A Study to Evluate Efficacy and Safety of HRS-8080 Combined With Dalpiciclib in Patients With Advanced or Metastatic Breast Cancer Resistant to Adjuvant Endocrine Therapy.

A Multicenter, Open-label, Randomized Controlled Phase III Clinical Study Evaluating the Efficacy and Safety of HRS-8080 Combined With Dalpiciclib Versus Fulvestrant Combined With Dalpiciclib in Patients With Locally Advanced or Metastatic Breast Cancer Resistant to Adjuvant Endocrine Therapy.

The study is being conducted to evaluate the efficacy and safety of HRS-8080 combined with dalpiciclib versus fulvestrant combined with dalpiciclib in patients with locally advanced/metastatic breast cancer who had developed drug resistance to prior adjuvant endocrine therapy.

Study Overview

• Status: Recruiting
• Conditions: Locally Advanced or Metastatic Breast Cancer
• Intervention / Treatment: Drug: HRS-8080 Tablet ; Dalpiciclib Isethionate; Drug: Fulvestrant injection ;Dalpiciclib Isethionate

• Study Type: Interventional
• Enrollment (Estimated): 912
• Phase: Phase 3

Contacts and Locations

• Study Contact: Name: Zhan Zhang; Phone Number: +86 17721286165; Email: Zhan.zhang@hengrui.com

Study Locations

• China
  • Beijing Municipality
    • Beijing, Beijing Municipality, China, 100000
      • Recruiting
      • Chinese PLA General Hospital Fifth Medical Center
      • Principal Investigator: Zefei Jiang

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

1. Women aged 18 - 75 years old;
2. Eastern Cooperative Oncology Group performance status (ECOG-PS) of 0 to 1;
3. Patients with histologically confirmed locally advanced or metastatic breast cancer;
4. Patients with prior adjuvant endocrine resistance following curative-intent surgery;
5. Menstrual status: postmenopausal, perimenopausal, or premenopausal;
6. Presence of evaluable lesions;
7. Organ function must meet required criteria.

Exclusion Criteria:

1. Patients with rapidly progressing disease, as judged by the investigator to be unsuitable for endocrine therapy;
2. Patients who have previously received fulvestrant or other novel SERMs (excluding tamoxifen and toremifene);
3. Patients with uncontrolled brain metastases, carcinomatous meningitis, or spinal cord compression;
4. Patients with a history of clinically significant cardiovascular disease;
5. Participants who have not recovered from adverse effects caused by prior therapies;
6. Participants with a history of another malignancy within the past 5 years or currently having another malignancy;
7. Known hypersensitivity to HRS-8080, fulvestrant, dalpiciclib, or any of their components, etc.

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: HRS-8080 combined with Dalpiciclib	Drug: HRS-8080 Tablet ; Dalpiciclib Isethionate; HRS-8080 Tablet; Dalpiciclib Isethionate
Active Comparator: Fulvestrant combined with Dalpiciclib	Drug: Fulvestrant injection ;Dalpiciclib Isethionate; Fulvestrant injection; Dalpiciclib Isethionate

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Investigator assessed Progression free survival (PFS)	PFS is defined as the time from randomization to the first occurrence of PD, as determined by the investigator according to Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST v1.1), or death from any cause during the study.	Up to 5 years.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Duration of response (DOR)		Up to 5 years
Overall survival (OS)		Up to 8 years
Overall response rate (ORR)		Up to 5 years
Progression free survival (PFS) evaluated by the blinded independent central review (BICR)		Up to 5 years
Clinical benefit rate (CBR)		Up to 5 years
The incidence and severity of adverse events (AEs)		Up to 5 years
The incidence and severity of serious adverse events (SAEs)		Up to 5 years
Number of participants with vital sign abnormalities over the course of the study. Vital signs include respiratory rate, pulse rate, systolic and diastolic blood pressure, and temperature		Up to 5 years
Number of participants with clinical laboratory test abnormalities for haematology and biochemistry parameters over the course of the study		Up to 5 years
Heart rate (beats per minute) measured by 12-lead electrocardiography.		Up to 5 years
QT interval (ms) measured by 12-lead electrocardiography.	Eastern Cooperative Oncology Group (ECOG) performance status. ECOG performance status was measured on a 6 point grade scale. 0: Fully active, able to carry on all pre-disease performance without restriction.; Restricted in physically strenuous activity but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work.; Ambulatory and capable of all self-care but unable to carry out any work activities. Up and about more than 50% of waking hours.; Capable of only limited self-care, confined to bed or chair more than 50% of waking hours.; Completely disabled. Cannot carry on any self-care. Totally confined to bed or chair.; Dead.	Up to 5 years
Plasma concentrations of HRS-8080 and dalpiciclib isethionate		Up to approximately 2 years

Collaborators and Investigators

• Sponsor: Shandong Suncadia Medicine Co., Ltd.

Study record dates

Study Major Dates

• Study Start (Actual): March 4, 2026
• Primary Completion (Estimated): December 1, 2028
• Study Completion (Estimated): December 1, 2031

Study Registration Dates

• First Submitted: January 8, 2026
• First Submitted That Met QC Criteria: January 20, 2026
• First Posted (Actual): January 21, 2026

Study Record Updates

• Last Update Posted (Actual): March 27, 2026
• Last Update Submitted That Met QC Criteria: March 26, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Neoplasms by Site; Neoplasms; Skin Diseases; Breast Diseases; Skin and Connective Tissue Diseases; Breast Neoplasms
• Other Study ID Numbers: HRS-8080-301

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