Prime Time Replay:
Dr. David Weiner
on New Developments in DNA-based vaccines
MsgId: *breakthrough(1)
Date: Wed Jul 2 20:34:32 EDT 1997
From: moderator At: 152.163.195.9
Hi, I'm Madeleine Lebwohl, moderator of Breakthrough Medicine. Please join me tonight at 9pm when I speak with Dr. David Weiner, of the University of Pennsylvania. Dr. Weiner will discuss the new developments in DNA-based vaccines and how they have immunized chimpanzees against the HIV virus.
MsgId: *breakthrough(2)
Date: Wed Jul 2 20:59:09 EDT 1997
From: moderator At: 152.163.195.9
Welcome, Dr. Weiner!
MsgId: *breakthrough(4)
Date: Wed Jul 2 21:00:34 EDT 1997
From: DBWeiner At: 152.163.197.35
Its a pleasure to speak with you.
MsgId: *breakthrough(6)
Date: Wed Jul 2 21:04:35 EDT 1997
From: moderator At: 152.163.195.9
The health of the chimpanzees, which proved their ability to fend off the HIV virus, proved your vaccine worked. How is the DNA-vaccine fighting HIV?
MsgId: *breakthrough(7)
Date: Wed Jul 2 21:07:33 EDT 1997
From: DBWeiner At: 152.163.197.35
Our recent reports demonstrated that a DNA vaccine composed of the core and part of the replication genes of the virus as well as the gene encoding the outer envelope of the virus could protect in this primate model from this particular challenge. However, effectiveness of any HIV vaccine will ultimately be tested in clinical studies. DNA vaccines induce immune responses in a somwhat unique manner. Genes encoding attenuated in this case viral proteins are taken up by the cells of the individual that receives the and those cells then are fooled into producing the viral protein. As they become the factory for these nonlive antigens the immune system reacts in two ways to this non host cell protein, 1- antibodies are produced, soluble proteins which can directly bind to invaders and inactivate them and 2- the two types of T cells of the immune system are activated to both expand the immune response in general and that can directly kill infected cells.
MsgId: *breakthrough(12)
Date: Wed Jul 2 21:16:51 EDT 1997
From: moderator At: 152.163.195.9
Why does this strategy seem to work better than others that have been tried?
MsgId: *breakthrough(13)
Date: Wed Jul 2 21:19:45 EDT 1997
From: DBWeiner At: 152.163.197.35
In the absence of completed clinical studies proving the concept, there exist conceptial advantages of this technology compared to the more traditional technologies of either live "weakened" vaccines or non live vaccine technologies, they are that DNA vaccines are non live and non replicating, that is they cannot inadvertantly spread infection (important for certain individuals with weak immune systems) this is similar to non live vaccines, however, non live vaccines traditionally are very poor at inducing killer T cell responses, the responses that clear the body of infected cells ( and they can clear cancer cells as well) since DNA vaccines are produced in the body they do induce killer T cells so the have some of the best aspects of both types of vaccine approaches, in concept.
MsgId: *breakthrough(17)
Date: Wed Jul 2 21:25:32 EDT 1997
From: moderator At: 152.163.195.9
What are the steps between this stage of your vaccine development and its availability to the public? How soon could someone expect to benefit from your work?
MsgId: *breakthrough(19)
Date: Wed Jul 2 21:32:06 EDT 1997
From: DBWeiner At: 152.163.197.35
After a large amount of preclinical testing, we have initiated, in collaboration with Dr. MacGregor at the University of Pennsylvania and Apollon Inc. the company which manufactures the vaccine, Therapeutic vaccine studies in infected individuals. This was the first FDA allowed study of a DNA vaccine and accordingly is a safety study, a study to first examine the safety of this approach in humans.A second, the first prophylactic study of this technology, again for HIV-1, was initiated with the NIH clincal center under the direction of Dr. Kovacs, this study was again a safety study. These studies have demonstrated in a preliminary fashion that this type of vaccine appears well tolerated. In additon the therapeutic study has moved far enough along to allow us to observe that there appears to be evidence for stimulation of both antibodies as well as T cell immunity. These results while in the HIV arena have implications for the use of this approach for other infectious diseases. The preliminary results are encouraging enough that some measure of additional examination is warranted, and so additional studies are being planned.
