Genetic Therapy Inc. said Monday that it started a multi-center PhaseI/II trial of its gene therapy product to treat inoperable malignantbrain tumors. The company already has a Phase I/II trial in operablemalignant brain tumors going at three sites.

Fifteen patients will be enrolled in the trial. It will involve directinjection of cells into the tumor that produce genetically alteredvectors, which transfer into tumor cells the gene for enzymethymidine kinase.

Cells expressing the gene produce thymidine kinase, making themsusceptible to the antiviral drug ganciclovir.

The trial is part of the HS-tk (herpes simplex-thymidine kinase gene)program for cancer being developed with Basel, Switzerland-basedSandoz Pharma Ltd. That deal was signed last summer. A separatecollaboration between the companies, signed in 1991, involves anundisclosed cancer project.

The start of the trial is the third involving GTI's HS-tk technology.The initial trial, started in late 1992 with the National Institutes ofHealth, showed antitumor response in five of eight patients.Preliminary results of that trial were presented in Norway in 1993;final results are being submitted for publication, said MarcSchneebaum, Genetic Therapy's chief financial officer.

The company's stock (NASDAQ:GTII) was down 75 cents Monday,closing at $8.25 per share. _ Jim Shrine

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