Regeneron Pharmaceuticals Inc.Ls stock plunged Tuesday afternews that its rival, Synergen Inc., was issued a third U.S.patent for CNTF (ciliary neurotrophic factor), used to treatamyotrophic lateral sclerosis (ALS).

Regeneron stock lost almost 17 percent of its value, dropping$1.75 a share on volume of 201,000 shares to close at $8.75for the day. SynergenLs stock, meanwhile, jumped $2.50 ashare, closing at $43.75.

Synergen of Boulder, Colo., on Tuesday was issued U.S. patentNo. 5,141,856, which covers the means of CNTF production.

Regeneron officials deferred comment to the companyLsattorneys. S. Leslie Misrock, an attorney representingRegeneron with Pennie & Edmonds in New York, told BioWorldthat Regeneron filed a patent application similar to SynergenLscovering the expression of human CNTF in E. coli eight weeksprior to SynergenLs.

Said Misrock, "On the basis of careful study, we believe thatRegeneron was the first to make human CNTF, the first toexpress human CNTF in E. coli, and the first to use human CNTFin the treatment of certain neurological diseases.''

''We expect to provoke an interference against Synergen to theextent and insofar as that patent (issued Tuesday) claimsexpression of human CNTF in E coli,'' she said.

David Stone, an analyst with Cowen & Co. in Boston, said,''RegeneronLs stocks have responded badly because itLs (CNTF)their lead product.''

Synergen said it is in Phase I trials with CNTF and isrecruiting patients for a Phase II study. Using a sportsanalogy, Stone said that at half-time in the CNTF race, onlySynergen has any points on the board.

The first patent for CNTF was issued to Synergen in March1991 for the human nucleic acid (DNA) sequence, and thesecond was issued in April 1991 for the process of purifyingCNTF.

The U.S. Patent and Trademark Office, at RegeneronLs request,agreed in July of this year to review SynergenLs second patent,No. 4,997,929, covering DNA sequencing and a patent coveringsimilar material filed by Regeneron in September 1989.Frederic Price, RegeneronLs chief financial officer, claims thatRegeneron invented the compound CNTF before Synergen.

Regeneron, which is based in Tarrytown, N.Y., has

received a notice of allowance for its patent, but no date hasbeen set for an interference hearing with the PTO.

CNTF is a nerve repair factor that promotes the survival ofmotor neuron cells. These cells degenerate and ultimatelycause death in people with ALS, commonly called Lou GehrigLsdisease. Analysts have placed a U.S. market potential for CNTFat between $300 million and $400 million. n

-- Michelle Slade Associate Editor

(c) 1997 American Health Consultants. All rights reserved.