Apalutamide delays spread of certain prostate cancers in trial

Cancer Research UK

An experimental hormone therapy delays the spread of prostate cancer that has stopped responding to standard treatment, according to new clinical trial results.

The drug, called apalutamide, reduced the risk of either the cancer spreading or death by over 70%.

Patients taking apalutamide lived without their cancer spreading (metastasis) for over three years on average, compared to 16 months for those taking placebo.

Professor Malcolm Mason, Cancer Research UK’s prostate cancer expert, said the results were “very welcome” because clinical trials have been badly needed for these patients.

The study was published in the New England Journal of Medicine and presented at the 2018 Genitourinary Cancers Symposium in San Francisco.

What did the clinical trial find?

The trial included 1207 men with prostate cancer that hadn’t spread but continued to grow even when testosterone levels had been reduced to very low levels. All the men had a high risk of their cancer spreading despite taking conventional hormone therapy.

As well as extending survival, the treatment also prolonged the time taken for symptoms linked to the disease to get worse compared to placebo.

One in 5 people taking apalutamide experienced serious side effects, which was similar to the group taking placebo. The main side effects linked to the treatment were rashes, underactive thyroid and bone fractures.

“Men with this type of prostate cancer often face a dilemma as the treatment options for them can be less clear cut,” said Mason.

“The development of metastases is a very significant event in the lives of these men, and there’s evidence that it correlates with overall survival.

“By measuring this in the trial we can get results more quickly, which is promising. The study can’t give us any comparison between apalutamide and other recently developed drugs, like abiraterone or enzalutamide. More work will be needed to establish how best to use apalutamide in the context of other treatments.”

How does apalutamide work?

Prostate cancer needs the hormone testosterone to grow.

Apalutamide stops the body from making testosterone by blocking a molecule called the androgen receptor. This can slow the growth of the cancer and may shrink it.

Unpublished clinical trial results of a different hormone therapy, enzalutumide (Xtandi), were presented at the same conference.

The drug works in the same way as apalutamide and was tested in the same type of prostate cancer as the apalutamide trial. The combination of enzalutamide and conventional hormone treatment reduced the risk of the disease spreading or death by 71% compared to standard hormone therapy alone.