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MO21 - Prognostic and Predictive Biomarkers V - EGFR (ID 98)
- Event: WCLC 2013
- Type: Mini Oral Abstract Session
- Track: Medical Oncology
- Presentations: 1
MO21.12 - AZD9291: an irreversible, potent and selective tyrosine kinase inhibitor (TKI) of activating (EGFRm+) and resistance (T790M) mutations in advanced NSCLC (ID 2289)
10:30 - 12:00 | Author(s): D. Cross
The first generation EGFR TKIs gefitinib and erlotinib provide significant clinical benefit in patients with advanced EGFR mutant NSCLC but many patients ultimately develop disease progression due to acquired resistance. The EGFR T790M mutation is the most common mechanism of acquired drug resistance, detected in more than 50% of gefitinib/erlotinib resistant patients. Current therapeutic strategies are limited for NSCLC patients with EGFR T790M.
AZD9291 is an oral, irreversible, third generation inhibitor of both EGFR activating (EGFRm+) and resistance mutations (T790M). The mechanistic and functional activity of AZD9291 was characterised in vitro across a number of cell lines harbouring various EGFR-mutations or wild type EGFR. Efficacy of AZD9291 was further evaluated across a number of different EGFR-mutant xenograft and transgenic models in vivo. One open label, dose escalation phase I study of AZD9291 (NCT01802632) is ongoing to determine the safety and tolerability [primary measure], pharmacokinetics and preliminary efficacy profiles of AZD9291, in patients with advanced NSCLC who have progressed following EGFR TKI. Sequential cohorts of 3-6 patients with advanced NSCLC who have had at least one prior regimen containing an EGFR TKI agent (with confirmed EGFRm+ status or Jackman criteria), were treated with AZD9291 once daily. Other key inclusion criteria were PS 0-1, measurable disease, and no prior history of ILD. RECIST assessments were scheduled 6 weekly. Dose escalation can occur after ≥ 3 patients complete both single dose and the first 21-day cycle of AZD9291 multiple dosing with no DLT.
AZD9291 potently inhibits EGFR phosphorylation in EGFRm+ (PC9; 14nM) and EGFRm+/T790M (H1975; 13nM) cell lines in vitro, whilst demonstrating much less activity against wild-type EGFR lines (LoVo; 400nM). Consistently, AZD9291 showed significantly more potent inhibition of proliferation in mutant EGFR cell lines compared to wild-type in vitro. In addition, AZD9291 treatment caused profound growth regression across multiple EGFRm+ (PC9; 250% growth inhibition) and EGFRm+/T790M (H1975; 132% growth inhibition) tumour models in vivo, at doses as low as 5mg/kg after 14 days. Tumour growth inhibition was associated with profound inhibition of EGFR activity and key downstream signaling pathways. Chronic long-term treatment of in vivo PC9 and H1975 xenograft tumours with AZD9291 led to a complete and sustained macroscopic response. In the phase I study, clinical activity with RECIST responses have already been observed at the starting dose level of 20mg once daily, with good tolerability, no reported events of EGFR wild-type rash, and only grade 1 diarrhoea (based on preliminary data, unvalidated and subject to change).
Preclinical data demonstrates that AZD9291 is a potent and effective inhibitor of both EGFR activating (EGFRm+) and resistance mutations (T790M) whilst sparing wild-type EGFR and, early clinical data have been promising. Taken together, these data support the further clinical investigation of AZD9291 in advanced EGFR mutant NSCLC.
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