Company Press Release

CARLSBAD, Calif., March 27 /PRNewswire/ -- The Immune Response Corporation announced today that it has made progress in identifying the gene expression patterns following anti-inflammatory treatment for spinal cord injury and the genetic basis underlying peripheral nerve regeneration. The results from microarray (gene chip) studies reported on March 23, 2000, at the, Washington, D.C., may provide the basis for developing new treatments for acute and chronic spinal cord injury.

"Methylprednisolone, an anti-inflammatory steroid, has been the standard of care for patients with acute spinal cord injury. We are now beginning to understand the genetic basis for its neuroprotective effect," said Dr. Adrian A. Cameron, Research Scientist, The Immune Response Corporation. "We have identified several hundred genes apparently involved in the injured spinal cord's response to methylprednisolone treatment, which may provide a basis for developing more specific and potent anti-inflammatory agents and new strategies for the treatment of acute spinal cord injury."

The latest "gene chip" technologies were employed to compare the changes in gene expression or activity in spinal cord-injured rats subsequently treated either with methylprednisolone or saline as a control. Gene chips, or gene expression microarrays, are a genomics tool that contains thousands of human genes arranged on a glass chip and can be used to catalogue gene activity in different nerve tissues or different experimental situations. By comparing gene expression profiles between the two groups of experimental rats, the scientists determined which genes were differentially turned on or off as a result of methylprednisolone treatment.

The results suggest that methylprednisolone administration appears to cause suppression of gene activity in the injured spinal cord, particularly of genes that promote inflammation and proliferation of cell types that may prohibit regrowth of damaged nerve tissue. A small percentage of genes were observed to increase in activity, and these were identified as genes encoding antioxidants, growth factors, and matrix proteins known to have neuroprotective effects.

"Such patterns of gene activity resulting from methylprednisolone treatment may underlie this drug's ability to suppress the immediate inflammation that occurs following trauma that is responsible for 'secondary damage' to the spinal cord tissues," said Dr. Cameron.

Data were also reported on experiments that examined the genetic basis of peripheral nerve regeneration. Gene expression profiles were obtained during the regeneration of experimentally injured dorsal root ganglia, masses of cell bodies located in the peripheral nervous system (PNS), and also of activated Schwann cells, which are specialized cells of the PNS that play a supportive role in nerve impulse transmission.

"In contrast to the central nervous system (the brain and spinal cord), the PNS can survive trauma and regrow damaged neurons to restore motor function. The PNS is therefore an important model to study in devising strategies for the treatment of chronic spinal cord injury. To this end, we have identified a whole cluster of genes that apparently can be turned off or on at different points during the 'regeneration cycle' of neurons in the PNS," said Dr. Cameron. "Our next steps are to determine which of these genes, if any, play a causal role in nerve regeneration and could potentially serve as candidates for drug targets or gene therapy to treat chronic spinal cord injury, in which neuron regeneration may be necessary for functional restoration."

The Immune Response Corporation is a biopharmaceutical company based in Carlsbad, California, developing immune-based therapies to induce specific T-cell responses for the treatment of HIV and autoimmune diseases. In addition, the Company is working on cancer vaccines and gene therapy.

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This news release contains forward-looking statements. Actual results could vary materially from those expected due to a variety of risk factors, including, but not limited to, whether clinical trials will be initiated, whether if initiated clinical trials will be successfully concluded and whether any potential product(s) will be approved for marketing or be successfully commercialized. Those factors are discussed more thoroughly in The Immune Response Corporation's SEC filings, including but not limited to its report on Form 10-K for the year ended December 31, 1998 and subsequent Forms 10-Q. The Company undertakes no obligation to publicly release the result of any revisions to these forward-looking statements which may be made to reflect events or circumstances after the date hereof or to reflect the occurrence of unanticipated events.