Fluctuation of Acquired Resistance Mutations and Re-Challenge with EGFR TKI in Metastatic NSCLC: A Case Report.

Osimertinib has become the preferred first-line therapy for epidermal growth factor receptor (EGFR) mutation-positive metastatic non-small cell lung cancer (NSCLC) in recent years. Originally, it was approved for second-line treatment after epidermal growth factor receptor EGFR tyrosine kinase inhibitors (TKIs) of the first and second generations had failed and EGFR T790M had emerged as a mode of resistance. Osimertinib itself provokes a wide array of on- and off-target molecular alterations that can limit therapeutic success. Liquid biopsy ctDNA (circulating tumor DNA) analysis by hybrid capture (HC) next-generation sequencing (NGS) can help to identify alterations in a minimally invasive way and allows for the detection of common as well as rare resistance alterations. We describe a young female patient who was initially diagnosed with metastatic EGFR L858R-positive NSCLC. She received EGFR TKI therapy at different timepoints during the course of the disease and developed sequential EGFR resistance alterations (EGFR T790M and C797S). In the course of her disease, resistance alteration became undetectable, and the tumor was successfully rechallenged with the original first-generation EGFR TKI as well as osimertinib and altogether showed prolonged response despite a prognostically negative TP53 alteration. To date, the patient has been alive for more than seven years, though initially diagnosed with a heavy metastatic burden.

Predictive value of mRNA expression and dynamic changes from immune related biomarkers in liquid biopsies before and after start of pembrolizumab in stage IV non-small cell lung cancer (NSCLC).

BACKGROUND: The aim of this study was to determine whether mRNA expressions and dynamic changes of immune-related genes before and after starting first-line treatment with the PD-1 inhibitor pembrolizumab in patients with NSCLC were of predictive value. METHODS: CD3, CD8, PD-1, PD-L1 and CTLA-4 mRNA expression levels were measured from peripheral blood before and after three weeks of treatment with the PD-1 inhibitor. Univariate and multivariate analyses were performed retrospectively. Response, progression-free survival (PFS) and overall survival (OS) were determined. RESULTS: In univariate analysis an increase of CD3 and CD8 mRNA expression after the first cycle of pembrolizumab were each associated with improved PFS and OS. In contrast, patients with no change or with a decrease in CD3 and CD8 mRNA expression showed significantly worse outcome. CD8 mRNA increase remained an independent predictive factor for PFS and OS in the multivariate analysis with p values of 0.011 and 0.006, respectively. CONCLUSIONS: An increase of CD8 mRNA expression predicts favorable outcome after first line monotherapy with pembrolizumab, while no change or decrease might serve as an indicator of poor outcome and might give cause for early treatment escalation for instance by addition of chemotherapy or additional ICI treatment, e.g., against CTLA-4.