Positive early results for experimental melanoma drug

It’s the ECCO (European Cancer Organisation) Conference this week in Berlin, and one of the biggest stories from the meeting is the result of an early-stage trial of a new targeted melanoma drug (called PLX4032) carried out in the US.

It sounds like a wonder-drug, but is it as good as it appears to be? How does it work? Will it be available for patients?  And if so, when?

An early-stage trial
Speaking to the BBC about the results, lead researcher Dr Paul Chapman said” We’ve seen responses in patients who didn’t respond to chemotherapy before. So far 70 per cent of patients have responded. So that is unprecedented for us”.

The numbers sound impressive – and it certainly is exciting news – but it’s important to point out that the trial involved relatively few patients , and the full data have not yet been published in a scientific journal.

In fact, only 31 patients with malignant melanoma received the new drug in this study.  These were patients whose disease had spread around the body, and had already tried all the available treatments.

Of those 31 patients, only 22 have so far been assessed to see if the drug was working.  Nevertheless, in 20 of these 22 patients the doctors found that their tumours had shrunk by varying amounts.  In addition, some patients were able to come off their pain medication, and stop using extra oxygen to help with their breathing – which is striking.

But we need to stress that nobody in the trial has been completely cured of their disease.  They still have cancer, but those who responded to the treatment are likely to survive longer – months (or possibly years longer) than might be expected.

How does PLX4032 work?
The drug is designed to target BRAF, a molecule that is faulty in more than half of all melanomas, and some other types of cancer as well.

As we wrote about recently in our Milestones series, Cancer Research UK helped to fund the work that led to the discovery that BRAF is faulty in many cancers. And we continue to support research and drug development work based on this finding. But the current research, from which the news stories originate, comes from researchers in the United States.

Importantly, the patients in this trial were all selected because they had faulty BRAF genes in their tumours. So discovering that the BRAF-blocking drug works in so many of them is an important proof of the principle, and shows that targeted cancer therapies may well live up to their promise.  And we can expect to see more trials like this – selecting patients based on their cancer’s individual gene profile – in the future.

When will PLX4032 be available for patients?
There is still a long way to go before this drug is widely available for cancer patients*. Larger trials must be done, to confirm that PLX4032 is safe and effective.

The researchers are now planning another small study involving 90 patients starting late in 2009, and they hope to begin a much larger trial with hundreds of patients within the next year.  If the results from these larger trials are positive, then there are regulatory hurdles to be cleared before the drug can be marketed worldwide, but it’s speculation to say when this might happen.

As we’ve mentioned before, the road for a new cancer drug can be long. For example, the discovery of the prostate cancer drug abiraterone was first made in 1995,  yet despite the success of smaller studies we are still waiting for the results of large-scale trials.

So although it may be some years before we see the drug – or others like it – in widespread use, today’s results are still an exciting announcement, as it shows that cancer researchers around the world are making progress in beating cancer.

Kat

*Update: PLX4032, now known as vemurafenib or Zelboraf, was approved by NICE in November 2012, and is now available routinely on the NHS across the UK for certain patients with advanced melanoma

If you are concerned about cancer, please contact our information nurses on 0207 061 8355 or freephone 0808 800 4040 (weekdays, 9-5pm) or by email.

Further reading

• About melanoma
• What’s new in melanoma
• High-Impact Science – Finding faults in BRAF
• Drug ‘shrinks skin tumours’ – NHS Choices blog