Trial of Promising HIV Vaccine Fails in South Africa

By Lenny Bernstein, The Washington Post

03 February 20

broad study of a promising vaccine for HIV has ended in failure after an interim analysis showed it was no more effective than placebo, researchers announced Monday.

Vaccinations were halted after an independent monitoring panel for the “Uhambo” study in South Africa determined on Jan 23 that 129 people who received the vaccine developed HIV while 123 who were given a placebo contracted the infection.

“It’s disappointing, but I’m not overly surprised by it,” said Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), which funded the $130 million research effort with the Bill & Melinda Gates Foundation. “It did not, essentially, bring it over the goal line.”

Susan Buchbinder, director of HIV prevention research for the San Francisco Department of Public Health, who was not involved in the South Africa study, agreed that the results were “quite disappointing. We had hoped, based on the data . . . that it would have similar or enhanced efficacy compared with what we’d seen before, but it didn’t.”

The trial began on a hopeful note in 2016. It tested a modified version of a vaccine that had proven 31 percent effective in 16,000 people in Thailand four years earlier — too modest an impact for use in a general population but effective enough to warrant further study.

The combination of two drugs was reformulated to attack the version of the virus that circulates in South Africa, where nearly 1 in 5 adults are infected, in the hope of boosting its effectiveness to about 50 percent. That would have made production of the vaccine worthwhile for the two companies, Sanofi Pasteur and GSK, experts said.

The study was only the seventh large-scale human trial of a vaccine for HIV, which newly infected 1.7 million people worldwide in 2018, according to the Joint United Nations Program on HIV and AIDS. Researchers enrolled more than 5,400 sexually active men and women between the ages of 18 and 35.

They were split evenly between those who received the vaccine and those who received a placebo. After at least 60 percent of the participants had been enrolled for 18 months, enough time for the vaccine to provoke an immune response, the independent monitoring board determined the vaccine was not effective and recommended halting the effort. NIAID concurred.

The panel did not raise any safety concerns about the vaccine.

In a statement, GSK said the company was “disappointed by the results” and “the fact that the development of this candidate vaccine, which was predominantly aimed at benefiting people in the developing world, is unlikely to be continued now.” A spokesman for Sanofi Pasteur did not return an email seeking comment

Two other major human trials also underway are examining another vaccine approach designed by Janssen Pharmaceuticals, part of the health-care giant Johnson & Johnson. That vaccine was designed as a broad-based approach to HIV, rather than a targeted regimen, according to Buchbinder, the primary investigator for one of the two research efforts.

That study is testing the vaccine on men who have sex with men and on transgender people in South America and Europe. The other is taking place in five African countries.

Other efforts to vanquish HIV under development include long-acting injectable treatments for the infection. The drugs have transformed HIV into a manageable virus by suppressing the level of the virus in the blood to undetectable levels in many people. But some people have difficulty staying on the medication.

Similarly, Fauci said, bridging the gap between the current circumstances and the arrival of a successful vaccine may require government to aggressively promote the use of “pre-exposure prophylaxis,” or PrEP medication. Those drugs have been found to be as much as 99 percent effective at blocking transmission of the virus, even during unprotected sex or intravenous drug use.