CollaGenex Pharmaceuticals Inc. said today it signed a $1.5 million licensing agreement with an Ann Arbor, Mich. company to develop and commercialize becocalcidiol, a Vitamin D-based psoriasis treatment in mid-stage clinical testing.

The Newtown company said it will pay an upfront $1.5 million licensing fee to QuatRx Pharmaceuticals Co., of Ann Arbor. CollaGenex, which specializes in dermatological medicines, will be responsible for all further development costs. The Bucks County company will pay additional fees based on future development and sales milestones.

According to the National Institutes of Health, about 7.5 million Americans have psoriasis, a skin condition characterized by itching and red, scaly patches.

CollaGenex shares fell 1 cent to $10.04 in midday trading on the Nasdaq.