Neoadjuvant SHR-A1811 Combined With Pertuzumab in HER2-Positive Breast Cancer: An Exploratory Clinical Study.

Exploratory Clinical Study of Neoadjuvant SHR-A1811 Combined With Pertuzumab in Patients With HER2-Positive Breast Cancer

This is a multicenter, two-arm, exploratory clinical study designed to evaluate the efficacy and safety of a response-guided neoadjuvant treatment strategy in patients with HER2-positive early or locally advanced breast cancer.

Breast cancer is the most common malignancy in women worldwide, and HER2-positive disease accounts for approximately 15-20% of cases and is associated with aggressive tumor biology and a higher risk of recurrence. The introduction of HER2-targeted therapies, including trastuzumab and pertuzumab, has significantly improved patient outcomes. However, a proportion of patients exhibit suboptimal response to standard neoadjuvant therapy, highlighting the need for more effective treatment strategies.

In this study, approximately 100 eligible patients will be enrolled. All patients will initially receive 2 cycles of standard neoadjuvant therapy with trastuzumab, pertuzumab, and chemotherapy (THP or TCbHP). Tumor response will be assessed according to RECIST version 1.1 criteria. Patients with tumor reduction greater than 40% will continue the same regimen for an additional 4 cycles. Patients with tumor reduction of 40% or less will switch to an alternative regimen consisting of SHR-A1811, a novel HER2-targeted antibody-drug conjugate, in combination with pertuzumab for 4 cycles.

SHR-A1811 is an investigational HER2-targeted antibody-drug conjugate designed to deliver a cytotoxic payload directly to tumor cells, potentially overcoming resistance to prior HER2-targeted therapies. Emerging clinical data have demonstrated promising anti-tumor activity and manageable safety in HER2-positive breast cancer.

Clinical data, including baseline characteristics, imaging findings, and pathological markers such as Ki-67, will be collected throughout the study. Efficacy will be evaluated based on imaging assessments according to RECIST 1.1 criteria and pathological response at surgery, while safety will be monitored during treatment.

The primary objective of this study is to explore whether switching to SHR-A1811 in combination with pertuzumab in patients with suboptimal early response can improve pathological complete response (pCR) rates. Secondary objectives include evaluation of safety and tolerability of the treatment strategies.

This study aims to provide evidence for an individualized, response-adapted neoadjuvant treatment approach in HER2-positive breast cancer, and to optimize treatment outcomes for patients with inadequate response to standard therapy.

Study Overview

• Status: Not yet recruiting
• Conditions: Breast Cancer
• Intervention / Treatment: Drug: Pertuzumab; Drug: trastuzumab; Drug: Chemotherapy; Drug: SHR-A1811

Detailed Description

HER2-positive breast cancer is driven by overexpression or amplification of the HER2 receptor, leading to activation of downstream signaling pathways such as MAPK and PI3K/AKT that promote tumor growth and survival. Although dual HER2 blockade with trastuzumab and pertuzumab in combination with chemotherapy has become a standard neoadjuvant treatment, a subset of patients exhibit insufficient tumor response, indicating biological heterogeneity and potential resistance to therapy.

Pathological complete response (pCR) after neoadjuvant treatment is associated with improved long-term outcomes in HER2-positive breast cancer. Therefore, early identification of patients with suboptimal response and timely treatment modification may represent an effective strategy to improve prognosis.

Antibody-drug conjugates (ADCs) are designed to selectively deliver cytotoxic agents to tumor cells through antigen-specific targeting. SHR-A1811 is an investigational HER2-directed ADC composed of a humanized anti-HER2 monoclonal antibody linked to a topoisomerase I inhibitor payload via a cleavable linker. Preclinical data have demonstrated potent anti-tumor activity in HER2-expressing models, including those with reduced sensitivity to prior HER2-targeted therapies.

Emerging clinical evidence supports the antitumor activity and manageable safety profile of SHR-A1811 in HER2-positive breast cancer. Its mechanism of action suggests potential benefit in patients with inadequate response to standard HER2-targeted neoadjuvant regimens.

This study is designed to investigate a response-adapted treatment strategy, in which early tumor response is used to guide subsequent therapy selection. By incorporating an alternative HER2-targeted approach for patients with suboptimal response, this study aims to explore strategies to improve treatment efficacy while maintaining an acceptable safety profile.

The results of this study are expected to provide evidence to support individualized neoadjuvant treatment strategies for patients with HER2-positive breast cancer.

