Pathwork Diagnostics, Sunnyvale, Calif, a genomics-based diagnostics company focused on oncology, reports its new tissue-of-origin test helps determine a tumor’s origin so tissue-specific management can begin.

The test’s proprietary analytics measure the expression of more than 1,600 genes and compare a tumor’s genetic signature against those of 15 known tissue types. The test uses microarray technology, which enables large numbers of genes to be evaluated at the same time.

The clinical validation study (“Validation of a gene expression-based tissue of origin test applied to poorly differentiated and undifferentiated cancers”) conducted by Federico Monzon, MD, Methodist Hospital, Houston, evaluated the test’s performance in a clinical setting. In the study, specimens of 477 metastatic and poorly differentiated and undifferentiated primary human tumors were obtained. All samples were of known origin (termed reference diagnosis).
 
Frozen tissue specimens were processed in two labs with a recommended protocol for gene expression with the Affymetrix platform. Data were analyzed with the test’s algorithm and a tissue of origin report was generated for each sample. The result was compared to the reference diagnosis to establish the performance characteristics of the test.

The tissue of origin test results matched the reported origin in 89% of samples tested and provided more than 92% agreement for at least eight tissues of origin. The result was compared to the reference diagnosis to establish the performance characteristics of the test.

Some 200,000 cancer patients annually in the United States may benefit from diagnostic information to determine the tissue of origin for their cancers. One study showed that, in some cases, the primary tumor site is identified only 25% of the time using traditional diagnostic tools. National Comprehensive Cancer Network guidelines emphasize the importance of identifying the tissue of origin so that management specific to the primary cancer can begin.

The test is not cleared by the FDA for sale in the United States; it is for investigational use only.