A new immunotherapy treatment has produced encouraging results in men with advanced prostate cancer.
Early trials showed the experimental drug VIR-5500 shrinking tumours in several patients.
Prostate cancer remains the most common cancer among men in many countries.
About 1.5 million men receive a diagnosis worldwide each year.
Researchers tested the drug in 58 patients whose disease no longer responded to standard therapies.
Most participants experienced only mild side effects.
VIR-5500 is an engineered antibody that links killer T-cells to cancer cells.
This design helps the immune system recognise and destroy tumours.
The drug activates mainly inside the tumour, which reduces harmful inflammation.
Its longer activity in the bloodstream may also allow fewer doses.
At the highest dose level, 82% of patients saw their PSA levels fall by at least half.
More than half recorded reductions of 90% or more.
Some patients showed measurable tumour shrinkage.
In one case, liver metastases disappeared completely after six treatment cycles.
Researchers described the responses as unprecedented for a cancer considered resistant to immunotherapy.
The findings come from an early-stage trial and still require peer review.
Larger studies are now planned to confirm safety and effectiveness.
Independent experts called the results highly promising.
They stressed the need for broader trials across diverse patient groups.
Charities and clinicians say new treatments are urgently needed.
They hope this approach could extend survival and improve quality of life for many men.
