👤 Gerard M McGeehan

Inhibitors of the menin-KMT2A interaction are promising agents for the treatment of KMT2A-rearranged leukemias. We evaluated menin inhibition in patient-derived xenografts of KMT2A-rearranged leukemias with high-risk features. Three acute myeloid leukemias with high-risk fusion partners (mixed-lineage leukemia-10 [MLLT10] and mixed-lineage leukemia-4 [MLLT4]) and two infant acute lymphocytic leukemia (ALL) samples were sensitive to menin inhibition. We also evaluated serial samples from two patients with multiply relapsed ALL. We found that highly pretreated KMT2A::AFF1 ALL samples were much less sensitive compared with cells obtained earlier in the same patients' disease course. Because none of the patients had been treated with a menin inhibitor, resistance in these highly pretreated samples was acquired in the absence of menin-inhibitor exposure. Transcriptomic analysis documented sustained on-target efficacy toward the canonical targets of the menin inhibitor in resistant cells. Targeted genomic analysis documented the emergence of multiple comutations, including RAS pathway and TP53 mutations, although neither was sufficient to induce menin-inhibitor resistance in vitro. Downregulation of KMT3D may account for resistance in one patient; inactivation of KMT2C/D has been reported to result in menin-inhibitor resistance, and KMT2C-edited cells from this patient were selected for in menin-inhibitor-containing growth conditions. Future studies will need to clarify more broadly which genomic/epigenomic alterations drive upfront resistance. Regardless of mechanism, our data support using menin inhibitors upfront or in early lines of therapy before substantial genomic or epigenomic evolution has occurred. Show less

This article describes the application of Contour to the design and discovery of a novel, potent, orally efficacious liver X receptor β (LXRβ) agonist (17). Contour technology is a structure-based drug design platform that generates molecules using a context perceptive growth algorithm guided by a contact sensitive scoring function. The growth engine uses binding site perception and programmable growth capability to create drug-like molecules by assembling fragments that naturally complement hydrophilic and hydrophobic features of the protein binding site. Starting with a crystal structure of LXRβ and a docked 2-(methylsulfonyl)benzyl alcohol fragment (6), Contour was used to design agonists containing a piperazine core. Compound 17 binds to LXRβ with high affinity and to LXRα to a lesser extent, and induces the expression of LXR target genes in vitro and in vivo. This molecule served as a starting point for further optimization and generation of a candidate which is currently in human clinical trials for treating atopic dermatitis. Show less

Liver X receptor (LXR) α and LXRβ function as physiological sensors of cholesterol metabolites (oxysterols), regulating key genes involved in cholesterol and lipid metabolism. LXRs have been extensively studied in both human and rodent cell systems, revealing their potential therapeutic value in the contexts of atherosclerosis and inflammatory diseases. The LXR genome landscape has been investigated in murine macrophages but not in human THP-1 cells, which represent one of the frequently used monocyte/macrophage cell systems to study immune responses. We used a whole-genome screen to detect direct LXR target genes in THP-1 cells treated with two widely used LXR ligands [N-(2,2,2-trifluoroethyl)-N-[4-[2,2,2-trifluoro-1-hydroxy-1-(trifluoromethyl)-ethyl]phenyl]-benzenesulfonamide (T0901317) and 3-[3-[N-(2-chloro-3-trifluoromethylbenzyl)-(2,2-diphenylethyl)amino]propyloxy] phenylacetic acid hydrochloride (GW3965)]. This screen identified the sphingomyelin phosphodiesterase acid-like 3A (SMPDL3A) gene as a novel LXR-regulated gene, with an LXR response element within its promoter. We investigated the regulation of SMPDL3A gene expression by LXRs across several human and mouse cell types. These studies indicate that the induction of SMPDL3A is LXR-dependent and is restricted to human blood cells with no induction observed in mouse cellular systems. Show less