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End in sight for omadacycline
BOSTON—Paratek Pharmaceuticals has announced positive data from two preclinical trials that bode well for its 15-year-long quest to develop a broad-spectrum antibiotic. The Boston-based company, which became publicly traded last year after a reverse merger with Transcept Pharmaceuticals, released preclinical data in April suggesting that its compound omadacycline was less likely than other broad-spectrum antibiotics to induce serious gastrointestinal bacterial infections such as Clostridium difficile.
Omadacycline, the first in a new class of tetracyclines known as aminomethylcyclines, is currently undergoing two Phase 3 trials, one for acute bacterial skin and skin structure infections (ABSSSI) and another for community-acquired bacterial pneumonia (CABP). Paratek expects data from the ABSSSI trial to be announced in the next several months and data from the CABP trial to be available in the second half of 2017.
Paratek Chief Medical Officer and President Evan Loh tells DDNews that the company is well positioned to move omadacycline through the final stages of development after many years of delay.
“Transitioning from a private company to a publicly traded company listed on NASDAQ has allowed us to bring an amount of capital that the company has never had access to previously, and that has allowed us to go forward with Phase 3 development for omadocycline,” he says.
Loh notes that a primary reason for the delayed development of omadacycline has been past regulatory uncertainty caused by unclear FDA guidelines regarding how new antibiotics are evaluated. Regulatory hurdles for Paratek were somewhat alleviated in 2012 when Congress passed the Generating Antibiotic Incentives Now Act (GAIN), which clarified the drug approval process in an effort to address the need for new drugs to fight antibiotic-resistant bacteria.
“All the big pharma companies had rotated out of developing new antibiotics because of various regulatory uncertainties, and Paratek lost nearly five years of work time developing this compound due to regulatory uncertainty,” Loh tells DDNews. “But now we are working tirelessly and energetically to move this compound forward.”
One of the risks of using broad-spectrum antibiotics is that most commonly used classes of these drugs have a strong potential to increase a patient’s risk for superinfections like C. difficile. This risk has caused many hospitals and physicians to scale back use of antibiotics.
“Even though antibiotics may cure a patient’s infection, they may present one to four weeks later with C. difficile, which can be debilitating, and in some high-risk populations it can be life-threatening,” says Loh.
Paratek announced data from two preclinical trials at the European Congress of Clinical Microbiology and Infectious Diseases in Amsterdam that addressed the risk of bacterial infection. One study, which evaluated the impact of omadacycline on gastrointestinal flora, showed that the compound, despite extensively disrupting the gut microbiome, has a low propensity to induce C. difficile infection. A separate study found that omadacycline exhibited potent in-vitro activity against C. difficile. Both studies were led by Mark Wilcox, a professor of medical microbiology at the University of Leeds.
The new preclinical findings support Paratek’s predictions that omadacycline could have an advantage over other broad-spectrum antibiotics due to a lower propensity to cause gastrointestinal infections. Risk of infection has historically been low in patients treated with the class of antibiotics known as tetracyclines, and the new study provides new evidence that this is specifically the case with omadacycline.
“Similar to other tetracyclines, it appears that the aminomethylcycline omadacycline has a low potential risk of inducing C. difficile infection, suggesting that it may offer an advantage for patients who need treatment with a broad-spectrum antibiotic in serious community-acquired infections where resistance is of concern,” said Loh in a news release.
Omadacycline is being developed as a once-daily oral and intravenous antibiotic. In addition to its efforts to develop the compound for ABSSSI and CABP, Paratek is also pursuing its development for urinary tract infection and sinusitis.