On June 23, 2025, Cidara announced positive topline results from its randomized, double-blind, placebo-controlled Phase 2b NAVIGATE trial evaluating CD388 for the prevention of seasonal influenza in healthy unvaccinated adults aged 18 to 64. Click here to read more.
Taking guesswork out of flu protection
Every year, manufacturers of influenza vaccines have to take a guess at which strains of flu will emerge in the following season. Given the six-month vaccine production time, they need to commit to their decision at an early stage.
When they guess wrong, as happened last year, vaccine coverage is incomplete. It’s a challenge that pharma has been striving to overcome for decades, in a quest for a universal flu vaccine.
An alternative approach – as pioneered by Cidara Therapeutics – is to use an antiviral drug. Cidara’s lead therapy, which recently completed its Phase 2B study and showed positive topline results, targets the neuraminidase enzyme, which is identical in every influenza strain.
The solution is more viable than the elusive universal vaccine, according to Cidara’s President and CEO, Jeff Stein.
“In the U.S., there are over 50 million people in high-risk or immune-compromised populations that simply don’t respond to vaccines – or if they get a flu inflection, it results in hospitalization or death,” he points out.
“At Cidara our mission is to address this population with this first molecule, CD388, which is designed to offer single-dose universal protection against all strains of influenza in all people.”
“A historically severe flu season is terrible for people – but it’s great if you’re enrolling a big clinical study.”
Jeff Stein, President and CEO, Cidara Therapeutics
Hyper-focus on lead therapy
It’s a mission on which the company is hyper-focused. While Cidara has a robust early-stage program of oncology molecules that are pre-clinical, these are “parked”, says Stein, in favor of the influenza effort.
The 40-person company managed full enrollment of a 5,000-subject Phase 2B study in the course of 10 weeks from the end of September to the beginning of December 2024.
“That happened to coincide with a historically severe flu season, which started about two weeks after we enrolled that study,” says Stein. “Obviously, a historically severe flu season is terrible for people – but it’s great if you’re enrolling a big clinical study.”
“We owe no royalties on CD388 back to Johnson & Johnson, and with that capital, we were able to embark on and successfully complete this large Phase 2B study.”
Jeff Stein, President and CEO, Cidara Therapeutics
Global rights regained from giant
The company had partnered with Johnson & Johnson on CD388 at a pre-clinical stage. But the pharma giant gave up global rights to the program as part of a strategic decision to exit the infectious disease space through a series of divestitures in 2023.
“We were able to intervene in that process by virtue of raising a $240 million private investment in public equity (PIPE) financing with top-tier biotech investors,” Stein says. “We outcompeted the big pharmas in that process and got the rights back.”
“We owe no royalties on it back to Johnson & Johnson, and with that capital, we were able to embark on and successfully complete this large Phase 2B study.”
Credibility puts company in the driver’s seat
Combined with a political trend to disincentivize interest in vaccines, all this has put Cidara in a strong position, Stein adds, with a “groundswell of interest” from investors.
“We’re more in the driver’s seat than a typical biotech company at our stage and size of development,” he observes.
This has not always been the case. Cidara has come close to running out of cash more than once before, Stein admits.
“The old adage is you lose credibility only once. So you have to maintain that credibility, and the best way to do that is through maintaining a high level of integrity in all your dealings,” he says. “We’ve applied those principles throughout our history: it has enabled us to weather very difficult times.”
