Thousands of men with incurable prostate cancer could live longer thanks to a breakthrough study that found combining two existing treatments can significantly delay the progression of the disease.
Researchers at University College London (UCL) led an international clinical trial involving 696 men with advanced, stage 4 prostate cancer, cases where the disease had spread beyond the prostate.
The trial focused on patients with specific mutations in genes responsible for repairing DNA, known as homologous recombination repair (HRR) genes. These mutations, which affect about one in four men with prostate cancer, make standard therapies less effective.
The study tested whether adding a tablet called niraparib to the standard hormone therapy abiraterone acetate and prednisone (AAP) could improve outcomes. Over a follow-up period of two and a half years, researchers found that the new combination “significantly prolong[ed] life expectancy,” cutting the risk of cancer growth by 37 per cent across all patients.
Among those with BRCA gene mutations, a subgroup of HRR mutations linked to tumour suppression, the benefit was even greater: the risk of tumour progression was reduced by 48 per cent compared with standard treatment alone.
Patients receiving niraparib also experienced a longer period before their symptoms worsened. The number of men reporting notable deterioration fell from 34 per cent to 16 per cent, effectively doubling the time until symptoms got worse.
Niraparib, already used to treat ovarian and fallopian tube cancers, is a PARP inhibitor, a targeted drug that blocks a protein called PARP from helping cancer cells repair themselves, causing those cells to die.
Professor Gerhardt Attard, lead author of the study from the UCL Cancer Institute, said:
“Although current standard treatments are very effective for the majority of patients with advanced prostate cancer, a small but very significant proportion of patients have limited benefit.
“We now know that prostate cancers with alterations in HRR genes account for a significant group of patients whose disease recurs quickly and has an aggressive course. By combining with niraparib we can delay the cancer returning and hopefully significantly prolong life expectancy.
“These findings are striking because they support widespread genomic testing at diagnosis with use of a targeted treatment for patients who stand to derive the greatest benefit.”
He added that for cancers with HRR mutations where niraparib is approved, doctors should consider “a discussion that balances the risks of side effects against the clear benefit to delaying disease growth and worsening symptoms.”
Prostate cancer is the most common cancer among men in the UK, with 55,300 new cases and 12,000 deaths each year. DNA mutations to HRR genes increase the risk of developing prostate cancer and are found in around a quarter of men with advanced disease.
The trial, conducted across 32 countries with participants averaging 68 years of age, was published in Nature Medicine and sponsored by Janssen Research & Development, part of Johnson & Johnson.
