Alpha-fetoprotein, which is produced by the fetus during pregnancy, is associated with remission of autoimmune diseases during the third trimester, when it reaches peak levels in maternal serum. A recombinant version of alpha-fetoprotein, MM-093, is currently being developed as an immunomodulator for treatment of autoimmune disease by Merrimack Pharmaceutical. Merrimack has announced the initiation of a randomized, double-blind, placebo controlled, Phase II study of MM-093 for rheumatoid arthritis (RA). Approximately 240 patients will be enrolled at 40 centers throughout the US, with each patient receiving a once-weekly subcutaneous injection of placebo or one of three doses of MM-093. Treatment will continue for 24 weeks, and will be followed by a 4-week evaluation period using ACR criteria for RA improvement.

In November 2003, a Phase I study found MM-093 to be safe and well-tolerated in healthy volunteers, and results from a recently completed Phase IIa safety and tolerability study at Kings College Hospital in London are pending. Plans are underway to conduct future clinical trials in patients suffering from psoriasis, multiple sclerosis, inflammatory bowel disease and other autoimmune diseases.