Palbociclib: a new treatment option for metastatic breast cancer

Palbociclib: a new treatment option for metastatic breast cancer

30 May 2015

Despite advances in managing and curing some forms of breast cancer, women with a metastatic form have fewer effective options. A new phase 3 study in some of the most difficult-to-treat patients, women with endocrine-resistant disease, showed that the approved drug, palbociclib, more than doubled the time to cancer recurrence for women with hormone-receptor (HR+) positive metastatic breast cancer.

"These are women with advanced metastatic cancer whose disease was kept in check without the use of toxic and life-disrupting chemotherapy," says Dr. Massimo Cristofanilli, M.D., Director of the Breast Care Center at Thomas Jefferson University and senior author of the study. "This is a major advance for this population of women for which we had very few active options and are often treated with chemotherapy alone."

Clinical study design and results

The study, called the PALOMA-3, enrolled 521 pre-/peri- and postmenopausal patients with hormone receptor positive and human epidermal growth factor receptor-negative (HR+/HER2-) advanced disease. These women had typically already relapsed on hormone therapy and were not candidates for the HER2-blocking therapy herceptin.

The patients were randomized to treatment and control arms with 345 treated and 172 receiving placebo. The treatment arm received palbociclib together with standard of care for this population, fulvestrant, a drug that blocks the hormone receptor via a different mechanism than first-line therapies. The placebo arm received fulvestrant plus placebo.

At the conclusion of the study, researchers reported that:

• Patients taking palbociclib plus fulvestrant showed a median progression-free survival of 9.2 months compared to 3.8 months on fulvestrant plus placebo.
• Progression or recurrence of cancer occurred in only 25% of palbociclib plus fulvestrant treated patients versus 50% of patients treated with fulvestrant alone.

Improved progression-free survival and a very good quality of life

"The PALOMA-3 study showed that palbociclib extends the time to progression of disease while maintaining very good quality of life." says Dr. Cristofanilli, who is also a researcher at the Sidney Kimmel Cancer Center at Thomas Jefferson University.

The most commonly reported side effects were:

• A decrease in certain populations of immune cells, conditions called neutropenia and leukopenia, an expected effect that indicates the drug is working.
• The rates of nausea and fatigue were low and overall slightly elevated over placebo group, but the increase was not statistically significant.
• The drug was better tolerated than other biological therapies used in this setting.
• There was a significant difference in quality of life as measured by the rate of clinical deterioration of symptomatic disease in patients treated with the investigational combination.

"Although palbociclib has yet to be approved for this population of women, this study is likely to be practice changing," says Dr. Cristofanilli, a practicing oncologist. 

Source: Science Daily