Search

Background: Targeted therapy with tyrosine kinases inhibitors (TKIs) against epidermal growth factor receptor (EGFR) is part of routine clinical practice for EGFR mutant advanced non-small cell lung cancer (NSCLC) patients. These patients eventually develop resistance, frequently accompanied by a gatekeeper mutation, T790M. Osimertinib is a third-generation EGFR TKI displaying potency to the T790M resistance mutation. Here we aimed to analyze if exosomal RNAs, isolated from longitudinally sampled plasma of osimertinib-treated EGFR T790M NSCLC patients, could provide biomarkers of acquired resistance to osimertinib. Methods: Plasma was collected at baseline and progression of disease from 20 patients treated with osimertinib in the multicenter phase II study TKI in Relapsed EGFR-mutated non-small cell lung cancer patients (TREM). Plasma was centrifuged at 16,000 g followed by exosomal RNA extraction using Qiagen exoRNeasy kit. RNA was subjected to transcriptomics analysis with Clariom D. Results: Transcriptome profiling revealed differential expression [log2(fold-change) >0.25, false discovery rate (FDR) P0.05] of 128 transcripts. We applied network enrichment analysis (NEA) at the pathway level in a large collection of functional gene sets. This overall enrichment analysis revealed alterations in pathways related to EGFR and PI3K as well as to syndecan and glypican pathways (NEA FDR 0.05 and NEA z-score exceeding 3 in at least one sample). Conclusions: Our study demonstrates a potential usability of plasma-derived exosomal RNAs to characterize molecular phenotypes of emerging osimertinib resistance. Furthermore, it highlights the involvement of multiple RNA species in shaping the transcriptome landscape of osimertinib-refractory NSCLC patients.

TTFields Delay Irradiation-Induced DNA Damage Repair in glioma cells. LN-18 cells were irradiated with 4 Gy RT and immediately treated with TTFields applied for 1 h, 2 h or 24 h (A-B). Effect on DNA repair was measured as tail moment in the comet assay. (PPTX 1940 kb)

RT treatment schedule and transducer replacement schedule. Rats received RT on days 0-4 and 7-11 (indicated by V). Groups 4 and 5 had arrays placed on their dorsal surface (arrays where replaced days indicated by V). Rats where euthanized on day 12. (DOCX 96 kb)

TTFields Delay Irradiation-Induced DNA Damage Repair in glioma cells. LN-18 cells were irradiated with 4 Gy RT and immediately treated with TTFields applied for 1 h, 2 h or 24 h (A-B). Effect on DNA repair was measured as tail moment in the comet assay. (PPTX 1940 kb)

TTFields effect on LN-18 glioma cells. Surviving fractions of LN-18 cells treated with TTFields (200 kHz, 1.0 V/cm) for 72 h either alone or immediately after irradiation with 4 Gy (A). Surviving fraction of LN-18 cells treated with RT alone or with RT at various doses followed by 200 kHz TTFields (1.0 V/cm RMS) for 72 h. Results of the combined treatments were normalized to the effect of TTFields alone (B). (PPTX 2783 kb)

TTFields effect on LN-18 glioma cells. Surviving fractions of LN-18 cells treated with TTFields (200 kHz, 1.0 V/cm) for 72 h either alone or immediately after irradiation with 4 Gy (A). Surviving fraction of LN-18 cells treated with RT alone or with RT at various doses followed by 200 kHz TTFields (1.0 V/cm RMS) for 72 h. Results of the combined treatments were normalized to the effect of TTFields alone (B). (PPTX 2783 kb)

In forthcoming multicentre studies on stereotactic body radiotherapy (SBRT) compliance with volume and dose prescriptions will be mandatory to avoid unnecessary heterogeneity bias. To evaluate compliance in a multicentre setting we used two cases from an ongoing phase II study of SBRT of T1-T2N0M0 inoperable NSCLC in a dummy run oriented on volumes and doses. Six Scandinavian centres participated. Each centre received CT-scans covering the whole lung volumes of two patients with instructions to follow the study protocol when outlining tumour and target volumes, prescribing doses and creating dose plans. Volumes and doses of the 12 dose plans were evaluated according to the study protocol. For the two patients the GTV volume range was 24 to 39 cm3 and 26 to 41 cm3, respectively. The PTV volume range was 90 to 116 cm3, and 112 to 155 cm3, respectively. For all plans the margin between CTV and PTV in all directions followed in detail the protocol. The prescribed dose was for all centres 45 Gy/3 fractions (isocentre dose about 66 Gy). The mean GTV doses ranged from 63 to 67 Gy and from 63 to 68 Gy, respectively. The minimum doses for GTV were between 50-64 Gy and between 55-65 Gy, respectively. The dose distribution was conformed to PTV for 10 of 12 plans and 2 of 12 plans from one centre had sub-optimal dose distribution. Most of the volume and dose parameters for the participating centres showed fully acceptable compliance with the study protocol