Therapeutic opportunities in noncutaneous melanoma.

Recent evidence suggests that the biology of noncutaneous melanoma differs significantly from cutaneous melanoma and may provide therapeutic opportunity. The most frequent sites of origin of noncutaneous melanoma are the eye and mucosal surfaces. Although noncutaneous melanomas are an uncommon group of cancers (representing less than 10% of all melanomas) a greater understanding of their genetic and molecular abnormalites is being translated into novel treatment strategies. These developments are important because there is currently no effective systemic therapy for noncutaneous melanoma. Significant attention has been focused on the role of c-kit (KIT, CD117), a transmembrane receptor with tyrosine kinase activity. In vitro and ex vivo evidence suggests that c-kit is frequently expressed/over expressed/mutated in noncutaneous melanoma. Anti-tumour effects with c-kit inhibitors are seen in pre-clinical models. A variety of multitargeted kinase inhibitors which have activity against c-kit are currently in early phase clinical trials in metastatic ocular, mucosal and acral melanoma. The few case reports of significant clinical activity with targeted therapies provides hope that greater understanding of the biology of noncutaneous melanoma can be translated into effective treatment.