HIV Vaccine Trial Ends in ‘Disappointment’ but Provides Valuable Data

  • A trial for a once-promising HIV vaccine ended in disappointment after the potential vaccine was found to be ineffective at preventing the virus.
  • The end of the South Africa–based trial — called HVTN 702, or the Uhambo trial — was announced Monday by the National Institute of Allergy and Infectious Diseases (NIAID), which sponsored the research.
  • Experts say the cancellation of the trial was disappointing, but not really a surprise.
  • They also say the trial provided valuable information that will be used in future research.
  • Additional efforts to develop a vaccine and tackle the global HIV epidemic are currently in progress.

A once-promising HIV vaccine trial was discontinued after being found ineffective at preventing the virus.

For researchers chasing after a long-hoped-for vaccine to prevent HIV transmission, the announcement was a disappointing setback.

That being said, other similar research currently being conducted underscores that the international effort to develop a vaccine and tackle the global HIV and AIDS epidemic continues on.

The news that the South Africa–based trial — called HVTN 702, or the Uhambo trial — ended was announced Monday by the National Institute of Allergy and Infectious Diseases (NIAID), which sponsored the research.

“An HIV vaccine is essential to end the global pandemic, and we hoped this vaccine candidate would work. Regrettably, it does not,” NIAID Director Dr. Anthony S. Fauci said in a press release. “Research continues on other approaches to a safe and effective HIV vaccine, which I still believe can be achieved.”

‘Disappointing, but not really a surprise’

The trial started in 2016, enrolling 5,407 volunteers who were HIV negative across 14 sites in South Africa.

The participants were sexually active men and women between 18 and 35 years old. Out of the total volunteer population, some were separated out randomly into two groups, with one given either the vaccine trial or placebo injections.

They were all closely monitored and given access to HIV preventive care, including oral pre-exposure prophylaxis (PrEP), according to the release.

An analysis of the study showed no major difference in eventual HIV infections among people in the placebo group and those who actually received the trial vaccine.

There were 129 HIV infections in people who received the vaccine and 123 new infections in the placebo group. While the trial wasn’t successful, the researchers will still monitor the participants’ health.

Dr. Ronald G. Collman, director of the Penn Center for AIDS Research, said the cancellation of the trial was “disappointing, but not really a surprise” to members of the HIV research community. This is due to past research using the same components of the Uhambo trial vaccine failing to prove effective.

“Why put them together when either one of them alone weren’t effective?” Collman told Healthline. “I don’t think too many scientists are surprised. We were hopeful, but perhaps not surprised.”

Dr. Alan Taege, an infectious disease specialist at Cleveland Clinic, echoes Collman’s thoughts on the disappointment of the trial ending but says this trial is just “scratching the surface.”

For Taege, just because this trial didn’t result in a vaccine doesn’t mean it was a waste.

“There’s still a whole lot of work going on in the HIV vaccine world. For this trial, like many others, there will be far more analyses that will be done on the results,” Taege told Healthline.

“They will go back and study analyses of these patients and see ‘was there any kind of antibody formation?’ for instance. They’ll see if there is something we can learn from this and then build on this work to try to arrive at a very good vaccine,” he said.

“I don’t feel totally discouraged,” he added.

A global, interconnected effort

Ever since the emergence of HIV, scientists have been trying in vain to develop an effective vaccine. Collman says there have been several different approaches to trying to crack the HIV vaccine code.

One is an “empiric approach,” in which he explains you basically take a hypothesis and “try some things and see if they work.”

He says the studies that have been done so far have largely been empiric, with some reducing the infection and others making it “milder,” but no success at eliminating the virus.

Collman adds that other approaches involve “neutralizing” the virus. This involves vaccinating people so they could hopefully develop antibodies to neutralize most or all of the strains of HIV.

Another approach is to try to create T cells — which play a central role in a person’s immune response to a virus — to essentially attack cells infected with HIV.

“The greatest area that has shown progress is creating broadly neutralizing antibodies. There’s been a huge amount learned in the past 10 years about what antibody you’d need to create to neutralize HIV,” Collman said. “It’s not like an antibody for the measles; it’s not like an antibody to the flu. It’s a really complicated antibody.”

He says there are several approaches to coming up with an effective antibody for HIV. One is to try to create just the right type of protein structure that would trigger a very specific immune response to HIV.

“Antibodies are really hard for the body to develop. For HIV, you’d have to sequentially analyze all kinds of types of immunogens that will ‘chaperone’ along with that antibody as it attacks the HIV cell,” Collman said. “There are studies going on right now to see how to create a broadly neutralizing antibody.”

The need to find a vaccine is understandably great. Since the beginning of the HIV epidemic, 75 million people have contracted HIV. About 32 million have died from it around the world, according to the World Health Organization.

Despite failures to find a cure or a vaccine, great strides have been made in HIV healthcare.

For instance, adhering to modern medications can ensure that people with HIV can achieve an “undetectable” HIV viral load in their bodies.

This means they effectively can’t transmit the virus to sexual partners, reports the Centers for Disease Control and Prevention.

When could we see the development of an HIV vaccine?

Both Taege and Collman say it’s difficult to know when that could be possible.

“I think it’s difficult to see in the next 5 years or 10 years if we will have a vaccine because there’s still so much to learn. I feel we are some distance away from a durable vaccine for HIV,” Taege said.

“It’s important to recognize this isn’t one site, one study. It’s an international, worldwide effort. People around the world right now are working on various aspects of developing a vaccine,” he said.

Collman say he’s encouraged by all the work on developing a broadly neutralizing antibody that could tackle an infected HIV cell.

“We know it should work, because if you take them and put them in a monkey, it can prevent the monkey from getting infected,” he said. “So, how do we get those antibodies to emerge in vaccination in a human?”

Taege says the global crusade to find a vaccine offers hope.

“In this interconnected effort among researchers around the whole world, every day someone is working on something useful to contribute to finding a vaccine,” Taege said. “I’m still hopeful.”

The bottom line

The National Institute of Allergy and Infectious Diseases (NIAID) announced Monday that a once-promising HIV vaccine trial in South Africa was discontinued.

This came after an analysis on trial participants showed nearly equal number of new HIV infections among both participants who received the trial vaccine and those given a placebo.

The vaccine was found to not prevent HIV transmission.

Researchers say the news was a disappointment, but not surprising. This comes after countless efforts over the past 3 decades to develop an HIV vaccine have failed to succeed.

That being said, there’s promising work being done around the world, including the hunt to try to create a broadly neutralizing antibody that would specifically target HIV-infected cells.

Source: Read Full Article