Abstract Number: A109
Presentation Title: AZD9291: an irreversible, potent and selective third generation tyrosine kinase inhibitor (TKI) targeting EGFR activating (EGFRm+) and resistance (T790M) mutations in advanced lung adenocarcinoma
Presentation Time: Sunday, Oct 20, 2013, 12:30 PM - 3:00 PM
Location: Exhibit Hall C-D
Author Block: Darren Cross1, Sue Ashton1, Caroline Nebhan2, Cath Eberlein1, M. Raymond V. Finlay1, Gareth Hughes1, Vivien Jacobs1, Martine Mellor1, Monica Red Brewer2, Catherine Meador2, Jonathon Orme1, Paula Spitzler2, Steve Powell1, Amar Rahi1, Paula Taylor1, Richard A. Ward1, Paula Daunt1, Anne Galer1, Teresa Klinowska1, Graham Richmond1, William Pao2. 1AstraZeneca, Macclesfield, United Kingdom; 2Department of Medicine/Division of Hematology-Oncology, Vanderbilt University, Nashville, TN
Abstract Body: The first generation EGFR TKIs gefitinib and erlotinib provide significant clinical benefit in patients with advanced lung adenocarcinoma harbouring activating EGFR mutants (EGFRm+), but patients will ultimately develop disease progression due to acquired resistance. Acquisition of the EGFR T790M mutation is the most common mechanism of drug resistance, detected in more than 50% of gefitinib/erlotinib resistant patients. Current therapeutic strategies are limited for advanced lung adenocarcinoma patients with EGFR T790M (EGFRm+/T790M), so this remains a key area of unmet need. AZD9291 (structure to be disclosed at meeting) is an oral, irreversible, third generation, selective inhibitor of both EGFR activating (EGFRm+) and resistance (EGFRm+/T790M) mutations. The mechanistic and functional activity of AZD9291 was characterised in vitro and in vivo across a number of cell lines harbouring various EGFR-mutations or wild type EGFR. Presented data shows AZD9291 potently inhibits EGFR phosphorylation in EGFRm+ (e.g. PC9; <25nM) and EGFRm+/T790M (e.g. H1975; <25nM) cell lines in vitro, whilst demonstrating much less activity against wild-type EGFR lines (e.g. LoVo; >500nM). Consistently, AZD9291 showed significantly more potent inhibition of proliferation in mutant EGFR cell lines compared to wild-type in vitro. In addition, AZD9291 administered once daily orally at 5mg/kg caused profound regression of tumours across EGFRm+ (PC9; 178% growth inhibition) and EGFRm+/T790M (H1975; 119% growth inhibition) tumour models in vivo, after 14 days dosing. Furthermore 5mg/kg AZD9291 was sufficient to cause significant shrinkage of EGFRm+ and EGFRm+/T790M transgenic mouse lung tumours. Tumour growth inhibition was associated with profound inhibition of EGFR phosphorylation and key downstream signaling pathways such as AKT and ERK. Chronic long-term treatment of PC9 and H1975 xenograft tumours with AZD9291 led to a complete and sustained macroscopic response, with no visible tumours after 40 days dosing, and being maintained beyond 100 days. Furthermore, pre-clinical data also indicates that AZD9291 could target tumours that have acquired resistance to the more recently identified HER2-amplification mechanism, thus potentially extending its benefit in TKI resistant patients. Taken together, preclinical data demonstrates that AZD9291 is a potent and effective inhibitor of both EGFR activating (EGFRm+) and resistance (EGFRm+/T790M) mutations whilst sparing wild-type EGFR. These data support the further clinical investigation of AZD9291 in advanced EGFR mutant lung adenocarcinoma.
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