FDA Hands Achaogen Split Approval and Rejection for Plazomicin

Shares of Achaogen are down more than 19 percent in early trading after the U.S. Food and Drug Administration handed down a split approval and rejection of Zemdri (plazomicin) for the treatment of complicated urinary tract infections and bloodstream infection, respectively.

South San Francisco-based Achaogen said the FDA approved Zemdri for adults with complicated urinary tract infections (cUTI), including pyelonephritis, that are caused by certain Enterobacteriaceae in patients who have limited or no alternative treatment options. But, the company also noted that the FDA issued a Complete Response Letter regarding its hope for Zemdri to be approved for bloodstream infections.

In its announcement this morning, Achaogen said the CARE study did not provide “substantial evidence” of the efficacy of plazomicin in treating bloodstream infections. The company intends to meet with the FDA to determine if there is a “feasible resolution to address the CRL.”

The federal regulator’s ruling mirrors a May review of the medication by an FDA panel. In May the panel voted unanimously in favor of evidence supporting the safety and effectiveness of plazomicin for treatment of urinary tract infections. However, panel members overwhelmingly voted against plazomicin when it came to evidentially supporting the safety and effectiveness of the treatment of bloodstream infections in patients who have had limited or no treatment options.

The company sought approval of plazomicin through the Limited-Population Antibacterial Drug Pathway. 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.

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 infects patients who have been hospitalized.

Despite the approval of Zemdri for urinary tract infections, Achaogen investors have reacted negatively. In premarket trading, the stock fell about 13 percent and shares have continued to fall since the market opened. The stock is trading at $9.80 as of 9:50 a.m., down from Monday’s close of $12.02 per share.

Blake Wise, Achaogen's chief executive officer, said the FDA approval of Zemdri is a milestone for the company. Administered intravenously, Wise said Zemdri is “designed to retain its potent activity in the face of certain difficult-to-treat MDR infections,” which include CRE (carbapenem-resistant Enterobacteriaceae) and ESBL- producing Enterobacteriaceae.

Achaogen said it will work with hospitals, providers, and insurers to ensure that patients will be able to receive the treatment. The company expects the medication will be available to patients by the end of July.

"Bacteria continue to circumvent existing antibiotics, making certain infections notoriously hard to treat and putting some patients at high risk for mortality," James A. McKinnell, assistant professor of medicine at the David Geffen School of Medicine and LA Biomed at Harbor-UCLA, said in a statement. "Aminoglycosides are a familiar and very effective class of antibiotics. I look forward to adding plazomicin to my short list of available treatment options and to its potential impact on patient outcomes."