Novel Specific Metallo-ß-lactamase Inhibitor, ANT2681, Restores Meropenem Activity to Clinically Effective Levels Against NDM-Positive Enterobacterales.

The global dissemination of metallo-s-lactamase (MBL)-producing carbapenem resistant Enterobacterales (CRE) is a serious public health concern. Specifically, NDM (New Delhi MBL) has been a major cause of carbapenem therapy failures in recent years, particularly as effective treatments for serine-s-lactamase (SBL)-producing Enterobacterales are now commercially available. Since the NDM gene is carried on promiscuous plasmids encoding multiple additional resistance determinants, a large proportion of NDM-CREs are also resistant to many commonly used antibiotics, resulting in limited and sub-optimal treatment options. ANT2681 is a specific, competitive inhibitor of MBLs with potent activity against NDM enzymes, progressing to clinical development in combination with meropenem (MEM). Susceptibility studies have been performed with MEM-ANT2681 against 1,687 MBL-positive Enterobacterales, including 1,108 NDM-CRE. Addition of ANT2681 at 8 μg/ml reduced MEM MIC50/MIC90 from >32/>32 μg/ml to 0.25/8 μg/ml. Moreover, the combination of 8 μg/ml of both MEM and ANT2681 inhibited 74.9% of the VIM-positive and 85.7% of the IMP-positive Enterobacterales tested. The antibacterial activity of MEM-ANT2681 against NDM-CRE compared very favourably to that of cefiderocol (FDC) and cefepime (FEP)-taniborbactam, which displayed MIC90 values of 8 μg/ml and 32 μg/ml, respectively, whereas aztreonam-avibactam (ATM-AVI) had an MIC90 of 0.5 μg/ml. Particularly striking was the activity of MEM-ANT2681 against NDM-positive E. coli (MIC90 1 μg/ml), in contrast to ATM-AVI (MIC90 4 μg/ml), FDC (MIC90 >32 μg/ml) and FEP-taniborbactam (MIC90 >32 μg/ml) which were less effective due to the high incidence of resistant PBP3-insertion mutants. MEM-ANT2681 offers a potential new therapeutic option to treat serious infections caused by NDM-CRE.