Metastatic melanoma drug promising in clinical trial

A clinical trial of a promising new experimental therapy for metastatic melanoma has shown positive results, including tumour shrinkage in the majority of patients. The positive results support previously reported positive data for the drug known as PLX4032 (RG7204) in a much larger patient population where all responses were confirmed by an independent review committee.

Jeffrey Sosman, MD, director of the Melanoma Program at Vanderbilt-Ingram Cancer Center, presented the data from the Phase II clinical trial at the International Melanoma Research Congress of the Society for Melanoma Research in Sydney, Australia.

Melanoma is the most serious type of skin cancer and is growing at a rate of about 5 per cent to 6 per cent annually. It is one of the deadliest cancers, with a historical five-year survival rate of less than 15 per cent due to the lack of effective treatments.

The new drug, PLX4032, which is being co-developed by Plexxikon and Roche, is a novel, oral, small molecule drug which targets melanoma and other cancers that harbour a mutation known as BRAF V600.

The Phase II trial of the drug is a single-arm study of previously treated metastatic melanoma patients who have the BRAF V600 mutation. The multicentre study enrolled 132 patients and as of 27 September, data showed a confirmed response rate of 52 per cent, including:

• Three confirmed complete responses (CR) (no evidence of disease);
• 66 confirmed partial responses (PR) (tumour shrinkage of at least 30 per cent).

In addition, 39 patients had stable disease. The median progression-free survival (PFS) was 6.2 months, compared to historical PFS of less than two months. The median duration of response was 6.8 months. Median overall survival has not yet been reached.

"PLX4032 represents a true paradigm shift in the treatment of melanoma and a real breakthrough in melanoma research," said Sosman, principal investigator for the Phase II trial. "For the first time, we have the possibility of offering a true personalised medicine targeted to melanoma patients who will benefit most from the treatment."

Vanderbilt-Ingram is now routinely testing all melanoma patients for the BRAF mutation as part of its newly launched Personalized Cancer Medicine Initiative.

(Source: Vanderbilt University Medical Center: 7th International Melanoma Research Congress, Sydney)