Iterum’s Antibiotic for Super Bugs Falls Short in Phase 3, Shares Sink
Iterum Therapeutics’ bid to bring patients a new antibiotic that’s safer than currently available drugs has fallen short of the main efficacy goal of a late-stage clinical trial. But the company is pinning its hopes on another Phase 3 study that will report data early next year.
Iterum (NASDAQ: ITRM) reported preliminary Phase 3 data late Tuesday for its antibiotic, sulopenem, which is being tested as a treatment for complicated intra-abdominal infections. The study’s primary goal was to show, after 28 days, a resolution of symptoms without the need for additional antibiotics or treatment.
The clinical trial compared the Iterum drug to ertapenem, an antibiotic that’s used to treat intra-abdominal infections but comes with the risk of central nervous system side effects, including hallucinations and seizures. In the preliminary analysis, Iterum said the response rate to sulopenem was 85.5 percent in the population of patients reflective of how the drug would be used in clinical settings. In the ertapenem group, the response rate was 90.2 percent. The outcome was just outside of the range that the FDA set for the study to show that the Iterum drug was no worse than ertapenem at treating infections.
In a prepared statement, Iterum CEO Corey Fishman characterized the result as “narrowly missing the primary endpoint.” He added that the data show potential for the drug to address growing antibiotic resistance. But investors were unpersuaded. Shares of Iterum, which has operations in Dublin, Ireland, and Chicago, fell to $2.86, down more than 40 percent from Tuesday’s closing price. When Iterum went public last year, it priced its shares at $13 apiece.
Sulopenem belongs to a class of drugs called beta lactam antibiotics. This class includes penicillin, among other drugs. Iterum intends to address the growing problem of drug-resistant bacteria with an antibiotic that can treat infections caused by gram negative bacteria. These bacteria that have a tough cellular wall that helps them resist antibiotics. Iterum developed an intravenous version of sulopenem for use in hospitals, as well as a pill formulation that patients would be able to take at home.
In addition to the intra-abdominal infections clinical trial, Iterum is also testing its drug as a treatment for complicated and uncomplicated urinary tract infections; Phase 3 results are expected in the first quarter of 2020. Fishman said that positive results from that study, combined with the safety and efficacy data from the intra-abdominal study, would be sufficient to support an FDA submission for both the oral and intravenous formulations of the drug.
Iterum says in its securities filings that it wants to offer an alternative to fluoroquinolones, a class of antibiotics whose side effects include tendonitis and tendon rupture. In the company’s statement about the sulopenem Phase 3 results, Chief Scientific Officer Michael Dunne said that more than 10 percent of patients in the study had gram-negative pathogens that resisted treatment by quinolones and beta lactam drugs, bolstering the case for sulopenem as another option for patients in the hospital or at home.
In a research note, SVB Leerink analyst Ami Fadia wrote that the totality of the Iterum’s data suggest that sulopenem has the potential to be an active drug, and the urinary tract infection study could be successful. But she added the chance of approval in intra-abdominal infections is low, as her firm knows of no antibiotics that received an FDA nod after missing the primary endpoint of a pivotal study.
Even if Iterum is able to secure FDA approval for sulopenem, reaching the market is no guarantee of commercial success. Take antibiotics developer Achaogen as an example. The South San Francisco company won approval for plazomicin as a treatment for complicated urinary tract infections last year. To save cash, Achaogen slashed its research and development staff and focused on commercializing the drug. But those efforts were not enough to keep Achaogen afloat, and the company reorganized under Chapter 11 bankruptcy earlier this year.
Iterum licensed sulopenem from Pfizer (NYSE: PFE) in 2015. The pharmaceutical giant is owed milestone payments linked to the progress of the drug, and royalties from sales if Iterum is able to bring it to the the market.