October 29, 1999

New HIV vaccine studied to replace multi-pill regimen

Featured Image

Dr. David Haas and research coordinator Victoria Harris are studying a new drug to treat HIV. (photo by Donna Jones Bailey)

New HIV vaccine studied to replace
multi-pill regimen

Researchers in the Vanderbilt AIDS Clinical Trials Center are studying an injectable immune therapy that could — for some HIV-positive patients — end the need to take thousands of dollars of pills each year to remain healthy.

The center is currently looking for healthy HIV-positive individuals to participate in the clinical trial.

The pilot study to see whether injections of the medication, HIV immunogen, can enable the patient’s own immune system to effectively fight the virus is being conducted at Vanderbilt and two other academic medical centers. Approximately 40 participants are being sought at the three sites for the 40-week study.

Current therapy for most HIV-positive individuals to remain healthy requires a rigorous schedule of pill-taking at specific times each day. The medications, in addition to costing as much as $10,000 per year per patient, can have serious and long-term side effects.

“What we are looking at is a way to boost a person’s immune system so it can specifically fight HIV,” said Dr. David W. Haas, associate professor of Medicine and Director of the Vanderbilt AIDS Clinical Trials Center. “We hope this therapy will allow the patient’s own immune system to control the virus.”

Haas says that this trial represents the next hurdle for HIV-positive individuals who are doing well by taking multi-drug combinations and that is to find a way to wean them off the pills to a more suitable long-term therapy.

“For most viruses a person’s immune system acts to control that virus once it enters the body even if it’s there permanently. For HIV that doesn’t work because the virus attacks the immune system itself,” he said.

Haas says that in every instance where an HIV-positive individual who has been successful at maintaining an undetectable viral level with multi-drug therapy stops taking medications, the virus has come roaring back.

“Their immune system may seem to be doing very well, but it does not recover the ability to fight HIV,” he said.

Carefully selected study participants will be given a series of three injections of HIV immunogen, also known as Remune, over a six-month period before being allowed to stop taking their current medications. “The compound is designed to stimulate specifically the patient’s immune system to HIV,” Haas said.

“It has been clearly shown that this compound, if given to people with HIV infection who are on effective therapy, does boost their HIV-specific immunity, “ he said. “What we don’t know is what benefit that immunity will provide in the long-term.”

Haas says there is a small group of HIV-positive individuals whose own immune system has the ability to effectively combat the virus. These people lead normal, healthy lives without the need for any medications. Haas hopes that this trial will offer other HIV-positive individuals on therapy a way to emulate these individuals whose own immune systems can fight the virus without the help of daily pills.

The study is designed to very carefully and safely monitor the status of each participant after they stop taking their medications. Participants will undergo frequent tests to carefully monitor the level of HIV in their blood.

“After the series of injections, assuming the participants are still doing very well, they will stop their medications completely. They will then be watched very closely to see if the virus comes back in their blood, and if so how rapidly and how much it returns,” Haas said. “Decisions would then be made about whether they will need to go back on therapy.”

The HIV immunogen, or Remune, is also known as the Salk HIV Vaccine and has been safely given to thousands of people enrolled in clinical trials with little or no side effects. The vaccine is a killed form of the whole HIV virus that is unable to cause infection. It works by causing the recipient’s immune system to respond to many of the specific parts of the virus.

Haas points out that like any study of a new treatment there will be a need for a control group that will receive injections of a placebo. However, at the end of the study all participants will be given the opportunity to receive the active vaccine.

“The study has been designed to be done in the safest way we can imagine. It is known that if HIV-positive individuals who are doing well on their first therapy with complete control of the virus, and stop that therapy and have the virus return, then the virus remains completely sensitive to their previous medications. So they could then resume their regular form of therapy if need be without any harm,” he said.

“We are minimizing the risk to the patient by having very specific criteria for the study.”

Patients suitable for the study have to be on their first treatment regimen of three drugs and have to have had no detectable HIV in their blood for at least six months.

“This therapy isn’t for everyone with HIV. For people with the virus who have had trouble controlling it with other therapies there is little reason to think that Remune would be of benefit to them presently,” Haas said.

“This doesn’t represent the next major leap in HIV therapy, but is one more step in a long process of finding out ways to improve the lives of persons living with HIV.”

For information about this study or other AIDS/ HIV clinical trials please contact Victoria Harris, Ed., at the Vanderbilt AIDS Clinical Trials Center at 936-1164 or email at victoria.harris@vanderbilt.edu.