Morning versus evening timing of hormone therapy for metastatic breast and prostate cancer

A Randomised, Multicentre Trial Evaluating the Dose Timing (Morning vs Evening) of Endocrine-based Therapies in Metastatic Breast and Prostate Cancers (REaCT-CHRONO-MetBP Pilot Study)

Phase 4 Interventional Ottawa Hospital Research Institute · NCT07252726

This pilot will test whether taking hormone-based cancer drugs in the morning or in the evening works better for people with metastatic breast or prostate cancer.

Quick facts

PhasePhase 4
Study typeInterventional
Enrollment50 (estimated)
Ages18 Years and up
SexAll
SponsorOttawa Hospital Research Institute Academic / other
Locations3 sites (Kitchener, Ontario and 2 other locations)
Trial IDNCT07252726 on ClinicalTrials.gov

What this trial studies

Participants with metastatic hormone receptor–positive breast cancer starting a CDK4/6 inhibitor plus endocrine therapy, and patients with metastatic castrate-sensitive prostate cancer starting an androgen receptor pathway inhibitor plus ADT, will be randomized to take their oral endocrine therapy in the morning or in the evening. The primary focus of this pilot is feasibility to determine if a larger definitive trial can be conducted, while secondary measures compare quality of life, tolerability, and preliminary efficacy within each cohort. The breast cohort will use ribociclib or palbociclib (abemaciclib is excluded because it is dosed twice daily), and the prostate cohort will include enzalutamide, apalutamide, or abiraterone. The phase 4 pilot will be conducted across multiple Canadian cancer centers to inform a future larger trial.

Who should consider this trial

Good fit: Adults (≥18) with metastatic HR+ breast cancer planned for first-line CDK4/6 plus endocrine therapy, or adults with metastatic castrate-sensitive prostate cancer planned for an ARPI plus ADT, who can provide consent and complete study questionnaires are ideal candidates.

Not a fit: Patients on twice-daily regimens (such as abemaciclib), those with contraindications to morning or evening dosing, or those not starting the specified endocrine regimens are unlikely to benefit from this timing comparison.

Why it matters

Potential benefit: If successful, timing therapy could reduce side effects or improve control of metastatic disease, making treatment easier to tolerate and potentially more effective.

How similar studies have performed: Chronotherapy has produced mixed results in other cancers and conditions, and timing of oral endocrine agents in metastatic breast or prostate cancer is relatively untested and therefore novel.

Eligibility criteria

Show full inclusion / exclusion criteria
Cohort A (Breast Cohort) Inclusion Criteria

* Patients with metastatic hormonal receptor positive breast cancer
* Plan to receive endocrine therapy and a CDK4/6 inhibitor (either Ribociclib or Palbociclib) in the first-line metastatic setting
* Age ≥18 years
* Able to provide oral consent
* Willing and able to complete questionnaires as per study protocol

Cohort A (Breast Cohort) Exclusion Criteria

* Any contraindication in taking endocrine therapy and CDK4/6 inhibitor in the morning or evening
* Plan to receive abemaciclib (as this requires twice a day dosing)

Cohort B (Prostate Cancer) Inclusion Criteria

* Patients with metastatic castrate sensitive prostate cancer
* Plan to receive androgen receptor pathway inhibitor (either enzalutamide, apalutamide or abiraterone acetate) in combination with androgen deprivation therapy
* Age ≥18 years
* Able to provide oral consent
* Willing and able to complete questionnaires as per study protocol

Cohort B (Prostate Cancer) Exclusion Criteria

* Any contraindication in taking androgen receptor pathway inhibitor in the morning or evening
* Plan to receive darolutamide (as this requires twice a day dosing)
* Plan to receive docetaxel in combination with androgen receptor pathway inhibitor

Where this trial is running

Kitchener, Ontario and 2 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Metastatic Breast CancerMetastatic Prostate CancerChronotherapybreast cancerprostate cancerendocrine therapymetastatic cancer
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.