As I understand it, metastases are still considered to be the same type as the original cancer.
So.....some non-melanomas have the mutation, you think?
About PLX4032 (R7204)-A Personalized Medicine for Cancer Treatment
PLX4032 is a novel, oral small molecule for the treatment of melanoma and other cancers harboring the V600E mutation of the BRAF kinase gene. This defect is present in approximately 60 percent of melanoma skin cancers, and occurs in about eight percent of all solid tumors, including melanoma, colorectal, thyroid and other cancers. Preclinical data suggest that Plexxikon's novel anti-cancer compound selectively targets and inhibits tumor cells which contain this cancer-causing mutation. In contrast to many other kinase inhibitors available, PLX4032 is highly selective for its primary target, and does not have significant activity on other kinase targets.
The article is very vague on details and talks mainly about particular people's experiences, rather than the specific mechanism the drug uses to work.
... All these patients had failed previous therapies, either chemotherapy or treatment with Interleukin 2, as well as surgery. However, we know that only 10-30% of patients will respond to standard chemotherapy, so it's not surprising that our patients had not responded, or have responded and then the cancer has recurred. In our study 64% of patients have had a partial response, but because we are only treating patients with the BRAF mutation, we are cutting out about 40% of melanoma patients who do not have this mutation...
.... the activity of the cancer-causing mutation of the BRAF gene, which is implicated in about 50% melanomas and 5% of colorectal cancers