Palbociclib and exemestane versus capecitabine in premenopausal women with hormone receptor-positive metastatic breast cancer

This study aimed to compare the safety and effectiveness of palbociclib and endocrine therapy to capecitabine chemotherapy in premenopausal women with hormone receptor-positive, HER2-negative metastatic breast cancer. 

This study concluded that palbociclib and endocrine therapy is more effective than chemotherapy alone in these patients. 

Endocrine treatment (hormone therapy) is the preferred treatment option for women with hormone receptor-positive, HER2-negative metastatic breast cancer (BC). However, many BC patients are treated with chemotherapy.  

Palbociclib (Ibrance) is a targeted therapy used for the treatment of hormone receptor-positivebreast cancer (BC). Exemestane (Aromasin) is an endocrine therapy and type of aromatase inhibitor used to treat BC. A gonadotropin-releasing hormone agonist (GnRH agonist) is a type of treatment that affects sex hormones. They can be used for many different cases including fertility medicine, BC and prostate cancer. Capecitabine (Xeloda) is a chemotherapy used to treat BC, among other cancers. 

It was unknown if palbociclib and endocrine therapy are safer and more effective than capecitabine chemotherapy in premenopausal women with hormone receptor-positive, HER2-negative metastatic BC. 

This study involved 178 premenopausal women with hormone receptor-positive, HER2-negative breast cancer that had relapsed or progressed during previous tamoxifen (Nolvadex) therapy. Patients were split into groups. 92 patients received palbociclib and combination endocrine therapy (exemestane and leuprolide). 86 patients received chemotherapy (capecitabine). The main outcome measured was progression-free survival (PFS).  

50% of the palbociclib group had not previously received treatment (treatment naïve) for metastatic BC. 51% of the chemotherapy group were treatment naïve for metastatic BC.  

After an average follow-up of 17 months, the PFS was 20.1 months in the palbociclib group compared to 14.4 months in the chemotherapy group. Palbociclib and endocrine therapy were associated with a 34.1% higher chance of a better survival without the cancer growing or spreading compared to chemotherapy. 

Treatment-related serious neutropenia (low level of white blood cells) was found in 75% of the palbociclib group compared to 16% of the chemotherapy group. 2% of patients in the palbociclib group and 17% of patients in the chemotherapy group had treatment-related serious adverse events (side effects). 

This study concluded that palbociclib and endocrine therapy is more effective than chemotherapy alone in premenopausal patients with hormone receptor-positive, HER2-negative metastatic BC. It was also concluded that palbociclib plus exemestane with ovarian suppression is a treatment option in these patients who have been pretreated with tamoxifen. 

This study has received funding from the Pharma Industry.