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GB268 Monotherapy or Combination Therapy for Locally Advanced/Metastatic Breast Cancer (Phase Ib/Ⅱ)

A Open-label, Multicenter Phase Ib/Ⅱ Study to Evaluate the Safety, Tolerability, and Antitumor Activity of GB268 for Injection as Monotherapy or in Combination Regimens in Patients With Locally Advanced Unresectable or Metastatic Breast Cancer

Status
Not yet recruiting
Phases
Phase 1Phase 2
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT07738341
Enrollment
270
Registered
2026-07-31
Start date
2026-08-01
Completion date
2030-08-01
Last updated
2026-07-31

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

Conditions

Breast Cancer (Locally Advanced or Metastatic)

Keywords

GB268, Immunotherapy, PD-1, CTLA-4, VEGF

Brief summary

This is a Phase Ib/II, open-label, multi-cohort, multi-center study to evaluate the safety, tolerability, and preliminary anti-tumor activity of GB268, a biological product, as monotherapy or in combination with other therapies in patients with locally advanced unresectable or metastatic breast cancer.

Detailed description

The Phase Ib part of the study will primarily assess the safety and tolerability of GB268 in combination therapies, including dose-limiting toxicities (DLTs). The Phase II part will primarily evaluate the preliminary anti-tumor activity of GB268 as monotherapy and in various combination regimens in corresponding breast cancer populations.

Interventions

DRUGGB268

GB268 is a tri-specific antibody targeting PD-1, CTLA-4, and VEGF. It is designed to block immune checkpoints (PD-1/CTLA-4) to enhance T-cell-mediated anti-tumor immune responses and simultaneously inhibit VEGF-mediated tumor angiogenesis

DRUGNab-Paclitaxel

Nab-Paclitaxel is a microtubule-stabilizing agent formulated as albumin-bound nanoparticles for IV administration.

Datopotamab Deruxtecan is an ADC targeting Trop-2, consisting of a monoclonal antibody linked to a topoisomerase I inhibitor payload.

DRUGSacituzumab Tirumotecan

A Trop-2-directed Antibody-Drug Conjugate \[ADC\] consisting of a humanized anti-Trop-2 monoclonal antibody covalently linked to a topoisomerase I inhibitor payload.

Sponsors

Eddingpharm (Zhuhai) Co., Ltd.
Lead SponsorINDUSTRY

Study design

Allocation
NON_RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE

Eligibility

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

Inclusion criteria

Cohort-Specific Requirements: Cohort A: Histologically confirmed locally advanced unresectable or metastatic Triple-Negative Breast Cancer \[TNBC\]; no prior systemic therapy for advanced disease; prior adjuvant/neoadjuvant taxane allowed if recurrence ≥6 months after last taxane dose; no prior Trop-2 Antibody-Drug Conjugate \[ADC\]. Cohort B: Histologically confirmed locally advanced unresectable or metastatic TNBC; no prior systemic therapy for advanced disease; prior adjuvant/neoadjuvant taxane allowed if recurrence ≥12 months after last taxane dose. Cohort E: Histologically confirmed locally advanced unresectable or metastatic HR+/HER2- breast cancer; disease progression after ≥1 line of endocrine therapy (aromatase inhibitor and/or fulvestrant) and CDK4/6i in advanced setting; received ≥1 line of systemic chemotherapy in advanced setting; no prior Trop-2 ADC. Cohort F: Histologically confirmed locally advanced unresectable or metastatic HR+/HER2- breast cancer; disease progression after ≥1 line of endocrine therapy and CDK4/6i with primary or secondary endocrine resistance; prior adjuvant/neoadjuvant taxane allowed if recurrence ≥12 months after last taxane dose. Cohort G: Histologically confirmed locally advanced unresectable or metastatic HR+/HER2- breast cancer; prior CDK4/6i and endocrine therapy in any setting; received a TROP2 or HER2 ADC in advanced setting. Inclusion Criteria: 1. Age ≥ 18 years, male or female. 2. Histologically confirmed locally advanced unresectable or metastatic breast cancer (Triple-Negative Breast Cancer \[TNBC\] or Hormone Receptor-Positive/Human Epidermal Growth Factor Receptor 2-Negative \[HR+/HER2-\]). 3. At least one measurable lesion per Response Evaluation Criteria in Solid Tumors version 1.1 \[RECIST v1.1\]. 4. No prior treatment with any immune checkpoint inhibitor (e.g., anti-Programmed Death-1 \[PD-1\], anti-Programmed Death-Ligand 1 \[PD-L1\], anti-Cytotoxic T-Lymphocyte-Associated Protein 4 \[CTLA-4\]) or Programmed Death-1/Vascular Endothelial Growth Factor \[PD-1/VEGF\] bispecific antibody, except for adjuvant therapy if relapse occurred ≥12 months after discontinuation. 5. Assessed by the investigator as suitable for the assigned combination therapy. 6. Eastern Cooperative Oncology Group \[ECOG\] performance status 0 or 1. 7. Life expectancy ≥ 3 months. 8. Adequate organ function (within 14 days before first dose, without transfusion or Granulocyte Colony-Stimulating Factor \[G-CSF\] support): Hemoglobin ≥ 9 g/dL, Absolute Neutrophil Count \[ANC\] ≥ 1.5×10\^9/L, Platelets ≥ 100×10\^9/L; Aspartate Aminotransferase \[AST\] and Alanine Aminotransferase \[ALT\] ≤ 3×Upper Limit of Normal \[ULN\] (≤5×ULN if liver metastases); Alkaline Phosphatase \[ALP\] ≤ 2.5×ULN (≤5×ULN if bone or liver metastases); Total Bilirubin ≤ 1.5×ULN (≤3×ULN for Gilbert's Syndrome); Serum Creatinine ≤ 1.5×ULN or Creatinine Clearance ≥ 50 mL/min (Cockcroft-Gault formula); Urine protein dipstick ≤ 1+ (if ≥2+, 24-hour urine protein quantification \< 1 g); Coagulation function: International Normalized Ratio \[INR\] or activated Partial Thromboplastin Time \[aPTT\] ≤ 1.5×ULN (for patients not on anticoagulation therapy). 9. Provide a Formalin-Fixed Paraffin-Embedded \[FFPE\] tumor tissue sample for biomarker testing. 10. Effective contraception for fertile participants.

