Noninvasive drug delivery using ultrasound: Targeting melanoma using siRNA against mutant (V600E) B-Raf

Melanoma is the most deadly form of skin cancer. Currently early surgical removal is the best treatment option for melanoma patients with little hope of successful treatment of late stage melanoma. Clearly new treatment options must be explored. Topical administration of drugs provides the advantage of being able to apply large quantities of drug in close proximity to the tumor without the issue of systemic side effects. However, the natural barrier formed by the skin must first be overcome for topical treatment to become a viable option. With this in mind we have sought to use low-frequency ultrasound to transiently permeabilize the stratum corneum and successfully deliver liposomal siRNA to melanoma cells residing at the basement membrane. B-Raf is one of the most frequently activated genes in melanoma, making it an ideal candidate for targeting via siRNA. The novel liposomes used in this study load siRNA, protect if from the outside environment and lead to knockdown of target message. Combining ultrasound with liposomal siRNA we show that siRNA can be delivered into melanoma cells. Additionally, we show that siRNA to mutant B-Raf can effectively inhibit melanoma growth in reconstructs and in mice by 60% and 30% respectively. Therefore, ultrasound with liposomal siRNA is a potentially valuable treatment option for melanoma patients.