Inovio is one step closer in the race to create an effective HIV vaccine. Data from an early-stage clinical study showed that its Pennvax-GP could elicit an immune response in nearly all participants.

The study, supported by the HIV Vaccine Trials Network (HVTN) and NIH’s National Institute of Allergy and Infectious Diseases, tested Inovio’s DNA vaccine in combination with an immune activator, IL-12. The four-shot regimen produced a T-cell immune response—CD4+ or CD8+—in 71 of 76 (93%) vaccinated subjects. Sixty-two of 66 (94%) evaluated participants showed an antibody response.

None of the nine placebo recipients showed an immune response, the investigators report. While it is an early-stage result, the news was enough for Inovio’s stock to jump nearly 30% Wednesday.

Studies on the vaccine have received financial support from NIAID, which first awarded Inovio and its collaborators $25 million in 2009, and followed that up in 2015 with an additional five-year contract that includes a $16 million grant.

"[T]hese high response rates are exceptional," Stephen De Rosa, protocol co-chair of the study dubbed HVTN 098, said in a statement. He presented the data at a plenary session at the 2017 HVTN Spring Full Group Meeting. Since this is the first clinical study of Pennvax-GP, further studies are needed to confirm the vaccine’s safety and effectiveness, he said.

Indeed, if the vaccine can maintain the efficacy level in later clinical stages, especially after long periods of time, that could mean a huge step forward in the fight against the HIV virus. The landmark RV144 trial in Thailand back in 2009 showed that an experimental vaccine was 31.2% effective at preventing HIV infection during a 3.5 year follow-up period.

NIAID scientists are now testing a new version of that HIV vaccine candidate—the farthest in clinical testing—supplied through a collaboration that includes Big Pharmas GlaxoSmithKline and Sanofi Pasteur, in a large-scale phase 2b/3 trial on 5,400 people in South Africa.

Inovio is also considering pairing Pennvax-GP with a checkpoint inhibitor, having nabbed additional government funding to explore that approach. Several other groups are also working in the field, including a team of Australian scientists who are developing an HIV vaccine that tries to protect humans from the virus at mucosal surfaces. That strategy has showed promise in a preclinical study.

At the same time, Inovio is forging ahead with other candidates for infectious diseases as well. J. Joseph Kim, Inovio’s president & CEO said in a statement that the HIV results "are among the highest ever responses we’ve seen with an HIV vaccine," and that they are consistent with some recent data coming out from the vaccine company’s Ebola, Zika and MERS trials.