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No longer recruiting (closed or complete)Last updated: 13 November 2025

This study is recruiting people with advanced or metastatic solid cancers that express HER2 to evaluate how safe, tolerable and effective a new targeted treatment isA Phase 1/2a, Multicenter, Open-Label, First in Human Study to Assess the Safety, Tolerability, Pharmacokinetics, and Preliminary Antitumor Activity of DB-1303/BNT323 in Patients with Advanced/Metastatic Solid Tumors

Trial purpose

Medical clipboardCancer treatment

Tumor type

Multi-Cancer Multi-Cancer

Age

People18+

Clinical summary

Summary

This is a dose-escalation and dose-expansion clinical trial to evaluate the safety and tolerability of a treatment called DB-1303/BNT323 in people with locally advanced, unresectable, recurrent or metastatic solid tumours that express HER2.

DB-1303/BNT323 is an antibody-drug conjugate which binds to the HER2 protein on cancer cells to deliver targeted treatment.

The study consists of two parts: Part 1 will identify the maximum tolerated dose (MTD) or recommended Phase 2 dose (RP2D) of DB-1303/BNT323; and Part 2 is a dose expansion phase to confirm how safe, tolerable and effective it is in select solid cancers when given at the MTD/RP2D identified in Part .

 

Conditions

This trial is treating people with HER2+ or HER2-expressing solid cancers that are advanced, recurrent, metastatic or unable to be removed with surgery (unresectable)

Eligibility

Inclusion

  • Has a pathologically documented HER2-positive or HER2-expressing (except for cohort 2h where the requirement is HER2-null), advanced/unresectable, recurrent, or metastatic malignant solid tumor that is refractory to or intolerable with standard treatment, or for which no standard treatment is available.
  • At least 1 measurable lesion (per RECIST 1.1)
  • Provide signed informed consent
  • ECOG performance status (PS) of 0-1.
  • LVEF ≥ 50% by ECHO or MUGA
  • Adequate organ functions
  • Provide pre-existing diagnosis of HER2 status or resected tumor samples or undergo fresh tumor biopsy for HER2 testing.
  • Life expectancy of ≥ 3 months.

Additional Inclusion Criteria for Part 2 Expansion Group 9:

1. Has pathologically documented advanced/unresectable, recurrent, or metastatic EC (including UCS and USPC) and has progressed on or after at least 1 line of systemic treatment including platinum-based therapy and exposure to ICI but no more than prior 3 lines of therapy for advanced/unresectable, or metastatic disease. Note: endocrine therapy will not qualify as a systemic therapy line.

Exclusion

  • History of symptomatic CHF (New York Heart Association [NYHA] classes II-IV) or serious cardiac arrhythmia requiring treatment.
  • History of myocardial infarction or unstable angina within 6 months before Day 1.
  • Average QTcF > 450 ms in males and > 470 ms in females
  • History of clinically significant lung diseases
  • Uncontrolled infection requiring IV antibiotics, antivirals, or antifungals.
  • HIV infection with AIDS defining illness or active viral hepatitis.
  • Clinically active brain metastases
  • Unresolved toxicities from previous anticancer therapy, defined as toxicities not yet resolved to NCI-CTCAE version 5.0, Grade ≤ 1 or baseline.
  • A known hypersensitivity to either the drug substances or inactive ingredients in the drug product.
  • Part 2 (expansion) Only:Multiple primary malignancies within 3 years, except adequately resected non- melanoma skin cancer, curatively treated in-situ disease, other solid tumors curatively treated, or contralateral breast cancer.

Inclusion

  • You have had treatment, but your cancer has come back (relapsed or recurrent).
  • Your cancer has spread to other parts of the body (metastatic) or has grown into nearby parts of the body (locally advanced).
  • Your cancer has not spread to other parts of the body, but it is not possible to perform surgery to remove it (unresectable).
  • You have had treatment but your cancer has gotten worse or has not responded to the treatment you have been given.

Exclusion

  • You have certain types of non-cancer medical conditions.
  • You have had certain treatments, surgical procedures or drugs.
Message

Clinical trials have complex eligibility criteria, and other criteria may apply for this trial. Ask your doctor about whether this trial could be right for you.

Participating hospitals

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No longer recruiting (closed or complete) hospitals

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More information

Trial Identifiers

Information on this page is partially produced from ClinicalTrials.gov *. View further details about this trial on the registry via the links below:

Trial sponsor

DualityBio Inc.

Scientific Title

A Phase 1/2a, Multicenter, Open-Label, First in Human Study to Assess the Safety, Tolerability, Pharmacokinetics, and Preliminary Antitumor Activity of DB-1303/BNT323 in Patients with Advanced/Metastatic Solid Tumors

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