The trial by the Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, could fill an "important gap" in previous evidence for abiraterone’s effectiveness pre-chemotherapy according to study lead Professor Johann de Bono.
It's key finding was that men with advanced, aggressive prostate cancer lived more than four months longer on average if they received abiraterone before chemotherapy than if they did not.
An earlier analysis, published in 2013, showed that abiraterone taken before chemotherapy increased the time before a man’s cancer progressed but did not prove an overall extension in life. This point was cited by NICE when rejecting abiraterone pre chemotherapy in guidance released last year.
Professor de Bono said: "These two new studies, from a major trial of abiraterone in men who are yet to receive chemotherapy, both represent very significant advances. In the overall trial analysis, we’ve shown definitively that the drug extends life if taken before chemotherapy, by an average of around four months.
"The second study shows that men with a particular type of genetic mutation in their tumour respond particularly well to abiraterone, and importantly that a subset of patients with a very bad outlook respond best of all.
"Those results could help provide a rationale for using abiraterone as early as possible in men with these mutations. Currently, men are not generally tested for mutations in their cancer over time – which is why a major focus of our research is on developing new tests to monitor cancer’s genetic progression in individual men, and ultimately match their disease to the best possible treatment."
The new results coincide with the publication of a second new international study of patients in the same trial, also led in the UK by researchers at The Institute of Cancer Research (ICR) and The Royal Marsden.
That study, published in Clinical Cancer Research, shows it is possible to identify a subgroup of men with very aggressive prostate cancer who may benefit particularly strikingly from abiraterone pre chemotherapy.
This second new study of 354 men given abiraterone before moving on to chemotherapy with 387 men who received a placebo instead showed that a subgroup of patients with a very aggressive form of prostate cancer may benefit the most from treatment with abiraterone.
They found a clear link between major ERG mutations and response to abiraterone. Although abiraterone improved survival generally regardless of ERG mutations, a subset of patients with the most pronounced mutations to the gene – accounting for 15 per cent of the men studied – responded particularly well.
These men lived for an average of 22 months without their disease progressing, compared with 5.4 months for men with the same ERG status who received a placebo.
Chief Executive of The Institute of Cancer Research Prof Paul Workman added: “Abiraterone has already transformed care for patients with advanced prostate cancer, but the latest trial evidence strengthens the already powerful case for it to be accepted for NHS use earlier in the course of treatment.
“Not only do the overall results find that abiraterone significantly extends lives when used before chemotherapy, but the second study shows it is possible to pick out a subgroup of men who benefit especially strikingly.”