July 6, 2015
AIDS vaccine developers do not, as a rule, set favorable pre-clinical monkey data as the sole basis for a go/no-go decision on whether to move forward in human trials. At the same time, favorable data can provide an important signal for advancing into product development. Monkey studies can provide critical immunological data hinting at how, not just whether, a vaccine might work in humans.
A new monkey study, Protective efficacy of adenovirus-protein vaccines against SIV challenges in rhesus monkeys, published July 2 in the journal Science sheds new light on a vaccine candidate being developed by Janssen Pharmaceuticals, part of Johnson & Johnson. The study was led by Dan Barouch from Beth Israel Deaconess Medical Center and the Ragon Institute of Massachusetts General Hospital, MIT and Harvard.
While the new data are from an animal model, the candidate vaccine strategy—Adenovirus type 26 (Ad26) and Modified Vaccinia Ankara (MVA) as vectors, in combination with an envelope (env) protein boost—is also being tested in humans in a Phase 1/2a international clinical study. (On AVAC’s recent webinar—Vaccines in Vivo: Advances in AIDS Vaccine Research—Janssen’s clinical head for HIV vaccines provided an overview of their research and development program, and the link provides a recording of his presentation and slides.)
The preclinical studies just published showed complete protection in half of the rhesus monkeys after six rectal challenges with SIV, a virus similar to HIV that infects monkeys. Similar adenovirus-based candidates have not demonstrated this degree of protection. These studies also showed the env protein boost enhanced antibody FC effector functions, which is believed to be a key factor in the functionality of antibody responses.
While these data are encouraging, the important work of testing this vaccine in human clinical trials is just beginning. So perhaps even more exciting than these preclinical results is that the corporate partner (Janssen) is actively engaged in funding the current human trial and seems committed to continued investment—and it has been almost a decade since a large vaccine developer invested significantly in clinical trials for AIDS vaccine development.