Figure 2. MIC, PK and key in vitro safety data are shown for five spiropyrimidinetriones variably substituted on the benzisoxazole 3-position.

Structure-activity correlations show that the pyrimidinetrione and morpholine moieties cannot be varied without diminishing antibacterial potency or compromising co-dependent physical properties and PPB. Importantly, ETX0914 did not show a signal for genotoxicity or bone marrow toxicity at the highest concentrations tested. Three fluoroquinolones are included as comparators.