17 April 2015 - - The US Food and Drug Administration has granted Orphan Drug Designation for US-based biotechnology company RXi Pharmaceuticals Corp.'s (NASDAQ: RXII) second clinical candidate, Samcyprone, for the treatment of Malignant Melanoma Stage IIb to IV, the company said on Friday. A number of patients with Stage IIb to IV malignant melanoma develop cutaneous metastases. Samcyprone is being developed for treatment of these metastases. Samcyprone is a topical formulation of Diphenylcylcopropenone in clinical development for the treatment of warts, alopecia areata and cutaneous metastases of melanoma. The mechanism of action for treatment cutaneous metastases of melanoma involves elicitation of an immune response in the skin that subsequently causes destruction of the cutaneous tumor. Melanomas, cancers that arise from melanocytes, are the most aggressive form of skin cancer. Once melanoma has spread beyond the localized area of the primary lesion, the survival rate decreases and melanoma becomes increasingly more difficult to treat successfully. Management of metastatic melanoma, including cutaneous metastases, is challenging and represents an area of great unmet need. Orphan drug status is granted for novel drugs or biologics to treat rare medical diseases or conditions that affect less than 200,000 people in the United States. The designation qualifies the sponsor for numerous incentives including seven years of market exclusivity after the drug's approval, tax credits for clinical research costs and application fee reductions. Samcyprone is a proprietary topical formulation of diphenylcyclopropenone. Samcyprone is being evaluated for the treatment of warts, alopecia areata and cutaneous metastases of malignant melanoma. DPCP is an immunomodulating agent that works by eliciting a T-cell response.