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ODAC Backs Adding HER-2 DNA Test to Herceptin Package Insert

ODAC Backs Adding HER-2 DNA Test to Herceptin Package Insert

SILVER SPRING, Maryland—The FDA’s Oncologic Drugs Advisory
Committee (ODAC) has unanimously recommended that the agency amend the labeling of Herceptin (trastuzumab, Genentech) to include a new gene-detection
test to identify women with metastatic breast cancer who are likely to benefit
from the therapy. The 16-to-0 vote backed adding the PathVysion HER-2 DNA Probe
Kit to the labeling. The kit is made by Vysis, Inc., now owned by Abbott
Laboratories.

The FDA approved Herceptin, a humanized monoclonal antibody, in September
1998 for use in combination with paclitaxel (Taxol) as a first-line treatment
for women with metastatic breast cancer whose tumors overexpress the protein
HER-2, an epidermal growth factor receptor. The antibody is also approved as a
single-agent therapy for HER-2-positive patients as second- and third-line
therapy.

Currently, the FDA has approved two tests for selecting Herceptin patients,
the HercepTest (DAKO, Inc.) and Pathway (Ventana, Inc.), although only the
HercepTest is listed in the Herceptin package insert. Both tests rely on
immunohistochemistry (IHC) to assess HER-2 status.

The PathVy-sion kit, on the other hand, uses fluorescence in situ
hybridization (FISH), which can determine the number of HER-2 genes in a woman’s
breast cancer cells. The gene codes for the HER-2 protein, and thus its
amplification in a tumor cell can reveal a patient’s potential to respond to
Herceptin therapy.

"A direct correlation exists between gene amplification and
overexpression," said Michael Press, MD, PhD, professor of pathology,
University of Southern California Norris Comprehensive Cancer Center.
"Amplification, as determined by FISH, is a clinically meaningful measure
associated with poor prognosis and predictive of therapeutic response."

Dr. Press described the biology of HER-2 and the ways to assess it on behalf
of Genentech.

The sponsor presented two studies in support of adding PathVysion to the
Herceptin package insert—a concordance study between the FISH test and the
IHC test used as the Herceptin clinical trials assay and a clinical outcomes
study that assessed FISH using archived tissue from Herceptin trials.

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