In early test, Inovio's HIV vaccine delivered immune responses that lasted at least 6 months

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Inovio's HIV vaccine delivered immune responses that lasted at least six months. (Army.mil)

Aiming at one of the biggest targets in vaccine development, Inovio reported that its HIV vaccine, Pennvax-GP, induced immune responses that lasted at least six months after vaccination in a phase 1 study.

Dubbed HVTN 098, the study tested the shot in combo with an immune activator IL-12 in 94 participants, 84 of whom received the vaccine combo. Nine participants received a placebo injection.  

Last year, the biotech reported that 71 of 76 (93%) of vaccinated subjects showed a T-cell immune response—CD4+ or CD8+—and that 62 of 66 showed antibody responses. No placebo recipients showed an immune response. 

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This week, the company said "immune responses were maintained in most subjects" six months after vaccination. The percentage of participants who showed CD8+ T cell responses "stayed the same or even increased slightly," according to the biotech. In a statement, Inovio CEO Dr. J. Joseph Kim said the company looks forward to advancing its shot into later-stage testing. 

RELATED: Inovio’s NIH-backed HIV vaccine shows near 100% immune response rate in early test 

Inovio is developing the vaccine as part of a collaboration with the National Institute of Allergy and Infectious Diseases that started with a $25 million contract in 2009. Since then, NIAID awarded another $16 million grant. The HIV Vaccine Trials Network is also involved in the work.  

Aside from HIV, the biotech is researching vaccines against Ebola, MERS and Zika, plus a later-stage program designed to treat cancers caused by HPV. 

HIV vaccines are one of the biggest targets in vaccine development, and the field has attracted some top global players in recent years. 

Johnson & Johnson's Janssen and partners reported last year that a "mosaic" HIV vaccine was well-tolerated and elicited HIV-1 antibody responses in a phase 1/2a study in 400 patients across the U.S, Rwanda, Uganda, South Africa and Thailand. The team designed the vaccine to protect against HIV subtypes all over the world, whereas past vaccines would have been limited to certain regions, the lead investigator said at the time. 

RELATED: J&J, Gates Foundation and NIAID launch efficacy study for their 'global' HIV vaccine 

Inovio, for its part, says its vaccine consists of four antigens to elicit cell and antibody responses, and to protect against HIV types across the globe.  

Since the early-stage results from J&J, the team kicked off a first efficacy study late last year, planning to test the vaccine in 2,600 sexually active women between the ages of 18 and 35 in five southern African countries. At the time, Hanneke Schuitemaker, Janssen's head of viral vaccines discovery and translational medicine, told FiercePharma that in order to develop a "global vaccine," other efficacy tests would be needed. 

But before J&J and that team advanced to efficacy testing, the NIH touted the start of a "historic" 2b/3 study in South Africa in late 2016. The regimen incorporates one experimental vaccine each supplied by Sanofi Pasteur and GlaxoSmithKline, combined with a GSK-supplied adjuvant called MF59. Results from the trial are expected in 2020. 

Plenty of other HIV vaccines are in the works, including at GeoVax and Aelix Therapeutics.