Phase 2: testing SMP-656 Injection for HER2-positive Breast Cancer

What this phase means

Phase 2: researchers already know a roughly safe dose (from phase 1). This stage asks whether the treatment actually helps the condition, and watches side effects more closely.

Phase labels are FDA/ICH categories applied to the registry Phase field. They are not a finding that this study succeeded.

What the registry says happens

If you join, the listed intervention(s) are SMP-656 Injection, or SMP-656 Injection. The registry lists allocation as randomized. The goal of this clinical trial is to learn if single-agent SMP-656 works to treat patients with HER2-positive locally advanced or metastatic breast cancer who have progressed after prior HER2-targeted topoisomerase inhibitor antibody-drug conjugate (ADC) treatment.

They plan to enroll about 60 people at 15 sites. Taking part typically means taking a study drug (or dummy pill) plus check-ins.

Official title (unrewritten)

A Randomized, Open-Label, Dose-Optimization Phase II Clinical Trial to Evaluate the Efficacy and Safety of Single-Agent SMP-656 in Patients With HER2-Positive Locally Advanced or Metastatic Breast Cancer Who Progressed After Prior Treatment With HER2-Targeted Topoisomerase Inhibitor ADCs

Interventions: SMP-656 Injection, SMP-656 Injection

Primary outcome (registry wording): Objective Response Rate (ORR) assessed by Independent Review Committee (IRC)

Who it is for (from inclusion criteria)

• Ages 18 Years to any
• Patients with histologically or cytologically confirmed unresectable HER2-positive locally advanced or metastatic breast cancer, regardless of hormone receptor (HR) status
• HER2-positive status confirmed by testing at the study center or an accredited laboratory, where HER2 positivity is defined as IHC 3+, or IHC 2+ with positive fluorescence in situ hybridization (FISH+) results
• Patients with HER2-positive locally advanced or metastatic breast cancer who have received prior treatment with one TOP inhibitor ADC targeting HER2 (e.g., DS-8201 and other ADCs with topoisomerase inhibitor payloads), and have experienced disease progression
• Bone marrow function: absolute neutrophil count (ANC) ≥ 1.5 × 10⁹/L; platelet count (PLT) ≥ 80 × 10⁹/L; hemoglobin (Hb) ≥ 90 g/L;
• Hepatic function: aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 2.5 × upper limit of normal (ULN); total serum bilirubin (TBIL) ≤ 1.5 × ULN, with the following exceptions;
• For participants with confirmed liver metastases: AST and/or ALT ≤ 5 × ULN;
• For participants diagnosed with Gilbert's syndrome: TBIL ≤ 3 × ULN;