28 September 2009
ByAppeared in BioNews 527
An early stage trial of a new drug has given hope to skin cancer patients. The phase I trial, the results of which were presented at the European Cancer Organisation and the European Society for Medical Oncology conferences in Berlin, tested the drug PLX4032 for the treatment of advanced metastatic melanoma.
The drug was given to 31 patients with advanced melanoma and with the BRAF gene mutation, which is thought to cause around 60 per cent of melanomas. The BRAF gene is involved in regulation of cell growth and PLX4032 works by suppressing this gene. All the patients involved in the trial had failed at least one previous therapy and many of them had attempted several different treatments.
At the time of the conference the authors could only report findings from 22 patients. 14 of these met the official criteria for partial response which involves the diameter of tumours shrinking by at least 30 per cent for at least a month. An additional six patients also showed some response but the authors were clear that it was too early to say whether the tumours would shrink far enough to meet the partial response criteria.
This study builds on a previous trial of PLX4032 which was aimed at finding the optimum dosage of the drug. The new trial gave all patients the optimum dose - a 960 mg pill twice a day - and reported results after 2 weeks of medication. The results of the trial are obviously exciting and potentially provide much hope for cancer patients and their families. However, the authors plan much larger scale studies before the work is published and are quick to point out that this study was only a short-term, small scale trial. Dr Paul Chapman, one of the lead researchers on the trial and an attending physician on the Melanoma/Sarcoma service at Memorial Sloan-Kettering Cancer Center, New York, US, said, 'We don't know yet how long these responses will last, and we have had patients whose cancer has progressed after initially responding; so we are putting a lot of effort in to studying the patients who do relapse, trying to understand how their tumours have become resistant. In addition, one of the main side effects we've seen is that some patients develop early, non-melanoma skin cancers such as squamous cell skin cancer. We are very vigilant about this and although they are very easy to cut out, it's something we are keeping a close eye on'.
Dr Chapman and his colleagues plan to start a phase II trial of 90 patients at the end of this year. A large phase III randomised controlled trial involving several hundred patients is also planned.