Interim Analysis of Key Clinical Outcomes from a Phase 1/2 Study of Weekly Intravenous DNL310 (Brain-Penetrant Enzyme Replacement Therapy) in MPS II

The synthesis of three fluorogenic chitobiosyl derivatives, modified at the non-reducing 4′-OH with, either a methyl, an isopropyl or a cyclohexylmethyl substituent, is described. The 4′-capped 4-methylumbelliferyl chitobiosides are hydrolysed by the human chitinase CHIT1 following Michaelis–Menten kinetics and in contrast to unmodified chitobiosyl-4-methylumbelliferone do not undergo transglycosylation. The compounds are also relatively poor hexosaminidase substrates and thus provide useful alternatives to 4′-deoxychitobiosyl-4-methylumbelliferone, previously reported by us as fluorogenic substrate to monitor CHIT1 activity as a marker for Gaucher disease state.