Evaluating palbociclib plus hormonal therapy for advanced breast cancer spread to the bone.

This trial was carried out to analyze whether the length of time without treatment and the length of time without active disease influences the survival of patients with advanced breast cancer (ABC) spread to the bone taking palbociclib (Ibrance) plus hormonal therapy (HT). The authors concluded that palbociclib plus HT was effective as the standard of care in ABC that has spread to the bone. 

BC is one of the most common forms of cancer found in women. Many patients have BC that responds to female sex hormones such as estrogen and/or progesterone. This is called hormone receptor (HR) positive BC. Some patients also have HER2 (a protein that results in uncontrolled growth in BC cells) positive BC. Being positive HR or HER2 often results in difficult to treat BC that spreads to the bone rapidly. 

Palbociclib is a targeted therapy that blocks the growth and spread of cancer cells. It is approed for the treatment of ABC that is HR positive and HER2 negative together with HT. HT is used to decrease the levels of female sex hormones that can increase the rate of spread of BC cells. Having BC that has spread to the bone often has a poor prognosis when compared to BC that does not spread. It is important to evaluate whether palbociclib with HT is effective in patients with ABC spread to the bone.

This study analized the resulta of 2 clinical trials on palbociclib and HT. One trial included 418 patients who received HT with palbociclib or with a placebo after surgery. The HT used was letrozole (Femara). The second trial included 355 patients that received HT with palbocicliob or a placebo before surgery. The HT used was fulvestrant (Faslodex).

In study 1, the average length of time without treatment was 37.1 months in the palbociclib group and 30.9 months in the placebo group. 23% of patients in study 1 had bone disease. The average survival without cancer worsening was slightly higher in the palbociclib group (36.2 months) compared to the placebo group (11.2 months) in patients with cancer spread to the bone.

In study 2, the average length of time without active disease was 49.2 months in the palbociclib group and 52 months in the placebo group. 24% (124 patients) of patients in study 2 had bone disease. The average survival without cancer worsening was slightly longer in the palbociclib group (14.3 months) versus the placebo group (9.2 months) in patients with cancer spread to the bone. 

The authors concluded that palbociclib plus HT was effective as standard care for patients with ABC including patients with cancer spread to the bone. 

This study was sponsored by Pfizer, the manufacturer of palbociclib.