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NCT Number: NCT06265428

A Study to Compare DB-1303/BNT323 Versus T-DM1 in Breast Cancer

This study is designed to compare efficacy and safety of DB-1303/BNT323 versus T-DM1 in HER2-positive, unresectable and/or metastatic breast cancer patients previously treated with trastuzumab and taxane.

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This study is active but is not currently recruiting participants.

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Key information

Conditions

HER2-positive Breast Cancer Breast Diseases Breast Neoplasms Neoplasms Neoplasms by Site Skin Diseases Skin and Connective Tissue Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 3

Primary location

015, Bengbu, Anhui, China

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About this study

This is a randomized controlled, 2-arm, open-label, multicenter phase III study to assess the efficacy and safety of DB-1303/BNT323 versus Trastuzumab Emtansine (T-DM1) in patients with human epidermal growth factor receptor 2 (HER2) -positive unresectable/metastatic breast cancer who have been treated with trastuzumab and taxanes. Approximately 224 patients with unresectable or metastatic HER2-positive breast cancer will be randomized 1:1 to receive DB-1303/BNT323 or T-DM1, respectively.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Male or female adults ≥ 18 years at the time of voluntary signing of informed consent.
  • Pathologically confirmed unresectable or metastatic HER2 positive breast cancer previously treated with trastuzumab and taxane
  • Eastern Cooperative Oncology Group (ECOG) performance status score is 0 or 1.
  • Presence of at least one measurable lesion according to RECIST v1.1
  • Expected survival time ≥ 12 weeks.
  • Patients must give informed consent to this study and voluntarily sign written informed consent form prior to the study.

Exclusion criteria

  • Prior anti-HER2 ADC therapy.
  • Previous history of interstitial lung disease/noninfectious pneumonitis/radiation pneumonitis requiring steroid therapy.
  • Known serious hypersensitivity to the active ingredients of the study drug, inactive ingredients in the formulation, or other antibody drugs.
  • Multiple primary malignancies within 3 years, except for adequately resected non-melanoma skin cancer, curatively treated in situ tumor, or contralateral breast cancer
  • Uncontrolled infection requiring intravenous antibiotics, antiviral or antifungal agents, autoimmune disease requiring treatment, uncontrolled diabetes, hypertension, or other systemic disease that makes compliance with study procedures difficult
  • Unrecovered toxicity from prior anticancer therapy, defined as toxicity (except for alopecia) not recovered to ≤Grade 1 (NCI-CTCAE v5.0) or baseline.

NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.

Treatment and study plan

DB-1303/BNT323

Drug

Administered I.V.

T-DM1

Drug

Administered I.V.

Primary outcomes

  1. Progression Free Survival (PFS) by Blinded Independent Central Review (BICR) assessment per Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1)

    Time frame: Up to approximately 24 months.

    Defined as the time from randomization to the first documented disease progression per RECIST 1.1 as assessed by BICR or death due to any cause, whichever occurs first

Secondary outcomes

  1. Overall Survival (OS)

    Time frame: Up to approximately 24 months.

    Defined as the time from randomization to death due to any cause.

  2. Progression Free Survival (PFS) by Investigator assessment per RECIST 1.1

    Time frame: Up to approximately 24 months.

    Defined as the time from randomization to the first documented disease progression per RECIST 1.1 as assessed by investigator or death due to any cause, whichever occurs first.

  3. Objective response rate (ORR) by BICR and investigator assessment per RECIST 1.1

    Time frame: Up to approximately 24 months.

    Defined as the percentage of patients who have a complete response (CR) or partial response (PR) per RECIST 1.1 as assessed by BICR and investigator assessment.

  4. Duration of response (DoR) by BICR and investigator assessment per RECIST 1.1

    Time frame: Up to approximately 24 months.

    Defined as the time from first response (CR or PR) to subsequent disease progression per RECIST 1.1 as assessed by BICR and investigator assessment, or death from any cause, whichever occurs first.

  5. PK parameters: maximum observed concentration (Cmax)

    Time frame: Up to approximately 24 months.

    Maximum observed concentration (Cmax) of DB-1303/BNT323 Antibody-drug conjugate (ADC) and free toxin P1003, etc. after DB-1303/BNT323 administration

  6. PK parameters: time to maximum concentration (Tmax)

    Time frame: Up to approximately 24 months.

    Time to maximum concentration (Tmax) of DB-1303/BNT323 ADC and free toxin P1003, etc. after DB-1303/BNT323 administration

  7. Adverse events (AEs)

    Time frame: Up to approximately 24 months.

    Number and percentage of patients who report serious adverse events (SAEs), treatment-emergent adverse events (TEAEs), TEAEs leading to study drug discontinuation, adverse events of special interest (AESIs) (graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events version 5.0[NCI-CTCAE v5.0])

  8. Patient reported outcomes (PROs): European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire (QLQ) - C30

    Time frame: Up to approximately 24 months.

    Change from baseline in the functioning/symptom/global quality of life (QoL) subscales of EORTC QLQ-C30. Scale scores range from 0-100. For functioning and global QoL scales, higher scores indicate better functioning or global health status. For symptom scales, higher scores indicate greater symptom burden.

  9. Patient reported outcomes (PROs): EORTC QLQ-BR45

    Time frame: Up to approximately 24 months.

    Change from baseline in the functioning/symptom subscales of EORTC QLQ-BR45. Scale scores range from 0-100. For functioning scales, higher scores indicate better functioning. For symptom scales, higher scores indicate greater symptom burden.

  10. Patient reported outcomes (PROs): European Quality of Life Five Dimension Five Level Scale (EQ-5D-5L)

    Time frame: Up to approximately 24 months.

    Change from baseline in EQ-5D-5L health state utility index score and Visual Analogue Scale (VAS) score. VAS score range from 0-100, higher scores indicate better health status.

  11. European Quality of Life Five Dimension Five Level Scale (EQ-5D-5L)

    Time frame: Up to approximately 24 months.

    EQ-5D-5L health state utility index score and Visual Analogue Scale (VAS) score. The change from baseline value will be reported.

  12. Anti-drug antibodies (ADA)

    Time frame: Up to approximately 24 months.

    Number and percentage of patients who develop anti-drug antibody (ADA) for DB-1303/BNT323.

Sponsors and collaborators

Lead sponsor

DualityBio Inc.

Industry

Collaborators

  • BioNTech SE

Registry information

Official study title

A Phase III, Multicenter, Open-label, Randomized Study to Compare DB-1303 Versus T-DM1 in Patients With HER2-positive Unresectable/Metastatic Breast Cancer Who Have Been Treated With Trastuzumab and a Taxane (Dynasty-Breast01)

Important dates

Study start
2024
Primary completion
2026
Study completion
2026
First posted
Feb 20, 2024
Registry last updated
Oct 20, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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