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Background : Non-small-cell lung cancer (NSCLC) is recognised as a particularly heterogeneous disease, encompassing a wide spectrum of distinct molecular subtypes. With increased understanding of disease biology and mechanisms of progression, treatment of NSCLC has made remarkable progress in the past two decades. Molecular testing is considered the hallmark for the diagnosis and treatment of NSCLC, with liquid biopsies being more and more often applied in the clinical setting during the recent years. Rearrangement of the ALK gene which results in the generation of fusion oncogenes is a common molecular event in NSCLCs. Among ALK fusion transcripts, EML4-ALK fusion is frequently observed and can be targeted with ALK tyrosine kinase inhibitors (TKI). However, acquired resistance and disease progression in many cases are inevitable. Method : Here, we present the case of a patient with NSCLC treated with TKIs, in which molecular profiling of the tumour was performed with different methods of tissue and plasma testing at each disease progression. A review of the literature was further conducted to offer insights into the resistance mechanisms of ALK-rearranged NSCLC. Conclusions : Based on the results, the EML4-ALK fusion initially detected in tumour tissue was preserved throughout the course of the disease. Two additional ALK mutations were later detected in the tissue and plasma and are likely to have caused resistance to the administered TKIs. Continued research into the mechanisms of acquired resistance is required in order to increase the benefit of the patients treated with targeted ALK TKIs., Competing Interests: Competing interests: GN and EP are employees of GeneKor Medical SA, Athens, Greece., (© Author (s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. Published by BMJ on behalf of the European Society for Medical Oncology.)

Background: Metastatic colorectal cancer represents a striking example of clonal heterogeneity and tumour evolution, which generates acquired resistance to therapy. Once hard to perform, the study of clonal heterogeneity is now significantly aided by the use of liquid biopsies., Method: We herein report a case of a patient with colorectal cancer and serial development of multiple metastases which were all resected and genotyped. A rare point mutation was identified in the primary tumour (but not in any of the organ metastatic sites), as well as in the first and the last out of three consecutive liquid biopsies. The review of the literature offered some insight in the evolution of the patient's tumour and general directions on how to interpret liquid biopsy results., Conclusions: This patient case emphasises the need for large prospective studies designed to bridge liquid biopsy data with useful clinical endpoints, in order to optimally integrate this revolutionary tool in everyday practice., Competing Interests: Competing interests: GN and EP are employees of GeneKor Medical SA, Athens, Greece.

Introduction: Gastrointestinal stromal tumours (GIST) are mesenchymal neoplasms that usually carry an activating mutation in KIT or platelet-derived growth factor receptor alpha ( PDGFRA ) genes with predictive and prognostic significance. We investigated the extended mutational status of GIST in a patient population of north-western Greece in order to look at geopraphic/genotypic distinctive traits., Patient and Methods: Clinicopathological and molecular data of 38 patients diagnosed from 1996 to 2016 with GIST in the region of Epirus in Greece were retrospectively assessed. Formalin-fixed paraffin-embedded tumours were successfully analysed for mutations in 54 genes with oncogenic potential. Next generation sequencing was conducted by using the Ion AmpliSeqCancer Hotspot Panel V.2 for DNA analysis (Thermofisher Scientific)., Results: Among 38 tumours, 24 (63.16%) and seven (18.42%) of the tumours harboured mutations in the KIT and PDGFRA genes, respectively, while seven (18.42%) tumours were negative for either KIT or PDGFRA mutation. No mutations were detected in five (13.16%) cases. Concomitant mutations of BRAF and fibroblast growth factor receptor 3 ( FGFR3 ) genes were observed in two patients with KIT gene mutation. Two patients with KIT / PDGFRA wild-type GIST had mutations in either KRAS or phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha ( PIK3CA ) genes. There was no significant survival difference regarding the exonic site of mutation in either KIT or PDGFRA gene. The presence of a mutation in pathway effectors downstream of KIT or PDGFRA , such as BRAF , KRAS or PIK3CA , was associated with poor prognosis. Adverse prognosticators were also high mitotic index and the advanced disease status at diagnosis., Conclusions: We report comparable incidence of KIT and PDGFRA mutation in patients with GIST from north-western Greece as compared with cohorts from other regions. Interestingly, we identified rare mutations on RAS , BRAF and PIK3CA genes in patients with poor prognosis., Competing Interests: Competing interests: None declared.