HIV Vaccine Efficacy Trial Mosaico to Launch in Americas, Europe

A vaccine for HIV will be put to the test in a new phase 3 efficacy trial enrolling men who have sex with men and/or transgender people in North America, South America, and Europe.

The study, HPX3002/HVTN 706 or Mosaico, plans to register 3800 HIV-negative participants aged 18 to 60 years when enrollment opens later this year at clinical research sites in the United States, Argentina, Brazil, Italy, Mexico, Peru, Poland and Spain.

“The Phase 3 Mosaico study…[is] evaluating investigational vaccines based on ‘mosaic’ immunogens—vaccine components comprising elements from multiple HIV subtypes—that aim to induce immune responses against the wide variety of global HIV strains,” the National Institutes of Health (NIH), one of the global partners on the study, announced in a press release.

Mosaico will be the third HIV vaccine efficacy trial currently in progress. HPX2008/HVTN 705 or Imbokodo, a complementary phase 2b study in women launched in 2017, completed enrollment in May 2019 with 2600 sexually active females aged between 18 and 35 years across Malawi, Mozambique, South Africa, Zambia, and Zimbabwe.

HVTN-702, an ongoing phase 2b/3 trial, was launched in 2016 and is evaluating a newer version of the vaccine regimen tested in the RV144 Thai trial. It completed enrollment of 5400 sexually active men and women aged 18 to 35 years in South Africa, according to the NIH.

Findings from a phase 1/2a clinical trial called APPROACH were published in The Lancet last year. In that study, an experimental HIV-1 vaccine regimen of mosaic adenovirus serotype 26 (Ad26) was well-tolerated and produced immune responses against HIV in humans and rhesus monkeys.

For Mosaico, participants will be randomly assigned to receive either the investigational vaccine regimen (6 shots administered in 4 sessions over 1 year) or a placebo. The first 4 doses of vaccine candidate Ad26.Mos4.HIV use an engineered common-cold virus to deliver 4 mosaic immunogens, while the final 2 doses comprise a bivalent HIV envelope protein formulation that combines clade C gp140 and mosaic gp140 envelope proteins, adjuvanted by aluminum phosphate, according to the NIH.

Trial participants will also have access to a comprehensive HIV prevention package, including pre-exposure prophylaxis, or PrEP.

“The Mosaico trial is an important step toward developing a safe and effective HIV vaccine for people worldwide, including men who have sex with men and transgender people, who could greatly benefit from a preventive HIV vaccine,” Susan Buchbinder, MD, of the University of California, San Francisco, and the HVTN protocol leadership chair of the Mosaico trial, said in a press release.

Mosaico is sponsored by Janssen Vaccines & Prevention, B.V., part of the Janssen Pharmaceutical Companies of Johnson & Johnson, and supported by NIH’s National Institute of Allergy and Infectious Disease. Additional partners include the HIV Vaccine Trials Network and US Army Medical Research and Development Command.