A Phase 1/2a, Multicenter, Open-Label, Non-Randomized First in Human Study to Assess the Safety, Tolerability, Pharmacokinetics, and Preliminary Antitumor Activity of DB-1303 in Patients With Advanced/Metastatic Solid Tumors. (DB-1303-O-1001)

Trial summary:

Dose-escalation and dose-expansion Phase 1/2a trial to evaluate the safety and tolerability of DB-1303 in subjects with advanced solid tumors that express HER2.

Receptor status / problem studied:

Low HER2 expressing Breast Cancer and Endometrial Cancer

Inclusion criteria

  • Has a pathologically documented HER2-positive or HER2-expressing 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.

Exclusion criteria

  • 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.
  • 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.
  • Part 2 only: Prior treatment with HER2 ADC agents except T-DM1, RC48-ADC

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Open for recruitment

Trial Title



Breast cancer Endometrial cancer

Type of trial


Type of treatement

Medical Oncology





Principal Investigator
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