Prostate cancer’s resistance to treatment can be reversed in some patients by stopping hijacked white blood cells from being ‘pulled into’ tumours, according to new research published in Nature.

In an early clinical trial, researchers showed that blocking the messages cancer uses to hijack white blood cells can re-sensitise a subset of advanced prostate cancers to treatment – shrinking tumours or halting their growth.

The research provides the first proof in a human trial that targeting ‘feeder’ myeloid white blood cells – which are co-opted by tumours to help fuel cancer growth, progression, and resistance to treatment – can reverse drug resistance and slow tumour progression.

The research, led by The Institute of Cancer Research, London, The Royal Marsden NIHR Biomedical Research Centre at The Royal Marsden and The Institute of Cancer Research (ICR), with support from the Experimental Cancer Medicines Centres (ECMC) Network.

Researchers tested a combination of AZD5069, an experimental drug which prevents myeloid cell recruitment to tumours, and enzalutamide, a hormone therapy commonly used to treat prostate cancer, in 48 patients with advanced disease.

Five of 21 (24 per cent) patients had evidence of their tumours responding to therapy.

This meant their tumours shrunk by over 30 per cent, they saw dramatic decreases in circulating levels of prostate specific antigen (PSA), a marker secreted by the prostate which is often elevated by cancer, or their blood levels of circulating tumour cells dropped, in response to the combination.

Blood levels of myeloid cells also dropped in patients who received treatment, and biopsies following treatment also revealed fewer myeloid cells within their tumours.

The research builds on over a decade of work by teams at the