• Study Type: Interventional
• Enrollment (Estimated): 100
• Phase: Phase 2

Contacts and Locations

• Study Contact: Name: Li Ma, MD; Phone Number: 13932116886; Email: mali1021@126.com

Study Locations

• China
  • Hebei
    • Shijiazhuang, Hebei, China, 050000
      • The Fourth Hospital of Hebei Medical University
      • Contact: Li Ma, MD; Phone Number: 13932116886; Email: mali1021@126.com

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

Participants must meet all of the following criteria:

1. Age ≥18 and ≤70 years.
2. Eastern Cooperative Oncology Group (ECOG) performance status of 0-1.
3. At least one measurable lesion according to RECIST version 1.1.
4. Histologically confirmed invasive breast cancer with clinical stage:

Stage II (T2N0-1M0 or T3N0M0), or Stage III (T2N2-3M0, T3N1-3M0, or T4N0-3M0). 5.HER2-positive invasive breast cancer confirmed by histopathology, defined as: HER2 immunohistochemistry (IHC) 3+, or HER2 IHC 2+ with fluorescence in situ hybridization (FISH) positivity, as determined by the pathology department of the participating center. 6.Adequate organ function, defined as:

1. Hematologic function (no blood transfusion, blood products, granulocyte colony-stimulating factor [G-CSF], or other hematopoietic growth factors within 14 days prior to testing):

   Hemoglobin (Hb) ≥100 g/L; Absolute neutrophil count (ANC) ≥1.5 × 10⁹/L; Platelet count (PLT) ≥100 × 10⁹/L.

2. Biochemical function:

   Total bilirubin (TBIL) ≤1 × upper limit of normal (ULN); Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤1.5 × ULN; Alkaline phosphatase (ALP) ≤2.5 × ULN; Blood urea nitrogen (BUN) and serum creatinine (Cr) ≤1.5 × ULN.

3. Cardiac function:

Left ventricular ejection fraction (LVEF) ≥55% by echocardiography; QT interval corrected by Fridericia's formula (QTcF) ≤450 ms. 7.Women of childbearing potential must have a negative serum pregnancy test within 14 days prior to enrollment and agree to use effective contraception during the study and for at least 8 weeks after the last dose of study treatment.

8.Willingness to participate in the study, provide written informed consent, and comply with study procedures and follow-up.

Exclusion Criteria:

Participants meeting any of the following criteria will be excluded:

1. Prior receipt of any anti-tumor therapy not specified in the study protocol, including but not limited to chemotherapy, radiotherapy, targeted therapy, or endocrine therapy for the current breast cancer.
2. Concurrent receipt of any other anti-tumor therapy during the study. Bilateral breast cancer, inflammatory breast cancer, or occult breast cancer. Stage IV (metastatic) breast cancer.
3. History of other malignancies within the past 5 years, except for adequately treated carcinoma in situ of the cervix.
4. Severe dysfunction of major organs, including but not limited to cardiac, hepatic, or renal insufficiency.
5. Participation in another interventional clinical trial within 4 weeks prior to enrollment.

6. Known hypersensitivity to any component of the study drugs; history of immunodeficiency, including positive human immunodeficiency virus (HIV) test, active hepatitis C virus (HCV) infection, active hepatitis B infection, congenital or acquired immunodeficiency disorders, or history of organ transplantation.

   History of significant cardiac disease, including but not limited to:

   Clinically significant arrhythmia requiring treatment; Myocardial infarction; Heart failure;

7. Any other cardiac condition that, in the investigator's judgment, makes the participant unsuitable for the study.
8. Pregnant or breastfeeding women; women of childbearing potential with a positive pregnancy test at baseline or unwilling to use effective contraception throughout the study period.

9. Any serious concomitant disease that, in the investigator's judgment, may compromise patient safety or interfere with study participation, including but not limited to uncontrolled hypertension, severe diabetes, or active infection.

   History of neurological or psychiatric disorders, including epilepsy or dementia.

10. Any other condition that, in the investigator's judgment, makes the participant unsuitable for participation in this study.

