MK-0752

Lipid nanoparticle‐messenger RNA formulations have garnered significant attention for their therapeutic potential in infectious diseases, cancer and genetic disorders. However, effective mRNA delivery to the central nervous system (CNS) remains a formidable challenge. To overcome this limitation, a class of brain‐targeting lipids (BLs) is developed by incorporating brain‐targeting small molecules with amino lipids and formulated them with helper lipids to generate brain‐targeting lipid nanoparticles (BLNPs) for mRNA delivery. Screening studies led to a lead formulation, TD5 BLNPs, outperforming FDA‐approved DLin‐MC3‐DMA LNPs in delivering mRNA to the brain upon intrathecal injection. Specifically, a single intrathecal injection of TD5 BLNP‐GFP mRNA led to GFP expression in 29.6% of neurons and 38.1% of astrocytes across the brain. In an Ai14 mouse model, TD5 BLNP‐Cre recombinase mRNA treatment induced tdTomato expression in ≈30% of neurons and 40% of astrocytes across major brain regions. Notably, delivery of Cas9 mRNA/sgRNA complex using TD5 BLNPs achieved effective genome editing in the brain. Additionally, TD5 BLNPs showed comparable safety profiles to MC3 LNPs, indicating promising biocompatibility. Overall, this TD5 BLNP formulation effectively delivers mRNA to brain tissues via intrathecal injection and facilitates efficient expression in both neurons and astrocytes, presenting a potential strategy for treating CNS diseases.

Aberrant activation of Notch signaling, mediated by the Notch intracellular domain (NICD), is linked to certain types of cancer. The NICD is released through γ-secretase-mediated cleavage of the Notch receptor. Therefore, development of a γ-secretase inhibitor (GSI) represents an anticancer strategy. Here we report the cryo-electron microscopy structures of human γ-secretase bound individually to five clinically tested GSIs (RO4929097, crenigacestat, BMS906024, nirogacestat and MK-0752) at overall resolutions of 2.4-3.0 Å. Three of the five GSIs are in active anticancer clinical trials, while nirogacestat was recently approved. Each of these GSIs similarly occupies the substrate-binding site of presenilin 1 but shows characteristic differences in detailed recognition pattern. The size and shape of the binding pocket are induced by the bound GSI. Analysis of these structural features suggest strategies for modification of the GSI with improved inhibition potency.