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Neoadjuvant Study Chemotherapy vs Letrozole + Abemaciclib in HR+/HER2- High/Intermediate Risk Breast Cancer Patients

Phase II, Randomized, Open-label, International, Multicenter Study to Compare Efficacy of Standard Chemotherapy vs. Letrozole Plus Abemaciclib as Neoadjuvant Therapy in HR-positive/HER2-negative High/Intermediate Risk Breast Cancer Patients

Status
Active, not recruiting
Phases
Phase 2
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT04293393
Acronym
CARABELA
Enrollment
200
Registered
2020-03-03
Start date
2020-10-02
Completion date
2033-02-28
Last updated
2026-03-12

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Early Breast Cancer

Keywords

Abemaciclib, Neoadjuvant, HR positive, HER2 negative, High/intermediate risk

Brief summary

Phase II, randomized, open-label, international, multicenter study to compare efficacy of standard chemotherapy vs. letrozole plus abemaciclib as neoadjuvant therapy in HR-positive/HER2-negative high/intermediate risk breast cancer patients

Detailed description

This is an international, multicenter, open-label, randomized phase II study in the neoadjuvant setting. Approximately 200 premenopausal and postmenopausal women with Hormone Receptor (HR)-positive/Human Epidermal Growth Factor Receptor 2 (HER2) negative Breast Cancer (BC) of intermediate/high risk determined by Ki67 index ≥ 20% on untreated breast tissue and centrally assessed, with indication of neoadjuvant treatment, will be included. Patients with Early Breast Cancer (EBC) on stages II-III (tumor size (T) \> 2cm - T3, T4b, and lymph node involvement (N) N0-2) according to the 8th edition of the Union for International Cancer Control (UICC) TNM Classification. The subgroup with tumors T2 N0 will include high risk patients based on Ki67 index \> 30% or Ki67 index between 20% and 30% and Progesterone Receptor (PgR) negative and/or histological grade 3. Patients will be stratified according to the disease stage (II vs. III), menopausal status (premenopausal vs. postmenopausal) and Ki67 index (Ki67 \< 30% vs. Ki67 ≥ 30%). Once the screening process (locally at site and at the central laboratory) is completed, fully eligible patients will be randomized in a 1:1 fashion to the control arm with standard Chemotherapy (CT) based on anthracyclines and taxanes or to the experimental arm with letrozole + abemaciclib. All patients will be treated according to the stipulations below, unless any of the following occur: unacceptable toxicity, progressive disease, or withdrawal of informed consent, whatever occurs first. After the last dose of any of the drugs in the neoadjuvant combinations, in both treatment arms definitive surgery will be performed. For Arm A not earlier than 21 days and not later than 42 days after the last dose of chemotherapy, and for Arm B within 7 days from the last dose of abemaciclib and/or letrozole, unless toxicities are not recovered completely in any treatment arm.

Interventions

DRUGDoxorubicin

Doxorubicin 60mg/m2 and cyclophosphamide 600mg/m2 (AC) every 21 days for 4 cycles followed by weekly paclitaxel 80mg/m2 for 12 weeks or 3-weekly docetaxel 100mg/m2 for 4 cycles.

DRUGCyclophosphamide

Doxorubicin 60mg/m2 and cyclophosphamide 600mg/m2 (AC) every 21 days for 4 cycles followed by weekly paclitaxel 80mg/m2 for 12 weeks or 3-weekly docetaxel 100mg/m2 for 4 cycles.

DRUGTaxane

Doxorubicin 60mg/m2 and cyclophosphamide 600mg/m2 (AC) every 21 days for 4 cycles followed by weekly paclitaxel 80mg/m2 for 12 weeks or 3-weekly docetaxel 100mg/m2 for 4 cycles.

DRUGLetrozole

Letrozole 2.5mg orally daily + abemaciclib 150mg orally every 12 hours on a continuous dosing schedule, +/- LHRH analogs in premenopausal women, up to 12 months, in 28-day cycles

DRUGAbemaciclib

Letrozole 2.5mg orally daily + abemaciclib 150mg orally every 12 hours on a continuous dosing schedule, +/- LHRH analogs in premenopausal women, up to 12 months, in 28-day cycles

Letrozole 2.5mg orally daily + abemaciclib 150mg orally every 12 hours on a continuous dosing schedule, +/- LHRH analogs in premenopausal women, up to 12 months, in 28-day cycles

Sponsors

Spanish Breast Cancer Research Group
Lead SponsorOTHER
Eli Lilly and Company
CollaboratorINDUSTRY

