AEGiS-PRn: Cell Genesys Scientists Report Killing of HIV-Infected Cells With T Cell Gene Therapy

Important note: Information in this article was accurate in 1997. The state of the art may have changed since the publication date.

Cell Genesys Scientists Report Killing of HIV-Infected Cells With T Cell Gene Therapy

PR Newswire, 810 Seventh Avenue, New York, NY 10019 - Monday October 13 5:00 PM EDT

FOSTER CITY, Calif., Oct. 13 /PRNewswire/ -- Cell Genesys, Inc. (Nasdaq:CEGE) reported today that a team of company scientists has demonstrated early and efficient killing of human immunodeficiency virus (HIV)-infected cells in laboratory studies using immune system T cells which have been genetically engineered to seek out and destroy HIV-infected cells. The "programmed" T cells target and kill infected cells as efficiently and early as naturally occurring HIV-specific T cells, which are lost during the early stages of HIV infection. In addition, the gene modified T cells demonstrated efficient killing of both types of immune cells -- T cells and macrophages -- where HIV infection has been shown to persist despite the best available antiviral drug therapy. The laboratory work, which was done in collaboration with Bruce D. Walker, M.D., director, Partners AIDS Research Center at Massachusetts General Hospital and Harvard Medical School, was published in the October 1997 issue of the journal, Proceedings of the National Academy of Sciences. The company is currently conducting Phase II human clinical trials of T cell gene therapy in HIV infection.

"We believe we have identified an important new treatment strategy for AIDS based on our findings in this study," stated Bruce D. Walker, M.D. "Not only did we demonstrate that the genetically modified T cells perform as efficiently as naturally occurring cells, but the cells also recognize the infected cells early enough to enable the genetically modified cells to destroy them before they produce virus, thus inhibiting viral replication."

"In light of the recent announcements reporting the deficiencies of even the best of the new antiviral drugs, it is clear that we need to continue to aggressively seek more effective and potentially complementary approaches for the treatment of AIDS," stated Dale G. Ando, M.D., vice president, clinical research of Cell Genesys. "Importantly, our genetically modified T cells have shown that in addition to killing HIV-infected T cells, they are also able to kill macrophages, a reservoir for virus which antiviral drugs are not able to eradicate."

Cell Genesys also demonstrated as reported in this published work that the genetically modified T cells are able to recognize and kill diverse mutated strains of HIV. This virus has been shown to continuously mutate, preventing the naturally occurring HIV-specific T cells from recognizing the HIV-infected cells and therefore disabling the patient's immune system to fight the mutated strains of virus. Infusion of the genetically modified T cells could enable the patient's immune system to again be able to fight the battle against HIV.

Cell Genesys has developed a proprietary gene therapy technology in which T cells are genetically modified to express receptors enabling the cells to target and destroy malignant or virally infected cells. In its AIDS gene therapy program, which is currently in Phase II human clinical trials, T cells have been modified with a proprietary gene to seek out "gp120," a cell surface protein expressed by HIV-infected cells.

Two types of cells which are eradicated early in HIV-infected patients are CD4 (helper) and CD8 (killer) T cells. Both are immune system cells, and their absence severely disables the patient to fight the infection on their own. Currently being evaluated in the company's AIDS clinical trials is a manufacturing process providing for the genetic modification of both CD8 and CD4 T cells. These cells are obtained from an AIDS patient using apheresis, a standard blood bank procedure, genetically modified and expanded in number and then infused back into the patient, potentially enabling a strong HIV-specific immune system response.

Cell Genesys is currently conducting Phase II human clinical trials in AIDS gene therapy. In the Phase I trial, no treatment-related safety problems were observed, and the data showed that the modified cells persisted in the circulatory system for up to nine months. In the Phase II trials, the company is testing its AIDS gene therapy in combination with antiviral drugs. The Phase II studies will help determine whether the company's gene therapy can reduce the requirement for long-term treatment with combinations of three or more antiviral drugs.

Cell Genesys is focused on the development and commercialization of ex vivo and in vivo gene therapies to treat major, life-threatening diseases and disorders such as cancer and AIDS. The company's AIDS gene therapy which is in Phase II human clinical testing, is being developed through a worldwide collaboration with Hoechst Marion Roussel. In the cancer area, Cell Genesys has recently initiated human clinical trials for its T cell gene therapy in colon cancer and for its GVAX(TM) cancer vaccine in lung, melanoma and prostate cancer. The company is conducting preclinical studies in other cancer indications, hemophilia, cardiovascular disease and neurodegenerative disorders. Cell Genesys' assets outside gene therapy include its Abgenix, Inc. subsidiary, which is developing antibody therapies for transplantation-associated medical conditions, inflammation, autoimmune disorders and cancer, as well as the company's licensing program in gene activation technology.

Statements made in this press release about the company's and its subsidiary's clinical trials and product pipelines, other than statements of historical fact, are forward looking statements and are subject to a number of uncertainties that could cause actual results to differ materially from the statements made, including risks associated with the success of clinical trials, research and product development programs, the regulatory approval process, and competitive products. See the company's Form 10-K/A dated April 30, 1997 for information about risks associated with clinical trials and product development programs and other risks which may affect the company.

SOURCE Cell Genesys, Inc.

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