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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
MINI10.10 - A Multicenter Prospective Biomarker Study in Afatinib-Treated Patients with EGFR-Mutation Positive Non-Small Cell Lung Cancer (ID 472)
16:45 - 18:15 | Author(s): K. Nozaki
Afatinib is an oral, irreversible ErbB family blocker and one of the key drugs for patients with EGFR mutation positive advanced non-small cell lung cancer (NSCLC). Although treatment with afatinib has a clinical benefit for these patients, such individuals inevitably develop drug resistance as with other TKIs. This is a multicenter prospective biomarker study to inform the usefulness of noninvasive liquid biopsy in the treatment of EGFR-tyrosine kinase inhibitors (EGFR-TKIs) and explore the molecular mechanism of acquired-resistance against afatinib.
Eligible patients were EGFR-TKIs naïve and had histologically and cytologically confirmed stage IIIB/IV adenocarcinoma of the lung with activating EGFR mutations. Patients remained on afatinib treatment until disease progression or unacceptable toxicity. Tumor samples were collected upon before afatinib treatment and after disease progression. Plasma samples were collected upon before and during afatinib treatment (4 and 24 weeks after initiation) and after disease progression. DNA derived both from tumors and plasma was analyzed using Scorpion-ARMS (ARMS), digital PCR (dPCR) and next generation sequencing (NGS). We used a nanofluidic dPCR system (BioMark HD System; Fluidigm) with a digital chip to detect activating or resistance mutations of EGFR in a quantitative and highly sensitive manner. NGS on an Ion Torrent PGM device (Thermo Fisher Scientific) was applied to detect target molecules which contribute to the survival and growth of lung cancer cells. We compared the sensitivity of these methods in detection of EGFR activating mutations in plasma DNA.
A total of 35 EGFR mutation positive NSCLC patients were enrolled. Twenty one patients harbored a deletion in exon 19 and fourteen patients had an L858R missense mutation in exon 21. Twenty seven (77.1%) patients had an objective response. In plasma DNA obtained before afatinib treatment, dPCR and NGS detected EGFR activating mutations more sensitively compared with ARMS (83.9% v 58.1%; p <0.005, 74.2% v 58.1%; p =0.059, respectively). Concordance of EGFR activating mutations detected by dPCR and NGS was 26/31 (84%) (kappa value: 0.52). All of the mutation type detected by NGS on plasma DNA completely corresponded to that found in matching tumor tissue by NGS. As of March 2015, serial plasma DNA was analyzed in 9 patients. The copy number of activating mutation was markedly decreased in 5 of 9 patients.
EGFR activating mutations in plasma DNA were frequently detected by dPCR or NGS. We will present the detailed data for monitoring mutation load in plasma DNA during the afatinib treatment.
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