Hi,
There are many survivors out there. A great resource for anyone seeking information about melanoma is the melanoma patient's information page (MPIP) - more specific for melanoma. Is your brother working with a melanoma specialist (versus a general oncologist). That seems like an important step. My wife is stage recurrent metastatic melanoma. She did interlukein-2 and is currently on carbo/paclitaxel/avastin.
I know this may sound cliche, but don't give up hope and take things one day at a time. There are many success stories, although the road in front of your brother may be a long one.