MsgId: *breakthrough(22)
Date: Wed Jul 2 21:40:47 EDT 1997
From: moderator At: 152.163.195.9
Who participates in a safety study? What is its scope--local, nationwide?
MsgId: *breakthrough(23)
Date: Wed Jul 2 21:48:16 EDT 1997
From: DBWeiner At: 152.163.197.35
It should be stated that none of the results imply anything more than additional studies are being planned, they are much too preliminary for any conclusions to be drawn. Our studies are made possible due to volunteers who agree to participate in these studies knowing that their most likely reward will be only that they participated. That is one of the most wonderful aspects of HIV research that there is a community of people who help in many different ways. There exist similar support for all initial medical studies, in areas as diverse as cancer and autoimmune disease to genetic diseases. People who agree to help with initial studies that are much more likely to benefit others rather than themselves,as the first persons in the door so to speak.
MsgId: *breakthrough(26)
Date: Wed Jul 2 21:56:13 EDT 1997
From: moderator At: 152.163.195.9
What is some of the progress with the other DNA vaccines under development? Why do DNA vaccines seem such a promising route in treating these diseases?
MsgId: *breakthrough(28)
Date: Wed Jul 2 22:00:58 EDT 1997
From: DBWeiner At: 152.163.197.35
There are DNA vaccine studies in progress from different laboratories for viral disease including Herpes, Hepatitis, Influenza, and for Bacterial infections including TB and for pathogens such as malaria, and there are studies in progress for cancer immunotherapy.DNA vaccines are only one tool for attacking infectious diseases and cancers, they are not the only tool. New tools are frequently and importantly ,examined in detail to help to determine if and where their place should be in the treatment and prevention of human diseases. However, the fact that DNA vaccines combine the power of molecular biology with aspects of immune stimulation which mimick infection, suggests that they are an important area for exploration. They allow us to examine aspects of immune stimulation in a rapid manner and therefore represents a very useful tool in this regard.
MsgId: *breakthrough(32)
Date: Wed Jul 2 22:07:12 EDT 1997
From: moderator At: 152.163.195.9
Going back to the chimpanzees, how are they doing as time passes? Do they need to be reinoculated?
MsgId: *breakthrough(33)
Date: Wed Jul 2 22:11:31 EDT 1997
From: DBWeiner At: 152.163.197.35
The chimpanzees that received the DNA vaccine( remember they are only a model system again and examination in other models is ongoing) were protected from HIV establishing infection. This protection in this experiment, is likely similar to any other vaccine such as the smallpox vaccine in that immunization prevents the virus from establishing infection in this model. Further experiments will have to be performed to tell us how long the protection could last. Some human vaccines protect us for life while others require several immunizations. Additionally, experiments in other model systems will likely give us additonal insight into the effectiveness of this approach. One important aspect of this type of vaccine is that we and others have recently reported that we can improve on those first generation DNA vaccines through engineering them to contain immune stimulatory molecules such as cytokine genes, and costimulatory molecules. These add ons demonstrate the flexibility of these vaccines and suggest that the next generation of these vaccines will have improved function and specificity.
MsgId: *breakthrough(36)
Date: Wed Jul 2 22:21:24 EDT 1997
From: moderator At: 152.163.195.9
So what lies ahead? What is the next phase for your study?
MsgId: *breakthrough(37)
Date: Wed Jul 2 22:26:15 EDT 1997
From: DBWeiner At: 152.163.197.35
Currently, we in collaboration with those listed above as well as with the NIH are focusing on several aspects at one time and those include, defining the immune responses observed in these first vaccine studies, additional animal model systems aimed at getting additonal insight into the utility of this approach and much more engineering to improve the potency with out losing the conceptial safety of this approach. Collectively we are hopeful that this approach will find its place in the treatement and or prevention of Human disease, but certainily more studies are required to get us there.
MsgId: *breakthrough(39)
Date: Wed Jul 2 22:33:13 EDT 1997
From: moderator At: 152.163.195.9
The progress of your study certainly offers great hope for a means to combat the HIV virus. Thank you for sharing your work with us!
MsgId: *breakthrough(40)
Date: Wed Jul 2 22:33:51 EDT 1997
From: DBWeiner At: 152.163.197.35
It was a pleasure to speak with you.
MsgId: *breakthrough(41)
Date: Wed Jul 2 22:39:21 EDT 1997
From: moderator At: 152.163.195.9
Goodnight!
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