Researchers have reported encouraging early results for a new prostate cancer treatment.
The immunotherapy drug VIR-5500 shrank tumours in some men with advanced disease.
Prostate cancer is the most common cancer in men in many countries.
About 1.5 million new cases occur worldwide each year.
VIR-5500 is an engineered antibody that redirects killer T-cells toward tumour cells.
It activates mainly inside the tumour, which helps limit harmful side effects.
Most patients in the trial experienced only mild reactions.
Fifty-eight men whose cancer no longer responded to standard therapies received the drug.
At the highest dose, many showed sharp falls in prostate-specific antigen levels.
Several patients recorded reductions of more than ninety percent.
Tumour shrinkage appeared in nearly half of those with measurable disease.
One patient saw liver metastases disappear after repeated treatment cycles.
Scientists described the findings as unprecedented for a cancer once considered resistant to immunotherapy.
They stressed that larger trials must confirm safety and long-term benefit.
Independent experts called the approach highly promising.
They also urged studies that include men from diverse ethnic backgrounds.
Researchers now plan expanded clinical trials.
They hope the therapy will extend survival and improve quality of life for patients.
