Achaogen Plunges Following Split Vote from FDA Panel for Antibiotic Treatment

Shares of Achaogen are down more than 30 percent in premarket trading following the results of split support from a U.S. Food and Drug Administration (FDA) panel for its lead antibiotic treatment, plazomicin, which is being developed for the treatment of adults with complicated urinary tract infections and bloodstream infections.

On Wednesday an FDA panel split its vote in support of the treatment for urinary tract infections. The panel voted unanimously in favor of evidence supporting the safety and effectiveness of plazomicin. However, the panel overwhelmingly voted against plazomicin when it came to evidentially support the safety and effectiveness of the treatment of bloodstream infections in patients who have had limited or no treatment options.

Plazomicin was developed to treat serious bacterial infections due to MDR Enterobacteriaceae, which includes extended-spectrum beta-lactamase (ESBL) producing and carbapenem-resistant Enterobacteriaceae (CRE). MDR gram-negative bacteria are a type of bacteria with resistance to multiple antibiotics. The bacteria often infect patients who have been hospitalized.

Investors were certainly disappointed and shares plunged following the announcement of the split vote. Trading of South San Francisco-based Achaogen was temporarily halted Wednesday during the panel hearing.

Blake Wise, Achaogen’s chief executive officer, said the company was encouraged by the unanimous support of plazomicin for treating complicated urinary tract infections.

“The discussion underscored the real-world challenges that healthcare providers face every day given limited or inadequate treatment options for certain pathogens," Wise said in a statement.

When it came to the committee’s rejection of plazomicin, Wise said that treating bloodstream infections with the Limited-Population Antibacterial Drug Pathway (LPAD) is a “novel approach that enables the FDA to consider the benefits and risks for the sickest patients who have few or no treatment options.” He said he believes plazomicin has the potential to address those limited patient populations.

The LPAD was developed as part of the 21st Century Cures Act, the new pathway was added due to heightened concerns over the rise of antibiotic resistance. According to a PEW report, the FDA noted that the pathway was important because it’s difficult to identify a sufficient amount of patients suffering from highly resistant bacterial infections and enroll them clinical trials.

The FDA is not bound by the vote of the panel when it comes to approving new therapies but typically follows the guidelines.

Achaogen submitted its New Drug Application to the FDA in January. Backed by Priority Review designation, the drug was pushed to the forefront for review. The FDA is expected to make its full decision by June 25.

When the company submitted its NDA Wise said the number of confirmed cases of CRE annually in the U.S. is at least 70,000. He added that projections estimate that number will double by 2022.