Pfizer’s ritlecitinib, a first-in-class, selective, oral covalent inhibitor of JAK3 and the TEC family of kinases, was FDA-approved in June 2023 for the treatment of severe alopecia areata. Ritlecitinib derives its JAK-family kinase selectivity from the covalent modification of a unique cysteine on JAK3. This annotation reviews the discovery of ritlecitinib, highlighting the interpretation of selectivity assays, the PK optimization, the evolution of the JAK3 therapeutic hypothesis, and how this 2023 Molecule of the Year nominee has become a classic case study for covalent drug discovery.

GDC-2394 (Genentech) is an oral NLRP3 inflammasome inhibitor. The NLRP3 inflammasome is the best studied and most characterized inflammasome , with the protein playing a key role in the detection of inflammatory danger signals which are a hallmark of many inflammatory diseases. Hyperactivation of the NLRP3 has been implicated in the [...]

Zunsemetinib (ATI-450, CDD-450) is a p38α- MK2 complex inhibitor discovered by Confluence Technologies and developed by Confluence spinout, Aclaris Therapeutics. The molecule has a unique molecular glue-like mechanism of action that held promise in immunology, but sadly recent results have led to its discontinuation. This article reviews the target, its mechanism, and why it mattered.

Compound 14f (Kyowa Kirin) is an oral ChemR23 inhibitor with two acidic sites. Nominated by Bryan McKibben , this article describes a scaffold hopping exercise to address the short half-life of previously described chemical matter, and the successful development of in-vivo tool inhibitors to probe ChemR23 biology in animal models of [...]

Zilucoplan is a macrocyclic peptide-containing drug with 15 amino acids in total, targeting the challenging-to-drug C5 complement protein and formulated for self-administered once-daily SC injection. In Sept. 2023, zilucoplan received its first global approval in Japan, followed in Oct. 2023 by FDA approval for gMG patients who are AChR antibody-positive, making zilucoplan the first drug derived from mRNA display for cyclic peptides to be approved. This case study discusses how zilucoplan was discovered and why it’s an important scientific milestone for the industry.