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Understanding Immune Response to Abemaciclib and Letrozole for Breast Cancer

This study is looking at how your immune system responds to treatment for hormone receptor-positive, HER2-negative breast cancer. Researchers want to see if the immune system's ability to fight cancer can be improved by combining two common oral medications: Letrozole (an endocrine therapy) and Abemaciclib (a kinase inhibitor). You may be able to join if you are an adult woman (18 or older) with operable stage I, II, or III invasive breast cancer that is estrogen receptor or progesterone receptor positive and HER2 negative. The main goal is to measure changes in T cell activation (a type of immune cell) after about two weeks of treatment. The current recruitment status for this study is unclear.

Study design
This is an interventional study planning to enroll 60 women. It is designed to understand the effects of specific treatments on the immune system.
What's involved
You would provide tumor tissue and blood samples before and after two weeks of treatment with Letrozole and Abemaciclib.
Compensation
Not stated in the trial record.
Follow-up
The primary endpoint is measured after treatment ends (14 +/- 3 days).

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.

NCT04614194

Single Cell Immune and Non-immune Correlates of Response to Neoadjuvant Abemaciclib

Recruiting
PHASE2Ages 18+InterventionalBasic science
University of Texas Southwestern Medical Center
~60 participants
Updated 2026-06-17 on ClinicalTrials.gov
What's tested:LetrozoleAbemaciclib

At a glance

Recruiting sites
1 of 2 listed sites are recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Change in T cell activation
Measured over After treatment ends (14 (+/- 3) days

Conditions

Breast Cancer

Explore related trials

Breast Carcinoma

Where it's being run

2 sites across 1 states
Texas2

Study leadership

  • Sangeetha Reddy, MD · PRINCIPAL_INVESTIGATOR · University of Texas Southwestern Medical Center

Who to contact

Shahbano Shakeel
[email protected]
214-648-7097
Email the study team

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Do you actually qualify for this trial?

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Eligibility criteria

Inclusion

Clinical stage operable stage I, II, or III invasive mammary carcinoma, which is estrogen receptor or progesterone receptor positive by immunohistochemistry and HER2 negative by Herceptest (0 or 1+) or not amplified by in situ hybridization as per routine clinical testing.
Have post-menopausal status, as defined by any of the following: Subjects at least 55 years of age OR Subjects under 55 years of age and amenorrheic for at least 12 months OR follicule stimulating hormone (FSH) values ≥ 40 IU/L and estradiol levels ≤ 40 pg/mL (140 pmol/L) or in postmenopausal ranges per local or institutional reference ranges.
Breast tumor ≥1cm in diameter by either physical exam or ultrasound and suitable for pre and post-treatment tissue sampling.
Meet either of 2 following criteria, for which neoadjuvant endocrine therapy for 2 weeks is deemed suitable: 1) disease that is planned for surgery as initial therapy, in which 2 weeks of neoadjuvant endocrine therapy is deemed suitable, 2) Disease for which neoadjuvant systemic therapy (either chemotherapy or endocrine therapy) may be planned, in which 2 weeks of neoadjuvant endocrine therapy prior to start of systemic therapy is deemed suitable.
At least 18 years of age
Performance status ECOG ≤ 2
Have adequate organ function (ANC ≥1,500/mcL, Platelets ≥100,000/mcL, Hemoglobin ≥8 g/dL, Total bilirubin ≤1.5 × upper limit of normal, ALT and AST ≤3 × upper limit of normal, Creatinine clearance \>30 mL/minute
The patient is able to swallow oral medications
Patients with a prior history of contralateral breast cancer are eligible if they have no evidence of recurrence of their initial primary breast cancer.
Women may have been taking tamoxifen or raloxifene as a preventive agent prior to study entry but must have discontinued the drug for at least 28 days prior to study enrollment.
Subjects have ended hormone replacement therapy at least 7 days prior to receiving the first dose of randomized therapy.
Ability to understand and the willingness to sign a written informed consent.

Exclusion

Active metastatic breast cancer, inflammatory breast cancer, or locally recurrent breast cancer.
The patient has serious and/or uncontrolled preexisting medical condition(s) that, in the judgment of the investigator, would preclude participation in this study (for example, interstitial lung disease, severe dyspnea at rest or requiring oxygen therapy, severe renal impairment \[e.g. estimated creatinine clearance \<30ml/min\], history of major surgical resection involving the stomach or small bowel, or a preexisting chronic condition resulting in baseline grade 2 or higher diarrhea).
Females who are pregnant, lactating, or premenopausal.
Severe uncontrolled malabsorption condition or disease (i.e. grade 2 or higher diarrhea, severe malnutrition, short gut syndrome).
Dementia, altered mental status, or any psychiatric condition that would prohibit the understanding or rendering of informed consent.
Chemotherapy, radiotherapy, or any other cancer therapy for current diagnosis of breast cancer.
Subjects may not have received or be receiving any other investigational agents for the treatment of the cancer under study.
History of allergic reactions attributed to compounds of similar chemical or biologic composition to abemaciclib or other agents used in study.
Uncontrolled intercurrent illness including, but not limited to ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that, in the opinion of the investigator, would limit compliance with study requirements.

What this trial measures

  • Change in T cell activationAfter treatment ends (14 (+/- 3) days

    Change in T cell activation between matched pre-treatment and on-treatment tissue samples of responder patients treated with abemaciclib and letrozole. T cell activation will be defined as the density of granzyme positive CD8 T cells detected on multiplex immunohistochemistry. Responders are defined as having complete cell cycle arrest by Ki-67.