Methods: We retrospectively examined the clinical records of 611 patients with lung cancer to investigate whether there is a correlation between thrombocytosis, other clinicopathologic factors, and survival Results: Ninety-eight of the patients (16%) manifested thrombocytosis at the time of their first evaluation at our hospital. Thrombocytosis and age (p = 0.0006) and thrombocytosis and performance status (p = 0.0002) are significantly correlated, but thrombocytosis is not related to gender, tumor histology, clinical stage, or serum lactate dehydrogenase concentrations. Survival is significantly shorter in patients with thrombocytosis: [median survival time (MST) 7.5 months; n = 98] than without thrombocytosis (MST 10.1 months; n = 513; p = 0.0029). Multivariate analysis of prognostic factors using the Cox proportional hazards model indicated that thrombocytosis had independent prognostic significance. Conclusion: Thrombocytosis at the first patient evaluation is an independent prognostic factor in lung cancer.

Association between cytokine removal by polymyxin B hemoperfusion and improved pulmonary oxygenation in patients with acute exacerbation of idiopathic pulmonary fibrosis

Acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF) is characterized by severe worsening dyspnea of unknown etiology and high mortality without effective treatment. Recently, direct hemoperfusion with polymyxin B (PMX)-immobilized fiber cartridge (PMX-DHP) has been reported to improve pulmonary oxygenation and survival in patients with AE-IPF although its mechanism of action remains unknown. To gain insights into the pathobiology of AE-IPF through the beneficial effects of PMX-DHP, we analyzed the profile of cytokines adsorbed onto PMX-fibers used in 9 AE-IPF patients. In addition, the sera of these AE-IPF patients collected immediately before and after PMX-DHP, 9 stable IPF patients and 8 healthy individuals were also analyzed. The serum levels of cytokines including IL-9, IL-12, IL-17, PDGF and VEGF were significantly decreased immediately after PMX-DHP (P<0.02), and VEGF and IL-12 were most prominently reduced. In addition to PDGF and VEGF, IL-1β, IL-1ra, IL-8, IL-23, FGF basic, GM-CSF, IP-10, RANTES and TGF-β were eluted from used PMX-fibers. Interestingly, improved pulmonary oxygenation after PMX-DHP was correlated well with the quantities of eluted VEGF. These results suggest that adsorption of proinflammatory, profibrotic and proangiogenic cytokines onto PMX-fibers is one of the mechanisms of action of PMX-DHP in AE-IPF. Notably, removal of VEGF by PMX-DHP may contribute to the rapid improvement in oxygenation by suppressing vascular permeability in the lung.

Survival and Prognostic Factors in Malignant Pleural Mesothelioma: A Retrospective Study of 314 patients in the West Part of Japan

OBJECTIVE The objective in our study was to examine baseline and other characteristics associated with survival in patients with malignant pleural mesothelioma in Japan. METHODS Three hundred and fourteen patients with an adjudicated diagnosis of mesothelioma were examined. Survival was evaluated by the Kaplan-Meier method with the log-rank test. The Cox model was used to estimate the hazard ratio for the possible prognostic factors. RESULTS Of 314 patients, 223 (71%) died and only 40 (13%) were still alive at the end of the observation period starting from the day of diagnosis, while 51 (16%) were transferred to other hospitals or had the last health service contact before the end of the study period yielding the median survival of 308 days. In the multivariate analysis, age older than 70 years (hazard ratio = 2.17; 95% confidence interval, 1.36-3.46), non-epithelioid type (hazard ratio = 1.58; 95% confidence interval, 1.15-2.18), poor performance status (hazard ratio = 3.22; 95% confidence interval, 1.19-8.74), high white blood cell count (hazard ratio = 1.49; 95% confidence interval, 0.99-2.26) and high C-reactive protein level (hazard ratio = 1.80; 95% confidence interval, 1.06-3.06) were negatively associated with survival, after adjustment for other factors. CONCLUSIONS Some baseline conditions including old age, poor performance status, non-epithelioid type, high white blood cell count and high C-reactive protein level were determinants of poor survival of patients with malignant mesothelioma.