Scientists discover new treatment to reverse prostate cancer’s resistance

Scientists say they may have discovered how to reverse prostate cancer’s resistance to treatment.

Some advanced forms of prostate cancer are able to evade therapy by using the immune system to resist the impact of drugs.

According to the results of a study published on Monday, scientists have discovered a possible way to stop cancer cells from being able to resist drugs by blocking the secret messages that they send to hijack healthy myeloid cells, a type of white blood cells.

In a trial led by the Institute of Cancer Research (ICR) and the Institute of Oncology Research in Switzerland, scientists recruited 23 patients with advanced prostate cancer that had stopped responding to hormone therapy.

The patients were given a combination of AZD5069, an experimental drug that prevents white blood cells from being dragged inside tumours, and enzalutamide, a hormone therapy commonly used to treat prostate cancer in patients with advanced disease.

Five of the 21 patients responded to the treatment.

According to the study, their tumours shrunk by more than 30 percent as they experienced “dramatic decreases” in circulating levels of prostate-specific antigen (PSA), a marker often elevated by cancer, 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 study builds on a decade of work by the team, which has been exploring how myeloid cells fuel prostate cancers.

The research started after it was observed that patients with aggressive and resistant forms of the disease had much higher levels of myeloid RNA in their blood.

Study leader Johann De Bono, a professor in experimental cancer medicine at ICR London, said the research proved 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,” he said.

“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.”