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE

Eligibility

Sex/Gender
FEMALE
Age
18 Years to No maximum
Healthy volunteers
No

Inclusion criteria

Patients are eligible to be enrolled in the study only if they meet all of the following criteria: 1. Written informed consent prior to any specific study procedures. 2. Women ≥ 18 years of age. 3. Documentation of histologically confirmed primary invasive adenocarcinoma of the breast. 4. Availability of a primary tumor tissue sample obtained during the diagnostic process before treatment for the central assessment of Ki67 index. 5. Documentation of Hormone Receptor (HR) positive and Human Epidermal Growth Factor Receptor 2 (HER2) negative Breast Cancer (BC) based on local laboratory determination. * HR positive is defined as more than or equal to 10% positive cells by Immunohistochemistry (IHC) for ER and/or progesterone receptor (PgR). * HER2 negative tumor is determined according to recommendations of American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) 2018 guidelines. 6. Intermediate and high risk patients based on Ki67 index value (≥ 20%) determined at a central laboratory. 7. Patients should be in the following clinical stages of disease according to the 8th edition of the TNM Classification of Breast Cancer by the Union for International Cancer Control (UICC): T2 (\> 2cm) - T3, T4b, N0 - N2, M0 (stages IIA, IIB, IIIA or IIIB). Subpopulation with tumors T2 N0 M0 will include high risk patients based on Ki67 index \> 30% or Ki67 index between 20-30% and PgR negative with or without histological grade 3. 8. Patients diagnosed with multifocal or multicentric breast cancer will be eligible for the study if only 2 tumor lesions have been confirmed in the clinical evaluation and both lesions comply with the characteristics required by the protocol (please, refer to previous inclusion criteria). 9. Indication of neoadjuvant treatment. 10. At the time of presentation, patients must be candidates for potentially curative surgery by surgeon's assessment. 11. Sentinel lymph node biopsy (SLNB) will be preferable after the neoadjuvant treatment. Those patients with SLNB before the neoadjuvant treatment will be eligible for the study only if the SLNB has a negative result (N0). One Step Nucleic Acid Amplification (OSNA) method is not allowed. 12. Premenopausal and postmenopausal women. Postmenopausal status is defined as: * Patient underwent bilateral oophorectomy, or * Age ≥ 60 years, or * Age \< 60 years and amenorrhea for 12 or more months (in the absence of chemotherapy, tamoxifen, toremifene or ovarian suppression) and Folliculostimulating hormone (FSH) and plasma estradiol are in the postmenopausal ranges per local normal ranges. All women who do not meet the criteria for postmenopausal status are considered premenopausal for the purpose of this trial. 13. Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0 or 1. 14. Patients are able to swallow oral medications. 15. Adequate organ and bone marrow function: * Absolute neutrophil count (ANC) ≥ 1,500/mm3 (1.5x109/L); * Platelets ≥ 100,000/mm3 (100x109/L); * Hemoglobin (Hgb) ≥ 8g/dL (80g/L) (erythrocyte transfusions are permitted; initial treatment must not begin earlier than the day after the erythrocyte transfusion); * Total serum bilirubin ≤ 1.5x Upper Limit of Normal (ULN) (≤ 2x ULN and direct bilirubin within normal limits if Gilbert´s disease); * Aspartate aminotransferase (AST) and Alanine aminotransferase (ALT) ≤ 3x ULN. 16. Left ventricular ejection fraction (LVEF) ≥ 50% measured by multiple-gated acquisition scan (MUGA) or echocardiogram (ECHO). 17. For premenopausal women: agreement to remain abstinent or use single or combined non-hormonal contraceptive methods that result in a failure rate of \< 1% per year during the treatment period and for at least 3 weeks after the last dose of study treatment. Abstinence is only acceptable if it is in line with the preferred and usual lifestyle of the patient. Periodic abstinence (e.g., calendar, ovulation, symptothermal, or post-ovulation methods) and withdrawal are not acceptable methods of contraception. Examples of non-hormonal contraceptive methods with a failure rate of \< 1% per year include tubal ligation, male sterilization, and certain intrauterine devices. Alternatively, two methods (e.g., two barrier methods such as a condom and a cervical cap) may be combined to achieve a failure rate of \< 1% per year. Barrier methods must always be supplemented with the use of a spermicide. 18. Negative serum pregnancy test within 7 days of the first dose of abemaciclib for premenopausal women, and for women who have experienced menopause onset \< 12 months prior to first dose of therapy. 19. Patients consent to biological sample provision for biomarker exploratory analyses. 20. Willingness and ability to comply with scheduled visits, treatment plan, laboratory tests and other study procedures.

