Medicines and Healthcare products Regulatory Agency ( MHRA ) in the United Kingdom has granted a new indication for Arimidex ( Anastrozole ).
MHRA has acted as the Reference Member State for the European Mutual Recognition Variation Procedure leading to further approvals in five other European countries - Austria, Germany, Italy, Portugal and Spain.

The new indication – “ Adjuvant treatment of postmenopausal women with hormone receptor positive early invasive breast cancer “ - will mean that more postmenopausal women whose breast cancer is fuelled by the hormone, estrogen - about 75 per cent of all postmenopausal cases - are now eligible to receive Arimidex after surgery to prevent their disease returning.

Arimidex offers a 26 per cent reduction in the risk of breast cancer coming back compared with Tamoxifen, the gold standard for breast cancer management of 30 years standing.

" It has recently been confirmed that Arimidex offers crucial advantages over Tamoxifen, in terms of enabling patients to stay disease free for longer. However, it is only now, with the new indication that more postmenopausal women with breast cancer may benefit from this drug at the earliest opportunity after breast surgery, “said Rob Carpenter, at St Bartholomew's Hospital, London.

The MHRA granted the indication on the basis of data from the ATAC ( Arimidex, Tamoxifen, Alone or in Combination ) trial, the largest breast cancer trial ever conducted.

These data demonstrate that Arimidex reduces the risk of breast cancer recurring anywhere in the body by an additional 26 per cent ( HR =0.74; p= <0.0002 ), over and above the 50 per cent reduction provided by Tamoxifen.
Moreover, it may prevent life-threatening 'distant' recurrence of the disease ( i.e. secondary cancers outside the breast ) by an additional 16 per cent compared with Tamoxifen though this difference has not yet reached statistical significance ( HR=0.84; p=0.056 ).

A new analysis from the ATAC trial, presented at the American Society of Clinical Oncologists in May 2005, demonstrated that the risk of breast cancer recurrence reaches a peak in the first two years after a patient receives surgery. This supports previous research clearly demonstrating the peak in the risk of recurrence in the first two to three years.

Women treated with Arimidex immediately after surgery saw a reduced risk of recurrence in the first 18-24 months at a time when recurrences are at their highest level.
The study authors concluded that this benefit in the first two years of treatment would be lost if patients did not start with an aromatase inhibitor immediately post-surgery.

Arimidex has also been shown to have a favourable side effect profile versus Tamoxifen, both in terms of serious life threatening side effects such as blood clots, stroke and cancer of the womb lining as well as symptoms that are important to women, such as hot flushes and vaginal discharge.

However, women taking Arimidex experienced an increased risk of joint pain and fracture, although fracture rates reported in the ATAC trial are similar to those seen in age-matched postmenopausal women. It is not known whether the fracture rates seen are due to a protective effect of Tamoxifen, a specific effect of Arimidex or both.

Source: AstraZeneca, 2005


XagenaMedicine2005