In short
Trastuzumab is a targeted cancer drug, a monoclonal antibody, used to treat HER2-positive breast cancer and certain stomach cancers. The substance described here is a radiolabelled form, 89Zr-trastuzumab, being studied as an imaging agent to predict response to antibody-drug conjugate therapy in advanced HER2-positive breast cancer. The clinical trial data includes three records: one withdrawn study, one completed study, and one authorised pilot study, all Phase 2.
89Zr-SucDf-Trastuzumab is an investigational imaging agent. It combines the HER2-targeting antibody trastuzumab with a radioactive tracer, zirconium-89, allowing HER2-positive tumours to be visualised with PET/CT scans.
Key points
- 89Zr-trastuzumab is a radiolabelled form of trastuzumab used for PET/CT imaging.
- It is being studied in advanced HER2-positive breast cancer.
- One trial was withdrawn with 31 planned participants.
- One trial is completed with 109 participants.
- One trial is authorised and plans to enrol 30 participants.
- All trials are Phase 2 interventional studies.
What is trastuzumab?
Trastuzumab is a targeted cancer drug, also known by the trade names Herceptin, Herzuma and Ontruzant. It is a humanised IgG1 monoclonal antibody produced by mammalian cell culture. The radiolabelled form, 89Zr-trastuzumab, is an investigational imaging agent used in clinical trials to visualise HER2 expression in tumours. Trastuzumab is classified as an antineoplastic agent, monoclonal antibody (ATC code L01XC03). The substance is already authorised as a medicine for treating HER2-positive breast cancer and gastric cancer.
How does trastuzumab work?
Trastuzumab works by locking onto a protein called human epidermal growth factor receptor 2 (HER2) on cancer cells. HER2 makes cells grow and divide, and some breast and stomach cancers have large amounts of it. By attaching to HER2, trastuzumab aims to stop the cancer cells from growing and to kill them. The radiolabelled version, 89Zr-trastuzumab, uses this same targeting mechanism but carries zirconium-89, which emits radiation detectable by PET/CT imaging. This allows researchers to see where HER2-positive tumour cells are located in the body.
Which conditions is it studied for?
- Advanced/metastatic HER2-positive breast carcinoma — breast cancer that has spread beyond the breast and tests positive for HER2.
- Locally advanced or metastatic breast cancer — breast cancer that is locally advanced or has spread, in patients eligible for trastuzumab deruxtecan therapy.
- HER2-positive early breast cancer — trastuzumab is also authorised for treating early-stage HER2-positive breast cancer.
- HER2-positive metastatic gastric cancer — trastuzumab is authorised for treating stomach cancer that is HER2-positive.
How is trastuzumab given?
Trastuzumab is given either as a drip into the bloodstream (intravenously) or as an injection under the skin (subcutaneously). Intravenous treatment takes between 30 and 90 minutes, with the first treatment given over 90 minutes. In the clinical trials, 89Zr-trastuzumab is given intravenously at doses of 37 to 40.7 MBq (megabecquerels). Trastuzumab is available as a powder for concentrate for solution for infusion in 150 mg, 420 mg, 100 mg and 160 mg strengths.
What do the clinical trials show?
Three clinical trial records investigate 89Zr-trastuzumab in HER2-positive breast cancer, all Phase 2 interventional studies. The trials aim to assess whether HER2 PET/CT imaging with 89Zr-trastuzumab can predict response to antibody-drug conjugate therapies such as trastuzumab emtansine (T-DM1) and trastuzumab deruxtecan (T-DXd).
The primary outcome measures include characterisation of genomic alterations and HER2 expression, time to treatment failure (TTF) defined as the time from T-DM1 start to discontinuation for any reason, and metabolic objective response rate (ORR) assessed by PERCIST 1.0 after 3 cycles of T-DXd. Participants are patients with advanced or metastatic HER2-positive breast cancer who have received at least one line of systemic therapy, or those eligible for T-DXd according to local approval.
What side effects are known?
Trastuzumab can cause side effects, and the healthcare team checks for these during the first infusion. The sources provided do not list specific common or serious side effects in detail. Trastuzumab only works in cancers that are HER2 positive, and tests are done on cancer cells to check for this.