Exclusion criteria

Patients will be excluded from the study if they meet any of the following criteria: 1. Previous anti-cancer treatment with therapeutic intent for current breast cancer is not allowed. 2. Inflammatory breast cancer, multifocal/multicentric breast cancer with ≥ 3 tumor lesions or synchronous bilateral invasive breast cancers are not eligible. 3. 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 preexisting Crohn's disease or ulcerative colitis or a preexisting chronic condition resulting in baseline Grade 2 or higher diarrhea). 4. Patients with rare hereditary problems of galactose intolerance, total lactase deficiency or glucose- galactose malabsorption. 5. Females who are pregnant or lactating. 6. Active systemic bacterial infection (requiring intravenous \[IV\] antibiotics at time of initiating study treatment), fungal infection, or detectable viral infection (such as known human immunodeficiency virus positivity or with known active hepatitis B or C \[for example, hepatitis B surface antigen positive\]. Screening is not required for enrollment. 7. Personal history of any of the following conditions: syncope of cardiovascular etiology, ventricular arrhythmia of pathological origin (including, but not limited to, ventricular tachycardia and ventricular fibrillation), or sudden cardiac arrest. 8. Diagnosis of any other malignancy within 5 years prior to randomization, except for adequately treated basal cell or squamous cell skin cancer, or carcinoma in situ of the cervix or colorectal. 9. Prior hematopoietic stem cell or bone marrow transplantation. 10. Other severe acute or chronic medical or psychiatric condition or laboratory abnormality that may increase the risk associated with study participation or investigational product administration or may interfere with the interpretation of study results and, in the judgment of the investigator, would make the patient inappropriate for entry into this study.

Design outcomes

Primary

MeasureTime frameDescription
Residual Cancer Burden (RCB) 0-I RateThrough study treatment, and average of 12 monthsEvaluation of the number of patients with a RCB 0-I index as a measure of efficacy. RCB is a continuous variable derived from the primary tumor dimensions, cellularity of the tumor bed, and axillary nodal burden. It is estimated from routine pathological sections of the primary breast tumor site and the regional lymph nodes after the completion of Neoadjuvant therapy. The pathological variables include bidimensional diameters of the primary tumor bed, the proportion of primary tumor area containing invasive carcinoma, the number of positive lymph nodes, and the diameter of the largest nodal metastasis

Secondary

MeasureTime frameDescription
Changes in Percentage of KI67 Dyed Cells2 weeks of treatmentThe percentage of decrease in the geometric mean of Ki67 after 2 weeks of treatment in both treatments arms. Number of patients with cell cycle arrest (Ki67 \< 2.7%) after 2 weeks of treatment in both treatment arms.
RCB 0+I Versus RCB-II Versus RCB-III24 weeksRCB is classified in four classes based on the residual disease (RD): * RCB-0 defined as pathological complete response. * RCB-I defined as minimal RD. * RCB-II defined as moderate RD. * RCB-III defined as extensive RD.
Number of Participants With Preoperative Endocrine Prognostic Index (PEPI) Score of 0 at Surgery24 weeksPEPI requires pathological stage (tumor size and nodal status), level of Ki67 protein, and Allred ER score measured on the surgical specimen. PEPI score 0 includes pT1 or pT2, pN0, Ki67 ≤ 2.7%, Allred score \> 2. Patients with a PEPI score of 0 are found to have a low risk of recurrence.
Clinical Response Measured by Magnetic Resonance Imaging (MRI)24 weeksAccording to RECIST v1.1 in both treatment arms. Clinical Response Rate (CRR) is defined as the proportion of subjects with complete or partial radiographic response. Complete Response (CR) and Partial Response (PR) definitions are assessed by MRI at baseline and prior to breast surgery, with or without regional lymph nodes surgery, and categorized according to percent reduction in tumor size.
Rate of Breast Conservative Surgery (BCS) in Both Treatment Arms.24 weeksRate of BCS: defined as the proportion of patients who achieved breast-conserving surgery between both treatment arms.
iEFS (Invasive Event Free Survival) in Both Treatment Arms.Up to 10 yearsInvasive event free survival (iEFS): defined as time from randomization to progressive disease or invasive disease recurrence (local, regional, distant, or contralateral), or death from any cause. Invasive disease recurrence is defined as: * Ipsilateral invasive breast tumor recurrence (including second primary invasive breast cancer): an invasive breast cancer involving the same breast parenchyma as the original primary lesion. * Ipsilateral regional invasive breast cancer recurrence (i.e., an invasive breast cancer in the axilla, other regional lymph nodes, chest wall, and/or skin of the ipsilateral breast). * Distant recurrence (i.e., evidence of breast cancer in any anatomic site outside local and/or regional location and that has been either histologically confirmed or clinically diagnosed as recurrent invasive breast cancer) * Contralateral invasive breast cancer * Second primary invasive cancer of non-breast origin.
The Number of Participants Who Experienced Adverse Events (AE) Related to Study TreatmentThrough study treatment, and average of 12 monthsSafety assessments were performed at baseline and during the study: Vital signs assessments (blood pressure, pulse and body temperature), measurement of left ventricular ejection fraction, standard 12-lead electrocardiogram, laboratory assessments (hemoglobin, White Blood Cell, Absolute Neutrophil Count, Lymphocytes, platelet count, fasting glucose, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, total bilirubin, serum creatinine, sodium, potassium, total calcium, blood urea nitrogen (or urea), pregnancy test , ophthalmologic assessments (visual acuity testing, slit lamp examination, fundoscopy), Viral serology. AEs will be graded according to National Cancer Institute Common Terminology Criteria for Adverse Events version 5.0. The toxicity of study treatments will be evaluated in the safety population.
To Assess Molecular Downstaging for High Risk Genomic Groups Defined by a Multigene Expression Panel.24 weeksGene expression data provided by a multigene expression panel in sequential tumor biopsies.

