A new immunotherapy drug has produced encouraging results in men with advanced prostate cancer.
Researchers reported tumour shrinkage and strong biomarker responses in an early clinical trial.
The treatment, called VIR-5500, uses engineered antibodies to direct killer T-cells toward cancer cells.
It activates mainly inside tumours, which helps limit harmful side effects.
Most participants experienced only mild reactions.
The phase one study involved 58 men whose disease no longer responded to standard therapies.
Doctors increased the dose gradually during the trial.
Among patients receiving the highest dose, most showed major falls in PSA levels.
Several men recorded reductions of more than ninety percent.
Scans revealed measurable tumour shrinkage in nearly half of the evaluable patients at the top dose.
One participant saw multiple liver metastases disappear after repeated treatment cycles.
Scientists have long considered prostate cancer resistant to immunotherapy.
The new findings challenge that view and suggest a possible new treatment class.
Researchers plan larger trials to confirm safety and effectiveness.
Experts welcomed the results but stressed the need for broader studies across diverse patient groups.
Prostate cancer remains the most common cancer in men in many countries.
Specialists say innovative therapies are urgently needed to extend survival and improve quality of life.
