Mutation enrichment next-generation sequencing for quantitative detection of KRAS mutations in urine cell-free DNA from patients with advanced colorectal and other cancers.

602 Background: Molecular testing of cell-free (cf) DNA from urine is a completely non-invasive approach for detection of actionable mutations in cancer. Methods: A quantitative mutation enrichment next-generation sequencing (NGS) urine cell-free (cf) DNA KRAS G12/G13 mutation test was developed and results compared to clinical testing of archival tumor tissue and research testing of plasma cfDNA from patients with advanced colorectal (n=56, 79%) and other advanced cancers (n=15, 21%). Results: The analytical sensitivity of the KRAS G12/G13 cfDNA test was 0.002%-0.006% mutant copies in wild-type background. In 71 patients, the agreement between urine cfDNA and tumor was 73% (sensitivity 63%; specificity 96%); the agreement increased to 89% for patients with recommended 90-110mL of urine. In 33 patients with available plasma samples, the agreement with tumor was 94% (sensitivity 92%; specificity 100%). In patients treated with systemic therapy there was lower number of KRAS G12/G13 copies in urine and plasma cfDNA on therapy compared to baseline and progression ( P<0.003). Decrease in urine and plasma cfDNA KRAS G12/G13 copies on therapy compared to no change/increase was associated with longer median time to treatment failure ( P<0.05). Conclusions: Mutation enrichment NGS detection of KRAS G12/G13 mutations in urine cfDNA has good concordance with archival tumor tissue. Changes in urine cfDNA correspond with time to treatment failure.