Palbociclib and Letrozole or Fulvestrant in Treating Patients With Estrogen Receptor Positive, HER2 Negative Metastatic Breast Cancer

Study Summary

This phase II trial studies the side effects and how well palbociclib and letrozole or fulvestrant works in treating patients aged 70 years and older with estrogen receptor positive, HER2 negative breast cancer that has spread to other places in the body. Palbociclib may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Drugs used in chemotherapy, such as letrozole or fulvestrant, work in different ways to stop the growth of tumor cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Giving palbociclib and letrozole or fulvestrant may work better in treating patients with breast cancer. The trial will explore factors other than chronologic age that can affect toxicity rates as identified using a cancer-specific geriatric assessment.

Primary Outcome

Defined as the proportion of patients with documentation of grade 3 - 5 toxicity (regardless of attribution using the National Cancer Institute \[NCI\] Common Terminology Criteria for Adverse Events \[CTCAE\] version \[v.\] 5.0 criteria). A 95% binomial confidence interval for single proportions will be constructed for the severe toxicity rate during treatment. Univariate relationships between the primary endpoint and various pre-treatment patient characteristics such as anemia, self-assessed fu

Interventions

• OTHER Quality-of-Life Assessment
• OTHER Questionnaire Administration
• DRUG Letrozole
• DRUG Fulvestrant
• DRUG Palbociclib