MicuRx Pharmaceuticals Receives NMPA Approval for Phase I Clinical Trial of Novel Antibiotic MRX-4 in China

Image from the official website of MicuRx Pharmaceuticals

On November 2, 2018, MicuRx Pharmaceuticals announced that its independently developed “super antibiotic,” MRX-4 (contezolid acefosamil), had received approval for clinical trials from the National Medical Products Administration (NMPA), authorizing the initiation of Phase I clinical trials in China.

This marks another milestone following MicuRx Pharmaceuticals’ successful completion of the Phase I clinical trial of MRX-4 in the United States and its receipt of Qualified Infectious Disease Product (QIDP) designation and Fast Track designation from the U.S. FDA in September 2018.

As MicuRx Pharmaceuticals’ second independently developed innovative anti-drug-resistant antibiotic with global intellectual property rights, MRX-4 is indicated for the treatment of infectious diseases caused by Gram-positive bacteria, including multidrug-resistant strains. In addition to its injectable formulation, MRX-4 is also available in an oral form, providing dual dosage form coverage that is expected to significantly enhance its clinical value.

As a Class 1 innovative drug receiving key national support, the clinical trial application for MRX-4 was granted priority acceptance by the NMPA through its special review pathway, with both the injectable and oral tablet formulations successfully passing evaluation and approval in succession.

MRX-4 is a next-generation oxazolidinone “super antibiotic.” This class of molecules has been known for over 30 years and represents one of only two new classes of antibacterial agents discovered in the past three decades.

It is well known that prolonged use of the same class of antimicrobial agents leads to the emergence of similar resistance mechanisms. For instance, widely used cephalosporins and penicillins have shown diminishing therapeutic efficacy over time due to the development of drug resistance.

Oxazolidinone antibiotics have been in use for 18 years and remain susceptible to 99% of current Gram-positive bacteria, with resistance still rarely observed.

It is understood that MRX-4 is expected to significantly reduce the bone marrow suppression toxicity associated with existing drugs, while maintaining their excellent efficacy against resistant Gram-positive bacteria. This advancement will expand potential indications and the eligible patient population, indicating a substantial clinical market opportunity.

It is worth noting that as early as September 2018, the U.S. Food and Drug Administration (FDA) granted Qualified Infectious Disease Product (QIDP) and Fast Track designations to Contezolid (MRX-I) and its prodrug Contezolid Acefosamil (MRX-4), independently developed by MicuRx Pharmaceuticals, for the treatment of acute bacterial skin and skin structure infections (ABSSSI).

QIDP designation is granted under the Generating Antibiotic Incentives Now (GAIN) Act, which is part of the FDA Safety and Innovation Act of 2012. This legislation provides incentives for the development of antimicrobial drugs targeting priority bacterial pathogens, including eligibility for priority review and an extension of market exclusivity by up to five years beyond any existing non-patent exclusivity period.

MRX-4 completed Phase I clinical trials in the United States in the first quarter of 2018. The results demonstrated that MRX-4 was well tolerated and exhibited a favorable safety profile in healthy subjects following oral or intravenous administration, while achieving the expected pharmacokinetic parameters.

Following the satisfactory results of the Phase I clinical trial, MicuRx Pharmaceuticals initiated a Phase II clinical trial in the United States in October. Meanwhile, the Phase I clinical trial of MRX-4 in China will further investigate the drug’s safety and pharmacokinetic profile in the Chinese population.