What happened

Shares of Inovio Pharmaceuticals (NASDAQ:INO) were jumping 4.2% higher as of 11:15 a.m. EDT on Thursday after rising as much as 17.7% earlier in the day. The gain came on Inovio's announcement Thursday morning of results from preclinical testing of COVID-19 vaccine candidate INO-4800.

So what

Inovio reported that INO-4800 was found to be effective in protecting rhesus macaques (a type of Asian monkey) that were infected with a live SARS-CoV-2 virus. The rhesus macaques showed durable antibody and T-cell responses for four months following vaccination.

Scientist holding syringe and vaccine bottle

Image source: Getty Images.

INO-4800 generated neutralizing antibodies (which hold the potential to protect against infection) in both the earlier strain of the novel coronavirus and the D614G strain that is more infectious and more prevalent now. Antibody levels in the rhesus macaques receiving INO-4800 were at least as high as those found in human patients who have recovered from COVID-19. T-cell response, another important immune response, was much higher than seen in humans who recovered from the novel coronavirus disease.

The preclinical results announced today were encouraging. Animal challenge studies (in which animals are infected with a live virus) can point to how a vaccine could affect humans. However, such preclinical testing isn't a substitute for results from clinical testing in humans. Inovio's initial surge faded as investors realized the limitations of the company's good news.

Now what

Inovio hopes to begin phase 2/3 clinical testing of INO-4800 later this summer. If that testing goes well, the biotech stock will almost certainly skyrocket. In the meantime, more news from Inovio and its rivals -- both positive and negative -- will likely cause high levels of volatility.