Exclusion criteria

1. Prior anti-cancer therapy within specified washout periods. 2. Systemic immunosuppressive therapy within 2 weeks before first dose. 3. Major surgery or significant traumatic injury within 4 weeks before first dose. 4. Unresolved toxicity from prior therapy \> Grade 1 (except alopecia or Grade ≤2 hypothyroidism stable on hormone replacement). 5. Prior immune-related adverse events \[irAEs\] ≥ Grade 3 leading to treatment discontinuation. 6. Active Central Nervous System \[CNS\] metastases (except stable asymptomatic lesions). 7. History of other malignancies within 3 years (except cured non-melanoma skin cancer or carcinoma in situ). 8. Uncontrolled pleural effusion or ascites requiring repeated drainage. 9. Clinically significant cardiovascular disease (e.g., myocardial infarction, unstable angina, stroke within 6 months; QTcF prolongation; New York Heart Association \[NYHA\] Class II-IV heart failure; pericarditis/myocarditis). 10. History of Interstitial Lung Disease \[ILD\] or non-infectious pneumonitis requiring steroids. 11. Active or history of autoimmune disease requiring systemic treatment in the past 2 years. 12. History of inflammatory bowel disease (e.g., Crohn's disease, ulcerative colitis, or chronic diarrhea). 13. History of hypertensive crisis or hypertensive encephalopathy. 14. Severe coagulation disorders or significant bleeding risk (e.g., severe vascular disease, hemoptysis, intracranial/spinal hemorrhage, tumor invading major vessels). 15. History of abdominal fistula, gastrointestinal perforation, or intra-abdominal abscess. 16. Active infection requiring systemic anti-infective therapy within 2 weeks; severe infection within 4 weeks. 17. Uncontrolled intercurrent illness (e.g., poorly controlled hypertension or Type 2 diabetes mellitus). 18. Known active tuberculosis \[TB\]. 19. Positive for Hepatitis B Virus \[HBV\] surface antigen \[HBsAg\] or core antibody \[HBcAb\] with HBV-Deoxyribonucleic Acid \[DNA\] \> 500 IU/mL; or positive Hepatitis C Virus \[HCV\] antibody with HCV-Ribonucleic Acid \[RNA\] above the lower limit of quantification. 20. Known primary immunodeficiency or positive Human Immunodeficiency Virus \[HIV\] antibody. 21. History of solid organ or hematopoietic stem cell transplantation (except corneal transplant). 22. Pregnant or breastfeeding women. 23. Known hypersensitivity to GB268 or its excipients; history of severe hypersensitivity to other monoclonal antibodies. 24. Any other condition that would make the participant unsuitable for the study. 25. History of severe hypersensitivity to other drugs in the combination regimen.

Design outcomes

Primary

MeasureTime frameDescription
Dose-Limiting Toxicities [DLTs] (Phase Ib)Within 21 days after first doseIncidence of Dose-Limiting Toxicities \[DLTs\] during the first treatment cycle
Objective Response Rate [ORR] (Phase II)Up to approximately 2 yearsORR is the proportion of subjects with complete response(CR) or partial response(PR) , based on Investigator per Response Evaluation Criteria in Solid Tumors version 1.1 \[RECIST v1.1\]

Secondary

MeasureTime frameDescription
Number of participants with adverse events [AEs] (Phase Ib and Phase II)Up to approximately 2 yearsSafety as assessed by clinical laboratory tests, 12-lead electrocardiogram (ECG), vital signs measurements, and the incidence, nature and severity of all adverse events (AEs) and serious AEs (SAEs)
Objective Response Rate [ORR] (Phase Ib)Up to approximately 2 yearsORR is the proportion of subjects with complete response(CR) or partial response(PR) , based on RECIST v1.1.
Duration of Response [DOR] (Phase Ib and Phase II)Up to approximately 2 yearsDOR assessed according to RECIST v1.1
Overall Survival [OS] (Phase Ib and Phase II)Up to approximately 2 yearsOS defined as the time from the first dose to death from any cause
Disease Control Rate [DCR] (Phase Ib and Phase II)Up to approximately 2 yearsDCR assessed according to RECIST v1.1
Progression-Free Survival [PFS] (Phase Ib and Phase II)Up to approximately 2 yearsPFS assessed according to RECIST v1.1
Cmax of GB268 of GB268 (Phase Ib and Phase II)Up to approximately 2 yearsPeak plasma concentration
Tmax of GB268 (Phase Ib and Phase II)Up to approximately 2 yearsTime to peak drug concentration
AUC of GB268 (Phase Ib and Phase II)Up to approximately 2 yearsArea under curve
Number and percentage of participants with Anti-Drug Antibodies [ADAs] (Phase Ib and Phase II)Up to approximately 2 years

Contacts

CONTACTBinghe Xu
xubinghe@medmail.com.cn86 10 67781331

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Aug 1, 2026