Neoadjuvant Imlunestrant Plus Abemaciclib Treatment Guided by Ki67 Index After 2 Weeks for ER-Positive HER2-Negative Breast Cancer

NCT07410559 | Not Yet Recruiting Phase 2

• 1 other identifier: IMPATIENS
• Study Type: interventional
• Target: 189
• Locations: 1 country
• Sites: 1

Brief Summary

This is a prospective, open-label, single-center, randomized controlled Phase II clinical study aimed at evaluating the efficacy and safety of neoadjuvant imlunestrant combined with abemaciclib guided by the Ki67 index after 2 weeks in patients with ER+/HER2- breast cancer.

Conditions

Breast Cancer

Outcome Measures

Primary Outcomes (2)

• ORR between Arm A and Arm B

  Defined as the proportion of patients whose tumor shrinks by a certain amount and maintains that reduction for a certain time, including cases of complete response (CR) and partial response (PR). Tumor objective response will be assessed using the Response Evaluation Criteria in Solid Tumors (RECIST version 1.1). Subjects must have measurable tumor lesions at baseline.

  Immediately after the surgery

• pCR rate between Arm A and Arm B

  Defined as achieving pCR (ypT0/is, ypN0) upon postoperative pathological assessment, meaning the absence of any residual invasive cancer in the pathological evaluation of hematoxylin and eosin-stained resected breast samples and all ipsilateral lymph node samples after completing neoadjuvant therapy and surgery.

  Immediately after the surgery

Secondary Outcomes (4)

• Relative changes of Ki67 index between Arm A and Arm B

  Immediately after the surgery

• 3-year EFS between Arm A and Arm B

  Following surgery until Year 3

• 3-year OS between Arm A and Arm B

  Following surgery until Year 3

• Adverse events assessed according to CTCAE v6.0 criteria

  Up to one year during follow-up

Other Outcomes (5)

• ORR between Arm A and Arm C

  Immediately after the surgery

• pCR rate between Arm A and Arm C

  Immediately after the surgery

• Relative changes of Ki67 index between Arm A and Arm C

  Immediately after the surgery

Study Arms (3)

Arm A (Imlunestrant + abemaciclib)

EXPERIMENTAL

If the Ki67 of the primary lesion after 2 weeks is \<7.4%

Drug: Imlunestrant + abemaciclib

Arm B [(dd)EC*4-T*4]

ACTIVE COMPARATOR

If the Ki67 of the primary lesion after 2 weeks is \<7.4%

Drug: (dd)EC*4-T*4

Arm C [(dd)EC*4-T*4]

ACTIVE COMPARATOR

If the Ki67 of the primary lesion after 2 weeks is ≥7.4%

Drug: (dd)EC*4-T*4

Interventions

Imlunestrant + abemaciclib DRUG

Imlunestrant (400 mg orally, once daily) combined with abemaciclib (150 mg orally, twice daily) for 24 weeks.

Arm A (Imlunestrant + abemaciclib)

(dd)EC*4-T*4 DRUG

Epirubicin (90 mg/m², intravenous infusion) combined with cyclophosphamide (600 mg/m², intravenous infusion, every 2 weeks or 3 weeks, determined by investigators) for 4 cycles, followed by docetaxel (100 mg/m², intravenous infusion, every 3 weeks) for 4 cycles.

Arm B [(dd)EC*4-T*4]; Arm C [(dd)EC*4-T*4]

