5 HIV Patients Virus-Free After Early Vaccine Trials
Posted: Mar 16th, 2017 at 09:55AM
HIV treatment using a new vaccine-based regimen has succeeded in suppressing the HIV virus in five patients. Researchers working on this vaccine-based intervention combined a drug used in cancer therapy and two innovative HIV vaccines. The two vaccines used have gene coding for proteins produced by all the known variants of HIV. Once in the blood, the immune system recognizes these proteins as foreign which then primes CD8 cyto-toxic T-cells (a type of white blood cells). Once a cell is infected with HIV and expresses these proteins on its surface, the proteins are recognized by the CD8 cells after which they are attacked and destroyed. This research has raised hopes that further research could lead to the prevention of AIDS with no need of using daily drugs.
The Study
The treatment trial was conducted over a period of three years in Barcelona, Spain, at the IrsiCaixa AIDS Research Institute. Of the 24 participants in the trial, five reported undetectable levels of the virus after receiving treatment. Additionally, the spread of the virus was stopped by their immune systems. This is as reported by the New Scientist. Of these five, one has been off drugs for seven months. Dr. Mothe (lead scientist for the trials) and her team gave patients recently diagnosed with HIV two doses of the vaccine to stimulate white blood cell production responsible for the destruction of cells infected with the HIV virus.
The participants were required to continue with anti-retroviral medication (ART) during the three years of the trial period while researchers monitored their immune systems and response. An additional booster dose of one of the vaccines and three doses of Romidepsin (a cancer drug) was given to 15 of the participants in 2017. Romidepsinhas have been shown to flush out the HIV virus from where it may be lying dormant in the tissues. Once flushed out, the virus can be attacked and destroyed by CD8 cells. So long as a cell contains even a small part of the virus, it can be destroyed. Another booster of the vaccine was then administered.
The Results look Encouraging
10 of those who were given this booster dose experienced a quick comeback of the virus which also began to spread. They resumed their ART medication. The remaining five participants maintained suppressed levels of the viral load. Their viral load was below detection levels meaning that they did not have to continue ART medication. One of the five has been drug-free for seven months. The other four have had undetectable levels of the virus for 6, 14, 19 and 21 weeks respectively. These results were revealed by Dr. Mothe at the Conference on Retroviruses and Opportunistic Infections in Seattle last week. She added that they would follow up with each of the participants to observe how long each of them would be able to control the virus. She added that it was not clear why two-thirds of the initial participants did not respond to the therapy and that they were still investigating this further.
According to the UN, almost half of those living with HIV (18 million people) take ART medication to slow down the progression of HIV infection. ART drugs work by preventing the HIV virus from replicating and damaging the immune system. These drugs are, however, expensive and have many adverse side effects. Additionally, patients have to remember to take their ART medication on a daily basis for their entire lives. If not, the virus can hide away in lymphoid and gut tissues and when ART medication is stopped, the virus quickly reappears from these cells and starts replicating. In 2015, it cost $19 billion to provide ART medication for patients in low and middle-income countries alone. According to the New Scientist, huge savings could be rendered if further research proves successful.
Sharon Lewis (Director of The Peter Doherty Institute for Infection and Immunity at the University of Melbourne, Australia) says that a positive response to the therapy, even in a small number of participants, is still good news. She noted that this was the first treatment that had stopped the replication of the HIV virus without daily ART medication.
The Executive Director of the AIDS Vaccine Advocacy Coalition (AVAC), Mitchell Warren, agreed with Lewis' sentiments. He told The Independent that despite the fact that the study was carried out on a small scale, the findings of the study were both interesting and important. He added that long-term treatment regimens that do not need patients to take medication on a daily basis would turn the tide on the HIV epidemic. Such treatment would expedite the process of getting the entire population living with HIV to undetectable virus levels, making them non-infectious. 37 million people are currently living with HIV globally. Warren further informed The Independent that such treatment is part of what is known as therapeutic vaccines which are used for people already infected with disease unlike preventive immunization employed in the case of viruses such as polio and mumps. According to him, the idea that ongoing control of the virus could be provided by a therapeutic vaccine is a huge step forward.
People are being cautioned against getting too excited about these results. In the past, treatments that appear to cure patients infected with HIV have been developed, only for the virus to bounce back. Dr. Mothe is, however, hoping that this time results will be different because in the past, treatment was either used to attack the virus as early as possible or to try to replace the whole immune system so as to get rid of any dormant virus.
This current research is different in that the vaccines are focusing on priming of immune cells that are capable of getting rid of the active HIV virus from the body as fast as possible after infection. Additionally, the cancer treatment which flushes out dormant HIV virus leaves no traces of the virus hiding in body tissues. Together with her team, Dr. Mothe is working even harder to find out the mechanism behind the observed immune response so as to simplify the treatment schedule. She added that though they still had a long way to go, she and her team were on the right path to coming up with an alternative treatment to ART medication.
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