In short
PSMA-T4 is an investigational radiopharmaceutical used to prepare a radioactive tracer for diagnostic imaging. It targets the prostate-specific membrane antigen (PSMA) protein found on certain cancer cells. Two clinical trials have studied PSMA-T4: one completed phase 4 trial in 80 patients with prostate cancer and one authorised phase 4 trial in 100 patients with triple-negative breast cancer.
Key points
- PSMA-T4 is a kit used to prepare a technetium-99m labelled tracer for SPECT/CT imaging.
- It targets the PSMA protein, which is present on prostate cancer cells and some other tumours.
- A completed phase 4 trial studied PSMA-T4 in 80 patients with prostate cancer.
- An authorised phase 4 trial is studying PSMA-T4 in 100 patients with triple-negative breast cancer.
- PSMA-T4 is given as an intravenous injection at a dose of 740 MBq.
- PSMA-T4 has no marketing authorisation and remains an investigational substance.
What is PSMA-T4?
PSMA-T4 is a chemically synthesised substance supplied as a kit for radiopharmaceutical preparation. The kit is used to prepare a radioactive tracer, [99mTc]Tc-PSMA-T4, by labelling PSMA-T4 with technetium-99m, a radioactive isotope commonly used in nuclear medicine imaging. PSMA-T4 is an investigational substance with no marketing authorisation in the product records. The product is supplied by the National Centre for Nuclear Research (Narodowe Centrum Badań Jądrowych) in Poland.
How does PSMA-T4 work?
PSMA-T4 binds to the prostate-specific membrane antigen (PSMA), a protein found in high amounts on the surface of prostate cancer cells. When labelled with technetium-99m, the tracer emits gamma rays that can be detected by a SPECT/CT scanner. This allows doctors to see where PSMA-positive cancer cells are located in the body. PSMA imaging has high sensitivity and specificity for detecting prostate cancer lesions, including metastases. The same PSMA target is also used for targeted radioligand therapy in advanced prostate cancer, where particle-emitting radioligands are delivered to PSMA-positive cells.
Which conditions is PSMA-T4 being studied for?
- Prostate cancer — PSMA-T4 imaging is being studied to detect prostate cancer lesions and metastases and to help plan treatment.
- Triple-negative breast cancer — a type of breast cancer that lacks three common receptors; PSMA-T4 imaging is being studied to assess whether PSMA expression can predict outcomes in patients receiving neoadjuvant therapy.
How is PSMA-T4 given?
PSMA-T4 is supplied as a kit for radiopharmaceutical preparation and is given by intravenous injection. In the clinical trials, the prepared tracer [99mTc]Tc-PSMA-T4 was administered at a dose of 740 megabecquerels (MBq). After injection, patients undergo SPECT/CT imaging to visualise PSMA-positive lesions.
What do the clinical trials show?
Two phase 4 clinical trials have investigated PSMA-T4 in cancer imaging. The first trial, completed in 80 patients with prostate cancer, assessed the feasibility and safety of [99mTc]Tc-PSMA-T4 for diagnosis and treatment planning. The primary outcome measured whether the imaging method could detect lesions confirmed by pathology or radiology, with a feasibility threshold of at least 80% sensitivity and specificity in two of the three patient cohorts.
The second trial, authorised but not yet completed, is studying PSMA-T4 in 100 patients with triple-negative breast cancer undergoing radical therapy. This trial aims to assess the prognostic value of [99mTc]Tc-PSMA-T4 SPECT/CT imaging by comparing imaging results with post-operative histopathological examination and immunohistochemical analysis of PSMA expression.
A pilot study published in 2021 reported initial clinical experience with [99mTc]Tc-PSMA-T4 in patients with prostate cancer. The study authors noted that PSMA-based imaging using PET/CT has revolutionised prostate cancer imaging, with main indications including staging of high-risk patients and evaluation of biochemical failure after treatment.
What side effects are known?
The available sources do not report specific side effects of PSMA-T4. The completed phase 4 trial evaluated the safety of [99mTc]Tc-PSMA-T4, but the registry record does not list adverse event results. As with all radiopharmaceuticals, the injected radioactivity is a consideration, but no specific safety findings are reported in the provided sources.