Eligibility Criteria

• Age: 18 Years - 75 Years
• Sex: female
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Female patients aged 18 to 75 years.
• Eastern Cooperative Oncology Group (ECOG) performance status of 0-1.
• Primary breast tumor diameter \> 1 cm.
• Histologically confirmed invasive ER+/HER2- breast cancer, meeting ER≥50% and Ki67≥10%. HER2 negativity is defined as HER2 immunohistochemistry (IHC) 0-1+, or IHC 2+ with fluorescence in situ hybridization (FISH) confirming no amplification.
• Clinical tumor stage: cT1c-T4, cN0-cN2, cM0.
• Willing to undergo breast cancer surgery once surgical criteria are met after neoadjuvant therapy.
• Adequate organ function, meeting all of the following:
• Hemoglobin (Hb)≥90 g/L and patients may receive erythrocyte transfusions to achieve this hemoglobin level at the discretion of the investigator. Initial treatment must not begin earlier than the day after the erythrocyte transfusion;
• Absolute neutrophil count (ANC)≥1.5×10\^9/L;
• Platelet count (PLT)≥100×10\^9/L;
• Total bilirubin (TBIL)≤1.5×the upper limit of normal (ULN) and patients with Gilbert's syndrome with a total bilirubin ≤2.0 times ULN and direct bilirubin within normal limits are permitted;
• Alanine aminotransferase (ALT) and aspartate aminotransferase (AST)≤2.5×ULN;
• Alkaline phosphatase (ALP)≤2.5×ULN;
• Serum creatinine (Cr)≤1.5×ULN;
• Prothrombin time (PT) and activated partial thromboplastin time (APTT)≤1.5×ULN, and international normalized ratio (INR)≤1.5×ULN (in patients not receiving anticoagulation).

You may not qualify if:

• Stage IV (metastatic) breast cancer or bilateral breast cancer.
• Prior history of invasive breast cancer.
• Prior history of ductal carcinoma in situ (DCIS) or lobular carcinoma in situ (LCIS).
• Any prior chemotherapy, endocrine therapy, or anti-HER2 therapy for breast cancer; or prior excisional biopsy of the primary breast tumor and/or axillary lymph nodes, or prior local radiotherapy (excluding diagnostic biopsy for primary breast cancer or surgery for benign breast tumors).
• Any other malignancy within the past 5 years, except cured cervical carcinoma in situ and non-melanoma skin cancer.
• Peripheral neuropathy≥Grade 2 per NCI-CTCAE v6.0.
• Serious cardiovascular or cerebrovascular disease within 6 months prior to randomization, including but not limited to congestive heart failure, unstable angina, severe arrhythmias uncontrolled by medication, severe conduction abnormalities or clinically significant valvular disease, uncontrolled severe hypertension, myocardial infarction, or cerebrovascular accident.
• Any 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).
• Major surgery within 4 weeks prior to randomization without full recovery, or an anticipated need for major surgery during study treatment.
• Known active liver disease, including but not limited to active hepatitis B (defined as HBsAg positive with HBV-DNA≥1000 IU/mL), hepatitis C (defined as HCV-Ab positive with HCV-RNA above the assay's lower limit of quantification), or autoimmune liver disease.
• Severe and uncontrolled infection or known HIV infection.
• Active systemic bacterial infection (requiring intravenous antibiotics at time of initiating study treatment) or fungal infection.
• Pregnant or breastfeeding.
• Known allergy to the study drug or any of its excipients, or a history of severe hypersensitivity reactions to other monoclonal antibodies.
• Known abuse of psychotropic substances, alcoholism, or drug abuse.

Sponsors & Collaborators

• Fudan University: lead

Study Sites (1)

Fudan University Shanghai Cancer Center

Shanghai, Shanghai Municipality, 200032, China

Location

MeSH Terms

Conditions

Breast Neoplasms

Interventions

Imlunestrant; abemaciclib

Condition Hierarchy (Ancestors)

Neoplasms by Site; Neoplasms; Breast Diseases; Skin Diseases; Skin and Connective Tissue Diseases

Study Design

• Study Type: interventional
• Phase: phase 2
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Professor

Study Record Dates

• First Submitted: February 8, 2026
• First Posted: February 13, 2026
• Study Start (Estimated): July 1, 2026
• Primary Completion (Estimated): April 1, 2029
• Study Completion (Estimated): July 1, 2031
• Last Updated: February 18, 2026

Record last verified: 2026-02

Data Sharing

• IPD Sharing: Will not share

Locations

CN (1)