Last September, we covered results from a small trial of an experimental drug called PLX4032, which has been developed to treat patients whose cancers are caused by a faulty version of a gene called BRAF. Today, yet more encouraging results were announced in the New England Journal of Medicine, which were reported widely in the media.
The trial was very small and carried out in two stages. The first stage involved 55 patients, and was simply to find the most suitable dose.
In the second stage, 32 patients whose cancers were caused by BRAF mutations were given the drug at this dose. Of these, 26 patients’ tumours shrank by 30 per cent or more, and in two of these patients, the cancers disappeared completely.
We discussed this with one of our leading skin cancer scientists, Professor Richard Marais, who was part of a team that discovered the underlying genetic fault in BRAF that PLX4032 is designed to target. He said:
“These results are extremely exciting. This is the first time in over 30 years that this level of response has been seen in melanoma patients in any clinical trial.
“While these results are very promising, there is still work to be done. Although patients initially respond they can often relapse during treatment, so now we need to learn how to get longer lasting responses in these patients.”
This last point is crucial. There’s no hard evidence – yet – that the drug actually prolongs patients’ lives. The trial has only demonstrated that it can cause tumours to shrink. Although several patients’ cancers eventually became resistant to the drug, we need more research to work out how best to use this addition to the doctor’s toolbox before we can be certain that this is going to save lives.
But for now, the results of these small, early trials show great promise, and we’ll be keeping an eye on what happens next.
Flaherty, K. et al (2010). Inhibition of Mutated, Activated BRAF in Metastatic Melanoma New England Journal of Medicine, 363 (9), 809-819 DOI: 10.1056/NEJMoa1002011