ST266 in UV-induced Inflammation

This phase II clinical study will include fifteen healthy light skinned adult volunteers. At screening subjects will be given a sunburn test. This procedure involves exposing eight 1 square cm areas of skin over increasing doses of simulated solar radiation (SSR). SSR is delivered by a 1,000-Watt xenon arc lamp, which emits ultraviolet wavelengths from 290-400 nm, closely resembling natural sunlight. The Minimal Erythema Dose (MED) will be determined approximately 24 hours after initial exposure by using a chromometer. The MED is calculated by linear regression. Each test site is a one inch square area on the buttock or lower back. Sites 1, 2, 3, 4, 5 will be irradiated with 2 MED of SSR. Site 1 will not receive any ST266 treatment. Sites 2 and 3 will be treated with ST266 immediately after irradiation. 8-12 hours later or at bedtime, Sites 2,3,4,5 with ST266 at home. ST266 will also be applied 24 hours after SSR. Between 24-36 hours after SSR, subject returns to the Skin Study Center for Minolta chromometer assessment of erythema at all test sites, as well as for high resolution digital photography (Canfield). These assessments will be repeated at 48 hours and 72 hours post SSR. Data will be graphed to quantify rate of erythema resolution. Punch biopsies will be obtained at Site 1 (control) and Site 2 (SSR + immediate ST266 Rx). If a difference in erythema is observed between Site 1 and Site 4, a biopsy will also be obtained from Site 4 (SSR + delayed ST266 Rx). Biopsy samples will be tested using Reverse Transcriptase -Polymerase Chain Reaction (RT-PCR) and/or immunohistochemistry for markers of UV inflammation such as Interleukin (IL)-6, Tumor Necrosis Factor (TNF) -alpha, etc. Subjects will continue to apply the ST266 twice daily on Sites 3 and 5 until study visit 5. An additional normal control skin biopsy may be performed in a subset of volunteers (4-5) to serve as reference control for the tissue analysis.