Introduction
The impact of different treatments on ctDNA changes are poorly understood. The real-world PCG study provides an opportunity to study ctDNA in patients with lung cancer receiving treatment. We report preliminary results on associations between ctDNA and real-world response (rwR) by treatment, providing insights on the impact of therapies on ctDNA changes and its usage for response assessment.
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Methods
As of 9/30/2021, 944 patients were enrolled. Patients with metastatic NSCLC or extensive-stage SCLC who initiated 1L or 2L systemic antineoplastic treatment in the Flatiron Health Research Network were investigated. Following consent, data were collected from electronic health records, including clinician assessment of disease burden change (real-world response [rwR]; cutoff 12/1/2021). ctDNA was analyzed using FoundationOne®Liquid at enrollment, and ≥1 of either on-treatment (±14 days of first
Results
Median baseline TF was 2.2% (IQR 0.6%-9.5%) among 385 patients with NSCLC and 42.8% (19.5%-65.4%) among 90 patients with SCLC. Baseline TF was similar across treatments in NSCLC (P=0.8) and SCLC (P=0.9) (data not shown). More NSCLC rw-responders had a decrease of ≥50% in TF from baseline than rw-non-responders (P=0.002; Table). For patients with NSCLC receiving chemotherapy, a greater proportion had a TF decline of >50% and a lower proportion had a TF increase than patients receiving CIT (alone
Conclusions
Rw-responder patients with NSCLC had greater decreases in TF versus rw-non-responders. ctDNA increase was associated with higher risk for progression. We also observed different associations between ctDNA changes and rwR by treatments in patients with NSCLC. Our results indicated that ctDNA response may complement rwR in assessing patients’ outcomes, however treatment may affect interpretation of ctDNA response.