Abstract 1197P
Background
The aim of this study is to investigate the predictive value of early changes in the plasma EGFR-M+ concentration in non-small cell lung cancer patients (NSCLC) undergoing therapy by EGFR tyrosine kinase inhibitors.
Methods
The study included 29 patients with EGFR-M+ TKI-naïve NSCLC receiving gefitinib (N = 19), erlotinib (N = 5), afatinib (N = 3) or osimertinib (N = 2). EGFR-M+ plasma DNA was detectable at diagnosis in 21/29 study participants. Sequential plasma specimens were collected before intake of the first tablet (at baseline) and at 6, 12, 24, 36 and 48 hours after the “starting point”. 178 plasma samples were subjected to EGFR-M+ allele measurement by ddPCR.
Results
11 subjects showed the decline of EGFR-M+ level in plasma within the first 48 hours of treatment. All these patients showed objective tumor response, with one instance of complete radiologic response. 10 patients showed either elevation of EGFR-M+ plasma concentration (n = 5) or stable content of circulating EGFR-M+ after the start of the therapy (n = 5); only three of these patients achieved an objective response (p = 0.026) when compared to the former group. The rapid decline of plasma EGFR-M+ DNA concentration also predicted for longer PFS (13.7 vs. 11.4 months, p = 0.030).
Conclusions
Monitoring of plasma EGFR-M+ concentration within the first hours of the TKI therapy may be used as an immediate predictor of tumour response to the treatment.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Russian Foundation for Basic Research (RFBR) grant 18-29-09153.
Disclosure
All authors have declared no conflicts of interest.