Swiss drugmaker Novartis and Roche subsidiary Chugai Pharmaceutical have joined forces to launch Femara, an aromatase inhibitor for post-menopausal breast cancer, in Japan.

According to the firms, the market for Femara (letrozole) has reached about 20 billion yen and is expected to reach some 30 billion yen in 2010. The market has an annual growth rate of 30% in Japan, where 40,000 people are diagnosed with the condition every year. Among these, 60%-70% are post menopausal and thus suitable for Femara treatment.

Femara is indicated in Japan for adjuvant treatment of early-stage breast cancer in post-menopausal women, as well as primary and secondary care for patients with advanced and recurrent breast cancer.

The drug is currently available in over 90 countries worldwide, and is one of Novartis fastest growing products, climbing 39% in 2005 to post $536 million for the year, despite strong competition for AstraZeneca’s Arimidex (anastrozole), the leading drug in the aromatase inhibitor class with annual sales of $1.2 billion last year. Arimidex is already available in Japan.

Novartis is conducting a major head-to-head trial of Femara and Arimidex in an attempt to show that its drug is superior and win market share from its rival. The FACE study will enroll 4,000 women with early breast cancer.