A Study to Evaluate the Pharmacokinetics, Efficacy, and Safety of HLX319 vs. EU-Phesgo® in the Neoadjuvant Therapy of HER2-Positive Early or Locally Advanced Breast Cancer

A Multicenter, Randomized, Double-Blind, Parallel-Controlled Phase I Clinical Study to Evaluate the Pharmacokinetics, Efficacy, and Safety of Phesgo® Biosimilar HLX319 vs. EU-Phesgo® in the Neoadjuvant Therapy of HER2-Positive Early or Locally Advanced Breast Cancer

This is a study to compare the similarity in Pharmacokinetics (PK) profile of HLX319 vs. EU-Phesgo® in patients with HER2-positive early or locally advanced breast cancer .

Study Overview

• Status: Not yet recruiting
• Conditions: HER2 + Breast Cancer
• Intervention / Treatment: Drug: HLX319; Drug: EU-Phesgo®

Detailed Description

This is a randomized, double-blind, parallel-controlled, multi-center Phase I equivalence study to compare the similarity in PK profile of HLX319 vs. EU-Phesgo® in patients with HER2-positive early or locally advanced breast cancer with a primary tumor > 2 cm or nodes-positive.

• Study Type: Interventional
• Enrollment (Estimated): 258
• Phase: Phase 1

Contacts and Locations

• Study Contact: Name: Qi Jin; Phone Number: 86 159 5516 0489; Email: Qi_jin@henlius.com

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Voluntary participation in the clinical study and signed the Informed Consent Form (ICF).
• Male or female aged ≥ 18 years old at the time of signing the ICF;
• Histologically confirmed invasive breast cancer, stage II-IIIC, Human Epidermal Growth Factor Receptor 2 (HER2) positive confirmed by central laboratory.
• Participants agree to undergo surgery while meeting the criteria for surgery after neoadjuvant therapy.
• Left ventricular ejection fraction (LVEF) at baseline ≥ 55%.
• An Eastern Cooperative Oncology Group (ECOG) performance status (PS) score of 0-1.
• Adequate major organ functions.
• Women with child-bearing potential have a negative result of serum pregnancy test at screening period (within 7 days prior to the first dose) or if they are infertile, non- lactating, reproduction-age men and women following highly effective contraceptive measures until 7 months after last dose.

Exclusion Criteria:

• Stage IV breast cancer, bilateral breast cancer, or multicentric breast cancer.
• History of other malignancy within 5 years.
• Prior systemic therapy for breast cancer treatment or radiotherapy.
• Patients with a history of ductal carcinoma in situ (DCIS) or lobular carcinoma in situ (LCIS) who have received systemic therapy or radiotherapy to the ipsilateral breast.
• Patients who have undergone excision biopsy of the primary tumor and/or axillary lymph nodes or lymph node dissection.
• Have severe heart disease or medical conditions.
• Participants with viral hepatitis or those with autoimmune hepatitis, sclerosing cholangitis, or liver cirrhosis.
• Human Immunodeficiency Virus (HIV) infection, HIV antibody positive.
• Daily use of corticosteroid treatment is required.
• Sensitivity to any study medications or any of its ingredients or excipients.
• Participants who underwent any major surgery within 28 days prior to the first dose. Or participants who have received local radiotherapy, radiofrequency ablation, or interventional therapy within 2 weeks prior to the first dose.
• Received another interventional clinical trial therapy within 4 weeks prior to enrollment in the study, or intentionally participated in another interventional clinical trial during the entire study period.
• Severe, uncontrolled systemic diseases that may currently interfere with the therapeutic plan.
• Any other conditions which are inappropriate 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: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: HLX319; The regimen in the experimental group is HLX319 in combination with docetaxel and carboplatin.	Drug: HLX319; HLX319 is a biosimilar of pertuzumab-trastuzumab monoclonal antibody injection (subcutaneous injection)
Active Comparator: EU-Phesgo®; The regimen in the control group is EU-Phesgo® in combination with docetaxel and carboplatin.	Drug: EU-Phesgo®; EU-Phesgo® is an original marketed drug product, with the generic name pertuzumab-trastuzumab monoclonal antibody injection (subcutaneous injection)

