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 NHS Foundation Trust, and The Institute of Oncology Research (IOR) in Switzerland, represents a major scientific advance following a decade of work into understanding how myeloid cells fuel treatment resistance.
New way to treat prostate cancer
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 (2%) patients responded to therapy, meaning that their tumours shrunk by over 30%, they saw dramatic decreases in circulating levels of prostate specific antigen (PSA), or their blood levels of circulating tumour cells dropped.
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 impact of this research could be very broad, across multiple cancer types.”
Study leader Professor Johann De Bono, Professor in Experimental Cancer Medicine at The Institute of Cancer Research, London, and Consultant Medical Oncologist at The Royal Marsden NHS Foundation Trust, said: “This research proves for the first time that targeting myeloid cells rather than the cancer cells themselves can shrink tumours and benefit patients. This is tremendously exciting, and it suggests we have an entirely new way to treat prostate cancer on the horizon.
“We’ve been studying these myeloid cells at the ICR for many years. More than a decade ago we first noticed that they were elevated in patients with much more aggressive tumours, and showed these tumours were more treatment resistant.
“It’s hugely rewarding to see our theory proven in a trial of patients with this disease. Myeloid cells may be implicated in treatment resistance in a range of cancers, so the impact of this research could be very broad, across multiple cancer types.”