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MA 11 - Emerging Diagnostic/Biomarkers in NSCLC (ID 668)
- Event: WCLC 2017
- Type: Mini Oral
- Track: Advanced NSCLC
- Presentations: 1
MA 11.09 - Real World Data of Rebiopsy, Mutation Status, and Its Association with Plasma Genotyping after EGFR TKI Failure in NSCLC (ID 8234)
11:00 - 12:30 | Author(s): H. Kim
After the introduction of third-generation epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKIs) in non-small cell lung cancer (NSCLC), the second tumor biopsy and EGFR mutation test to confirm T790M status is an established standard practice. But second biopsy is invasive, cost and time-consuming and occasionally impossible. We aimed to investigate the success rate of tissue rebiopsy and incidence of T790M mutation in tissue and plasma at the time of progression with earlier-generation EGFR TKIs in real world setting. Also, we studied the association between the efficacy of osimertinib and the status of tissue and/or plasma T790M mutation.
We analyzed patients who were screened and enrolled into ASTRIS trial in Yonsei Cancer Center (NCT02474355). Key inclusions were advanced/metastatic NSCLC with tissue and/or plasma T790M mutation and prior EGFR-TKI therapy. Tissue and plasma EGFR mutation tests were performed using PNAClamp[TM] and PANAMutyper[TM], respectively.
We screened 193 patients with NSCLC harboring EGFR-activating mutation who experienced disease progression upon earlier-generation EGFR TKIs during study period. The second biopsy including tissue and/or cytology was performed only in 60.1% of the patients (116/193) and the success rate was 86.2% (100/116). The reasons for not trying a biopsy were as follow: inaccessibility (n=25), poor PS (n=8), previously reported plasma T790M+ (n=8), and patients’ refusal (n=4). The parenchymal lung tissue (n=61) was most commonly targeted lesion and bronchoscopy was the most frequently used method (n=35). Six patients underwent video-assisted thoracoscopic surgery. Tumor T790M mutation was reported in only 25.9% of patients (50/193). Of 193 patients, 88 patients were enrolled into ASTRIS trial and 43 patients were registered based on the plasma test only. With a median follow-up of 25.1 weeks, the objective response rate (ORR), median progression-free survival (PFS), and duration of the response (DoR) were 44.3%, 32.7 weeks, and 27.0 weeks, respectively. Median overall survival (OS) was not reached. The ORR, median PFS and DoR of tumor T790M+ (n=45) vs. plasma T790M+ (n=54) were 57.8% vs. 35.2%, 45.0 vs. 20.4 weeks, and 26.3 vs. 25.9 weeks, respectively.
With the increasing importance of tissue rebiopsy after EGFR-TKI failure, there is a growing interest to overcome the challenge of subsequent biopsy. Even though relatively lower ORR and shorter PFS in patients with plasma T790M+ compared with tissue T790M+, the plasma EGFR genotyping may be good alternative to the tissue biopsy in consideration of long DoR when treated with osimertinib and low yield rate of tissue T790M testing.
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