Editor's Note: Delayed by the sudden emergence of COVID-19 last January, the multinational rollout of Mosaico — an important trial of a new kind of HIV vaccine — is back on track. This story describing Mosaico was published last July and marked the announcement of the trial at an International AIDS Society conference in Mexico City.
An international consortium that includes Seattle’s Fred Hutchinson Cancer Research Center will begin recruiting thousands of volunteers on three continents in late 2019 for a trial of a vaccine designed to protect people against multiple strains of HIV.
The new trial announced on July 16 is called Mosaico and was described as a “complementary study” to an ongoing one among women in Africa. Consortium members will discuss the trial next week at the 10th International AIDS Society Conference on HIV Science taking place July 21–24 in Mexico City.
Mosaico will test a vaccine that closely resembles the one being tested in the African women’s trial, but it will be studied in other parts of the globe — in the United States, Latin America and Europe. There, it will be provided to members of communities where the risk of HIV is also high: among people who are transgender and men who have sex with men.
Both vaccines under study come from Johnson & Johnson, parent company of vaccine developer Janssen Pharmaceuticals.
Mosaico will bring to five the number of large-scale trials running concurrently and coordinated by the HIV Vaccine Trials Network, or HVTN, which is headquartered at Fred Hutch. There are nearly 12,700 participants enrolled in the other four studies now underway, each evaluating the effectiveness of a different vaccine strategy.
“These public-private partnerships are critical to develop a globally effective HIV vaccine. No one organization can take on HIV alone,” said Dr. Larry Corey, principal investigator of the HVTN. “The HVTN is appreciative of the ability to work with a global consortium of partners in this program.”
Mosaico’s complementary trial in Africa, named Imbokodo or HVTN 705, was launched in November 2017 and is well underway in five nations where girls and young women have a much higher risk of infection than males of the same age. In May, Johnson & Johnson said that Imbokodo was fully enrolled, with 2,600 women participating. First results are expected in 2021.
Mosaico, also known as HVTN 706, is designed to enroll 3,800 participants, and results will be released after it is completed in late 2023.
In contrast with Africa — where women bear the brunt of new infections — in the U.S. and Europe men who have sex with men account for 57% of new infections, according to the International AIDS Society.
Also at a higher risk of HIV are transgender people. In a survey of 3 million HIV test results reported to the Centers for Disease Control and Prevention, the percentage of transgender people who newly acquired HIV was triple the U.S. national average.
The HIV-negative volunteers in the new Mosaico trial, as in Imbokodo, will receive four injections over the course of a year, assigned to either the vaccine or a placebo. Neither the participants nor the researchers will know who is getting the actual vaccine.
All participants will receive a comprehensive HIV prevention package, according to trial designers. That includes risk-reduction counseling, condoms, and testing and treatment for sexually transmitted disease. In countries where pre-exposure prophylaxis, or PrEP, is licensed or available, it will be offered to potential participants who may accept it in lieu of a vaccine.
Imbokodo and Mosaico are both testing a new vaccine inspired by the concept of a mosaic, in that it is built using parts — like tiles — from many different HIV strains found around the world. The idea is to overcome HIV’s ability to rapidly escape, through mutation, the protection offered by a vaccine containing a single strain. Imbokodo was tailored from a patchwork of strains predominant in Africa. Mosaico will use a slightly different formulation because it will add, in the third and fourth injections, a protein from a family of HIV strains found more often outside Africa.
The first enrollees in Mosaico will be seen at a yet-to-be-chosen site in one of 16 participating American cities. Eventually, the trial will expand to 55 sites worldwide. Among the 21 U.S. sites will be the Hutch’s Seattle Vaccine Trials Unit.
Dr. Susan Buchbinder, an epidemiologist at the University of California at San Francisco and a principal investigator for HVTN, is leading the Mosaico study. “We are committed to ensuring that HIV vaccine trial results are generalizable to the populations that carry the greatest burden of HIV infection,” she said.
The Mosaico trial (HVTN 706/HPX3002) is supported by a collaboration led by Janssen Vaccines & Prevention B.V., part of the Janssen Pharmaceutical Companies of Johnson & Johnson; the National Institute for Allergy and Infectious Diseases, which is a part of the National Institutes of Health; and HVTN, which is funded by NIAID. Additional collaborators include the U.S. Army Medical Materiel Development Activity.
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Sabin Russell is a former staff writer at Fred Hutchinson Cancer Center. For two decades he covered medical science, global health and health care economics for the San Francisco Chronicle, and he wrote extensively about infectious diseases, including HIV/AIDS. He was a Knight Science Journalism Fellow at MIT and a freelance writer for the New York Times and Health Affairs.