Abiraterone continues to show promising results in clinical trials

Regular readers of this blog will know that we’ve been following the story of abiraterone – an exciting experimental prostate cancer drug, for over two years.

Today saw the announcement of yet more encouraging news – a large-scale phase III trial involving nearly 1,200 men has confirmed the drug’s ability to extend survival – by an average of nearly four months – in men whose advanced prostate cancer had already been treated, and who had no other treatment.

The drug’s manufacturers will now apply for a licence to market the drug, and we hope that it’ll eventually be available to patients in the UK in the not-too-distant future.

However, despite today’s headlines, we do need to stress that this drug is not currently available yet in the UK.

Caveats out the way, let’s have a quick look at the drug’s history…

The story of abiraterone

Many prostate cancers’ growth is fuelled by the male hormone testosterone. In the early 90s, Professor Mike Jarman and his colleagues, in what is now the Cancer Research UK Cancer Therapeutics Unit at The Institute of Cancer Research (ICR), were looking for drugs that could shut off testosterone production, thereby stopping prostate cancer cells from growing.

In 1994, they found it in a chemical called CB7360, later renamed abiraterone. With Cancer Research UK funding, they worked out how to ‘formulate’ the drug – that is, work out exactly to package it into a pill that patients could take.

Years of testing followed, led principally by researchers and doctors at the ICR, and funded primarily by a pharmaceutical company called Cougar Biotechnologies – now part of Johnson & Johnson.

Fourteen years later, in July 2008, this testing and investment finally began to bear fruit. The results of a small phase I trial of just 21 men, funded by Cougar, showed that the drug could shrink prostate tumours in men with advanced prostate cancer. And less than a year later, the drug hit the headlines again, when researchers found that men with a certain gene were more likely to respond to the drug.

Earlier this year, more good news arrived, when a larger phase II trial of 47 men showed that abiraterone could reduce PSA levels in men with advanced prostate cancer that is resistant to hormone treatment – the first time any benefit had been shown for men with such advanced disease.

The new trial results released today by the ICR team build on this promise.

Men on the trial were either given abiraterone together with a steroid hormone treatment called prednisone, or just prednisone and a placebo (dummy tablet). Men on the placebo part of the trial survived an average of nearly 11 months; men who were given abiraterone survived for nearly 15 months.

This result was so encouraging that the men who had been getting the placebo were switched to abiraterone.

A risky investment

For such a promising drug, it’s surprising to learn that at one stage it was very nearly left on the shelf.

Cancer Research UK saw its potential at a very early stage and we helped to fund the pre-clinical work on the drug. The theory behind the drug was certain but the investment was risky – however, it was one that we believed was worth taking.

But this investment has paid off, and will give hope to men who currently have no other treatment options.

Not the end of the story

Before we get too excited, we have to point out that this drug is not yet licensed for use. There is no way, as yet, to get it in the UK.

And the results so far only show that the drug works in very ill men who have no other treatment options. There’s a lot more work to do to find out how best to give the drug to men with prostate cancer at earlier stages in the disease’s progression.

Nevertheless, this story is one that we at Cancer Research UK are extremely encouraged by.

It shows how a detailed understanding of the biology of cancer cells can lead to a new idea for treatment; how the charity sector can work with academia and the pharmaceutical industry to turn that idea into a reality; and how the painstaking work of researchers and doctors can, ultimately, help improve cancer patients’ lives.