Afatinib is an oral, irreversible ErbB family blocker and effective for EGFR-mutations positive advanced non-small cell lung cancer (NSCLC). This is a multicenter prospective biomarker study to investigate the usefulness of non-invasive liquid biopsy in the treatment of EGFR-tyrosine kinase inhibitors (EGFR-TKIs) and explore the molecular mechanism of acquired-resistance against afatinib (UMIN 000013806).
Eligible patients (pt.) had histologically and cytologically confirmed stage IIIB/IV adenocarcinoma of the lung with activating EGFR mutation. Afatinib was taken orally once daily at 40 mg/day. Plasma samples were collected upon before and during (4 and 24 weeks after initiation of treatment) afatinib treatment and disease progression. Plasma DNA (cfDNA) was analyzed using Scorpion-ARMS (ARMS), digital PCR (dPCR) and next generation sequencing (NGS).
A total of 35 EGFR -mutation positive NSCLC pt. were enrolled from 10 institutions between May to Nov 2014. Twenty one pt. harbored a deletion in exon 19 and fourteen pt. had an L858R missense mutation in exon 21. Twenty seven (77.1%) of the 35 pt. had an objective response. CfDNA obtained from 32 pt. has been analyzed by ARMS, dPCR and NGS. Serial cfDNA up to 24 weeks has been monitored by dPCR and NGS. EGFR activating mutations in cfDNA obtained from pre-treatment plasma were identified in 84.3% (27/32), 75.0% (24/32) and 59.4% (18/32) by dPCR, NGS and ARMS, respectively. In 19 of 27 pt., active mutations turned to be undetectable by dPCR in cfDNA obtained at 4 weeks. As of Jul 2015, all of them have not experienced PD yet. In 18 of 24 pt., mutation frequency of active mutations in cfDNA calculated by NGS significantly decreased in 4 weeks and turned to be zero in 24 weeks.
EGFR activating mutations in plasma samples were frequently detected by dPCR or NGS. There is a possibility that evaluation of activating mutation levels in cfDNA is useful for estimating the efficacy of afatinib.
Clinical trial identification
K. Nosaki: speaker's bureau; Nippon Boehringer Ingelheim Co., Ltd. K. Hotta: Taiho Pharmaceutical, Eli Lilly Japan, Daiichi Sankyo Company, Phizer Japan, Nippon Kayaku, Boehringer Ingelheim, Chugai Pharmaceutical, AstraZeneca, Sanofi, MSD. T. Kurata: Eli Lilly Japan, Phizer Japan, Chugai Pharmaceutical, AstraZeneca. K. Goto: Nippon Boehringer Ingelheim Co., Ltd (clinical trial grants and lectures)
Y. Nakanishi: Boehringer Ingelheim (lectures). I. Okamoto: Boehringer Ingelheim. All other authors have declared no conflicts of interest.