Repligen Corp. announced Monday that it has begun threeopen-label clinical trials to evaluate the efficacy of its drugcandidate recombinant platelet factor 4 (rPF4) in treatingKaposi's sarcoma (KS) in AIDS patients.

One trial, a year-long Phase II study in which the compoundwill be injected intralesionally, began four to six weeks ago andwill eventually enroll 30 patients. Arthur Staddon of theGraduate Hospital of Philadelphia is the lead investigator. Datafrom the Phase I safety trials on intralesional injection of rPF4were presented in May at the meeting of the American Societyof Clinical Oncology. Those trials, conducted by James Kahn atSan Francisco General Hospital, involved 12 patients.

The other two clinical trials, which mark the first systemicadministration of rPF4 for treating KS, are Phase I/IIs. Kahn isconducting one of these trials, which is designed to study theeffect of intravenous administration of rPF4 and will enroll 18-20 patients. That trial started about a week ago, according toClare Clifford, Repligen's (NASDAQ:RGEN) director of corporatecommunications.

Twenty patients will also be enrolled in the Phase I/II trialbeing conducted by Parkash Gill at the University of SouthernCalifornia's Norris Cancer Center. That trial, which also startedfour to six weeks ago, will test rPF4's effects when it isadministered subcutaneously.

Kaposi's sarcoma, a form of cancer that occurs in 15 to 20percent of AIDS patients, is characterized by purple or red skinlesions. It can also affect internal organs, with debilitating orfatal consequences.

Repligen of Cambridge, Mass., is banking on the fact that rPF4,by blocking angiogenesis (or the development of new bloodvessel networks), is able to deprive solid growing tumors oftheir blood supply.

Repligen's approach to treating the tumors associated with KSby blocking their blood supply is apparently unique. Othertherapies under development for treating KS include liposome-formulated versions of chemotherapeutic drugs as well as an exvivo method aimed at activating killer T cells.

Liposome Technology Inc. (NASDAQ:LTIZ) is currently in PhaseIII clinical trials with Doxil, its liposomal version of the drugdoxorubicin. And Vestar Inc. (NASDAQ:VSTR) has beendeveloping liposome-formulated daunorubicin (or adriamycin,another anti-cancer drug) as DaunoXome.

Although an FDA advisory committee voted not to approveVestar's new drug application (NDA) on DaunoXome in June(which was based on Phase II data), Vestar had alreadyinitiated -- and is continuing -- Phase III trials comparingDaunoXome with standard combination chemotherapy(bleomycin, vincristine and adriamycin).

In addition, Applied Immune Sciences Inc. (NASDAQ:AISX) isusing its CELLector device to isolate killer T cells from HIV-positive patients with KS, expand those cells ex vivo in thepresence of interleukin-2, and then infuse the activated cellsback into the patients.

The idea is that the activated cells can stop HIV frommultiplying and thus eliminate those cells infected with thevirus. In early studies, reported in June at the InternationalAIDS Conference in Berlin, the treatment has proved capable ofshrinking KS tumors.

-- Jennifer Van Brunt Senior Editor

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