Sarah-Louise Ryan

74P Elucidating drug resistance mechanisms using 2D and 3D culture systems.

targeted therapies. EGFR is commonly expressed in LSCC, while FGFR1 amplification and DDR2 mutations are less common. Necitumumab, an anti-EGFR monoclonal antibody (mAb), is the only targeted therapy approved, in combination with chemotherapy, as a 1st-line treatment of metastatic LSCC patients. A major clinical challenge is that all patients who initially benefit from targeted therapies eventually develop resistance. AXL overexpression, STAT3 or YAP pathway activation, as well as hedgehog-GLI signaling have been described as mechanisms of resistance to anti-EGFR therapy. p21-activated kinase 1 (PAK1), which regulates ERK, is overexpressed in LSCC, diminishing the efficacy of anti-EGFR mAbs. Herein, we are evaluating the relevance of these pathways in LSCC cell lines, illustrating the potential for synthetic lethal approaches. Methods: mRNA expression of AXL, STAT3, YAP, GLI2 and PAK1 were examined by quantitative real-time PCR in 6 LSCC cell lines: H2286, HCC366, H520, H1703, SK-MES-1, and EBC1. Results: EGFR was homogeneously overexpressed in all tested cell lines, but a differential expression pattern of the other transcripts was identified. Regarding the two DDR2 mutant cell lines, the H2286 had AXL and YAP overexpression, while the HCC366 had STAT3 overexpression. The analysis of the two FGFR1 amplified cell lines demonstrated that the H1703 had STAT3 overexpression, while the H520 cells overexpressed GLI2 and PAK1. High expression of PAK1 was also detected in the p53 mutant EBC-1 cell line. The results are the mean of three independent experiments. Immunoblotting analysis is ongoing while the combined effect of necitumumab with different drugs (STAT3, PAK1, GLI and AXL inhibitors), will also be evaluated. Conclusions: Diverse biological behavior of LSCC cancer cell lines may result from diverse underlying genetic profiles and gene expression. The awareness of these differences makes it necessary to take them into account, while planning efficient targeted strategies and synergistic drug interactions. Legal entity responsible for the study: Catalan Institute of Oncology Germans Trias i Pujol Health Sciences Institute and Hospital Campus Can Ruti 08916 Badalona, Barcelona Spain Funding: This Research Project was supported by ESMO with the aid of a grant from Roche. Disclosure: All authors have declared no conflicts of interest.

68P Inflammatory meditated mechanisms of cisplatin resistance in non-small cell lung cancer.

Background The majority of non-small cell lung cancer (NSCLC) patients present with advanced stage disease, where chemotherapy is usually the most common treatment option. While somewhat effective, patients treated with cisplatin-based chemotherapy will eventually develop resistance. Multiple pathways have been implicated in chemo-resistance, however the critical underlying mechanisms have yet to be elucidated. The aim of this project is to determine the role of inflammatory mediators in cisplatin resistance. Methods A qPCR array was utilised to screen a panel of matched Parental (Cisplatin sensitive) and CisR (Cisplatin resistant) NSCLC cell lines for NFKB and its downstream targets. Through Ingenuity Pathway analysis software, a number of mediators where selected for further study at the gene (qPCR) and protein level (Western Blot/ELISA). Treatment with an NFKB inhibitor, DHMEQ, alone or in combination with cisplatin was also used to determine the effect of blocking NFKB pathways in Parental and CisR cells. The response was characterised in terms of proliferation (BrdU ELISA), viability (Cytell) and the DNA damage response (IR/gammaH2AX/Comet). In addition, the response of Parental and CisR cells to a number of recombinant chemokines was examined in terms of cisplatin sensitivity. Results Array studies demonstrated that a number of inflammatory mediators are elevated in the CisR cells compared with Parental cells. Initial results suggest that resistance may be driven through a possible TNF regulated induction of CCL chemokines. Blocking NFKB, led to increased cisplatin efficacy and elevated IR induced DNA damage. In addition, recombinant CCL chemokines provided a protective effect against cisplatin. However, this was overcome by the addition of DHMEQ. Conclusions Inflammation may play a critical role in acquired and intrinsic cisplatin resistance. The drug, DHMEQ, may provide a possible means to overcome this resistance and re-sensitise patients to therapy. Given the promising studies arising in the immuno-oncology arena, the immune regulators identified in this project may provide innovative targets for immune mediated therapy in NSCLC.