AMSTERDAM – that had identified the most effective dosing strategy for the vaccine.
The 96-week follow-up data showed durable humoral and cellular immunity induction by the vaccine and its associated booster, a durable breadth of immune responses to the multiple HIV clades that the vaccine targets, and no serious or grade 3 or 4 adverse effects in the 393 people who participated in the early-phase study, Frank L. Tomaka, MD, said at the 22nd International AIDS Conference.
The 96-week results he reported came from follow-up of the 393 people who received one of several different dosing regimens for an engineered, mosaic HIV vaccine. The vaccine incorporates genes for three different HIV envelope antigens that contain components drawn from several different HIV clades (to induce more broadly protective immunity) into a serotype 26 adenovirus. The immunization regimen also includes treatment with HIV glycoprotein 140 as a booster agent. Dr. Tomaka and his associates reported the primary endpoints from this placebo-controlled study, APPROACH, measured just after the fourth and final immunizing regimen at 48 weeks after the first treatment in a recently published article (Lancet. 2018 Jul 21;392[10143]:232-43).
As part of the study, the investigators administered the vaccine and booster to rhesus monkeys and found that the regimens produced a pattern of immune responses in the monkeys similar to that seen in people. When the monkeys that received the regimen that performed best in people received six monthly challenges with a simian-human immunodeficiency virus that’s related to HIV, the researchers found a 67% efficacy for protection against infection. These “very encouraging” findings led the company developing the vaccine to launch in November 2017 a phase IIb trial, named Imbokodo, in five African countries, with a plan to enroll 2,600 people, Dr. Tomaka said.
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“What’s unique and very exciting” about the APPROACH findings are the nonhuman primate findings, and the fact that the vaccine was designed to provide protection against several different HIV clades, Dr. Tomaka said in a video interview. The 67% level of protection against viral challenge in the monkeys is at a level that would be clinically meaningful if replicated in people. A vaccine and booster regimen that provided something in the range of 50%-60% protection or better might be an attractive option in a region with relatively low resources, while in a more developed country a vaccine with a protective efficacy of 70% or better would also likely be seen as an attractive intervention, said Dr. Tomaka, clinical leader for HIV/STI vaccines for Janssen in Titusville, N.J.
SOURCE: Tomaka FL et al. AIDS 2018, Abstract TUAA0104.