Monitoring Daily Dynamics of Early Tumor Response to Targeted Therapy by Detecting Circulating Tumor DNA in Urine

Abstract

Purpose Non-invasive drug biomarkers for the early assessment of tumor response can enable adaptive therapeutic decision-making and proof-of-concept studies for investigational drugs. Circulating tumor DNA (ctDNA) is released into the circulation by tumor cell turnover and has been shown to be detectable in urine. Experimental Design We tested the hypothesis that dynamic changes in epidermal growth factor receptor (EGFR) activating (exon 19del and L858R) and resistance (T790M) mutation levels detected in urine could inform tumor response within days of therapy for advanced non-small cell lung cancer (NSCLC) patients receiving osimertinib, a second line third generation anti-EGFR tyrosine kinase inhibitor. Results Eight of nine evaluable NSCLC patients had detectable T790M-mutant DNA fragments in pre-treatment baseline samples. Daily monitoring of mutations in urine indicated a pattern of intermittent spikes throughout week 1 suggesting apoptosis with an overall decrease in fragment numbers between baselines to day 7 preceding radiographic response assessed at 6-12 weeks. Conclusions These findings suggest drug-induced tumor apoptosis within days of initial dosing. Daily sampling of ctDNA may enable early assessment of patient response and proof-of-concept studies for drug development.

A field guide for cancer diagnostics using cell‐free DNA: From principles to practice and clinical applications

“…Acute changes in plasma ctDNA levels within 26 hours of treatment onset were observed in response to EGFR tyrosine kinase inhibitor therapy in NSCLC patients . Indications for early therapy response were also found by daily ctDNA quantification in urine samples from NSCLC patients . Besides targeted therapies, an initial peak followed by a rapid decrease of ctDNA levels as an indicator for early response was reported for T‐cell transfer immunotherapy in patients with metastatic melanoma .…”

Preoperative Circulating Tumor DNA in Patients with Peritoneal Carcinomatosis is an Independent Predictor of Progression-Free Survival

“…7 This reproducible, minimally invasive, and spatially unbiased technology has been used to identify targeted therapies, measure residual disease, and assess response to therapy. 8–10 …”

Urine test for EGFR analysis in patients with non-small cell lung cancer

“…More specifically, the longitudinal assessment of EGFR mutant allele burden represents a non-invasive and cost-effective mechanism to evaluate patient response to EGFR-TKIs compared to repeat tissue biopsies or imaging. Several proof-ofconcept studies show a clear correlation between urinary EGFR mutant levels and response to EGFR-TKIs, whereby a near-complete and sustained decline from baseline of ctDNA levels is associated with radiographic response (37,42). A case series in which urinary EGFR mutational burden was assessed during the course of treatment with first-line and approved or experimental third-generation EGFR-TKIs clearly depicted the utility of urine testing in the detection of response and resistance (60).…”

“…The sensitive and quantitative detection of EGFR, BRAF, and KRAS mutations in urine has been achieved using a short-footprint mutation enrichment polymerase chain reaction (PCR) coupled with nextgeneration sequencing (NGS) approach (37)(38)(39)(40)(41). Reported limits of detection (LOD) for the EGFR L858R, exon 19 deletion, and T790M mutations in urine, or plasma, using this platform is 0.006%, 0.006%, and 0.01%, respectively, comparing favorably with the FDA-approved cobas ® EGFR Mutation Test (LOD ≥0.2%) (37,42,43).…”

“…Such a scenario could be indicative of incomplete response due to the outgrowth of tumor cells exploiting alternative bypass signaling pathways. A recent evaluation of the day-to-day kinetics of urinary EGFR mutant load also unveiled the potential clinical utility of urine testing as an early indicator of response to targeted therapies (42). Daily monitoring of EGFR mutations in urine of patients with NSCLC receiving EGFR-TKIs revealed a pattern of intermittent spikes throughout the first week of treatment.…”