The Feasibility of Dynamic Liquid Biopsy Monitoring During Neoadjuvant Treatment for EGFR-mutated NSCLC

This study aimed to prospectively enroll approximately 300 resectable stage II-IIIB (T1-4N0-2M0, excluding T4 with invasion of vital structures and bulky or infiltrative N2) NSCLC patients with histologically confirmed EGFR 19del or L858R mutations. Peripheral blood samples will be collected at baseline before neoadjuvant 3rd-generationEGFR TKI therapy, and ctDNA levels will be quantitatively assessed. For patients with positive baseline ctDNA, peripheral blood will be collected again after 3 weeks of neoadjuvant TKI therapy to assess if ctDNA has turned negative, and HRCT will be performed to evaluate the treatment efficiency simultaneously. In patients with positive baseline ctDNA, for ctDNA-negative patients after 3 weeks of neoadjuvant TKI treatment, radical resection surgery will be performed after continuing TKI treatment for 9-12 weeks (Group A). For ctDNA-positive patients after 3 weeks of neoadjuvant TKI treatment, in combination with imaging changes in the lesions, a multidisciplinary team (MDT) evaluation will be conducted. After discussion between the attending physicians and the patient, the subsequent treatment will either continue TKI treatment for 9-12 weeks (Group B), undergo 3 cycles of TKI plus chemotherapy (Group C), or undergo sequential neoadjuvant immunotherapy plus chemotherapy for 3 cycles (Group D) before radical resection surgery.The study intends to evaluate the correlation between the rate of major pathological response (MPR) and ctDNA levels at 3 weeks after TKI treatment, to compare the difference in pathological response between ctDNA-negative and ctDNA-positive groups after 3 weeks of neoadjuvant TKI treatment and to evaluate the guiding value of dynamic ctDNA monitoring during neoadjuvant therapy for optimizing subsequent treatments.