FDA Licenses Regeneron Manufacturing Facility.

TARRYTOWN, N.Y.--(BUSINESS WIRE)--Dec. 9, 1999--

Regeneron Begins Commercial Manufacture Of

Vaccine Intermediate For Merck

Regeneron Pharmaceuticals, Inc. (NASDAQ: REGN) announced that the United States Food and Drug Administration has approved Regeneron as a contract manufacturer of an intermediate for an existing Merck & Co., Inc. (NYSE: MRK) pediatric vaccine. Regeneron manufactures the intermediate at its Rensselaer, New York facility under an FDA-approved supplement to Merck's Establishment License Application.

Commercial production of the intermediate under Regeneron's long-term manufacturing agreement with Merck will extend over the next six years. Payments from Merck will depend on the volume of intermediate supplied each year. At the minimum quantities in the agreement, total payments over the six years are expected to be in excess of $50 million.

Leonard S. Schleifer, M.D., Ph.D., President and Chief Executive Officer of Regeneron, commented, "Regeneron's production of pharmaceutical material under the FDA's current Good Manufacturing Practices moves us closer to fulfilling our long-term objective of becoming a fully integrated pharmaceutical company. The Merck agreement permits us to fully utilize our production capacity and our experience and expertise in manufacturing pharmaceutical products. It also provides revenue that helps fund our drug development programs. We are pleased to have this ongoing relationship with one of the premier firms in the pharmaceutical industry."

Regeneron also produces brain-derived neurotrophic factor (BDNF) at its Rensselaer facility for use by Sumitomo Pharmaceuticals Company, Ltd. in clinical trials in Japan. Regeneron and Sumitomo are jointly developing BDNF for the treatment in Japan of amyotrophic lateral sclerosis, commonly known as Lou Gehrig's disease.

Regeneron is a leader in the application of molecular and cell biology to the search for novel human therapeutics. Regeneron uses its expertise in growth factors and their mechanisms of action to discover and develop protein-based and small molecule drugs. Regeneron is currently conducting a clinical program for AXOKINE second generation ciliary neurotrophic factor for the treatment of obesity and complications of obesity such as Type II diabetes. Regeneron is also conducting clinical trials, in partnership with Amgen Inc., of brain-derived neurotrophic factor for the treatment of amyotrophic lateral sclerosis and of neurotrophin-3 for the treatment of constipation associated with spinal cord injury and other medical conditions. The Company has a number of research collaborations, including a broad-based, long-term agreement with The Procter & Gamble Company.

This news release discusses historical information and includes forward looking statements about Regeneron's products, programs, finances, and business, all of which involve a number of risks and uncertainties, such as risks associated with preclinical and clinical development of drugs and biologics, determinations by regulatory and administrative governmental authorities, competitive factors, technological developments, the availability and cost of capital, the costs of developing, producing, and selling products, the potential for any collaboration agreement to be canceled or to terminate without any product success, and other material risks. A more complete description of factors that may affect future operating results can be found in Regeneron's Form 10-K for the year ended December 31, 1998 and current Form 10-Q, copies of which should be read before making any investment decision regarding Regeneron common stock.

Additional information about Regeneron and recent news releases are available on Regeneron's Worldwide Web Home Page at www.regeneron.com. Fax copies of news releases can be obtained from Regeneron's News-on-Demand Service by dialing [phone].