Faslodex Benefits Patients With Advanced Breast Cancer

Postmenopausal women with locally-advanced or metastatic HR-positive breast cancer benefited from the use of Faslodex (fulvestrant) as a frontline treatment. 
BY Silas Inman
PUBLISHED May 31, 2016
Progression-free survival (PFS) were improved for postmenopausal patients with locally-advanced or metastatic HR-positive breast cancer by the use of Faslodex (fulvestrant) as a frontline treatment, when compared with Arimidex (anastrozole), according to the phase 3 FALCON trial that was announced by AstraZeneca, the company developing the hormonal therapy.

PFS was the primary endpoint of the FALCON study, which enrolled 524 patients to receive Faslodex at 500 mg or Arimidex at one mg. Safety profiles were consistent with expectations for each medication in the trial. Full data from the trial have not yet been released and are being prepared for presentation at an upcoming medical meeting, according to AstraZeneca.

“The FALCON results bring us closer to offering more and earlier treatment options to postmenopausal women with HR+ locally-advanced or metastatic breast cancer; the potential to delay disease progression is important for these patients as there is currently no cure,” Sean Bohen, executive vice president, Global Medicines Development and Chief Medical Officer at AstraZeneca, the company developing Faslodex, said in a statement.

Secondary endpoints of the study, which are still being assessed, included overall survival (OS), objective responses rate (ORR), and safety. Additionally, the trial, which was launched in 2012, was designed to compare health-related quality of life, duration of clinical benefit and other response-specific endpoints.

Prior to the phase 3 trial, the open-label phase 2 FIRST study compared frontline Faslodex with Arimidex for postmenopausal women with HR-positive metastatic breast cancer. In this trial, treatment with 500-mg Faslodex reduced the risk of death by 30 percent compared with one-mg Arimidex, according to findings presented at the 2014 San Antonio Breast Cancer Symposium.

In the phase 2 open-label study, postmenopausal patients with ER-positive primary breast cancer were randomized to receive Faslodex at 500 mg on day 0, 14 and 28 followed by every 28 days (102 patients) or continuous Arimidex at one mg (103 patients). Patients who received prior adjuvant therapy were permitted to enroll in the trial. The median age of patients was 67 years.

The primary endpoint of the study was clinical benefit rate (CBR), defined as objective response or stable disease for at least 24 weeks. Secondary outcome measures focused on ORR and time to progression (TTP). OS was not defined as an original endpoint of the study.

The median OS was 54.1 months with Faslodex compared with 48.4 months with Arimidex. Additionally, the benefit was seen across predefined subgroups of patients by age, tumor size, prior treatments and other stratification factors.

An earlier analysis of the study revealed a 72.5 percent CBR with Faslodex compared with 67 percent for Arimidex. The ORR was 36 percent with Faslodex and 35.5 percent with Arimidex. The TTP with Faslodex was 23.4 versus 13.1 months with Arimidex.

Serious adverse events (AEs) in the trial were similar between Faslodex (23.8 percent) and Arimidex (21.4 percent). The incidence of AEs coincided with the known toxicity profiles for both agents.

“Faslodex has over 10 years of clinical evidence and we are committed to exploring its potential along with the rest of our outstanding oncology portfolio,” said Bohen.

The FDA initially approved Faslodex in 2002, at a lower 250-mg dose. At the 500 mg dose, the agent is currently approved for postmenopausal women with HR+ metastatic breast cancer following antiestrogen therapy. In March 2016, Faslodex was also approved in combination with palbociclib following endocrine therapy for women with HR-positive/HER2-negative breast cancer.
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