GALAGEN ANNOUNCES PROMISING PHASE I/II CLINICAL RESULTS FOR SPORIDIN-G IN THE JOURNAL OF ACQUIRED IMMUNE DEFICIENCY SYNDROME AND HUMAN RETROVIROLOGY.

ARDEN HILLS, Minn.--(HealthWire)--December 2, 1996--

Product Shows Potential as Treatment for AIDS-Related Diarrhea

GalaGen Inc. (Nasdaq: GGEN) today announced that use of its lead product in development, Sporidin-G(TM), showed favorable clinical results and an acceptable safety profile in the treatment of diarrhea caused by Cryptosporidium parvum (C. parvum) in patients with AIDS. The results are from a Phase I/II study in 24 patients and are published today in the December 1996 issue of The Journal of Acquired Immune Deficiency Syndrome and Human Retrovirology. Based on these positive results, GalaGen is currently conducting a Phase II/III double-blind placebo-controlled study using an advanced, more potent formulation of Sporidin-G.

In the Phase I/II study, the product was demonstrated to be safe and palatable with a statistically significant 49 percent reduction in stool weight observed in the 12 C. parvum-infected patients treated with an oral formulation of Sporidin-G. The study was conducted by researchers at the University of California, San Francisco, led by John P. Cello, M.D., Professor of Medicine and Surgery and Chief of Gastroenterology at San Francisco General Hospital.

"The current oral formulation of Sporidin-G that is being studied in the ongoing trial has a nearly four-fold greater concentration of antibodies specific for C. parvum than the product used in this initial clinical study," said Robert A. Hoerr, M.D., Ph.D., President and CEO of GalaGen. "Based on the results of this initial study, we have great confidence in the new formulation of our product as a clinically attractive, safe and viable treatment for cryptosporidiosis."

"With the new antiviral therapies available, cryptosporidiosis remains one of the most devastating infections for people with AIDS," said Dr. Cello. "This product was very well tolerated, and we were impressed by the significant reduction in diarrheal symptoms in the earlier trial. The ongoing Phase II/III multicenter trial could demonstrate compelling clinical benefits."

The initial open-label study compared powder and capsule formulations of Sporidin-G in patients with C. parvum infection, with or without opportunistic infections, and in patients with nonspecific AIDS-associated diarrhea. Twenty-four patients with severe chronic diarrhea and AIDS were stratified to one of three cohorts: C. parvum infection alone, C. parvum and a second opportunistic infection, or idiopathic AIDS enteropathy (diarrhea with no identified source of infection). Patients with C. parvum infection alone were randomized to receive the medication in powder or capsule form, while patients in the other cohorts received the powder form only. The primary clinical endpoints were reduction in the weight of daily stool production and safety. Patients with C. parvum infection, with or without a second opportunistic infection, who were treated with Sporidin-G in powder form experienced a significant reduction in mean stool weight, from 1,158 +/- 114 grams/day at baseline, to 595 +/- 63 grams/day (P=0.04) at the end of treatment. No serious side effects were observed and the medication was well tolerated. All groups of patients receiving the powder form gained or stabilized their body weight.

The Company anticipates that the current Phase II/III trial, being conducted at multiple sites throughout the U.S., will be fully enrolled in early 1997. If the trial demonstrates efficacy, GalaGen believes that the data may support the filing of a Product Licensing Application (PLA) with the Food and Drug Administration (FDA) and with regulatory authorities in Europe and Latin America.

C. parvum, the parasite responsible for cryptosporidiosis, is an opportunistic infection in AIDS patients that can cause intractable diarrhea, profound weight loss, malnutrition, dehydration and, in some cases, death. Although more than 90 compounds have been tested to treat this infection, no FDA-approved treatment currently exists for this disease.

GalaGen Inc. is developing a portfolio of oral therapeutics derived from its platform technology that target life-threatening and emerging pathogens. The Company currently has three polyclonal antibody products in clinical trials. GalaGen's lead product, Sporidin-G, is being developed for parasite-induced chronic, life-threatening diarrhea in AIDS and immunocompromised patients. Candistat-G(TM) is an oral antibody product in development for the treatment of thrush, or infection of the throat and oral cavity with the fungus Candida. Diffistat-G(TM) is being developed for the treatment and prevention of antibiotic-associated diarrhea, which annually affects an estimated 400,000 patients in the U.S.

The estimated completion date for the trial stated in this press release is a forward-looking statement which involves risks and uncertainties, and the actual completion date could be materially different. Factors that could cause the completion date to differ include the rate at which the Company can enroll patients meeting the participation criteria for the trial and the likelihood of encountering problems in the trial that could cause the Company or the FDA to delay the trial and other factors listed in the Company's Prospectus dated March 27, 1996. The estimates of clinical benefits from Sporidin-G expressed above are also forward-looking statements which involve risks and uncertainties, and there can be no assurance that Sporidin-G will ultimately prove safe and effective in clinical trials. Other factors that could cause the trial results to be unfavorable are also listed in the Company's Prospectus dated March 27, 1996.

CONTACT: Robert A. Hoerr, M.D., Ph.D Karen L. Bergman (media)

President and CEO Jonathan M. Nugent (investors)

GalaGen Inc. Burns McClellan, Inc.

612/481-2105 212/505-1919