Merrimack Pharmaceuticals, Inc (CAMBRIDGE, Massachusetts), a privately-held biotechnology company focused on the discovery and development of novel treatments for diseases in the areas of autoimmunity and cancer, announced that enrollment in a phase II trial has been completed. The objective of the study is to evaluate the safety and efficacy of MM-093, a nonglycosylated, recombinant version of human alpha-fetoprotein (AFP), in patients suffering from rheumatoid arthritis (RA). The company expects to complete the study and report the results later in 2008.

The randomized, double-blind, placebo-controlled study of 100 patients with moderate-to-severe, active RA despite treatment with methotrexate is being conducted at 20 centers throughout the US. Patients will receive 60 mg/week of MM-093 or placebo for 12 weeks and thereafter followed for 4 weeks. In addition to evaluating the safety of MM-093, patients will be assessed for changes in the signs and symptoms of their disease using standard clinical outcome measurements for RA, such as ACR20 and DAS28 scores. Patients who complete the study are eligible to participate in an ongoing open-label extension study, which has enrolled >35 patients to date.

Merrimack is conducting a phase II clinical study of MM-093 in ~30 patients with moderate-to-severe chronic plaque psoriasis. The study will evaluate the safety, tolerability, and preliminary efficacy of MM-093. Patients will receive either MM-093 or placebo for 12 weeks. The study is being conducted at two clinical sites in the US, the University of Utah, Salt Lake City, and at the Texas Dermatology Research Institute in Dallas.

In addition to the ongoing studies in RA and psoriasis, MM-093 is being tested in a pilot study for patients with certain types of autoimmune uveitis. The randomized, double-blind, placebo-controlled, phase II study is being conducted at the Massachusetts Eye Research and Surgery Institute in Cambridge. The study objective is to examine the safety and efficacy of MM-093 in ~20 patients with either sarcoid or birdshot uveitis. Patients will discontinue their current uveitis therapy and will be treated with MM-093 or placebo for up to 36 weeks. The study is a flare design where the number of patients whose uveitis relapses after discontinuing the use of their background therapy will be assessed at study’s end. Patients who experience a flare of uveitis during the study will be retreated with their original therapy.

AFP is a serum protein normally produced in high levels by the fetus and is present in low levels in adults and children. Research suggests that AFP may play a role in modulating the immune system of the mother in order to protect the developing fetus. The presence of AFP in the pregnant mother’s blood has long been associated with remission of several autoimmune diseases, including RA, psoriasis, and multiple sclerosis, during the third trimester of pregnancy and with a coincident increase in levels of AFP. In vitro and animal studies have shown that AFP has immunomodulatory properties.