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ALK-break positive non-small cell lung cancer (NSCLC) patients initially respond to crizotinib, but resistance occurs inevitably. In this study we aimed to identify fusion genes in crizotinib resistant tumor samples. Re-biopsies of three patients were subjected to paired-end RNA sequencing to identify fusion genes using deFuse and EricScript. The IGV browser was used to determine presence of known resistance-associated mutations. Sanger sequencing was used to validate fusion genes and digital droplet PCR to validate mutations. ALK fusion genes were detected in all three patients with EML4 being the fusion partner. One patient had no additional fusion genes. Another patient had one additional fusion gene, but without a predicted open reading frame (ORF). The third patient had three additional fusion genes, of which two were derived from the same chromosomal region as the EML4-ALK. A predicted ORF was identified only in the CLIP4-VSNL1 fusion product. The fusion genes validated in the post-treatment sample were also present in the biopsy before crizotinib. ALK mutations (p.C1156Y and p.G1269A) detected in the re-biopsies of two patients, were not detected in pre-treatment biopsies. In conclusion, fusion genes identified in our study are unlikely to be involved in crizotinib resistance based on presence in pre-treatment biopsies. The detection of ALK mutations in post-treatment tumor samples of two patients underlines their role in crizotinib resistance. [ABSTRACT FROM AUTHOR]

Purpose: Leiomyosarcomas (LMS) of deep and superficial tissues were examined to identify prognostic markers explaining their different biological behaviour and to define differences between cutaneous and subcutaneous LMS. LMS and leiomyomas (LM) of the skin were compared to find consistent differences that could aid in the (sometimes difficult) diagnosis. Patients: Material was obtained from 27 patients with a deep LMS, 14 with a superficial LMS, and 21 with a LM. Methods: Proliferation markers (mitotic and Ki-67 indices), DNA ploidy, size, grade, and the amount of apoptosis were studied. Statistical analysis was performed and survival curves were constructed by the Kaplan-Meier method and compared by the log-rank test. Results: Superficial LMS were smaller than deep LMS (p < 0.05), and the overall survival of patients with a superficial LMS was better than with a deep LMS (p < 0.05).Within the group of superficial LMS only entirely subcutaneous, and not cutaneous tumors metastasized. No differences were found in the other examined parameters. Proliferation and apoptotic indices were significantly higher in superficial LMS compared to superficial LM. Discussion: The difference in clinical outcome between patients with a superficial and deep LMS, seems to be related to site and size.The metastatic potential of subcutaneous LMS, however, seems to be related to location alone and not to size.The amount of apoptosis and proliferation can be used as additional criteria in the differentiation between superficial LMS and LM. [ABSTRACT FROM AUTHOR]