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MINI 10 - ALK and EGFR (ID 105)
- Event: WCLC 2015
- Type: Mini Oral
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
MINI10.12 - Preclinical Activity of AZD9291 in EGFR-Mutant NSCLC Brain Metastases (ID 410)
16:45 - 18:15 | Author(s): M.R.V. Finlay
AZD9291 is an oral, potent, irreversible epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) selective for the EGFR-TKI-sensitizing (EGFRm) and T790M resistance mutations. We examined how the level of AZD9291 brain penetration and activity compared to that of other EGFR-TKIs in preclinical models of EGFRm non-small cell lung cancer (NSCLC) brain metastases (BM).
Brain exposure of AZD9291 and an active circulating metabolite of AZD9291 (AZ5104), CO-1686 (rociletinib), gefitinib, erlotinib, and afatinib were evaluated in mouse models. Brain distribution following intravenous administration of microdoses (<3 micrograms) of [C]AZD9291 and [C]CO-1686 were compared in healthy cynomolgus macaques using positron emission tomography (PET) imaging. In vivo efficacy of AZD9291 and CO-1686 were assessed in a mouse EGFRm (exon 19 deletion) BM xenograft (PC9) model. Human doses that could potentially deliver BM efficacy were predicted using a preclinical pharmacokinetic/pharmacodynamic (PK/PD) mathematical model, adapted to account for the differential exposure and binding of AZD9291 and AZ5104 in brain compared with plasma.
In preclinical studies, AZD9291 showed significant exposure in the brain with concentrations in mouse brain tissue approximately 2-fold higher than plasma, although the metabolite, AZ5104, did not show similar levels of exposure to parent. AZD9291 also showed higher brain exposure than other tested EGFR-TKIs. Furthermore, under microdosing conditions [C]AZD9291 showed marked exposure in a cynomolgus macaques brain PET study in contrast to [C]CO-1686. At clinically relevant doses, AZD9291 distribution to the mouse brain was approximately 10-fold higher than gefitinib. In the PC9 BM model, AZD9291 showed tumor growth inhibition at 5 mg/kg/day. Using an adapted preclinical PK/PD model, simulations with clinical AZD9291/AZ5104 PK data predicted that a human dose of 80 mg may be sufficient to target EGFRm BM.
Preclinical studies indicate AZD9291 has significant exposure in the brain and activity against EGFRm BM, compared with the other EGFR-TKIs tested. In light of early clinical activity of AZD9291 observed in patients with EGFRm NSCLC BM, further investigation into the potential benefit of AZD9291 in patients with EGFRm NSCLC BM is warranted.
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