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Standard Neoadjuvant Therapy (THP/TCbHP); All enrolled patients will initially receive 2 cycles of standard neoadjuvant therapy with trastuzumab, pertuzumab, and chemotherapy (THP or TCbHP). Patients who achieve a tumor reduction greater than 40% according to RECIST version 1.1 will continue the same regimen for an additional 4 cycles.	Drug: Pertuzumab; Pertuzumab is a monoclonal antibody targeting HER2, administered intravenously as part of dual HER2 blockade.; Drug: trastuzumab; Trastuzumab is a HER2-targeted monoclonal antibody administered intravenously as part of standard neoadjuvant therapy.; Drug: Chemotherapy; Chemotherapy includes taxane-based regimens with or without carboplatin (THP or TCbHP) administered according to institutional standards.
Experimental: SHR-A1811 Plus Pertuzumab; All enrolled patients will initially receive 2 cycles of standard neoadjuvant therapy. Patients with a tumor reduction of 40% or less according to RECIST version 1.1 will switch to SHR-A1811 in combination with pertuzumab for 4 cycles.	Drug: Pertuzumab; Pertuzumab is a monoclonal antibody targeting HER2, administered intravenously as part of dual HER2 blockade.; Drug: SHR-A1811; SHR-A1811 is a HER2-targeted antibody-drug conjugate administered intravenously in combination with pertuzumab as neoadjuvant therapy.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Total Pathological Complete Response (tpCR)	Number of participants achieving total pathological complete response, defined as no residual invasive cancer in both breast and axillary lymph nodes (ypT0/is ypN0) at the time of surgery following completion of neoadjuvant therapy.Metric：Proportion of participants (%)	At surgery (approximately 18 weeks after initiation of treatment)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Objective Response Rate (ORR) per RECIST v1.1	Proportion of participants with a best overall response of complete response (CR) or partial response (PR) according to RECIST version 1.1.	From baseline to surgery (approximately 18 weeks)
Event-Free Survival (EFS)	Time from treatment initiation to the occurrence of disease progression, local or distant recurrence, or death from any cause.Metric：Time-to-event (months).	From first dose up to 3 years
Breast Conservation Rate	Proportion of participants who undergo breast-conserving surgery after completion of neoadjuvant therapy.	At surgery (approximately 18 weeks)
Number of Participants With Treatment-Related Adverse Events (TRAEs)	Number of participants experiencing treatment-related adverse events, assessed according to CTCAE version 5.0.	From first dose to 30 days after last dose
Number of Participants With Grade ≥3 Adverse Events	Number of participants experiencing Grade 3 or higher adverse events according to CTCAE version 5.0.	From first dose to 30 days after last dose
Number of Participants With Serious Adverse Events (SAEs)	Number of participants experiencing serious adverse events as defined by ICH guidelines.	From first dose to 30 days after last dose

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Circulating Tumor DNA (ctDNA) Levels	Change in ctDNA levels from baseline to post-treatment timepoints (after 2 cycles and pre-surgery), measured using next-generation sequencing.	Baseline, after 2 cycles (~6 weeks), and pre-surgery (~18 weeks)
Predictive Performance of Multi-modal Biomarker Model for Treatment Response	Evaluation of a predictive model integrating genomic features, clinicopathological characteristics, imaging findings, and laboratory biomarkers to predict pathological response.Metric：Area under the curve (AUC).	Up to surgery (~18 weeks)

Collaborators and Investigators

• Sponsor: Hebei Medical University Fourth Hospital
• Collaborators: Jiangsu Hengrui Pharmaceutical Co., Ltd.

Study record dates

Study Major Dates

• Study Start (Estimated): May 1, 2026
• Primary Completion (Estimated): July 1, 2027
• Study Completion (Estimated): July 1, 2029

Study Registration Dates

• First Submitted: April 1, 2026
• First Submitted That Met QC Criteria: April 7, 2026
• First Posted (Actual): April 14, 2026

Study Record Updates

• Last Update Posted (Actual): April 14, 2026
• Last Update Submitted That Met QC Criteria: April 7, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Neoadjuvant therapy; HER2-positive; HER2-targeted therapy; Antibody-drug conjugate; SHR-A1811
• Additional Relevant MeSH Terms: Neoplasms by Site; Neoplasms; Skin Diseases; Breast Diseases; Skin and Connective Tissue Diseases; Breast Neoplasms; Amino Acids, Peptides, and Proteins; Proteins; Therapeutics; Antibodies, Monoclonal, Humanized; Antibodies, Monoclonal; Antibodies; Immunoglobulins; Immunoproteins; Blood Proteins; Serum Globulins; Globulins; Trastuzumab; pertuzumab; Drug Therapy
• Other Study ID Numbers: OBU-BC-II-279

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Individual participant data that underlie the results reported in this study, after de-identification, will be made available upon reasonable request. The study protocol, statistical analysis plan, and informed consent form may also be available. Data will be available beginning 6 months after publication and ending 3 years after publication. Requests should be directed to the corresponding author or sponsor.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF

Drug and device information, study documents

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