A Phase II Study of SSGJ-612 Plus a HER2-Targeted ADC in HR-Positive, HER2-Low or HER2-Ultralow Expression Metastatic Breast Cancer

NCT07757230 | Not Yet Recruiting Phase 2

• 1 other identifier: SSGJ-612-201
• Study Type: interventional
• Target: 87
• Locations: 1 country
• Sites: 1

Brief Summary

This study is a phase II clinical trial of SSGJ-612 combined with a human epidermal growth factor receptor 2 (HER2)-targeted antibody-drug conjugate (ADC) in patients with hormone receptor (HR)-positive, HER2-low or HER2-ultralow metastatic breast cancer.

Conditions

Metastatic Breast Cancer

Outcome Measures

Primary Outcomes (1)

• Objective Response Rate (ORR)

  The primary efficacy end point

  2 years

Secondary Outcomes (2)

• Incidence and Severity of Adverse Events (AEs)

  2 years

• Progression-Free-Survival (PFS)

  2 years

Study Arms (2)

Part 1

EXPERIMENTAL

Breast cancer patients who have received at least one line of chemotherapy for metastatic disease

Drug: SSGJ-612 (HER2-targeted antibody); Drug: HER2-targeted ADC

Part 2

EXPERIMENTAL

Breast cancer patients who have not received any chemotherapy for metastatic disease

Drug: SSGJ-612 (HER2-targeted antibody); Drug: HER2-targeted ADC

Interventions

SSGJ-612 (HER2-targeted antibody) DRUG

Intravenous injection

Part 1; Part 2

HER2-targeted ADC DRUG

Intravenous injection

Part 1; Part 2

Eligibility Criteria

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

You may qualify if:

• Voluntary participation in this study, signed informed consent form, good treatment compliance, and willingness to cooperate to complete all trial procedures.
• Expected survival duration ≥ 3 months.
• Histopathologically confirmed breast cancer meeting all of the following criteria simultaneously:
• Metastatic tumor;
• Tumor samples tested by central laboratory confirmed as HER2-low or HER2 ultra-low expression;
• No prior test results reporting HER2 positivity;
• Tumor sample testing confirms hormone receptor-positive (HR+) status.
• Patients must satisfy either of the following conditions:
• Disease progression within 6 months after initiation of first-line endocrine therapy combined with cyclin-dependent kinase 4/6 (CDK4/6) inhibitors for metastatic disease;
• Received at least 2 lines of prior endocrine therapy for metastatic disease, with disease progression post-treatment.
• Participants in Part 1: Breast cancer patients who have received at least one line of chemotherapy for metastatic disease; Participants in Part 2: Breast cancer patients who have not received any chemotherapy for metastatic disease.
• At least one repeatedly and accurately measurable tumor lesion as target lesion assessed per RECIST v1.1 criteria.

You may not qualify if:

• Uncontrolled or severe cardiovascular disease.
• History of interstitial lung disease (ILD)/pneumonia requiring corticosteroid therapy (non-infectious), or current ILD/pneumonia, or suspected ILD/pneumonia not excluded by screening imaging.
• Presence of pulmonary-specific, clinically significant comorbid conditions.
• Presence of spinal cord compression, or clinically active central nervous system metastases.
• Female patients who are pregnant, breastfeeding, or planning pregnancy.
• Presence of drug abuse, or other diseases (e.g., psychiatric disorders) that, in the investigator's judgment, may interfere with patient participation in the trial or affect the assessment of trial outcomes.

Sponsors & Collaborators

• Shenyang Sunshine Pharmaceutical Co., LTD.: lead

Study Sites (1)

Sun Yat-sen University Cancer Center

Guangzhou, Guangdong, China

Location

MeSH Terms

Conditions

Breast Neoplasms

Condition Hierarchy (Ancestors)

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

Central Study Contacts

Shusen Wang M.D.

CONTACT

+86 139 2616 8469; wangshus@susucc.org.cn

Study Design

• Study Type: interventional
• Phase: phase 2
• Allocation: NON RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: August 6, 2026
• First Posted: August 11, 2026
• Study Start (Estimated): September 1, 2026
• Primary Completion (Estimated): February 1, 2028
• Study Completion (Estimated): July 1, 2029
• Last Updated: August 11, 2026

Record last verified: 2026-08

Data Sharing

• IPD Sharing: Will not share

Locations

CN (1)