Diagnostics & Imaging Week

To freeze or not to freeze, that was the Shakespearean question posed toward Pathwork Diagnostics (Sunnyvale, California) when it came down to the development of an additional version of its Tissue of Origin Test.

The company previously developed the test, which uses a microarray to measure the expression pattern, comprising more than 1,500 genes in the uncertain tumor and compares it to expression patterns of a panel of 15 known tumor types, representing 60 morphologies overall to help determine the tumor's origin.

In a sense, the test has the capability of analyzing formalin-fixed, paraffin-embedded (FFPE) tissue specimens.

The problem with the previous test is that it did not have the capability to process frozen tissue biopsies – for which there is a high demand.

"The No. 1 question we get is, 'Why don't you use a frozen technology?" David Craford, VP of commercial operations at Pathwork, told Diagnostics & Imaging Week. "When we said we were still developing that application, the response would be "Call us when you do.' So now we're calling them back."

By using the Tissue of Origin Test, physicians will be able to use objective criteria to identify the primary site of a tumor's origin, the first step in beginning standard-of-care, tumor-specific therapy per National Comprehensive Cancer Network (NCCN) Clinical Practice Guidelines. Targeting therapy to specific tumor types can also allow patients to avoid the toxicity of broader, and in some cases, ineffective chemotherapy.

The test may also allow physicians to arrive at a diagnosis sooner, which can benefit cancer patients by enabling treatment to begin more quickly and allowing patients to enroll in and benefit from appropriate clinical trials.

The length of RNA you can extract is much shorter than if you were to use frozen tissue, according to the company.

In the clinical validation study utilizing FFPE tumor specimens, the test demonstrated 89% positive agreement (akin to sensitivity) with available diagnoses and greater than 99% negative agreement (akin to specificity). This statistically significant study consisted of 352 metastatic, poorly differentiated and undifferentiated tumors that had been identified as one of the 15 tumor types on the panel using existing methods.

The FDA-cleared test will be available as an in vitro diagnostic kit, meaning that clinical laboratories can run the test themselves. The test is now available as a service through Pathwork's CLIA-certified laboratory.

"We do have plans to eventually go into Europe with the test," Craford told D&IW.

The test also uses PathChip; a gene expression array customed designed for the company by Affymetrix (Santa Clara, California). PathChip is the first custom Affymetrix gene expression array to be cleared for diagnostic use.

The new application comes on the heels of a major financing coup for the growing company. In late summer, it reported closing a $20 million financing led by Abingworth, which joins the existing investors participating in the round, including Prospect Venture Partners, Advent Venture Partners, Novus Ventures, Venrock and Versant Ventures.

The funding was said to help pay for the commercialization of products and to further build the company's pipeline.

The new product joins a line of cancer and tumor-specific tests.

The fist such test was MammaPrint, developed by Agendia (Amsterdam, the Netherlands). A genetic test cleared nearly two years ago, MammaPrint is used to determine the likelihood of breast cancer returning within five to 10 years after a woman's initial cancer.

In July 2007, the FDA issued a draft guidance document to address pre-market pathways and post-market requirements for IVDMIAs. IVDMIA tests combine the values of multiple variables to yield a single, patient-specific result.

Another test was developed by DiagnoCure Oncology Laboratories (West Chester, Pennsylvania), a wholly-owned subsidiary of DiagnoCure (Quebec City). The company launched its Previstage GCC Colorectal Cancer Staging Test.

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