Arcus Biosciences recently disclosed the structure and discovery story of their oral HIF-2α inhibitor casdatifan (AB521) at the ACS Fall 2024 First Time Disclosures session in Denver. Read on to find out how the team overcame serum shifts and metabolism issues to deliver into the clinic what could potentially be a best-in-class compound, superior to the recently approved inhibitor, belzutifan.

Vactosertib is an orally bioavailable TGFβ type I receptor kinase inhibitor, that has demonstrated safety, tolerability, and clinical efficacy in combination with pomalidomide in a Ph. Ib trial for RRMM.

RMC-9805 is a first-in-class, covalent KRAS(G12D)(ON) molecular glue inhibitor from Revolution Medicines that uses a cyclophilin A (CypA)-recruiting tricomplex mechanism combined with a finely tuned aziridine covalent handle to inhibit the previously “undruggable” KRAS(G12D) mutant. Read our coverage of the discovery story, disclosed at the AACR 2024 meeting in San Diego, to discover how structural and modeling insights were key to engaging a poorly nucleophilic mutant Asp, how RMC-9805 synergizes with PD-1 inhibitors, and the progress this remarkable compound is making in the clinic.

RMC-6236 is a non-covalent pan-RAS(ON) inhibitor from Revolution Medicines, which shows remarkable efficacy in tumors driven by RAS mutants that were previously considered “undruggable,” such as G12V/D/A/S, G13X, and Q61X. RMC-6236 exerts its action via a “tri-complex” mechanism, gluing RAS to the ubiquitously expressed chaperone protein, cyclophilin A. Our in-depth article covers the presentation given at the AACR 2024 meeting, which outlines the discovery and preclinical profile of RMC-6236 as well as the latest clinical updates.

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.