The evolving genomic landscape of circulating tumor DNA represents an early predictor of immunotherapy response in lung cancer

Circulating tumor DNA (ctDNA) analyses are informative as an early indicator of immunotherapy response in advanced non-small cell lung cancer (NSCLC), however the clinical role of ctDNA molecular response requires further validation. As part of a prospective clinical protocol (NCT05995821), we performed ctDNA (n=328) and matched white blood cell DNA (WBC; n=109) targeted error-correction sequencing from 109 patients with advanced/metastatic NSCLC who received anti-PD-(L)1 as monotherapy or in combination. Following variant cellular origin resolution, landmark molecular response (mR) was defined as undetectable ctDNA within 3-9 weeks of treatment initiation. Among 2,818 plasma variants, 23% were clonal haematopoiesis-related, which confounded driver gene associations with clinical outcomes and molecular responses. Implementing a tumor-naïve WBC DNA-informed approach increased the number of evaluable cases while maintaining the overall accuracy of landmark ctDNA molecular responses. Pre-treatment ctDNA burden but not blood tumor mutation burden predicted survival. A significant enrichment in landmark ctDNA mR was noted among patients with progression-free survival (PFS) ≥6 months with immunotherapy (p=2.5e-05) and chemo-immunotherapy (p=0.02). Patients in the landmark mR group attained longer progression-free (p=1.6e-06) and overall survival (p=2.5e-05) compared to those with molecular progression. Our findings indicate that landmark ctDNA molecular response provides a real-time and accurate approach for monitoring immunotherapy clinical outcomes. Although not currently validated for regulatory use, these findings demonstrate the potential utility of ctDNA as an early endpoint in clinical trials.

• Type: Cancer Genomics
• Archive: European Genome-phenome Archive (EGA)