An Observational, Multi-centre Study on EGFR T790M Mutation Testing Practices and Outcomes Conducted Among Locally Advanced/Metastatic NSCLC Patients Who Progressed on Previous EGFR Tyrosine-kinase Inhibitor (TKI) Therapy in Hong Kong

This is a multi-center, observational study of patients with locally advanced/metastatic NSCLC who progressed on previous EGFR TKI treatment. Eligible patients will be recruited from participating sites in Hong Kong over a 12 months enrolment period.

Plasma and urine samples will be collected from enrolled patients. Plasma circulating tumor DNA (ctDNA) and urine ctDNA will be analyzed by droplet digital PCR (ddPCR) for detection of T790M mutation and EGFR sensitizing mutations. Patients who are T790M plasma-negative, regardless of the urine testing results, will be recommended to undergo re-biopsy (defined as tissue sampling or cytology sampling), tissue/cytology T790M testing, and to provide a second plasma sample for a second plasma T790M test (tested by ddPCR).

Enrolled patients who subsequently receive osimertinib treatment will be followed up as per routine practice at the investigational site. Patient data will be collected for 12 months or until death or loss to follow-up, whichever occurs earlier, from the first prescription of osimertinib. All clinical decisions will be at the discretion of the treating physician.