An experimental immunotherapy has produced remarkable early results in men with advanced prostate cancer.
Researchers say the drug, VIR-5500, shrank tumours in several patients who had exhausted other treatments.
Prostate cancer affects about 1.5 million men worldwide each year.
Immunotherapy has transformed care for other cancers but rarely benefits this disease.
VIR-5500 works by linking killer T-cells directly to tumour cells.
It activates mainly inside the tumour, which reduces harmful immune reactions.
The design also allows the drug to remain longer in the bloodstream.
Fifty-eight men received the treatment in a phase one trial.
Most experienced only mild side effects.
At the highest dose, prostate-specific antigen levels fell sharply in many patients.
Fourteen of seventeen men saw their PSA drop by at least half.
Nine recorded reductions of ninety percent or more.
Tumour shrinkage appeared in nearly half of the men with measurable disease.
One patient saw multiple liver metastases disappear after six treatment cycles.
Researchers called the findings unprecedented for an “immune-cold” cancer.
They are now planning larger trials to confirm safety and effectiveness.
Independent experts welcomed the results but urged broader studies across diverse populations.
They said new therapies are urgently needed to reduce prostate cancer deaths.
