The U.S. Food and Drug Administration (FDA) have extended the indication of palbociclib 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.

“Today we are expanding the indication for palbociclib to include male patients based upon data from postmarketing reports and electronic health records showing that the safety profile for men treated with palbociclib is consistent with the safety profile in women treated with palbociclib,” said Richard Pazdur, M.D., 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. “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 only 2,670 cases of male breast cancer estimated in 2019 - less than 1 percent of all cases of breast cancer.

The majority of breast tumours in male patients express hormone receptors.

Men are more likely to be diagnosed at an older age, with a more advanced stage of the disease.

Metastatic breast cancer is breast cancer that has spread beyond the breast to other organs in the body (most often the bones, lungs, liver or brain).

When breast cancer is hormone-receptor positive, patients may be treated with hormone therapy (also called endocrine therapy) or chemotherapy.

Endocrine therapy slows or stops the growth of hormone-sensitive tumours by blocking the body’s ability to produce hormones or by interfering with effects of hormones on breast cancer cells.

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.

Palbociclib 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.

The results of an analysis of real-world data (RWD) from electronic health records (EHRs) served 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 palbociclib are infections, leukopenia (low levels of white blood cells), fatigue, nausea, stomatitis (inflammation of the mouth and lips), anaemia (low levels of red blood cells), hair loss, diarrhoea and thrombocytopenia (low levels of thrombocytes, also known as platelets, in the blood).

Other common side effects reported are rash, vomiting, decreased appetite, asthenia (abnormal physical weakness or lack of energy) and fever.

Health care providers are advised to monitor a patient’s blood count for neutropenia (low levels of white blood cells called neutrophils).

Patients should have their blood count checked prior to starting palbociclib 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 (damage to cells), health care providers are advised to tell male patients with female partners of reproductive potential to use effective contraception during treatment with palbociclib and for three months after the last dose.

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

Source: The U.S. Food and Drug Administration (FDA)