Researchers have reported striking early results for a new prostate cancer treatment.
The drug VIR-5500 shrank tumours in some men with advanced disease.
Prostate cancer affects about 1.5 million men worldwide each year.
Many advanced cases stop responding to standard therapies.
Scientists tested the new immunotherapy in 58 such patients.
VIR-5500 links killer T-cells directly to tumour cells.
It activates mainly inside the tumour, which limits harmful inflammation.
Most participants experienced only mild side effects.
Doctors tracked prostate-specific antigen levels to measure response.
At the highest dose, 82% of patients saw PSA fall by at least half.
More than half recorded drops of 90% or greater.
Tumour scans also showed encouraging changes.
Five of eleven men had measurable tumour shrinkage.
One patient saw multiple liver lesions disappear completely.
Researchers called the findings unprecedented for prostate cancer.
The disease has long resisted immunotherapy approaches.
Larger trials will now test effectiveness and long-term safety.
Cancer specialists say the treatment could open a new drug class.
They stress the need for diverse patient groups in future studies.
Experts hope the therapy will extend survival and improve quality of life.
