On April 25, 2002, the FDA approved fulvestrant (Faslodex®, a trademark of AstraZeneca Pharmaceuticals LP) 250 milligrams monthly intramuscular injections for the treatment of hormone receptor-positive metastatic breast cancer in postmenopausal women with disease progression following antiestrogen therapy.

Intramuscular fulvestrant was compared with oral anastrozole (Arimidex®, also a trademark of AstraZeneca) in two randomized, controlled clinical trials (a North American double-blinded study and a European open-label study) in postmenopausal women with locally advanced or metastatic breast cancer. All patients had progressed after previous therapy with an antiestrogen or progestin for breast cancer in the adjuvant or advanced disease setting. The majority of patients in these trials had estrogen receptor-positive (ER+) and/or progestin receptor-positive (PgR+) tumors. Patients who had ER-/PgR- or unknown disease must have shown prior response to endocrine therapy. A total of 851 patients were enrolled, with 428 randomized to receive fulvestrant 250 milligrams monthly by intramuscular injection and 423 patients randomized to receive anastrozole 1 milligram daily. Response rates of 17 percent and 20 percent were reported in the fulvestrant treatment arms in the North American and European trials, respectively; these rates were similar to the 17 percent and 15 percent response rates reported in the anastrozole treatment arms. There were no significant differences in time to progression or survival between the two arms in either trial.

The safety profile of fulvestrant was similar to that of anastrozole. Most commonly reported adverse events were of mild to moderate severity and included nausea, vomiting, constipation, diarrhea and abdominal pain, headache, back pain, vasodilatation (hot flashes) and pharyngitis. Mild injection site reactions were reported in 7 percent and 27 percent of patients (1 percent and 5 percent of treatments) given single 5 milliliter and 2 x 2.5 milliliter fulvestrant injections, respectively.

Full prescribing information is available, including clinical trial information, safety, dosing, drug-drug interactions and contraindications.

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