Tolerability of Dalpiciclib vs. Abemaciclib/Ribociclib in Early HR+/HER2- Breast Cancer

Tolerability of Dalpiciclib Versus Abemaciclib/Ribociclib in Combination With Standard Endocrine Therapy for HR-Positive/HER2-Negative Early Breast Cancer: A Prospective, Multicenter, Randomized Controlled Trial

In recent years, the successful application of cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) has transformed the treatment landscape for HR+/HER2- advanced breast cancer and driven research into their use in adjuvant settings. Large Phase III trials including MONARCH-E and NATALEE have demonstrated that combining CDK4/6i with standard endocrine therapy significantly reduces the risk of recurrence or death in high-risk patients with early breast cancer. This regimen has been recommended by leading domestic and international clinical guidelines. Nevertheless, patients' quality of life, symptom burden and treatment adherence are also critical in clinical practice. Patient-reported outcomes (PROs), especially electronic PROs (ePROs), can effectively complement conventional study endpoints and provide important evidence for the comprehensive evaluation of long-term treatment.

This is a prospective, multicenter, randomized controlled clinical trial. The primary objective is to compare the tolerability of dalpiciclib versus abemaciclib/ribociclib, each combined with standard endocrine therapy, in the adjuvant treatment of patients with high-risk HR+/HER2- early breast cancer. Eligible patients who have received curative local therapy will be randomized to either the experimental group (dalpiciclib plus endocrine therapy) or the control group (ribociclib/abemaciclib plus endocrine therapy). Stratified block randomization will be applied, with stratification factors including menopausal status and prior history of neoadjuvant/adjuvant chemotherapy.

The total duration of endocrine therapy is 5 years. The treatment duration of CDK4/6i is approximately 104 weeks for dalpiciclib, 156 weeks for ribociclib, and 104 weeks for abemaciclib. CDK4/6i will be discontinued in cases of disease recurrence, intolerable toxicity, patient withdrawal, or discontinuation as determined by the investigator. Patients will be regularly asked to complete ePRO questionnaires throughout the treatment period.

Study Overview

• Status: Not yet recruiting
• Conditions: Breast Cancer
• Intervention / Treatment: Drug: Dalpiciclib; Drug: Abemaciclib/Ribociclib

• Study Type: Interventional
• Enrollment (Estimated): 456
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Zhenzhen Liu; Phone Number: 13603862755; Email: zlyyliuzhenzhen0800@zzu.edu.cn

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Age ≥18 years with clinical stage II-III breast cancer at the time of signing informed consent.

2. Post-operative pathological confirmation of invasive breast cancer that is hormone receptor-positive (HR+) and human epidermal growth factor receptor 2-negative (HER2-), as confirmed by the research center's pathology department:

   • ER positive and/or PR positive defined as ≥10% of tumor cells showing positive nuclear staining.

     • HER2 negative defined as immunohistochemistry (IHC) 0 or 1+, or negative by in situ hybridization (ISH).
3. Pathologically confirmed unilateral primary invasive breast cancer, with the date of breast cancer diagnosis on the pathology report no more than 18 months before randomization. For patients with multicentric or multifocal tumors, all pathologically examined lesions must meet the pathological requirements in criterion .
4. For patients who received adjuvant chemotherapy: the last chemotherapy dose must be at least 21 days before randomization.
5. For patients who received adjuvant radiotherapy: the last radiotherapy session must be at least 14 days before randomization.
6. The last non-endocrine treatment (including surgery, radiotherapy, chemotherapy) must be within 90 days before randomization.

7. Has undergone curative surgical resection with tumor-free margins on pathological examination, and meets one of the following high-risk categories:

   • Pathologically confirmed tumor involvement in ≥4 ipsilateral axillary lymph nodes; OR ② Pathologically confirmed tumor involvement in 1-3 ipsilateral axillary lymph nodes AND at least one of the following:

     a. Pathological primary invasive tumor size ≥5 cm; b. Primary tumor histological grade 3 (G3); c. Ki-67 ≥20%; d. Known genetic test indicating high risk of recurrence.

8. Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1.
9. No evidence of recurrence or metastatic disease after surgery.

10. Adequate organ and bone marrow function, meeting the following criteria:

    • White blood cell (WBC) count ≥3,000/mm³ (3.0 × 10⁹/L) (without G-CSF within 14 days);

      • Absolute neutrophil count (ANC) ≥1,500/mm³ (1.5 × 10⁹/L) (without G-CSF within 14 days);

        • Platelet count (PLT) ≥100,000/mm³ (100 × 10⁹/L) (without corrective treatment within 7 days);

          • Hemoglobin (Hb) ≥9 g/dL (90 g/L) (without corrective treatment within 7 days); ⑤ Serum creatinine ≤1.5 × upper limit of normal (ULN) or creatinine clearance ≥60 mL/min (without corrective treatment within 7 days); ⑥ Total bilirubin (TBIL) ≤1.5 × ULN (without corrective treatment within 7 days); ⑦ Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤3 × ULN (without corrective treatment within 7 days); ⑧ QTcF ≤470 ms.
11. Female patients of childbearing potential must have a negative serum pregnancy test within 7 days before randomization, and must agree to use acceptable non-hormonal contraception from the signing of informed consent until 7 months after the last dose of dalpiciclib, or 21 days after the last dose of abemaciclib/ribociclib, or 2 months after the last dose of aromatase inhibitor or tamoxifen/toremifene (whichever is longer).
12. All toxicities from prior anti-cancer therapy must have recovered to grade 0-1 (CTCAE version 6.0), except for those explicitly stated in the inclusion/exclusion criteria.
13. Has voluntarily signed the informed consent form, and is willing and able to comply with scheduled visits, treatment plan, laboratory tests, and other study procedures.

Exclusion Criteria:

