The FDA (American Food and Drug Administration) Has Approved Palbociclib for Postmenopausal Women With Advanced Breast Cancer

On 2 February 2015, the FDA approved the active substance palbociclib (brand name Ibrance) for advanced (metastatic) breast cancer. Palbociclib works by inhibiting the cyclin-dependent kinase enzyme, known to contribute to cancer cell growth. It was considered appropriate for postmenopausal women with metastatic breast cancer if estrogen receptor-positive (ER-positive), human epidermal growth factor 2-negative (HER2-negative), and not previously treated with hormonal therapy. Its use was envisaged with letrozole, also used to treat a group of postmenopausal breast cancer patients.

The FDA granted approval after the manufacturer demonstrated through preliminary clinical evidence that the drug was superior to existing treatments.

Based on available data, the FDA included palbociclib in its accelerated approval program and authorized early patient access in clinical trials.

The drug's effectiveness was demonstrated in metastatic breast cancer that was ER-positive, HER2-negative, with no previous treatment for metastatic disease, in 165 postmenopausal patients. They were compared in a clinical trial divided into 2 groups: letrozole alone or letrozole with palbociclib. Average progression-free survival (time without disease worsening) was 20,2 months with palbociclib versus 10,2 months with letrozole alone. However, information on overall survival is not currently available.

The most common reported side effects were reduced white blood cell counts (leukopenia, neutropenia), fatigue, anemia, upper respiratory infection, nausea, mouth sores, hair loss, diarrhea, thrombocytopenia (reduced platelets), drowsiness, peripheral neuropathy, and nosebleeds. As with all drugs, healthcare professionals should discuss possible side effects and what patients should do if they occur.

In conclusion, palbociclib holds considerable promise for prolonging survival in postmenopausal women with metastatic breast cancer. Research continues to obtain clearer results about its effects. Nevertheless, these striking findings indicate that it will become a powerful part of standard treatment for breast cancer patients in the future.