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There are an estimated 200,000 cancer patients each year in the UnitedStates who may benefit from diagnostic information to determine the tissue oforigin for their cancer. One study showed that, in some cases, the primarytumor site is identified only 25 percent of the time using traditionaldiagnostic tools. National Comprehensive Cancer Network guidelines emphasizethe importance of identifying the tissue of origin so that management specificto the primary cancer can begin.
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The Pathwork Tissue of Origin Test's proprietary analytics are designed tomeasure the expression of more than 1600 genes and compare a tumor's genetic"signature" against those of 15 known tissue types. The test uses microarraytechnology, which enables large numbers of genes to be evaluated at the sametime, using the proven, commercially available Affymetrix instrument system.
"This test has the potential to be an effective aid in the diagnosis ofcancer patients presenting with poorly differentiated and undifferentiatedtumors," concluded Federico Monzon, M.D., Methodist Hospital, Houston, TX,(Poster #ST102, Friday, November 9, 1:00-3:00 PM, Constellation and OlympicBallroom).
Dr. Monzon's clinical validation study ("Validation of a geneexpression-based tissue of origin test applied to poorly differentiated andundifferentiated cancers") evaluated the performance of the Pathwork Tissue ofOrigin Test in a clinical setting. In the study, specimens of 477 metastaticand poorly differentiated and undifferentiated primary human tumors wereobtained. All samples were of known origin (termed reference diagnosis).
Frozen tissue specimens were processed in two laboratories with arecommended protocol for gene expression with the Affymetrix platform. Datawere analyzed with the Pathwork Tissue of Origin algorithm and a Tissue ofOrigin report was generated for each sample. The result was compared to thereference diagnosis to establish the performance characteristics of thePathwork test. The Tissue of Origin Test results matched the reported originin 89% of samples tested and provided greater than 92% agreement for at least8 tissues of origin.
In the second study, Catherine I. Dumur, Ph.D., Virginia CommonwealthUniversity, Richmond, VA, led a group which examined the analyticalperformance characteristics and reproducibility of the Tissue of Origin Test,"Analytic performance of a microarray-based gene expression test to determinetissue of origin in uncertain primary cancers" (Poster #ST01, Thursday,November 8, 2:30-4:30 PM, Constellation and Olympic Ballroom).
In Dr. Dumur's study, 60 archived tissue specimens from poorly andundifferentiated tumors (metastatic and primary) were analyzed at fourlaboratories representing a wide range of pre-analytical conditions.Reproducibility was analyzed by cross-wise comparisons of all 4 sites.Cross-laboratory comparisons, performed using a variety of measures, showedhighly reproducible results between laboratories. In addition, an average of93.8% overall concordance between laboratories in terms of final tissue oforigin calls was obtained.
"As a result of the study, we concluded that the Pathwork Tissue of OriginTest is a robust assay that produces consistent results in diverse laboratoryconditions reflecting the pre-analytical variations found in the everydayclinical practice of molecular diagnostics laboratories," explained Dr. Dumur.
Note: The Pathwork Tissue of Origi