1. Pathological diagnosis of HER2-positive breast cancer (HER2-positive defined as immunohistochemistry [IHC] 3+ or positive by in situ hybridization [ISH]).
2. Local or regional recurrence of breast malignancy.
3. Clinical stage IV (metastatic) breast cancer.
4. Bilateral breast cancer (including contralateral carcinoma in situ).
5. History of any malignancy other than breast cancer within 5 years before randomization, excluding adequately treated cervical carcinoma in situ, basal cell carcinoma, or squamous cell carcinoma of the skin.
6. History of severe pulmonary disease such as interstitial pneumonia.
7. Prior treatment with any CDK4/6 inhibitor, other anti-cancer biologic therapy, targeted therapy, or cancer immunotherapy.
8. Concurrent participation in another clinical trial of anti-cancer therapy (including endocrine therapy or immunotherapy).
9. Major surgical procedure, receipt of any investigational drug, other anti-cancer treatment, or use of immunomodulators within 4 weeks before randomization (excluding chemotherapy, radiotherapy, and endocrine therapy for breast cancer).
10. Known infection with human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS); active hepatitis B (HBV DNA ≥500 IU/mL); hepatitis C (positive hepatitis C antibody with HCV-RNA above the lower limit of detection of the assay); or co-infection with hepatitis B and hepatitis C.
11. Any of the following within 6 months before randomization: myocardial infarction, severe/unstable angina pectoris, New York Heart Association (NYHA) class ≥2 heart failure, persistent arrhythmia of grade ≥2 (according to NCI CTCAE version 6.0), atrial fibrillation of any grade, coronary/peripheral artery bypass grafting, symptomatic congestive heart failure, cerebrovascular accident (including transient ischemic attack), or pulmonary embolism.
12. Severe infection within 4 weeks before randomization (e.g., requiring intravenous antibiotics, antifungals, or antivirals per clinical practice guidelines), or unexplained fever >38.5°C during screening or before the first dose.
13. Inability to swallow, intestinal obstruction, or other factors affecting drug administration or absorption.
14. Known hypersensitivity to aromatase inhibitors, tamoxifen-class drugs (e.g., tamoxifen, toremifene), and LHRH agonists; known hypersensitivity to dalpiciclib/abemaciclib/ribociclib or any of their excipients
15. History of allogeneic organ transplantation or allogeneic hematopoietic stem cell transplantation.
16. Known history of substance abuse (including psychoactive drugs).
17. Women within 1 year postpartum or currently breastfeeding.
18. Presence of any other serious physical or psychiatric condition, or laboratory abnormality that may increase the risk of study participation, interfere with study results, or render the patient unsuitable for the study in the opinion of the investigator.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Experimental: Dalpiciclib + Standard Endocrine Therapy; Participants will receive Dalpiciclib 125 mg orally once daily on days 1-21 of a 28-day cycle (3 weeks on, 1 week off) for 24 months (26 cycles). In addition, participants will receive standard adjuvant endocrine therapy for 5 years. The choice of endocrine therapy depends on menopausal status: Premenopausal/perimenopausal: LHRH agonist (goserelin or leuprorelin) + aromatase inhibitor (letrozole or anastrozole) or tamoxifen/toremifene if intolerant to aromatase inhibitor. Postmenopausal: aromatase inhibitor (letrozole or anastrozole) or tamoxifen/toremifene if intolerant to aromatase inhibitor. Endocrine therapy is administered continuously every 28 days.	Drug: Dalpiciclib; Description: 125 mg orally once daily on days 1-21 of a 28-day cycle (3 weeks on, 1 week off) for 24 months (26 cycles). Receive 5 years of standard endocrine therapy. The recommended treatment drugs are as follows: Letrozole Description: 2.5 mg orally once daily continuously for 5 years as part of standard endocrine therapy. Anastrozole Description: 1 mg orally once daily continuously for 5 years as part of standard endocrine therapy. Tamoxifen Description: 10 mg orally twice daily continuously for 5 years as part of standard endocrine therapy. Toremifene Description: 60 mg orally once daily continuously for 5 years as part of standard endocrine therapy. Premenopausal: Preferred treatment is LHRH agonist plus an aromatase inhibitor. Perimenopausal: LHRH agonist and endocrine therapy may be used per investigator's assessment. Goserelin Description: LHRH agonist administered subcutaneously (e.g., 3.6 mg every 28 days) for ovarian function suppression in premenopausal/perimenopausal
Active Comparator: Control：Abemaciclib/Ribociclib + Standard Endocrine Therapy; Participants will receive either Abemaciclib or Ribociclib according to the approved product labeling for dose, administration, and treatment duration. Abemaciclib is given for 24 months; Ribociclib is given for 36 months (as per label). In addition, participants will receive the same 5-year standard adjuvant endocrine therapy as described in Arm 1, based on menopausal status. The choice between Abemaciclib and Ribociclib is at the investigator's discretion following local guidelines.	Drug: Abemaciclib/Ribociclib; Abemaciclib Description: Administered according to approved product labeling. Typical dose: 150 mg twice daily continuously for 24 months. Investigator's choice between abemaciclib and ribociclib. Ribociclib Description: Administered according to approved product labeling. Typical dose: 400 mg orally once daily (3 weeks on, 1 week off) for 36 months. Investigator's choice between abemaciclib and ribociclib. Receive 5 years of standard endocrine therapy. The recommended treatment drugs are as follows: Letrozole Description: 2.5 mg orally once daily continuously for 5 years as part of standard endocrine therapy. Anastrozole Description: 1 mg orally once daily continuously for 5 years as part of standard endocrine therapy. Tamoxifen Description: 10 mg orally twice daily continuously for 5 years as part of standard endocrine therapy. Toremifene Description: 60 mg orally once daily continuously for 5 years as part of standard endocrine therapy. Premenopausal: Preferred treatment is LHRH

