FDA Grants Accelerated Approval of Palbociclib
Pfizer, a company that makes and sells medicine, announced Feb. 3 that the U.S. Food and Drug Administration (FDA) granted accelerated approval of its anticancer medicine, palbociclib (Ibrance) – in combination with letrozole (Femara) – for postmenopausal women with estrogen receptor-positive, HER2-negative metastatic breast cancer.
Background and Reason for the Accelerated Approval
Palbociclib is the first cyclin-dependent kinase 4/6 inhibitor to be approved by the FDA. It targets two specific kinases, or enzymes, that help tumor cells grow and divide.
Letrozole is an aromatase inhibitor (AI). AIs are the standard treatment for women who have hormone-positive breast cancer and have permanently stopped having their monthly period (called postmenopausal). When breast cancer is hormone-positive, it grows because of estrogen. AIs, such as letrozole, treat cancer by stopping the body from making estrogen. Both medicines are taken as pills.
During the phase II PALOMA-1 clinical trial, 165 women were split into two groups – one group received palbociclib and letrozole, and the other group received a placebo, or inactive substance, and letrozole. Researchers wanted to see which group would have longer progression-free survival (PFS), the time from the start of treatment until the cancer grows or spreads.
The results of PALOMA-1 were presented in April 2014 at the annual meeting of the American Association for Cancer Research. They showed PFS of:
- About 10.2 months for women in the placebo plus letrozole group
- About 20.2 months for women who took palbociclib plus letrozole
Usually medicines aren’t approved by the FDA until after a phase III trial. However, this treatment’s ability to extend PFS from less than a year to almost two years caused the FDA to accelerate its approval process.
A phase III trial, PALOMA-2, is being held to confirm palbociclib’s effectiveness.
What This Means for You
If you are a postmenopausal woman with hormone-positive, HER2-negative, metastatic breast cancer, you may now have a new treatment option that could delay the growth and spread of cancer. Talk to your doctor about palbociclib. Ask him or her if this medicine could be right for you.
Keep in mind that palbociclib may cause side effects. The most common side effects of palbociclib are:
- low white blood cell count, which can make infection more likely
- low red blood cell count, which can lead to fatigue
- low blood platelet count, which can cause abnormal bleeding
- nausea, irritation of the mouth and lips, hair loss, diarrhea, low appetite, vomiting, weakness, nerve damage, and nosebleeds
The PALOMA-1 trial showed that palbociclib is safe and effective. But it was not able to comment on overall survival (OS), the time from the start of treatment to death from any cause. The phase III PALOMA-2 trial will look at overall survival and will look to confirm, in a larger group of women, how well palbociclib works.
LBBC will post more information about palbociclib as it becomes available.