FDA Panel Recommends Approval of Breast Cancer Drugs

SILVER SPRING, Md-In addition to recommending approval of Taxotere(docetaxel) at its most recent meeting (see " Panel RecommendsTaxotere Be Approved for Advanced Breast Cancer"), the FDA'sOncologic Drugs Advisory Committee (ODAC) also voted on two othernew drug applications and heard a presentation on a new imagingagent.

The panel voted 8 to 2 to recommend approval of Orion-Farmos'antiestrogen Fareston (toremifene citrate), 60 mg/day, for thetreatment of locally advanced and advanced breast cancer in postmenopausalwomen. In three studies in the United States, Norway, and theformer USSR, the safety profile of Fareston was shown to be similarto that of tamoxifen (Nolvadex). Schering-Plough has US marketingrights to Fareston.

The FDA panel also voted unanimously to recommend approval ofZeneca Pharmaceuticals' Arimidex (anastrozole) for the treatmentof postmenopausal women with advanced breast cancer followingtamoxifen failure.

The agent, a nonsteroidal compound, is the first entry in a newclass of selective oral aromatase inhibitors. Inhibition of aromatasereduces the production of estrogen. Because anas-trozole has along half-life (50 hours), once-daily dosing is adequate.

Two trials, conducted in North America, Europe, Australia, andSouth Africa, showed that 1 mg/day of Arimidex obtained the sameresults as a 10 mg/day Arimidex dose or 160 mg/day of meges-trolacetate, the company said. While survival rates and quality oflife were equal for all three groups, significant weight gainoccurred in patients on megestrol.

The FDA panel also listened to a presentation from Immunomedics,Inc. on its monoclonal antibody imaging agent CEA-Scan (arcitumomab).The company is seeking FDA approval of the agent for diagnosticimaging in presurgical patients who are being considered for resectionof recurrent/metastatic colorectal cancer and, in combinationwith standard diagnostic modalities, for more accurate localizationof CEA-producing colorectal cancers.

Phase III studies have shown that CEA-Scan identified colorectalcancers of 1 cm or less that had been missed by CT scans. In trialsconducted at more than 20 US sites, the antibody consistentlyfound tumors that could not be detected by other methods and werehistologically confirmed, the company said.

While a vote was not taken, Immuno-medics asked for input fromthe panel regarding standards for evaluating monoclonal antibodyimaging agents.

Three Standards Might Apply

At least three standards might be applied: (1) clinical benefit,which requires randomized trials showing improved outcomes inpatients receiving the test; (2) clinical utility, in which thetest provides diagnostic information that might reasonably beexpected to provide benefits that outweigh any disadvantages;and (3) diagnostic performance, including data on sensitivityand specificity, with questions of clinical utility or benefitleft to the postmarketing phase.