No company keeps investors abreast of its progress in developing a Zika virus vaccine like Inovio Pharmaceuticals (NASDAQ:INO). The biotech announced yet another update before the market opened on Wednesday. What's the latest Zika buzz -- and what does it potentially mean for investors?

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Early results

Inovio launched an early stage clinical study in July of the GLS-5700 Zika vaccine that it's developing with partner GeneOne Life Sciences and academic collaborators in the U.S. and Canada. This clinical study followed successful pre-clinical testing of GLS-5700 in mice and monkeys in the first half of 2016.

The study includes 40 patients who had no previous exposure to the Zika virus. Patients were divided into two groups, with one group receiving a low dose of GLS-5700 and the other group receiving a high dose. After one or two vaccinations, patients in both groups demonstrated Zika antigen-specific antibody responses.

Inovio also reported more good news from the study. The Zika vaccine appears to be well tolerated by patients. No significant safety concerns have been identified in any of the patients so far.

What it means

So what exactly does demonstrating "Zika antigen-specific antibody responses" mean? When the body's immune system detects a virus like Zika, B cells and T cells are activated. B cells are white blood cells that produce antibodies. T cells are also white blood cells that play an important role in immune responses.

The antibodies produced by B cells attack the virus. However, they also stay in the blood after that first response. The next time the body is infected by the same virus, the antibodies go on the attack before the virus can cause sickness.

Inovio's finding of Zika antigen-specific antibody responses in its clinical study means that the GLS-5700 vaccine is doing what it should do. The vaccine is provoking the creation of B cells, which in turn create antibodies that specifically target the Zika virus. In theory, those antibodies will remain in the patients' blood streams and prevent future infection by the Zika virus.

These results are early, however. Inovio's announcement was made after 14 weeks of observation. The full study runs 60 weeks. Also, the results were from a phase 1 study. Drugs and vaccines typically must go through three clinical study phases before they can be approved by regulators (although in some cases candidates can be approved after only two phases). 

That context is important in understanding what Inovio's latest update means for investors. GLS-5700 producing antibody responses for the Zika virus after 14 weeks is definitely good news. However, it doesn't ensure that Inovio ultimately emerges as the big winner in the race to develop a Zika vaccine.

French drugmaker Sanofi (NASDAQ:SNY) is one of several other companies also working on a Zika vaccine. Sanofi is part of a team including Walter Reed Army Institute of Research, Beth Israel Deaconess Center, Harvard University, and the National Institute of Allergy and Infectious Diseases that has two other phase 1 clinical studies under way.

What's next

Inovio's next steps are to first complete the early stage study for which initial results were announced. The company also will finish another larger early stage study of GLS-5700 being conducted in Puerto Rico.

Both studies should wrap up in the second half of 2017. Assuming all goes well, Inovio plans to meet with regulators to develop a plan for conducting additional clinical studies needed to gain approval.

It won't be surprising, though, if the Sanofi team isn't far behind Inovio. Their first phase 1 study began in October, just four months after Inovio dosed its first patients. Sanofi and its partners initiated a second early stage study in November.

Inovio has reeled off multiple firsts so far, including first to create a Zika vaccine, first to announce pre-clinical data, first to begin human testing, and first to report positive clinical data. But there's still a long way to go for a winner to be declared in the race to develop a Zika vaccine.

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