Early plasma circulating tumor DNA (ctDNA) changes to predict response to first-line pembrolizumab +/- chemotherapy in non-small cell lung cancer (NSCLC).

3518 Background: ctDNA shedding into plasma can be prognostic in lung cancer, and changes in plasma ctDNA levels correlate with response to systemic therapy. However, is unknown whether early detection of ctDNA levels change predicts response to first-line pembrolizumab +/- chemotherapy. We hypothesized that serial assessment of plasma ctDNA by next generation sequencing would enable early detection of response to immunotherapy in NSCLC prior to...