Tissue of Origin Test to Aid in Diagnosis of Cancer of Unknown Primary

Pathwork Diagnostics Inc--which obtained FDA approval for the use of its Pathwork Tissue of Origin Test in determining the origin of uncertain tumors in July--announced on Halloween that company representatives would present three studies that day involving their Pathwork Tissue of Origin Test at the Association for Molecular Pathology Annual Meeting, held October 29-November 2. The studies, presented by Fabiola Medeiros, MD, assistant professor of Laboratory Medicine and Pathology, Mayo Clinic, found that the genetic test indicated a probably origin of metastatic CUP in 73% of tested tumors.

The Pathwork Tissue of Origin Test uses a microarray to measure the expression pattern—derived from more than 1500 genes—in the uncertain tumor and compares this to expression patterns from 15 known tumor types, representing 60 morphologies overall, to help determine the tumor’s origin. According to its manufacturer, it is the first such test to receive FDA clearance. Pathwork estimates that, every year, up to 200,000 patients in the United States with a new cancer diagnosis may have a tumor for which the site of origin remains uncertain after the initial diagnostic workup.

In the in vitro diagnostics clinical validation study submitted to the FDA, the test demonstrated 89% positive agreement (akin to sensitivity) with available diagnoses and 99% negative agreement (akin to specificity). The study consisted of 545 metastatic, poorly differentiated and undifferentiated tumors that existing methods had identified as 1 of 15 tumor types on the panel. On average, the test demonstrated 94% overall concordance across 4 laboratories in a cross-laboratory comparison study of 60 metastatic, poorly differentiated and undifferentiated tissue specimens.

The Pathwork Tissue of Origin Test is currently available as a service through Pathwork’s CLIA-certified laboratory, but it will soon be offered as an in vitro diagnostic kit, which means that clinical laboratories will be able to run the test themselves.

“Knowing the primary tumor site with greater certainty enables more appropriate cancer treatment. The growing trend in cancer care is the use of therapies that target specific tissues and their genomic components, rather than relying on a one-size-fits-all treatment approach,” stated Deborah J. Neff, president and CEO, Pathwork Diagnostics. “We believe the Pathwork Tissue of Origin Test will help provide more certainty in tumor diagnosis, which will enable more patients to realize the benefits of this new era in genomics-based diagnostics,” she added.