Bondronat prevents Arimidex-induced bone loss in breast cancer

Swiss pharmaceutical company Roche's Bondronat/ Bonviva (ibandronic acid) has been shown to prevent bone loss caused by AstraZeneca's (AZ) Arimidex (anastrozole) in post-menopausal women on adjuvant therapy for early breast cancer.

The ARIBON study data presented at the American Society of Clinical Oncology (ASCO) annual meeting in Chicago also demonstrated that the treatment significantly increased bone mineral density in the treated women.

Dr Jim Lester, lead study investigator at Cancer Research Centre in the UK, said: "These study results are very encouraging as they demonstrate that Bondronat can prevent loss of bone in early breast cancer patients with low bone density who are given anastrozole. It is an important therapy against breast cancer but we clearly want to avoid reducing bone density and increasing the risk of fractures and osteoporosis in our at-risk patients."

The ARIBON study evaluated the use of ibandronic acid, 150mg orally once a month, in post-menopausal early breast cancer patients taking anastrozole who exhibited mild thinning of bones (osteopoenia) or demonstrated more severe osteoporosis symptoms.

After one year, women with osteopoenia on the drug arm of the trial gained 2.8 per cent and 1.4 per cent of bone density at the lumbar spine and hip, respectively. Patients treated with a placebo lost 2.6 per cent at the lumbar spine and 2.3 per cent at the hip. Women with osteoporosis gained 5.1 per cent at the lumbar spine and 2.6 per cent at the hip after one year.

Data from an additional study presented at ASCO showed that ibandronic acid 6mg, infused over 15 or 60 minutes, did not deteriorate renal function in women with advanced breast cancer and bone metastases. When administered over 15 minutes every three to four weeks, it was well tolerated with a safety profile consistent with the 60-minute infusion. The data reinforce previous study results which demonstrate a positive safety profile and good tolerability. 

In March 2007, the EU Commission approved the administration of ibandronic acid as a 15-minute infusion. It is available as both intravenous and oral formulations. Both are indicated for the prevention of skeletal events in patients with breast cancer and bone metastases.

Ibandronic acid is not currently licensed for bone loss associated with aromatase inhibitors (A-I) in women with surgically treated breast cancer, but the EU Commission approved a new indication for Roche's Herceptin for use in combination with an A-I for the treatment of postmenopausal patients with HER2 and hormone-receptor co-positive metastatic breast cancer in May 2007. The new indication was not approved by the FDA for use in the US.

In FY06, Arimidex sales for AZ were up 29 per cent to rest at USD 1.5bn. The increase was due to positive clinical evidence from the landmark ATAC trial (Arimidex, Tamoxifen, Alone or in Combination). Arimidex has emerged as a new gold standard treatment for post-menopausal women with early breast cancer.

Bondronat/ Bonviva now accounts for approximately 16 per cent of new bisphosphonate prescriptions in the US, according to the FY06 Roche company report. Bonviva/Boniva Injection was approved in the US and the EU in January and March 2007, respectively. Bondronat is sold in Japan by Roche's Chugai subsidiary. The drug racked up sales of CHF 400m (USD 400.3m/ EUR 296m) in FY06.