Tempus TO is an RNA-based sequencing test that provides guidance for physicians in cases in which imaging and immunohistochemistry stains yield uncertainty about the diagnosis of a patient’s tumor. The Tempus TO test compares a patient’s tumor molecular data to a large internal database of annotated tumor data to identify a likely diagnosis that may impact standard of care therapy decisions, clinical trial enrollment, and reimbursement for therapies. Given that Tempus performs transcriptomic profiling on the vast majority of its patients, it is uniquely positioned by virtue of the size of its internal RNA database to identify a tumor’s tissue of origin.