Breast Cancer: Good News From AstraZeneca Camp


AstraZeneca’s Faslodex (fulvestrant) brought good news for the company after the heart breaking disapproval of its ZS-9, a potassium-lowering drug by FDA.

astrazeneca and sun pharma collaboration for anti-diabetic drugsFaslodex showed positive results in its Phase III trial, FALCON for treatment of locally-advanced or metastatic breast cancer, in post-menopausal women without prior hormonal treatment for hormone-receptor-positive (HR+) breast cancer.

Advanced breast cancer denotes stage IV level of breast cancer with no hope for a cure. In this stage, the cancer has metastasized and spread to other parts of the body other than the initial tumour site. There are no advancements for a cure and the only treatment strategy adopted is to delay the disease progression.



It refers to Fulvestrant and AnastrozoLe COmpared in hormonal therapy Naive advanced breast cancer trial.

Fulvestrant breast cancer

It is a double-blind, randomised, multicentre Phase III trial. In this trial the anti-tumor effects and tolerability profile of a 500 mg dose of Faslodex plus placebo was compared with a 1 mg dose of Arimidex (anastrozole) plus placebo. The trial was carried out in postmenopausal women with HR+ locally-advanced or metastatic breast cancer that have not previously undergone any hormonal therapy.

In this FALCON trial, Faslodex 500 mg demonstrated superiority compared with Arimidex 1 mg and reached its primary endpoint of extended progression-free survival. An adverse event profile generally consistent with current knowledge of the safety profile of the medicines was exhibited by this trial.

Faslodex is an estrogen receptor (ER) antagonist administered intramuscularly. Faslodex binding to ER inhibits receptor dimerisation. Thereby, inactivating the activating function (AF) -1 and AF-2, reducing the translocation of the receptor to the nucleus and accelerating the degradation of estrogen receptor. Faslodex 500 mg was approved in combination with palbociclib on 2, March 2016 by the U.S. FDA to treat women with hormone-receptor-positive (HR+), human-epidermal-growth-factor-receptor 2-negative (HER2-) advanced or metastatic breast cancer, that has progressed after endocrine therapy.

AstraZeneca’s Faslodex (fulvestrant) pharmacology

Figure 2. Mechanism of action of fulvestrant at the level of transcriptional regulation. ERE=oestrogen response element; ER=oestrogen receptor; F=fulvestrant. (Photo credit: Br J Cancer. 2004 Mar; 90(Suppl 1): S2–S6. doi: 10.1038/sj.bjc.6601629)

Arimidex is an aromatase inhibitor used as a first-line treatment for women with advanced HR+ breast cancer post menopause. Arimidex works by reversible binding to aromatase enzyme and through competitive inhibition, it inhibits the conversion of androgens to estrogens in peripheral tissues.

Anastrozole mechanism of action

Figure 3. Mechanism of action of the aromatase inhibitors (Photo credit: N Engl J Med 2003; 348:2431-2442, DOI: 10.1056/NEJMra023246).

Executive Vice President, Global Medicines Development and Chief Medical Officer of AstraZeneca, Sean Bohen announced, “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. 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.”

Featured image credit: mammography breast scan X – ray image © Photoprofi30 (Stock Photo ID: 64989382)

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