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Seki Y.,National Cancer Center Research Institute | Seki Y.,Jikei University School of Medicine | Fujiwara Y.,National Cancer Center Hospita | Kohno T.,National Cancer Center Research Institute | And 11 more authors.
Oncologist | Year: 2016

Purpose. The objective of this study was to evaluate the utility of analyzing cell-free plasma DNA (cfDNA) by picoliter-droplet digital polymerase chain reaction (ddPCR) to detect EGFR mutations that confer resistance to tyrosine-kinase inhibitors (TKIs) used for treatment of lung adenocarcinoma (LADC). Experimental design. Thirty-five LADC patients who received epidermal growth factor receptor (EGFR)-TKI therapy, including ten who received tumor rebiopsy after development of resistance, were subjected to picoliter-ddPCR-cfDNA analysis to determine the fraction of cfDNA with TKI-sensitive (L858R and inflame exon 19 deletions) and -resistant (i.e., T790M) mutations, as well as theirconcordance with mutationstatus in rebiopsied tumor tissues. Results. cfDNA samples from 15 (94%) of 16 patients who acquired resistance were positive for TKI-sensitive mutations. Also, 7 (44%) were positive for the T790M mutation, with fractions of T790M (1) cfDNA ranging from 7.4% to 97%. T790M positivity in cfDNA was consistent in eight of ten patients for whom rebiopsied tumor tissues were analyzed, whereas the remaining cases were negative in cfDNA and positive in rebiopsied tumors. Prior to EGFR-TKI therapy, cfDNAs from 9 (38%) and 0 of 24 patients were positive for TKIsensitive and T790M mutations, respectively. Next-generation sequencing of cfDNA from one patient who exhibited innate resistance to TKI despite a high fraction of TKI-sensitive mutations and the absence of the T790M mutation in his cfDNA revealed the presence of the L747P mutation, a known driver of TKI resistance. Conclusion. Picoliter-ddPCR examination of cfDNA, supported by next-generation sequencing analysis, enables noninvasive assessment of EGFR mutations that confer resistance to TKIs. © AlphaMed Press 2016. Source


Yoshida A.,National Cancer Center Hospita | Yoshida A.,University of Tokyo | Tsuta K.,National Cancer Center Hospita | Fukayama M.,University of Tokyo | And 2 more authors.
American Journal of Surgical Pathology | Year: 2012

Ewing sarcoma is a high-grade round cell sarcoma that affects bones and soft tissues in children and young adults. Its diagnosis can be challenging, and the differential diagnoses include a wide variety of small round cell tumors. CD99 and FLI-1 are the currently accepted immunohistochemical markers for Ewing sarcoma, but their accuracy has been controversial. NKX2.2 is a homeodomain-containing transcription factor that plays a critical role in neuroendocrine/glial differentiation. The NKX2.2 gene was recently identified as a target of EWS-FLI-1, the fusion protein specific to Ewing sarcoma, and was shown to be differentially upregulated in Ewing sarcoma on the basis of array-based gene expression analysis. However, the immunohistochemical diagnostic potential of this marker has not been tested. We immunostained representative sections of 30 genetically confirmed Ewing sarcomas and 130 non-Ewing small round cell tumors by using an antibody to NKX2.2. Nuclear staining in at least 5% of the cells was deemed positive. Twenty-eight (93%) of the 30 Ewing sarcomas were positive for NKX2.2. The staining was diffuse (>50%) in all the positive cases and was moderate or strong in intensity for most cases (25 of 28). NKX2.2 was also positive in 14 non-Ewing tumors, including all the olfactory neuroblastomas and a minor subset of small cell carcinomas, synovial sarcomas, mesenchymal chondrosarcomas, and malignant melanomas. All the other non-Ewing tumors tested were negative for this marker. NKX2.2 is a valuable marker for Ewing sarcoma, with a sensitivity of 93% and a specificity of 89%, and aids in the differential diagnosis of small round cell tumors. © 2012 by Lippincott Williams & Wilkins. Source

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