RXi Pharmaceuticals has posted results from its second placebo-controlled Phase I study with RXI‑109, an sd-rxRNA compound that targets Connective Tissue Growth Factor (CTGF), and is being developed for the treatment of abnormal dermal scars such as hypertrophic scars and keloids in conjunction with scar revision surgery.

In this study, subjects received small skin incisions in their abdomen and were treated with three intradermal doses of RXI‑109 during a two-week period. The dose escalating portion of the study consisted of four cohorts of three healthy volunteers each. A fifth cohort was added at the highest dose, in which the treatment period was delayed by two weeks. Subjects received RXI‑109 on one side of the abdomen, and placebo on the other side. Subjects were monitored for safety and local and systemic side effects over a total study period of 84 days.

Multiple dermal injections were well tolerated at all doses, and treatment with RXI‑109 resulted in dose-dependent silencing of CTGF mRNA in the treated areas. In the fourth cohort of this study, three doses of 10 mg dose per incision during the initial two-week period following the incision averaged approximately 50% reduction of CTGF mRNA expression compared to placebo when measured three days after the last dose. In the fifth cohort, where the dosing period with 10 mg RXI-109 per incision was delayed by two weeks after the incisions were made, no additional benefit was seen on mRNA reduction. Both treatment regimens were safe and well tolerated. However, delay of dosing resulted in fewer local skin effects for both placebo and active.

Based on the safety profile shown in Phase I, a Phase II study was initiated in November 2013 in which subjects will receive multiple doses of RXI-109 in conjunction with revision surgery on existing hypertrophic scars. Additional studies in hypertrophic scars and keloids are planned.