The US Food and Drug Administration (FDA) has begun a review of Merck’s combination antibiotic Recarbrio, which could provide a new option for hard-to-treat Gram-negative infections.
The regimen combines Merck’s imipenem/cilastatin duo – sold as Primaxin as a broad-spectrum antibiotic – with a new beta lactamase inhibitor called relebactam that is designed to restore the susceptibility to imipenem in resistant strains.
It will be reviewed to treat adult patients with hospital-acquired bacterial pneumonia and ventilator-associated bacterial pneumonia caused by certain susceptible carbapenem-resistant Gram-negative microorganisms.
Gram-negative bacteria are increasingly becoming a huge global health problem, causing prolonged hospital stays and steep healthcare costs.
The World Health Organization (WHO) has highlighted “in particular the threat of gram-negative bacteria that are resistant to multiple antibiotics. These bacteria have built-in abilities to find new ways to resist treatment and can pass along genetic material that allows other bacteria to become drug-resistant as well”.
Certain bacteria have become resistant to a large number of antibiotics, including carbapenems and third generation cephalosporins – the best available antibiotics for treating multi-drug resistant bacteria.
The WHO has highlighted this type of bacteria as critically needing new antibiotics – the demand could bode well for Merck if Recarbrio is approved following the six month priority review.
“Infections caused by Gram-negative bacteria continue to be a major problem for hospitalised patients,” commented Amanda Paschke, senior principal scientist, infectious disease clinical research, at Merck Research Laboratories.
“The prevalence of carbapenem-resistant pathogens is increasing globally, highlighting the need for effective new antibacterial agents with Gram-negative coverage,” she added.
A pivotal phase 3 trial of Recarbrio showed that the combination regimen was comparable to the combination of imipenem/cilastatin plus colistin – a drug first introduced in the 1950s that has been resurrected to help fight challenging Gram-negative infections. Both regimens demonstrated 70% efficacy at day 28 of the study.
For Merck, this result was significant as colsitin has been the last-line therapeutic for Gram-negative infections for some time, despite some controversy surrounding the drug causing toxicity issues, including kidney damage.
As global concerns grow over the danger of multi drug-resistant infections, experts have called for a new system for the development of antibiotics, with the hope that financial incentives could draw more researchers to the field.
Merck is one of the only big pharma players still investing in antibiotic R&D, with many companies abandoning efforts in the field because of the lack of financial return.
GlaxoSmithKline is also one of the only players left in the field, with a new-class antibiotic in phase three for the treatment of uncomplicated urinary tract infection (UT) and urogenital gonorrhoea
To incentivise more pharma companies to re-start efforts in antibiotic research, the UK government has proposed a new scheme which would trial a subscription-style payment model. This would include an upfront payment made for access to any drugs developed that can treat antibiotic-resistant infections.