Genentech announced that fenebrutinib (GDC-0853), a non-covalent BTK inhibitor entering Ph. III, showed significant human CNS exposure and reduced new brain lesions in Ph. II for relapsing multiple sclerosis. Fenebrutinib is the only reversible BTK inhibitor in Ph. III for MS, and has the opportunity to differentiate on safety relative to covalent inhibitors. This case study highlights notable challenges overcome in the discovery of fenebrutinib including surprising metabolism, animal-specific on-target toxicity, and more.

AZD4747 is a CNS-penetrant, oral KRAS G12C covalent inhibitor for the treatment of CNS-metastatic KRAS-mutant cancers. KRAS inhibitors have tended to be quite large and fall outside the range of physicochemical properties generally required for CNS permeability. (MW < 360 Da, cLogD < 2, TPSA < 90 Å2. AZD4747 is much smaller than marketed KRAS G12C inhibitors but maintains exceptional cellular potency. The team also encountered an unexpected toxicity that scientists working on covalents should pay attention to.

Vertex’s VX-548 is a potential first-in-class, exquisitely selective, oral NaV1.8 inhibitor that recently captured headlines for its positive Ph. III data. With the ongoing opioid epidemic throughout the US, there is an urgent unmet medical need for non-addictive pain medications as alternatives to opioids. They plan to file an NDA by mid-2024 for the treatment of moderate-to-severe acute pain. This case study highlights what’s publicly known about Vertex’s journey in pain leading up to the Ph. III readout for VX-548, and why this is such a watershed moment for pain management.

STX-478 is a wild-type-sparing, oral, CNS-penetrant, novel allosteric inhibitor of mutant PI3Kα (phosphatidylinositol-3 kinase α) targeting a cryptic pocket near the ATP-binding site. PI3Kα plays a central role in many cancers, and has been recently highlighted in coverage of 2021 Molecule of the Year nominee and PI3Kα degrader inavolisib. Currently approved PI3Kα modulators are limited by their off-target activities on WT PI3Kα and other kinases, leading to significant side effects including hyperglycemia and rash.

Cerevance’s CVN293 is an oral, CNS-penetrant, selective inhibitor of potassium efflux-mediated NLRP3-inflammasome activation in microglia for the treatment of neurodegenerative disorders. Cerevance’s NETSseq platform was used to discover a microglia-specific potassium efflux channel, KCNK13, which allows modulation of the NLRP3-inflammasome in the CNS without affecting peripheral innate immunity. Read the full article to discover highlights on the CNS-penetration of highly polar compounds and how particle size can be key to oral bioavailability