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FDA Accepts Regulatory Review Filings for 2 of Merck's Antibacterial Agents

The US Food and Drug Administration (FDA) has accepted for review 2 regulatory filings for antibacterial agents being developed by Merck.

A New Drug Application (NDA) was accepted for the Priority Review of the combination of relebactam with imipenem/cilastatin for the treatment of complicated urinary tract infections (cUTI) and complicated intra-abdominal infections (cIAI) caused by susceptible gram-negative bacteria in adults with limited or no alternative therapies available.

A supplemental NDA (sNDA) was accepted for the Priority Review of ceftolozane/tazobactam (ZERBAXA) to treat adult patients with nosocomial pneumonia, including ventilator-associated pneumonia caused by particular susceptible gram-negative microorganisms including Enterobacter cloacaeEscherichia coliKlebsiella oxytocaKlebsiella pneumoniaeProteus mirabilisPseudomonas aeruginosaBacteroides fragilisStreptococcus anginosusStreptococcus constellatus, and Streptococcus salivarius.

“There is a major unmet need for new treatment options to address the growing danger of serious and potentially life-threatening infections caused by Gram-negative bacteria,” Nicholas Kartsonis, MD, senior vice president and head of clinical research for infectious diseases and vaccines with Merck Research Laboratories, said in a statement.  

In the United States, ceftolozane/tazobactam is currently approved for the treatment of adult patients with cUTI, including pyelonephritis, caused by particular gram-negative microorganisms, as well as in combination with metronidazole for the treatment of cIAI caused by susceptible gram-negative and gram-positive microorganisms in adult patients.

The NDA for imipenem/cilastatin/relebactam was based on the results of the phase 3 RESTORE-IMI1 trial. Relebactam is an investigational, intravenous, class A and C beta-lactamase inhibitor.

RESTORE-IMI 1 was a phase 3, randomized, active-comparator, controlled, double-blind study in which investigators set out to evaluate the efficacy and safety of imipenem/cilastatin/relebactam (IMI/REL) compared with imipenem/cilastatin plus colistin (IMI+CST) in patients enrolled at multiple sites.

In a Poster Abstract Session at ID Week 2018 in San Francisco, California, Keith Kaye, MD, professor of medicine at the University of Michigan Medical School and Contagion® Editorial Advisory Board member, presented data on the RESTORE-IMI study which evaluated relebactam as a potential treatment option for treating carbapenem-resistant infections when used in combination with imipenem/cilastatin.

Dr. Kaye sat down for an exclusive interview with Contagion® to discuss the results of the study for the supplemental microbiological modified intent-to-treat population.


“One of the major findings, as well, is IMI/REL(imipenem/cilastatin/relebactam)  had a significant advantage over (IMI+CST) in regard to toxicity, particularly acute kidney injury,” Dr. Kaye explained. “Colistin is notorious for its nephrotoxic effects and IMI/REL performed much better than IMI+CST (imipenem/cilastatin +colistin) in regards to nephrotoxicity.”
Merck also notes that the sNDA for ceftolozane/tazobactam were based on the phase 3 ASPECT-NP trial, which enrolled patients with ventilated hospital-acquired bacterial pneumonia or ventilator-associated bacterial pneumonia. The results of the phase 3 study will be announced at a future scientific conference, the company added.

The Prescription Drug User Fee Act (PDUFA) target action date for imipenem/cilastatin/relebactam is July 19, 2019, and the PDUFA date for ceftolozane/tazobactam is June 3, 2019.

Applications for both antibacterial agents have been filed with the European Medicines Agency (EMA) and are currently under review.
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