XenoPort psoriasis drug successful in phase 2 study but with higher side effects

Around 7.5 million Americans are afflicted by psoriasis, according to the American Academy of Dermatology. The disease is defined as "a common, chronic, inflammatory disease of the immune system that mostly involves the skin and joints. It also may affect the fingernails, the toenails, the soft tissues of the genitals and inside the mouth." Furthermore, the AAD reports that in 2004, $1.2 billion was spent on the treatment associated with psoriasis.

Recently, a Phase 2 clinical trial of XenoPort's psoriasis drug was done to determine if it could be a potential treatment for moderate-to-severe chronic plaque-type psoriasis, Yahoo! Finance reports. The drug, called XP23829, is a patented prodrug of monomethyl fumarate (MMF) in a novel oral formulation, designed to provide physicians and patients an effective, better tolerated, and easier to use therapeutic option to other current fumarate products.

The results of the study showed that the drug was successful in meeting its primary endpoint in 800 mg once a day and 400 mg twice a day doses. The study analyzed 200 participants in 22 sites in the U.S., divided into 3 treatment groups of XP23829, with a group taking 400 mg once daily, 800 mg once daily, and 400 mg twice daily. The study lasted for 12 weeks, followed by a 3 week long titration period and a 9 week long treatment at a targeted dose.

The study showed that XP23829 was safe and well tolerated by the participants. Reuters also reports that both the 800 mg and 400 mg doses of the drug was successful in reducing the severity of psoriasis. However, researchers also reported several gastrointestinal-related side effects, which according to them were non-serious and mild to moderate in severity. Some 22 to 40 percent of participants experienced diarrhea, which is a common side effect in fumaric acid drugs. Other participants experienced nausea, abdominal pain, vomiting and headache.

Nonetheless, Richard Kim, M.D., chief medical officer of XenoPort told Yahoo! Finance, "We believe these clinical data demonstrate for the first time that a MMF prodrug other than dimethyl fumarate (DMF) can be effective in reducing lesions in psoriatic patients."

He added that "The magnitude of XP23829’s effect on the primary efficacy endpoint met our expectations for this relatively short duration trial and we are particularly encouraged by the results with 800 mg once-daily dosing."

Kim also said, "We believe that this demonstration of efficacy, safety and tolerability of XP23829 could lead to a differentiated product in psoriasis. We also believe that there is potential for the observations from this study to read through to other potential indications such as multiple sclerosis (MS)."

24/7 Wall St. reports that XenoPort that this study was undertaken to support Phase 3, which the company wishes to begin in 2016.