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Peak concentration (Cmax)	Peak concentration after a single drug administration in Cycle 1.	up to 180 days
Area under the serum drug concentration-time curve from 0 to 21 days (AUC0-21d)	Area under the serum drug concentration-time curve from 0 to 21 days after a single drug administration in Cycle 1.	up to 180 days
Steady-state peak concentration (Cmax,ss)	The steady-state peak concentration after multiple doses administration in Cycle 4.	up to 180 days
Steady-state area under the serum drug concentration-time curve within a dosing interval (AUCss)	Steady-state area under the serum drug concentration-time curve within a dosing interval after multiple doses administration in Cycle 4.	up to 180 days

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Trough concentration (Ctrough)	Trough concentration after a single dose administration	up to 180 days
Area under the serum drug concentration-time curve from time 0 to infinity (AUC0-inf)	Area under the serum drug concentration-time curve from time 0 to infinity after a single dose administration	up to 180 days
Percentage of extrapolated area in the total AUC (%AUCex)	Percentage of extrapolated area in the total AUC after a single dose administration	up to 180 days
Time to peak concentration (Tmax)	time to peak concentration after a single dose administration	up to 180 days
Elimination half-life (T1/2)	elimination half-life after a single dose administration	up to 180 days
Total clearance (CL/F)	total clearance after a single dose administration	up to 180 days
Terminal phase distribution volume (Vz/F)	terminal phase distribution volume after a single dose administration	up to 180 days
Mean residence time (MRT)	mean residence time after a single dose administration	up to 180 days
Steady-state trough concentration (Ctrough,ss)	steady-state trough concentration after multiple doses administration in Cycle 4	up to 180 days
Average steady-state concentration (Caverage,ss)	average steady-state concentration after multiple doses administration in Cycle 4	up to 180 days
Steady-state time to peak concentration (Tmax,ss)	steady-state time to peak concentration after multiple doses administration in Cycle 4	up to 180 days
Elimination half-life (T1/2,ss)	elimination half-life after multiple doses administration in Cycle 4	up to 180 days
Steady-state volume of distribution (Vss/F)	steady-state volume of distribution after multiple doses administration in Cycle 4	up to 180 days
Steady-state total clearance (CLss/F)	steady-state total clearance after multiple doses administration in Cycle 4	up to 180 days
accumulation ratio based on Cmax (RCmax)	accumulation ratio based on Cmax after multiple doses administration in Cycle 4	up to 180 days
Accumulation ratio based on AUC (RAUC)	accumulation ratio based on AUC after multiple doses administration in Cycle 4	up to 180 days
The total pathological complete response (tpCR) rate assessed by the investigator		up to 180 days
Breast pathologic complete response (bpCR) rate assessed by the investigator		up to 180 days
Objective response rate (ORR) assessed by the investigator	according to Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 criteria	up to 180 days
Incidence and severity of adverse events (AEs)	severity determined according to National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) Version 6.0	up to 180 days
Number of participants with abnormal vital signs	Detailed Outcome Measure will be defined in the Statistical Analysis Plan	up to 180 days
Number of participants with abnormal physical examination findings	Detailed Outcome Measure will be defined in the Statistical Analysis Plan	up to 180 days
Number of participants with abnormal Laboratory tests results	Detailed Outcome Measure will be defined in the Statistical Analysis Plan	up to 180 days
Number of participants with abnormal 12-lead ECG readings	Detailed Outcome Measure will be defined in the Statistical Analysis Plan	up to 180 days
Positivity rates of anti-drug antibodies (ADA)		up to 180 days
Positivity rates of neutralizing antibodies (NAb)		up to 180 days

Collaborators and Investigators

• Sponsor: Shanghai Henlius Biotech

Study record dates

Study Major Dates

• Study Start (Estimated): July 3, 2026
• Primary Completion (Estimated): April 23, 2027
• Study Completion (Estimated): July 22, 2027

Study Registration Dates

• First Submitted: May 8, 2026
• First Submitted That Met QC Criteria: May 15, 2026
• First Posted (Actual): May 22, 2026

Study Record Updates

• Last Update Posted (Actual): May 22, 2026
• Last Update Submitted That Met QC Criteria: May 15, 2026
• Last Verified: May 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: HLX319-BC001

Drug and device information, study documents

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