The US Food and Drug Administration (FDA) has extended its indication for Ibrance (palbociclib) in metastatic breast cancer to include men.

The extension is for the drug is in combination with specific endocrine therapies for hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced versions of the disease.

The Pfizer kinase inhibitor was initially approved as the first hormonal-based therapy in women who have gone through menopause, or with Faslodex (fulvestrant) in patients whose disease progressed following hormonal therapy.

“Today we are expanding the indication for Ibrance to include male patients based upon data from postmarketing reports and electronic health records showing that the safety profile for men treated with Ibrance is consistent with the safety profile in women treated with Ibrance,” said Richard Pazdur., director of the FDA’s Oncology Center of Excellence and acting director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research.

He continued, “Some approved indications for breast cancer treatments do not distinguish by gender, but in certain cases if there is a concern that there may be a difference in efficacy or safety results between men and women, then further data may be necessary to support a labeling indication for male patients.”

The FDA has however warned that because of the potential for genotoxicity, health care providers are advised to tell male patients with female partners of reproductive potential to use effective contraception during treatment with Ibrance and for three months after the last dose.

Women who are pregnant or breastfeeding should not take Ibrance because it may cause harm to a developing fetus or newborn baby.

There are only around 370 new cases of male breast cancer in the UK each year, compared to nearly 55,000 new cases in women. Men are more likely to be diagnosed at an older age and with a more advanced stage of disease, with three quarters (75%) of male breast cancer deaths in the UK found in men aged 65 and over.