Alternative Dosing Schedule of Palbociclib in Metastatic Hormone Receptor Positive Breast Cancer

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.

Conditions

• Breast Cancer
• Breast Carcinoma
• Cancer of Breast
• Malignant Tumor of Breast

Interventions

DRUG

Palbociclib

Palbociclib at a dose of 125 mg should be taken by mouth with food on a 5 days on/2 days off schedule

DRUG

Letrozole

Patients who are receiving letrozole will take it daily by mouth, every day of each 28-day cycle, at a dose of 2.5 mg.

DRUG

Fulvestrant

Patients who are receiving fulvestrant will receive it at a dose of 500 mg as two 5 mL intramuscular injections (one into each buttock) on Days 1 and 15 of Cycle 1 and then on Day 1 of each cycle thereafter.

PROCEDURE

Optional research biopsy

Patients may consent to paired tumor biopsies at baseline and time of progression.

DRUG

Goserelin

Goserelin is given as a subcutaneous injection every 28 days. It is preferred to be given on Day 1 of each cycle, but it may be administered on any day of the treatment cycle to accommodate its specific Q28-day cycle. It will be given to pre- and peri-menopausal women only.

PROCEDURE

Research blood draw

-Blood will be drawn at the following time points for serum, plasma, cfDNA, and germline DNA (only at baseline): * Baseline * C1D15 * C2D1 * Every 2-3 months thereafter (to coincide with imaging studies) * Time of progression

PROCEDURE

Circulating tumor cell blood draw

-Baseline, cycle 2 day 1, post 2 or 3 months of therapy (to coincide with first tumor imaging), and progression

PROCEDURE

Tumor biopsy (optional)

-Baseline and progression

Sponsors & Collaborators

• Pfizer

  collaborator INDUSTRY

• Washington University School of Medicine

  lead OTHER

Principal Investigators

• Cynthia X Ma, M.D., Ph.D. · Washington University School of Medicine

Study Design

Allocation

NA

Purpose

TREATMENT

Masking

NONE

Model

SINGLE_GROUP

Eligibility

Min Age

18 Years

Sex

FEMALE

Healthy Volunteers

No

Timeline & Regulatory

Start

2017-06-15

Primary Completion

2020-03-13

Completion

2023-03-31

FDA Drug

Yes

Countries

• United States

Study Locations