Countries

Spain

Contacts

STUDY_DIRECTORStudy Director

Hospital General Universitario Gregorio Marañon

Baseline characteristics

Characteristic
Age, Categorical
<=18 years
0 Participants
Age, Categorical
>=65 years
16 Participants
Age, Categorical
Between 18 and 65 years
84 Participants
Age, Continuous53 years
Body Mass Index Category
Missing
0 Participants
Body Mass Index Category
normal weight
32 Participants
Body Mass Index Category
obese type I
24 Participants
Body Mass Index Category
obese type II
8 Participants
Body Mass Index Category
obese type III
2 Participants
Body Mass Index Category
overweight
35 Participants
Body Mass Index Category
underweight
3 Participants
cN
N0
34 Participants
cN
N1
50 Participants
cN
N2
6 Participants
cT
T1
4 Participants
cT
T2
70 Participants
cT
T3
24 Participants
cT
T4
2 Participants
Disease Stage
Stage II A
67 Participants
Disease Stage
Stage II B
91 Participants
Disease Stage
Stage III A
18 Participants
Disease Stage
Stage III B
2 Participants
Eastern Cooperative Oncology Group (ECOG) status
ECOG 0
91 Participants
Eastern Cooperative Oncology Group (ECOG) status
ECOG 1
23 Participants
HER2 status
HER2-
198 Participants
HER2 status
HER2+
1 Participants
Histopathologic Grade
G1, Well Differentiated
4 Participants
Histopathologic Grade
G2, Moderately Differentiated
57 Participants
Histopathologic Grade
G3, Poorly Differentiated
34 Participants
Histopathologic Grade
GX, Unknown
1 Participants
Histopathologic Grade
Not Available/Not Done
10 Participants
Hormonal Receptor status
ER+/PgR-
24 Participants
Hormonal Receptor status
ER+/PgR+
69 Participants
Hormonal Receptor status
ER+/PgR not available
1 Participants
Ki67 Index
<30%
22 Participants
Ki67 Index
>=30%
154 Participants
Menopausal Status
Postmenopausal
56 Participants
Menopausal Status
Premenopausal
44 Participants
Multicentric tumor
No
99 Participants
Multicentric tumor
Yes
2 Participants
Multifocal tumor
No
96 Participants
Multifocal tumor
Yes
8 Participants
Race (NIH/OMB)
American Indian or Alaska Native
0 Participants
Race (NIH/OMB)
Asian
0 Participants
Race (NIH/OMB)
Black or African American
0 Participants
Race (NIH/OMB)
More than one race
0 Participants
Race (NIH/OMB)
Native Hawaiian or Other Pacific Islander
0 Participants
Race (NIH/OMB)
Unknown or Not Reported
3 Participants
Race (NIH/OMB)
White
99 Participants
Region of Enrollment
Spain
200 participants
Sex: Female, Male
Female
100 Participants
Sex: Female, Male
Male
0 Participants

Adverse events

Event typeEG000
affected / at risk
EG001
affected / at risk
deaths
Total, all-cause mortality
1 / 1004 / 99
other
Total, other adverse events
97 / 10094 / 99
serious
Total, serious adverse events
7 / 1008 / 99

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Mar 13, 2026