An Immune Based Therapy for HIV

Summer, 2010

From: Search For A Cure

Authors: David Scondras & Christopher Brennan

I. A new kind of Medicine for HIV

In the Laboratories of Massachusetts General Hospital under the guidance of Dr. Eric Rosenberg, the Chairman of Harvard University's microbiology department and well known HIV researcher, a type of medicine for HIV called a 'monoclonal antibody' is being studied in the test tube to see if the results are consistent with what scientists have previously noticed in the laboratory and when the drug was given to patients.

If things go well, there may be additional clinical trials in people with HIV in the spring of 2011.

Since there are many antiretrovirals that put HIV infection on hold by stopping the virus from replicating, and new ones are coming out every year, it makes sense to ask about the difference between this medicine and the others.

First, the medicine, which is called Cytolin and made by a company called CytoDyn in New Mexico, does not attack HIV directly.  It is an immune based therapy, which purports to repair the mismanagement of HIV by the immune system rather than directly attacking the virus.

This has several benefits that no antiviral medicine has or can have.

First, HIV probably can't become resistant to the medicine because the medicine doesn’t attack it directly.

Secondly, the medicine is given infrequently, at most once every two weeks, which means that it would be hard to miss dosages, unlike the medicines we have today, which have to be used every single day at a particular time.

Third, this medicine might be able to delay how much time passes before a person with HIV needs to start taking antivirals, thereby avoiding side effects, delaying the problems of resistance, simplifying the need to take drugs on time every day, and reducing the high cost of antivirals ―often paid by taxpayers.

Finally, Cytolin might work in people who have exhausted all of their viral medicines or who cannot take them consistently, giving people already taking an HIV cocktail a 'safety net', that helps make sure their antiviral ‘cocktails’ keep working.

Cytolin is an unusual drug in another way: it was used long ago to help people with HIV in a clinical trial as well as in doctor's offices. Usually a new drug is a better version of an older one that we already know a lot about, or is attacking a new part of the HIV life cycle and little is known about how practical it is in people because nobody has used it yet. In Cytolin's case, about 200 people had used Cytolin by 1996 and later in a Phase I(b)/II(a) clinical trial, and in summary the following was observed:

A significant increase in t cells, and a log drop in viral load.

II. How does Cytolin work?

To understand how Cytolin is thought to work, it is important to understand how HIV causes AIDS.  HIV causes a type of cell that is designed by nature to attack and get rid of infected cells to overreact and kill off a lot of uninfected t cells.  This had been proven by 1996 in several studies.  These killer cells called 'CD8+ cytotoxic T lymphocytes' get hyperactive and in their effort to kill infected T cells also kill bystander T cells reducing the number of T cells a person has.  When this number gets low enough (below, say, 350 in the tests that are used to measure this) the body has a hard time fighting off infections. As the number of T cells keeps getting lower, the diseases that attack the body grow harder to stop until a person dies from these 'opportunistic infections'.  This type of overreaction by the body is called an 'autoimmune' response and can be deadly.

Cytolin acts like a kind of tranquilizer for these killer cells, causing them to be more careful and only kill off infected T cells--not all the T cells, which the body needs to fight infections.

It does this by binding to a part of the killer cell called the LFA-1 region of the cell. It replaces the killer cell's bazooka with a hand pistol that's a lot more accurate and causes a lot less peripheral damage.

By doing this in a person with HIV, Cytolin lets their body make more good T cells and reduces the amount of virus in the body.

Cytolin is credited by doctors with helping many patients in the days before we had antiretrovirals.

III. What's next?

The clinical trial that is studying the action of Cytolin has completed its enrollment, which means the study is going forward right now and the results from this first study should be available by January.  After that, if the study shows that Cytolin acts like researchers think it should, given the history of its use in the past, the drug will be studied again in people with HIV and will go through the standard set of trials that the FDA requires before approving a drug for sale in the U.S.

IV. How can I find out more about this medicine?

You can check out the government site (ClinicalTrials.gov), our site (www.searchforacure.org), and the company site (Cytodyn.com) which have the latest information on the drug's development.

It is an important experiment that is going on at Massachusetts General Hospital because fixing the immune system's response to HIV could help a lot of people, and could provide some insight into developing other drugs to help people with other illnesses that have an autoimmune component as HIV does.

It is good that researchers at Harvard and the small company in New Mexico are working on this kind of medicine because immune-based therapies could become another line of defense against many kinds of illnesses.