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Introduction: Nivolumab is effective in the treatment of previously treated patients with advanced NSCLC. However, its radiological evaluation is challenging because of atypical patterns of response such as pseudoprogression. We examined the characteristics and outcomes of previously treated patients with NSCLC who were treated with nivolumab and experienced development of pseudoprogression. Methods: We conducted a 15-center retrospective cohort study of previously treated patients with advanced NSCLC who received nivolumab monotherapy. For the patients who showed pseudoprogression, we defined progression-free survival 1 (PFS1) as the time to Response Evaluation Criteria in Solid Tumors-defined first progressive disease and progression-free survival 2 (PFS2) as the time to Response Evaluation Criteria in Solid Tumors-defined second progressive disease or death.

Background: Because mesothelioma initially progresses on the surface of the pleura and peritoneum without forming masses, it has been difficult to diagnose at an early stage. It would be very useful to identify a tumor marker that could be used for screening to enable more diagnoses to be made at an early, treatable stage. Materials and Methods: We had previously identified N-ERC/mesothelin as a potential biomarker for mesothelioma. In the current work, we used a newly developed ELISA system to gain data on N-ERC/mesothelin levels in various clinical settings. A total of 102 healthy volunteers were recruited. In addition, 39 patients were diagnosed with mesothelioma, 53 patients were diagnosed with diseases that should be distinguished from mesothelioma, and 201 subjects were diagnosed with asbestos-related nonmalignant diseases (including simple exposure to asbestosis) who were treated at any of the cooperating hospitals were enrolled. Results: Serum N-ERC/mesothelin levels measured by a new ELISA system showed that the median values from patients with mesothelioma were extremely high compared with levels obtained from other patients. Analysis in terms of histologic type showed that serum levels of N-ERC/mesothelin were elevated in epithelioid type mesothelioma, especially. In four important models of clinical settings, the sensitivity and specificity of N-ERC/mesothelin were about 71% to 90% and 88% to 93%, respectively. Conclusion: N-ERC/mesothelin is a very promising tumor marker for mesothelioma, especially epithelioid mesothelioma.Mesothelioma initially progresses along the surfaces of the pleura and peritoneum without forming masses; it is anatomically difficult to diagnose at an early stage and to completely remove with surgery. Moreover, mesothelioma typically has a long incubation period before it becomes clinically evident among high-risk individuals with severe exposure to asbestos. Sugarbaker et al.(1) has reported a groundbreaking result: for patients with early stage disease, 5-year survival after trimodality therapy exceeded 40%. This finding that early disease may be effectively treated emphasizes the importance of identifying a tumor marker that is practical for screening and can allow physicians to make an early diagnosis.Recently, osteopontin, soluble mesothelin-related protein, and serum mesothelin have been reported as candidates for a mesothelioma tumor marker (2 -7). We have postulated (8) that another product may be useful as a tumor marker: N-ERC/ mesothelin, a NH 2 terminal 31-kDa fragment of mesothelin gene products that was first cloned as a megakaryocytepotentiating factor in humans and that is physiologically secreted into blood. Since the time of that report, we have established a new ELISA system that detects the NH 2 terminal fragments of ERC/mesothelin products at a higher sensitivity and specificity. The current work was done to obtain data for Materials and MethodsPreparation of novel anti-ERC/mesothelin antibodies. The anti -N-ERC/mesothelin monoclonal antibody (Mo...

umin.ac.jp/ctr Identifier: UMIN000001277.

IntroductionNext-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have been developed to overcome resistance to earlier generations of such drugs mediated by a secondary T790M mutation of EGFR, but the performance of a second tumor biopsy to assess T790M mutation status can be problematic.MethodsWe developed and evaluated liquid biopsy assays for detection of TKI-sensitizing and T790M mutations of EGFR by droplet digital PCR (ddPCR) in EGFR mutation–positive non–small cell lung cancer (NSCLC) patients with acquired EGFR-TKI resistance.ResultsA total of 260 patients was enrolled between November 2014 and March 2015 at 29 centers for this West Japan Oncology Group (WJOG 8014LTR) study. Plasma specimens from all subjects as well as tumor tissue or malignant pleural effusion or ascites fluid from 41 patients were collected after the development of EGFR-TKI resistance. All plasma samples were genotyped successfully and the results were reported to physicians within 14 days. TKI-sensitizing and T790M mutations were detected in plasma of 120 (46.2%) and 75 (28.8%) patients, respectively. T790M was detected in 56.7% of patients with plasma positive for TKI-sensitizing mutations. For the 41 patients with paired samples obtained after acquisition of EGFR-TKI resistance, the concordance for mutation detection by ddPCR in plasma compared with tumor tissue or malignant fluid specimens was 78.0% for TKI-sensitizing mutations and 65.9% for T790M.ConclusionsNoninvasive genotyping by ddPCR with cell-free DNA extracted from plasma is a promising approach to the detection of gene mutations during targeted treatment.