Comparing immune effects of three cancer drugs in early breast cancer

A Randomized, Open-label, Parallel-group Study Comparing the Immune Modulation Effect of Ribociclib, Palbociclib, and Abemaciclib in Early ER+/HER2- Breast Cancer

Phase 2 Interventional National Taiwan University Hospital · NCT05766410

This study is testing how three different cancer drugs affect the immune system in women with early breast cancer to see which one works best when combined with another treatment.

Quick facts

PhasePhase 2
Study typeInterventional
Enrollment60 (estimated)
Ages20 Years and up
SexFemale
SponsorNational Taiwan University Hospital Academic / other
Locations2 sites (Taipei and 1 other locations)
Trial IDNCT05766410 on ClinicalTrials.gov

What this trial studies

This study aims to compare the immune modulation effects of three FDA-approved CDK4,6 inhibitors—palbociclib, ribociclib, and abemaciclib—when used alongside letrozole in neoadjuvant treatment for estrogen receptor-positive, HER2-negative early breast cancer. By collecting tumor tissue, blood, and stool samples at various stages of treatment, researchers will analyze the immune responses and tumor microenvironment changes associated with each drug. The study seeks to provide insights into how these treatments differ in their effects on the immune system and tumor biology, which could inform future therapeutic strategies.

Who should consider this trial

Good fit: Ideal candidates are female patients aged 20 years or older with stage II to III estrogen receptor-positive, HER2-negative breast cancer.

Not a fit: Patients who are pregnant, nursing, or have active systemic infections may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could lead to more effective treatment options for patients with early hormone receptor-positive breast cancer.

How similar studies have performed: While there have been studies on CDK4,6 inhibitors, this head-to-head comparison of all three in a neoadjuvant setting is novel.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Female patients aged ≥ 20 years old at the time of informed consent.
* Patient has a histologically and/or cytologically confirmed diagnosis of estrogen-receptor positive and/or progesterone receptor positive breast cancer based on the most recently analyzed tissue sample and all tested by local laboratory. with estrogen receptor positive (\>10%) on IHC staining and HER2 negative (IHC 0+/1+, or IHC 2+ plus FISH negative)
* Stage II to III
* With adequate organ function
* ECOG 0-1

Exclusion Criteria:

* Pregnant or nursing (lactating) women
* Women of child-bearing potential unless using highly effective methods of contraception during study drug dosing and for 12 months post-dosing
* Patients with active systemic infections or known to have AIDS or to test positive for HIV antibody at Screening
* Any other disease or condition that could interfere with participation in the study according to the study protocol, or with the ability of the patients to cooperate and comply with the study procedures.

Where this trial is running

Taipei and 1 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 Breast CancerHormone Receptor-positive Breast CancerHormone TherapyCDK4, 6 inhibitorNeoadjuvant therapyHormone therapy
Last reviewed 2026-06-10 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.