BRD7586 is a potent and selective Streptococcus pyogenes Cas9 (SpCas9) inhibitor. BRD7586 specifically engages SpCas9 but not Cas12a in cells and enhances SpCas9 specificity at multiple loci. BRD7586 inhibits SpCas9 at multiple genomic loci irrespective of the mode of SpCas9 delivery[1].