37. The clinical utility of the TSO500 clinically-verified test in patients with solid tumors: The Mayo Clinic experience

Clinical Laboratories reimbursement for large cancer panels has been challenging with many health care payers arguing about the clinical utility of such panels. We sought to investigate the clinical utility of the TSO500 kit in patients with solid tumors (ST) by determining its ability to detect a target for an FDA-approved drug in tumor type (FDA-in-TT), and in other tumor type (FDA-in-OTT).

The TSO500 kit which is commercially offered by Illumina company along with an analysis pipeline has been clinically verified in our laboratory and has been offered since 2021 for clinical care. A total of 1194 cases representing over 25 solid tumor types that were tested on the TSO500 platform were included in the study.

The top 3 indications for testing were lung cancer (35.6%), unknown primary (UNP) (14.5%), and other tumor types (12.5%). FDA-in-TT and FDA-in-OTT variants were identified in 531/1194(44.5%), and (257/1194)(15.4%), total (788/1194)(66%) cases, respectively. Immunotherapy markers including microsatellite instability (MSI-H) and/or high tumor mutation burden (TMB-H) were detected in 324 cases representing 60% of cases with FDA-in-TT and FDA-in-OTT, and 30% of all tested cases, respectively. Interestingly, 43/172(25%) of UKP cases had FDA-approved-drug, of which 35/43(81%) had TMB-H.

The detection of an FDA-in-TT and FDA-in-OTT target in 66% of patients, 60% of whom had TMB-H, a biomarker for FDA-approved immunotherapy drugs that requires interrogating over one megabase of the genome for accurate detection, provides strong evidence for the clinical utility of a large panels testing like the TSO500 in patients with solid tumors.