As the “Guardian of the Genome,” the tumor suppressor transcription factor p53 has been a much sought-after target in oncology, with over 50% of malignancies showing mutations in p53. The p53(Y220C) mutant has been of particular interest as it creates a pocket which small molecule stabilizers are able to bind to and restore p53 function. PMV Pharma is the first to enter the clinic with their p53(Y220C) stabilizer rezatapopt, which was optimized from a hybrid of known binders and which is showing real promise against a swath of solid tumors.

RLY-2608 is an oral, mutant-selective PI3Kα allosteric inhibitor from Relay Therapeutics. Current FDA-approved PI3Kα modulator (alpelisib) and a clinically advanced molecule (inavolisib) are limited by their off-target toxicities associated with the inhibition of WT PI3Kα, leading to hyperglycemia and rash. RLY-2608 is currently in a Ph. I as a single agent and in combination with fulvestrant for HR+/HER2- breast cancer treatment. This article reviews the discovery of RLY-2608, its mechanism of mutant selectivity, how it compares to other molecules, recent clinical developments, and more.

AbbVie’s ABBV-467 is a highly potent, selective MCL-1 (myeloid cell leukemia-1) inhibitor which entered the clinic in 2022 in a Ph. I trial in patients with advanced hematologic cancers. MCL-1 has had a rough time in the clinic with multiple trials being halted or terminated due to cardiac toxicity, which is suspected to be an on-target effect. AbbVie’s approach with ABBV-467 was to target a highly potent/short half-life compound which could induce rapid apoptosis and tumor regressions in a short exposure period before the onset of any adverse events. Is this the end for MCL-1?

EOS-984 is an oral, potential first-in-class, highly selective ENT1 inhibitor from iTeos currently in clinical trials for advanced solid tumors. The drug, which was identified through SBDD and optimization of the vasodilator dilazep, targets the immunosuppressive effects of adenosine, which helps tumors evade immune detection. This is an excellent case study on the importance of understanding a molecule's bioactive conformation to reduce the entropy of binding and enhance potency.

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.