Before J&J become one of three companies that earned Food and Drug Administration approval for a coronavirus vaccine, the pharma was already a leader in vaccine development. The drugmaker won the first approval for an Ebola virus vaccine and is one of several competing to develop the first shot for respiratory syncytial virus.
HIV has been another major component of its vaccine work. But the disease has proven difficult to target with vaccines because of how frequently it mutates and because it attacks the very cells vaccines are usually designed to assemble against invading pathogens.
In addition, researchers don’t know what level of immune response, known as a correlate, represents effective protection against HIV, and lack good animal models to guide their research. Use of live attenuated or inactivated viruses to spur an immune response — two well-tested approaches for other infectious diseases — is considered an inappropriate approach in HIV.
J&J and its global partners hoped to address some of those challenges by developing a “mosaic” immunogen, or one that would prompt an immune response to multiple strains and subtypes of HIV. They used an adenovirus vector, similar to what J&J used in its coronavirus vaccine, to deliver the immunogen.
Trial researchers used four shots of that vaccine, and, together with the third and fourth shot, also administered injections of an HIV protein and an immune-boosting adjuvant.
Called Imbokodo, the trial enrolled 2,600 sexually active women between age 18 and 35 and randomized half to take the vaccine regimen and half to receive a placebo. All enrollees were offered pre-exposure prophylaxis treatment. They were followed for two years.
Among the women given a placebo, 63 became infected with HIV, compared with 51 of those who received the vaccine regimen, a protection level that the development partners said was not sufficient.
“HIV is a unique and complex virus that has long posed unprecedented challenges for vaccine development because of its ability to attack, hijack and evade the human immune system,” Paul Stoffels, J&J’s chief scientific officer, said in a statement.
“While we are disappointed that the vaccine candidate did not provide a sufficient level of protection against HIV infection in the Imbokodo trial, the study will give us important scientific findings in the ongoing pursuit for a vaccine to prevent HIV,” he added.
The remaining trial in men and transgender people who have sex with men, called Mosaico, is still recruiting enrollees, aiming for a total of 3,800 who will be followed for up to 30 months. Results are not expected until 2024.
