Silicon Investor (SI) -- The First Internet Community

STOCKTALK

We've detected that you're using an ad content blocking browser plug-in or feature. Ads provide a critical source of revenue to the continued operation of Silicon Investor. We ask that you disable ad blocking while on Silicon Investor in the best interests of our community. If you are not using an ad blocker but are still receiving this message, make sure your browser's tracking protection is set to the 'standard' level.

Biotech / Medical : Cell Genesys (CEGE) -- Ignore unavailable to you. Want to Upgrade?

To: Mike McFarland who wrote (576)	3/11/1999 10:47:00 PM
From: Dan Spillane	Respond to of 1298

If I am not mistaken, Cell Genesys is one of the companies that has tried T-cell therapy using T-cells changed outside the body, which are then put back. But apparently now we know why this didn't go far. The new discovery described below could make such a therapy important again. Look at the last comments in the story... (from the story below) Killer memory cells programmed to attack HIV, grown outside the body and then injected into a patient, could be an effective weapon against the virus. Prof Ashton-Rickardt said: "We have the technology to try this already. Perhaps now we know how to use it." (full story) Cancer and Aids vaccines move closer Scientists boosted the immune systems of laboratory mice Scientists believe they have discovered a way to mobilise the body's specialised defence cells to fight diseases such as cancer and Aids. Most of the body's immune cells self-destruct after they have attacked foreign invaders such as bacteria and viruses. However, a special type of cell, known as memory T lymphocyte, remains on patrol after the immune system has defeated an infection. If the same invader turns up again, the memory cells recognise it instantly and launch an early counter-attack. Scientists believe these memory cells can be used to develop far more effective vaccines. Until now no vaccine has been able to produce significant numbers of the memory cells. American researchers from the University of Chicago believe they have discovered why. They say memory T cells are slow learners, and it takes several generations of intense instruction to "train" them. This means it takes prolonged exposure to an invader to create large numbers of memory cells. Assistant Professor of Pathology Philip Ashton-Rickardt said: "This finding suggests that the typical approach to vaccines for treatment of cancer or Aids is not often likely to produce the desired result. "But it also shows us how we can get around the problem." The Chicago team discovered that most T cells will die after defeating an invader. Only a few survive and develop into memory cells, which remain eternally vigilant for any subsequent attack. But without strong stimulation by an invader for three to four days, few memory cells emerge. Normal vaccines administer a low dose of the foreign material which triggers an immune response, and this is insufficient to generate memory cells. Mice experiments Powerful new vaccines could be on the way The scientists, whose research was reported in the journal Science, grew memory T cells in the laboratory. This enabled them to challenge the cells constantly with high levels of foreign protein for four or five days. They then injected the activated cells into mice without immune systems. Ten weeks later, the injected T cells were still effective and able to react to the invading protein they had been programmed to attack. Professor Ashton-Rickardt said: "The great thing was that the memory cells were primed and ready. "They remembered and went after their targets as soon as they were exposed to them again. "Although mice with normal immune systems take two or three days to mount an immune response, these memory T cells responded immediately." The discovery could be especially useful in the treatment of the Aids virus, HIV. People infected with HIV normally lose a different kind of "helper" T cell whose chemical signals are needed to activate killer T cells. Although killer cells are not damaged by HIV, the loss of their helpers means they are rendered powerless. Killer memory cells programmed to attack HIV, grown outside the body and then injected into a patient, could be an effective weapon against the virus. Prof Ashton-Rickardt said: "We have the technology to try this already. Perhaps now we know how to use it." news.bbc.co.uk

To: Mike McFarland who wrote (576)	3/11/1999 11:53:00 PM
From: Dan Spillane	Read Replies (2) \| Respond to of 1298

I did more research and studied the article again. Cell Genesys has indeed been using T-cells programmed to go after HIV, which are first collected from the body. So it seems this new discovery could be important. In fact, CEGE is currently doing this in trials with plain T-cells (they haven't already given up like I thought), but it looks like they have only been having limited success, since they were planning on combining this T-cell therapy with anti-retroviral drugs, instead of -- dare I say it -- eliminating or "curing" AIDS. However, as the new article suggests, there may be a way to boost the effectiveness of T-cell AIDS therapies by using the special "memory" type of T-cell to contain the modification which targets AIDS. Since the memory T-cell persists better in the body than the plain T-cell, effectiveness could be vastly increased. This seems pretty exciting. (from the Cell Genesys web page) AIDS Cell Genesys is conducting a 40-patient, multi-center Phase II trial in patients with undetectable HIV in their blood while receiving antiretroviral drug therapy. Using standard blood bank techniques, T cells are collected from patients with AIDS, genetically modified to recognize and destroy HIV-infected cells, expanded in number and then returned to the patient as a form of AIDS gene therapy. Cell Genesys' genetically modified cells target the cells which harbor HIV, in contrast to the commonly used antiretroviral drugs which do not eliminate such cells. Clinical data from an earlier Phase II trial, which was conducted in patients with detectable HIV in their blood, has shown no treatment-related safety problems, persistence of the genetically modified T cells for greater than 100 days following infusion and preliminary evidence of antiviral activity as measured by levels of HIV in gastrointestinal lymph tissue, a primary reservoir for HIV-infected cells. The company believes that the gene therapy and antiretroviral drug therapy could be combined and could potentially decrease the requirement for long term antiretroviral drug therapy. Data from this trial are expected to be reported during 1999. This program is supported by funding from the company's collaborator, Hoechst Marion Roussel. (full page) cellgenesys.com