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Higher Dose Fulvestrant Shown to Reduced Risk of Disease Progression Compared to Lower Dose
"Findings from CONFIRM provide additional data showing that increasing the dose of fulvestrant from 250 mg to 500 mg may improve the effectiveness of a currently available treatment option to help maintain disease control longer -- a primary objective of treatment for women with metastatic breast cancer," said Dr. Angelo Di Leo, M.D., Ph.D, Head of Sandro Pitigliani Medical Oncology Unit, Hospital of Prato, Italy, and CONFIRM principal investigator.
Patients were randomized to receive either fulvestrant 500 mg (2 x 250 mg intramuscular injections) or fulvestrant 250 mg/month on days 0, 14 and 28, followed by 500 mg every 28 days thereafter. The primary objective was to compare the efficacy, as measured by TTP, of fulvestrant 500 mg with the approved 250-mg regimen. Secondary objectives included: objective response rate, clinical benefit rate (complete or partial response or stable disease lasting greater than or equal to 24 weeks), duration of clinical benefit, overall survival and quality of life. Safety and tolerability were also assessed.
The CONFIRM Study showed fulvestrant 500 mg significantly prolonged time to progression compared to fulvestrant 250 mg, with a median TTP of 6.5 months at 500 mg dose vs. a median TTP of 5.5 months with 250 mg dose (HR 0.80; p=0.006). The study also showed a non-significant 16% reduction in the risk of death for patients receiving fulvestrant 500 mg compared with fulvestrant 250 mg (HR 0.84; 95% CI: 0.69, 1.03, p=0.091). The objective response rates were similar, 13.8% at 500 mg and 14.6% at 250 mg (p= 0.795). Clinical benefit rate was 45.6% vs. 39.6% for the 500 mg versus 250 mg arms; odds ratio 1.28 [95% CI 0.95, 1.71]; p=0.1). Median duration of clinical benefit was 16.6 months for fulvestrant 500 mg compared with 13.9 months for fulvestrant 250 mg. The safety profile was comparable between the two groups: no new safety concerns were identified with the 500 mg dose. The most common side effects included nausea, bone pain, back pain and injection site pain.
CONFIRM (COmparisoN of FASLODEX In Recurrent or Metastatic breast cancer) is a Phase III, randomized, double-blind, parallel-group, multi-center trial comparing fulvestrant 500 mg (n=362) and 250 mg (n=374) in postmenopausal women with estrogen receptor-positive advanced breast cancer, failing on prior endocrine therapy (antiestrogen or aromatase inhibitor). Eligible patients were randomized 1:1 to fulvestrant 500 mg or 250 mg, and assessed for tumor progression every 12 weeks. The primary objective was to compare the efficacy of both treatment groups in terms of time to progression (TTP). Secondary objectives included: objective response rate (ORR), clinical benefit rate (CBR; complete or partial response or stable disease lasting greater than or equal to 24 weeks), duration of clinical benefit (DoCB), overall survival and quality of life (QoL). Safety and tolerability were also assessed.