Alternative Dosing Schedule of Palbociclib in Metastatic Hormone Receptor Positive Breast Cancer
Status:
Active, not recruiting
Trial end date:
2022-02-14
Target enrollment:
Participant gender:
Summary
The investigators propose to conduct a study to test an alternative dosing schedule of
palbociclib. With the current three-week on and one week off schedule, a significant number
of patients develop grade 3 or higher degree of neutropenia and require dose reduction and
sometimes discontinuation. This potentially compromises the efficacy of the drug. In
addition, as the half-life of palbociclib is 27 hours, 1 week break with the standard 3 weeks
on and 1 week off dosing schedule could potentially lead to recovery of Rb phosphorylation
during the off week. Hence, the investigators propose a 5 days on and 2 days off schedule
each week without any weeks off drug. Although the cumulative doses each 28-day cycle is
roughly the same with this schedule compared to conventional dosing, the bone marrow is not
exposed to the drug continuously for 21 days and rather gets frequent breaks from therapy.
The investigators hypothesize that the 5 days on and 2 days off schedule is more tolerable
with less frequent high grade neutropenia and dose interruption/reduction. In addition, this
schedule also provides for a more continuous drug delivery to the patient since there is not
a week's break in therapy, which could ultimately prove to be more efficacious.