Manhattan Pharmaceuticals, Inc (NEW YORK, NY), a specialty pharmaceutical company that acquires and develops drug candidates primarily for the treatment of dermatologic disorders, announced top-line results from its phase IIa clinical study of a reformulated topical PTH (1-34) for the treatment of psoriasis. The data did not demonstrate a statistically significant improvement in the overall disease severity of treatment lesions or signs and symptoms of psoriasis (redness, scaling, plaque thickness, and itch) compared with vehicle gel.

The US multicenter, randomized, double-blind, vehicle-controlled, parallel group study was designed to assess the safety and preliminary efficacy of topical PTH (1-34) 0.10% and 0.05% for the treatment of mild-to-moderate plaque psoriasis. The study did achieve the primary safety objective, and the agent appeared to be well tolerated with no hypercalcemia or serious adverse events reported. Manhattan Pharmaceuticals intends to further analyze and assess these data in order to determine appropriate next steps for the program. Originally planned for late 2005, dosing of PTH (1-34) in a phase IIa psoriasis study was postponed due to “issues identified with the current formulation and the difficulty of conducting a psoriasis study in the summer.”

A previously completed double-blind, placebo self-controlled phase I/II study was conducted under an investigator-IND at Boston University Medical Center. Fifteen adult patients with chronic plaque psoriasis who had failed to respond to at least one standard treatment were treated with the agent, which demonstrated a 67% improvement in the global severity score compared with a 17.8% improvement for placebo.

Human skin produces PTHrp (parathyroid hormone related peptide), a potent peptide inhibitor of epidermal cell growth. PTHrp, is significantly reduced in the skin of psoriasis patients, leading to skin cell hyperproliferation, poor differentiation of skin cells, and ultimately the accumulation of plaques. PTH (1-34), an agonist that mimics PTHrp, appears to help restore the normal development, migration, and turnover of skin cells, reducing cell accumulation and the formation of plaques.