Another HIV vaccine fails to provide protection in halted trial

Janssen announced on Wednesday that it had stopped Mosaico’s Phase 3 trial because the experimental HIV vaccine regimen it was testing was not effective in preventing HIV infection compared to placebo.

No safety issues were identified, but the study’s independent data and safety monitoring committee determined that the study would not achieve its primary objective of HIV prevention.

“We are disappointed with this result and stand in solidarity with people and communities vulnerable and affected by HIV,” Penny Heaton, MDhead of the global vaccine therapeutic area within Janssen’s research and development unit, said in a press release.

It was the last HIV vaccine trial to be stopped because the experimental regimen being tested didn’t work. Janssen stopped the Imbokodo phase 2 trial – which tested a vaccine regimen similar to Mosaico – in 2021, and the National Institute of Allergy and Infectious Diseases stopped a phase 2b/3 clinical trial in early 2020 that was testing a regimen based on the only experimental combination of HIV vaccines never to demonstrate the effectiveness in a large clinical study.

Stephane E. Wallace, Ph.D., MSdirector of outreach for the HIV Vaccine Trials Network (HVTN), which conducted the study, told Healio that the organization “currently has no HIV vaccine efficacy trials in the field that are recruiting.”

The Mosaico and Imbokodo studies are being followed up, Wallace said.

“In the coming weeks, study participants (Mosaico) will have a final study visit, during which they will learn which study group they were assigned to, undergo blood draws for diagnostic testing HIV infection, receive information about vaccine-induced seropositivity and seroreactivity, and again receive counseling on HIV prevention options and [be] provided with appropriate references,” Wallace said.

The study included approximately 3,900 cisgender men and transgender people who have sex with cisgender men, transgender people, or both at more than 50 trial sites in Argentina, Brazil, Italy, Mexico, Peru , Poland, Puerto Rico, Spain and the United States.

Beginning in 2019 and with vaccinations completed in October 2022, participants received either a placebo or a vaccine regimen containing a mosaic-based adenovirus serotype 26 vector given in four doses over 1 year, with the second two doses comprising a mixture of soluble proteins.

Since the completion of the study vaccine series, “the number of HIV infections was equivalent between the vaccine and placebo arms of the study,” NIAID said in a statement, adding that “the results of Mosaico follow the developments of the phase 2b clinical trial Imbokodo”. .”

In the Imbokodo study, which recruited 2,637 women aged 18-35 from Malawi, Mozambique, South Africa, Zambia and Zimbabwe, the vaccine tested was estimated to be 25.2% effective .

“We remain steadfast in our commitment to advancing HIV innovation, and we hope Mosaico’s data will provide insights for future efforts to develop a safe and effective vaccine,” Heaton said.

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