Stocks have bounced back sharply in the past week, and so it's reasonable for market participants to take a slight pause coming into Monday morning's open. As of 8:30 a.m. EDT, futures on the Nasdaq Composite (^IXIC 1.59%) were down about a quarter percent, which was in line with the broader stock market.

However, there was news from a couple of smaller biotech players that led to massive moves in their stock prices. Valneva (VALN -2.24%) saw its shares move strongly higher in premarket trading Monday morning, while the news was bad for industry peer Revance Therapeutics (RVNC 0.55%). Below, we'll look more closely at the stories that have investors paying attention to these normally low-profile biotech stocks.

A better vaccine than AstraZeneca?

Shares of Valneva soared 35% in premarket trading on Monday. The specialty vaccine company reported highly encouraging results for its COVID-19 vaccine candidate, and shareholders are excited about what that could mean for Valneva's future.

Medical professional administering an injection to a patient.

Image source: Getty Images.

Specifically, Valneva released positive top-line results from its phase 3 trial of its VLA2001 vaccine candidate. The trial included more than 4,000 adults in the U.K., and it had the ambitious goal of proving superiority over a rival vaccine from AstraZeneca in producing neutralization antibodies, as well as being at least as effective as AstraZeneca's vaccine in seroconversion rates. VLA2001 was successful on both counts, and Valneva said that patients generally tolerated the vaccine well, with fewer adverse side effects.

CEO Thomas Lingelbach was optimistic about the potential impact of VLA2001. "These results confirm the advantages often associated with inactivated whole virus vaccines," Lingelbach said. Valneva is now looking to move forward in several directions, including working with U.K. and European regulators as well as starting a trial in New Zealand and preparing for a trial to cover children 5 to 12 years old.

The upward move follows previous concerns about the U.K.'s decision to pull out of a vaccine supply deal with Valneva. It'll be interesting to see whether the British government changes its mind based on the latest results.

Revance gets a shock

Moving the other way, shares of Revance Therapeutics plunged 35% in premarket trading. The aesthetics-focused biotech company got unexpectedly bad news in regard to its DaxibotulinumtoxinA injection for treating moderate to severe glabellar lines, also known as frown lines.

A press release from Revance after the market closed on Friday said the U.S. Food and Drug Administration had issued a complete response letter regarding the company's biologics license application for DaxibotulinumtoxinA. The FDA said it couldn't approve the application in its present form, citing deficiencies related to its onsite inspection of Revance's manufacturing facility.

Revance shareholders had already known about some concerns because of the release of information pursuant to a Freedom of Information Act request about the FDA's inspection, which revealed concerns. However, investors had taken heart from the response that Revance's management gave, which noted that such regulatory notices aren't uncommon in the approval process of any treatment.

The setback was unexpected, and CEO Mark Foley expects to request to seek further clarity from the FDA in hopes of bringing the frown-line treatment to market as soon as it can. For now, though, shareholders aren't giving Revance the benefit of the doubt.