The accelerated approvals of Ras(OFF)-targeting KRAS G12C inhibitors sotorasib and adagrasib, decades in the making, marked the beginning of a new phase of KRAS drug discovery. While an increasing number of follow-on KRAS inhibitors are emerging with similar mechanisms of action, Revolution Medicines’ 2023 Molecule of the Year Nominee, RMC-6291, is representative of a completely novel approach that could become a strong addition to the clinical toolbox for KRAS, but also serves as proof-of-concept for a new class of small molecule therapeutics entirely.

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.

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.

VVD-214/RO7589831 is an oral covalent, reversible, and allosteric inhibitor of WRN helicase discovered by the San Diego-based biotech Vividion Therapeutics and being developed by Roche for tumors marked by microsatellite instability and/or mismatch repair deficiency. Vividion has utilized its chemoproteomics platform to discover and develop novel treatment options for oncology targets. The structure and initial preclinical pharmacology data for VVD-214 were recently disclosed at the AACR Annual Meeting 2024 in San Diego. VVD-214 is currently being evaluated in a Ph. I trial.

AM-2-19 (SF001) is an analog of the notoriously toxic IV antifungal drug, amphotericin B (AmB). Compared with AmB, AM-2-19 is significantly less toxic against primary human cells and in mice, while more broadly active against fungal pathogens including antifungal drug-resistant strains. SF001 received Fast-Track Designation from the FDA in 2023 and has progressed to Ph. I clinical development. This article highlights the history of antifungal polyene natural products, a new mechanistic hypothesis for polyene antibiotic activity, and the design of 3rd generation Erg-specific polyenes.