Serial Genome-Wide Sequencing Of Cell-Free Dna (Cfdna) By Assays Used In Non-Invasive Prenatal Testing (Nipt) To Identify Copy Number Alterations (Cnas) Associated With Immunotherapy Response.

e14533Background: cfDNA derived from tumor cells can be detected in the plasma of many cancer patients. Noninvasive methods to detect CNAs have been developed to detect chromosomal abnormalities in the setting of prenatal screening. We hypothesized that similar methods can be used to enable quantitative detection of CNAs in cfDNA, as represented by a genome instability number (GIN), in patients with cancer and used to monitor response to immunotherapy. Methods: Peripheral blood for CNA analysis was collected from patients with diverse cancers for whom immunotherapy was planned. Plasma was separated from peripheral blood using centrifugation. cfDNA was collected and subjected to low-coverage, genome-wide sequencing. CNAs were detected using methods developed for noninvasive prenatal testing. GIN was calculated as the cumulative sum of the deviation from baseline for all detected …