In a nutshell
The authors aimed to determine if palbociclib (Ibrance) could help treat women with metastatic (spread to other areas of the body) breast cancer.
The researchers concluded that palbociclib showed good response rates from women with metastatic breast cancer whose cells expressed a protein called retinoblastoma (Rb).
Some background
Abnormalities in how cells grow and divide play an important role in the growth and spread of tumor cells. The presence of the protein Rb on tumor cells is often a sign of increased cell growth. Blocking cell growth is one way to limit cancer progression.
Palbociclib is a therapy designed to inhibit or stop cell growth. It is not fully known, however, if previous treatments used by patients (such as chemotherapy) will have an effect on the effectiveness of palbociblib.
Methods & findings
The aim of this study was to determine the effects of pablociclib on women with Rb positive breast cancer and to evaluate the safety of this drug.
A total of 37 women with metastatic breast cancer were evaluated for this study. 89% had hormone receptor positive (HR+, dependent on hormones such as estrogen for growth). 89.8% were positive for Rb. Each patient received 125 mg of palbociclib daily for 28 days.
A response to this treatment was seen in 19% of all women and in 21% of those with HR+ breast cancer. A response was seen in t44% of women who had received less than 2 lines of chemotherapy previously, compared to 11% of those who had received more than 2 chemotherapy treatments.
Progression-free survival (PFS, time from treatment until disease progression) was longer in women with HR+ breast cancer (an average of 4.5 months) compared to those with HR negative breast cancer (an average of 1.5 months). HR+ women who had received more than 2 lines of hormone treatment had a PFS of 5 months, compared to 2 months in those who received less than 2 hormonal treatments.
51% of women developed fever associated with low white blood cell levels (cells that fight infection) and 22% experienced low platelet levels (a type of red blood cell).
The bottom line
The authors concluded that pablociclib was effective in women with Rb+ metastatic breast cancer, with particular response from women with HR+ breast cancer.
The fine print
This study contained a small group of women. Larger studies should be done to determine if the results can be generalized to a larger population.
Published By :
Clinical Cancer Research
Date :
Dec 11, 2014
