Repligen Corp. said it is extending its offer, until June 24,to exchange new warrants issued in February 1992 inconnection with the formation of the company's researchand development partnership, Repligen Clinical PartnersLtd., which funds testing of recombinant platelet factor-4(rPF4).The proposed exchange offer gives warrant holders theoption to exercise their existing warrants for new warrantswith an exercise price that will be reduced from $22.73 to$9. Warrant holders' royalty rate on future product saleswould be reduced from 12.85 percent to 9 percent. Thewarrant period will be extended one year, to March 31,2000.Clare Clifford, Repligen's director of corporatecommunications, told BioWorld there are 2.6 millionwarrants outstanding. She said the expiration date wasextended by about a week because a number of investorsindicated they wanted to exchange their warrants butneeded additional time.The stock closed Thursday at $4 per share. Clifford said thepurpose of the warrant exchange was to give investors amore realistic opportunity to exchange their warrants, andgive the company more readily available access to capital.Also, the reduced royalty rate to investors would makerPF4 more attractive to potential European marketing anddistribution partners.The platelet factor is in two Phase II trials _ one forKaposi's sarcoma and one for cardiac catheterization. Therealso are ongoing Phase I/II studies of rPF4 in renal cellcarcinoma and malignant melanoma, and colon cancer, andadditional Phase I/II studies for Kaposi's sarcoma. Earlierthis month Repligen initiated a Phase I/II study for rPF4 incoronary artery bypass graft surgery. _ Jim Shrine

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