FDA Expands Approved Use of Palbociclib for Metastatic Breast Cancer

Extended indication concerns treatment of male patients

On 4 April 2019, the US Food and Drug Administration (FDA) extended the indication of palbociclib (Ibrance) capsules in combination with specific endocrine therapies for hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced or metastatic breast cancer in male patients.

Expanded indication for Ibrance to include male patients is based upon data from postmarketing reports and electronic health records that showed that the safety profile for men treated with Ibrance is consistent with the safety profile in women treated with Ibrance.

Dr 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 said: “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.”

Breast cancer is rare in males with number of cases of male breast cancer estimated in 2019 as less than 1% of all cases of breast cancer. The majority of breast tumours in male patients express HRs. Men are more likely to be diagnosed at an older age, with a more advanced stage of disease. There are several FDA-approved endocrine based therapies available for HR-positive metastatic breast cancer patients. Certain treatments are gender-neutral in their indication, but some therapies have been approved only for women, although they are often prescribed for male patients. According to the current clinical practice standards, male patients with breast cancer are treated similarly to women with breast cancer.

Ibrance was initially approved in 2015. It is a kinase inhibitor, approved in combination with an aromatase inhibitor as the first hormonal-based therapy in women who have gone through menopause and in men, or with fulvestrant in patients whose disease progressed following hormonal therapy. Pfizer provided the results of an analysis of real-world data from electronic health records as additional supportive data to characterise the use of palbociclib in combination with endocrine therapy (aromatase inhibitor or fulvestrant) in male patients with breast cancer based on observed tumour responses in this rare subset of patients with breast cancer.

The most common side effects of patients taking Ibrance are infections, leukopaenia, fatigue, nausea, stomatitis, anaemia, hair loss, diarrhoea and thrombocytopenia. Other common side effects reported are rash, vomiting, decreased appetite, asthenia and fever. Healthcare providers are advised to monitor a patient’s blood count for neutropenia. Patients should have their blood count checked prior to starting Ibrance and at the beginning of each cycle, as well as on day 15 of the first two cycles and as clinically indicated.

Because of the potential for genotoxicity, healthcare 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 foetus or newborn baby.

The FDA granted the approval of Ibrance to Pfizer.