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Study of BNT323 and BNT327 for Advanced Breast Cancer

This study is testing two investigational treatments, BNT323 and BNT327, given together as an intravenous infusion (into a vein). The goal is to find the best dose of this combination and see if it is safe and helpful for people with advanced breast cancer that is locally advanced, cannot be removed by surgery, or has spread (metastatic). The study is looking for people aged 18 and older with breast cancer, and your HER2 status (a protein found on some breast cancer cells) will be checked. The treatments work as antibody-drug conjugates, which are designed to deliver medicine directly to cancer cells. The study will measure side effects and how well the treatment works.

Study design
This is a two-part study with 380 planned participants. Part 1 will find the best dose, and Part 2 will further evaluate the treatment's effectiveness and safety. Some participants in Part 2 may be randomly assigned to different treatment groups.
What's involved
Not specified in the trial record.
Compensation
Not stated in the trial record.
Follow-up
You would be monitored for side effects from the start of treatment until 90 days after your last dose of the study medication.

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.

NCT06827236

A Clinical Study to Find the Optimal Dose of an Investigational Treatment Called BNT323 When Used in Combination With Another Investigational Treatment, BNT327, and to Test if That Combination Treatment is Safe and Beneficial for Patients With Advanced Breast Cancer

Recruiting
PHASE1Ages 18+InterventionalTreatment
BioNTech SE
~380 participants
Updated 2026-08-27 on ClinicalTrials.gov
What's tested:BNT323BNT327

At a glance

Recruiting sites
78 of 78 listed sites are recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Part 1 - Occurrence of dose limiting toxicities (DLTs)
Measured over During the DLT evaluation period (Cycle 1), i.e., the time of initiation of the first dose of investigational medicinal product (IMP) up to 21 days
+3 more outcomes measured

Conditions

Locally Advanced Breast Cancer
Unresectable Breast Carcinoma
Metastatic Breast Cancer

Explore related trials

Breast Carcinoma

Where it's being run

78 sites across 19 states
Turkey (Türkiye)11
China9
New York8
Spain7
United Kingdom7
Italy5
New Jersey4
France4

Study leadership

  • BioNTech Responsible Person · STUDY_DIRECTOR · BioNTech SE

Who to contact

BioNTech clinical trials patient information
[email protected]
+49 6131 9084 · ext. 0
Email the study team

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Do you actually qualify for this trial?

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Eligibility criteria

Inclusion

Have pathologically documented BC that:
Is locally advanced, unresectable or metastatic.
Has a confirmed HER2 status as determined by the local laboratory as standard of care testing prior to study screening (Part 1, Part 2 Cohorts 2 and 4) or the central laboratory (Part 2, Cohorts 1 and 3) from the most recently collected pre-randomization tumor sample.
Has a documented history of HER2 expression consistent with the subgroup definitions (i.e., HER2-low, HER2-ultralow, HER2-null, HER2-positive, or TNBC) as per current American Society of Clinical Oncology/College of American Pathologists guidelines.
Have measurable disease defined by RECIST v1.1.
Has left ventricular ejection fraction ≥55% by either echocardiography or multi-gated acquisition (scanning) within 28 days before randomization/enrollment.

Exclusion

Have history of small bowel obstruction requiring hospitalization within the past 3 months prior to the first dose of IMP.
Have an uncontrolled intercurrent illness that would limit compliance with study requirement or substantially increase risk of incurring adverse events.
Have clinically uncontrolled pleural effusion, ascites or pericardial effusion requiring drainage, peritoneal shunt, or cell-free concentrated ascites reinfusion therapy within 2 weeks prior to randomization/enrollment.
Have a history of (non-infectious) interstitial lung disease (ILD)/pneumonitis that required steroids, have current ILD/pneumonitis, or where suspected ILD/pneumonitis cannot be ruled out by imaging at screening.
Had prior treatment with topoisomerase I inhibitors, including antibody-drug conjugates with topoisomerase I inhibitor payloads such as trastuzumab deruxtecan.
Have received any of the following therapies or drugs prior to the initiation of the study:
Participants who have received prior treatment with BNT323.
Participants who received prior treatment with a programmed death-ligand 1 (PD-L1) / vascular endothelial growth factor (VEGF) bispecific antibody. Note: Prior treatment with programmed death 1 (PD-1)/VEGF bispecific antibodies, PD-1/PD-L1 inhibitors or anti-VEGF therapies are permitted.
Have received other systemic immunostimulatory agents or immunosuppressive therapies (such as interferon-α, interleukin-2, or methotrexate) within 4 weeks prior to the initiation of study treatment or are within five half-lives of the treatment drug (whichever is longer). Exception: excluding local, intranasal, intraocular, intra-articular or inhaled corticosteroids, short term use (≤7 days) of corticosteroids for prophylaxis (e.g., prevention of contrast agent allergy) or treatment of non-autoimmune conditions (e.g., delayed hypersensitivity reactions caused by exposure to allergens).
Have received systemic corticosteroids (at a dosage greater than 10 mg/day of prednisone or an equivalent dose of other corticosteroids) within 3 weeks prior to the initiation of study treatment.

What this trial measures

  • Part 1 - Occurrence of dose limiting toxicities (DLTs)During the DLT evaluation period (Cycle 1), i.e., the time of initiation of the first dose of investigational medicinal product (IMP) up to 21 days

    By dose level.

  • Occurrence of Treatment-emergent adverse events (TEAEs), Grade ≥3 TEAEs, serious adverse events (SAEs), treatment-related TEAEs, treatment-related Grade ≥3 TEAEs, and treatment-related SAEsFrom the time of initiation of the first dose of IMP to 90 days after the last IMP dose

    In Part 1 by dose level. In Part 2 by cohort and arm.

  • Occurrence of dose interruption, reduction, and discontinuation due to TEAEsFrom the time of initiation of the first dose of IMP to 90 days after the last IMP dose

    In Part 1 by dose level. In Part 2 by cohort and arm.

  • Part 2 - Objective response rate (ORR)From the time of initiation of the first dose of IMP to last tumor assessment scan, i.e., up to 36 months.

    ORR defined as the proportion of participants in whom a confirmed complete response (CR) or partial response (PR) (per Response Evaluation Criteria in Solid Tumors version 1.1 \[RECIST v1.1\] based on the investigator's assessment) is observed as best overall response. By cohort and arm.