ROCKVILLE, MarylandThe Food and Drug Administration has approved the
inclusion of the PathVysion HER-2 DNA Probe Kit, a new genedetection test, in the labeling of Herceptin (trastuzumab, Genentech).
PathVysion is made and marketed by Vysis, Inc., a subsidiary of Abbott
Laboratories. It joins HercepTest (DAKO) as the second screening test listed
in the Herceptin
Herceptin, a humanized monoclonal antibody, first won FDA approval in
September 1998 for use with paclitaxel (Taxol) in the first-line treatment of
women with metastatic breast cancer whose tumors overexpress the protein
HER-2, which is a human epidermal growth factor. Multiple copies of the gene
for HER-2 result in aggressive growth of tumor cells in about 25% to 30% of
patients. Herceptin is also approved as a single agent in second- or
third-line therapy of HER-2-positive patients with metastatic disease.
Studies have shown increased survival among HER-2-positive women treated
with Herceptin, which demonstrates "the importance of identifying appropriate
candidates for Herceptin therapy," noted Gwen Fyfe, MD, Genentech’s senior
director of oncology, medical affairs.
The FDA has approved three HER-2 tests to determine which women might
benefit from Herceptin treatment. HercepTest and Pathway (Ventana), which is
not listed on the Herceptin labeling, both rely on immunohistochemistry (IHC)
to assess the HER-2 receptor status of women. In contrast, PathVysion uses
fluorescence in situ hybridization (FISH) to determine the number of copies
of the gene that codes for HER-2.
PathVysion received FDA marketing approval on the last day of 2001. The
agency’s approval of Genentech’s application to include the new detection
test in the Herceptin labeling came 8 months after the agency’s Oncologic
Drugs Advisory Committee (ODAC) unanimously recommended that it do so.
During the ODAC meeting, Genen-tech presented two studies to support its
request. The first, a concordance study between the FISH and IHC
technologies, showed a concordance in a 1:1 population of 82% between
PathVysion and the clinical trials assay.