Repligen Corp. announced Monday that it has started a double-blind, multicenter Phase II study comparing the ability ofrecombinant platelet factor-4 (rPF4) to reverse the anti-coagulant effects of heparin in cardiac catheterization patientswith the current therapy, protamine.

The anti-coagulant heparin is used in essentially every open-heart operation and a good portion of the diagnostic cardiaccatheterization procedures performed annually in the U.S. Oncethe procedure is complete, the heparin is normally neutralizedwith protamine. However, protamine produces unpredictableside effects that can be quite serious or even fatal.

The Phase II trial is the first time that Repligen of Cambridge,Mass., has done a head-on comparison of rPF4 with protamine.

Results of the Phase I trial on rPF4 were presented at theannual meeting of the American Heart Association by principalinvestigator Gregory Dehmer, director of the C.V. RichardsonCardiac Catheterization Laboratory at the University of NorthCarolina, on Nov. 10.

In the initial studies on 18 patients, the compound proved tobe safe and highly effective. It was able to completelyneutralize the anti-coagulant effect of heparin at all dosestested -- from 0.5 to 5.0 milligrams rPF4 per kilogram bodyweight -- over one-to three-minute time frames.

Approximately 40 patients will be enrolled in the Phase IItrial, which will take place at the University of North CarolinaHospitals under the direction of Dehmer, and at the Universityof Texas Southwestern Medical Center under the direction ofRick Lange.

"The start of this Phase II study advances our parallel clinicaltracks for rPF4 as both an agent to neutralize heparin and as apotential cancer therapy (also in Phase IIs)," commentedSandford Smith, president and chief executive officer ofRepligen (NASDAQ:REGN).

Repligen's stock closed unchanged on Monday at $8.25 a share.

-- Jennifer Van Brunt Senior Editor

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