Comparing Oral Drug Dosing Strategies in Older Patients With Metastatic Breast Cancer to Maximize Tolerance and Reduce Discontinuation: The CDK4/6 Inhibitor Dosing Knowledge (CDK) Study

Summary

The purpose of this study is to generate evidence on an alternative dosing strategy for CDK4/6 inhibitors to help more patients with Metastatic Breast Cancer (MBC) (age ≥ 65 years) tolerate side effects and stay on treatment longer, to derive the most clinical benefit from these drugs. The primary objective of the CDK Study is to compare time to treatment discontinuation (TTD) on the approved dosing for palbociclib (125 mg orally daily on days 1-21 of 28-day cycle) or ribociclib (600 mg orally daily on days 1-21 of 28-day cycle) vs. TTD using titrated dosing approach with the same schedule but starting at a lower dose of palbociclib (100 mg or 75 mg) or ribociclib (400 mg or 200 mg) and escalating the dose if well-tolerated in combination with provider/patient choice endocrine therapy (aromatase inhibitor (AI) or fulvestrant) in patients age 65 or older with HR+/HER2- MBC. The secondary and exploratory objectives will generate evidence needed to personalize treatment decisions by comparing patient-centric secondary outcomes and evaluating baseline factors. Together with their treating physician, participants will choose the CDK4/6 inhibitor (palbociclib or ribociclib) and which endocrine therapy (aromatase inhibitor or fulvestrant) of their choice but will be randomized to either Arm 1 (indicated dosing) or Arm 2 (titrated dosing). Note: Telehealth visits are allowed at any time per institutional guidelines. In addition, the study allows for remote consenting per institutional guidelines.

Description

Eligibility

Age range

65+ years

Sex

All

Healthy volunteers

No

Interventions

• Drug
  Palbociclib 125mg

  Arm 1: Indicated dosing for palbociclib (125 mg orally daily on days 1-21 of 28-day cycle)

• Drug
  Ribociclib 600mg

  Arm 1: Indicated dosing of ribociclib (600 mg orally daily on days 1-21 of 28-day cycle)

• Drug
  Ribociclib

  Arm 2: Titrated dosing approach with the same schedule but starting at a lower dose of ribociclib (400 mg or 200 mg) and escalating the dose if well-tolerated in combination with provider/patient choice of endocrine therapy.

• Drug
  Palbociclib

  Arm 2: Titrated dosing approach with the same schedule but starting at a lower dose of palbociclib (100 mg or 75 mg) and escalating the dose if well-tolerated in combination with provider/patient choice of endocrine therapy.

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