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Rate of CDK4/6 inhibitor dose reduction or permanent discontinuation due to any cause by Week 12	Rate of CDK4/6 inhibitor dose reduction or permanent discontinuation due to any cause by Week 12	From randomization up to Week 12 (Day 84, ±7 days)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Health-Related Quality of Life - Time to Deterioration (HRQOL-TTD)	Time from randomization to the first clinically meaningful deterioration (defined as a ≥10-point decrease from baseline) in global health status/quality of life score measured by the EORTC QLQ-C30 (version 3.0). Death before deterioration is handled as a competing risk event.	Up to 5 years (from randomization until deterioration, death, or end of study)
Change in Functional Domain Scores	Change from baseline in physical, role, cognitive, emotional, and social functioning scores measured by the EORTC QLQ-C30 at months 1, 3, 6, 12, 18, and 24. Mixed model for repeated measures (MMRM) will be used to compare trajectories between arms.	Baseline to month 24
. Safety - Incidence and Severity of Adverse Events	Incidence, severity (graded by NCI-CTCAE version 6.0), and duration of all-grade and grade ≥3 adverse events, serious adverse events (SAEs), adverse events leading to dose modification or treatment discontinuation, and adverse events related to study drugs.	From signing of informed consent until 28 days after last dose of study drug (up to approximately 5.5 years)
Rate of CDK4/6 Inhibitor Dose Reduction or Permanent Discontinuation by Month 6	Proportion of participants with a permanent dose reduction or permanent discontinuation of the CDK4/6 inhibitor due to any cause by month 6 (Day 168, window ±14 days), using the same definition as the primary endpoint.	From randomization up to month 6 (Day 168, ±14 days)
Treatment Adherence - Median Treatment Duration and Relative Dose Intensity	Median duration of CDK4/6 inhibitor treatment (in months) and relative dose intensity (actual delivered dose / planned dose × 100%) for each treatment arm.	From start of treatment to end of CDK4/6 inhibitor treatment period (up to 24 months for dalpiciclib/abemaciclib, up to 36 months for ribociclib)
Health Economic Outcome - Quality-Adjusted Life Years (QALYs)	Quality-adjusted life years calculated from EQ-5D-5L utility scores using a country-specific value set. Differences in QALYs between arms will be estimated using a generalized linear model, and incremental cost-effectiveness ratios (ICERs) will be calculated.	From baseline through 5 years of follow-up
Invasive Disease-Free Survival (iDFS)	Time from randomization to the first occurrence of any of the following events: invasive ipsilateral or contralateral breast cancer recurrence, local/regional invasive recurrence, distant recurrence, second primary invasive cancer (non-breast), or death from any cause.	From randomization up to 5 years (or until event, censoring, or study completion)

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Agreement Between Investigator-Reported AEs and Patient-Reported PRO-CTCAE Symptoms	Weighted kappa coefficient for concordance between investigator-graded adverse events (CTCAE) and patient-reported symptom severity/frequency measured by the PRO-CTCAE custom survey for selected symptoms (e.g., nausea, diarrhea, fatigue, joint pain). Detection rate and under-reporting rate will also be calculated.	From baseline through end of CDK4/6 inhibitor treatment period (up to 24-36 months)

Collaborators and Investigators

• Sponsor: Henan Cancer Hospital

Study record dates

Study Major Dates

• Study Start (Estimated): August 1, 2026
• Primary Completion (Estimated): June 30, 2028
• Study Completion (Estimated): June 30, 2033

Study Registration Dates

• First Submitted: July 11, 2026
• First Submitted That Met QC Criteria: July 11, 2026
• First Posted (Actual): July 16, 2026

Study Record Updates

• Last Update Posted (Actual): July 16, 2026
• Last Update Submitted That Met QC Criteria: July 11, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: HR+; ePRO; early breast cancer; Dalpiciclib
• Additional Relevant MeSH Terms: Neoplasms by Site; Neoplasms; Skin Diseases; Breast Diseases; Skin and Connective Tissue Diseases; Breast Neoplasms; abemaciclib; ribociclib; dalpiciclib
• Other Study ID Numbers: HELEN-B 027

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No