We recently reported the discovery of AM-8553 (1), a potent and selective piperidinone inhibitor of the MDM2-p53 interaction. Continued research investigation of the N-alkyl substituent of this series, focused in particular on a previously underutilized interaction in a shallow cleft on the MDM2 surface, led to the discovery of a one-carbon tethered sulfone which gave rise to substantial improvements in biochemical and cellular potency. Further investigation produced AMG 232 (2), which is currently being evaluated in human clinical trials for the treatment of cancer. Compound 2 is an extremely potent MDM2 inhibitor (SPR KD = 0.045 nM, SJSA-1 EdU IC50 = 9.1 nM), with remarkable pharmacokinetic properties and in vivo antitumor activity in the SJSA-1 osteosarcoma xenograft model (ED50 = 9.1 mg/kg).

The eukaryotic initiation factor 4E (eIF4E) plays a central role in the initiation of gene translation and subsequent protein synthesis by binding the 5' terminal mRNA cap structure. We designed and synthesized a series of novel compounds that display potent binding affinity against eIF4E despite their lack of a ribose moiety, phosphate, and positive charge as present in m7-GMP. The biochemical activity of compound 33 is 95 nM for eIF4E in an SPA binding assay. More importantly, the compound has an IC(50) of 2.5 μM for inhibiting cap-dependent mRNA translation in a rabbit reticular cell extract assay (RRL-IVT). This series of potent, truncated analogues could serve as a promising new starting point toward the design of neutral eIF4E inhibitors with physicochemical properties suitable for cellular activity assessment.

Bruton's tyrosine kinase (BTK) plays a key role in cell survival in B cell malignancies, such as chronic lymphocytic leukemia (CLL). Covalent inhibitors of BTK, such as ibrutinib and acalabrutinib, while effective, have been associated with the occurrence of resistance mutations. The most prevalent site of mutation, C481, renders covalent BTK inhibitors unable to form a covalent bond with BTK leading to diminished efficacy and disease progression. Small molecule-induced protein degradation offers a unique approach to target BTK for the treatment of B-cell malignancies. Chimeric Targeting Molecules (CTMs) catalyze ubiquitylation and proteasomal degradation of target proteins and are comprised of a ubiquitin ligase binding element ("harness"), a linker, and a target binding element ("hook"). NX-2127 is a CTM that contains a BTK hook linked to a cereblon (CRBN) harness. NX-2127 degrades 50% of cellular BTK (DC50) at < 5 nM across multiple cancer cell lines and in human PBMCs. BTK CTMs impair viability in the BTK-dependent ABC-DLBCL cell line, TMD8 (EC50: < 15 nM after 72 hours). Importantly, NX-2127 induces degradation of the mutated BTK-C481S in cells and inhibits proliferation of BTK-C481S mutant TMD8 cells more effectively than ibrutinib (NX-2127 EC50 values of < 30 nM versus > 1 μM for ibrutinib). Oral administration of NX-2127 in mice leads to dose-proportional exposure in plasma and BTK degradation to <10% of baseline levels in circulating and splenic B cells. In both WT TMD8 and C481S mutant xenograft models, daily oral administration of NX-2127 resulted in superior tumor growth inhibition (TGI) as compared to ibrutinib. NX-2127 also demonstrates potent degradation of BTK in cynomolgus monkeys with oral administration. Following 14 days of once daily, oral dosing in cynomolgus monkey, BTK levels are suppressed to <10% of baseline levels at doses as low as 1 mg/kg. In addition to potent BTK degradation, NX-2127 possesses IMiD-like properties through the design of the CRBN binding harness that catalyzes the degradation of CRBN neosubstrates Aiolos (IKZF3) and Ikaros (IKZF1). This activity is associated with increased T cell activation and anti-tumor effects of the IMiD drugs lenalidomide and pomalidomide. In primary human T cells, NX-2127 catalyzes the degradation of Aiolos and Ikaros with of 25 nM and 54 nM, respectively, potencies which are similar to those of lenalidomide (20 nM and 343 nM, respectively). Corresponding with such degradation, NX-2127 stimulates T cell activation as measured by increased IL-2 production in primary human T Cells in a manner similar to lenalidomide and pomalidomide. The dual activity of BTK degradation combined with immunomodulation of NX-2127 supports its development for the treatment of B-cell malignancies. Disclosures Robbins: Nurix Therapeutics: Current Employment, Current equity holder in publicly-traded company. Kelly:Nurix Therapeutics: Current Employment, Current equity holder in publicly-traded company. Tan:Nurix Therapeutics: Current Employment, Current equity holder in publicly-traded company. McIntosh:Nurix Therapeutics: Current Employment, Current equity holder in publicly-traded company. Wu:Nurix Therapeutics: Current Employment, Current equity holder in publicly-traded company. Konst:Nurix Therapeutics: Current Employment, Current equity holder in publicly-traded company. Kato:Nurix Therapeutics: Current Employment, Current equity holder in publicly-traded company. Peng:Nurix Therapeutics: Current Employment, Current equity holder in publicly-traded company. Mihalic:Nurix Therapeutics: Current Employment, Current equity holder in publicly-traded company. Weiss:Nurix Therapeutics: Current Employment, Current equity holder in publicly-traded company. Perez:Nurix Therapeutics: Current Employment, Current equity holder in publicly-traded company. Tung:Nurix Therapeutics: Current Employment, Current equity holder in publicly-traded company. Kolobova:Nurix Therapeutics: Current Employment, Current equity holder in publicly-traded company. Borodovsky:Nurix Therapeutics: Current Employment, Current equity holder in publicly-traded company. Rountree:Nurix Therapeutics: Current Employment, Current equity holder in publicly-traded company. Tenn-McClellan:Nurix Therapeutics: Current Employment, Current equity holder in publicly-traded company. Noviski:Nurix Therapeutics: Current Employment, Current equity holder in publicly-traded company. Ye:Nurix Therapeutics: Current Employment, Current equity holder in publicly-traded company. Basham:Nurix Therapeutics: Current Employment, Current equity holder in publicly-traded company. Ingallinera:Nurix Therapeutics: Current Employment, Current equity holder in publicly-traded company. McKinnell:Nurix Therapeutics: Current Employment, Current equity holder in publicly-traded company. Karr:Nurix Therapeutics: Current Employment, Current equity holder in publicly-traded company. Powers:Nurix Therapeutics: Current Employment, Current equity holder in publicly-traded company. Guiducci:Nurix Therapeutics: Current Employment, Current equity holder in publicly-traded company. Sands:Nurix Therapeutics: Current Employment, Current equity holder in publicly-traded company.

No abstract

Eukaryotic mRNAs are appended at the 5' end, with the 7-methylguanosine cap linked by a 5'-5'-triphosphate bridge to the first transcribed nucleoside (m7GpppX). Initiation of cap-dependent translation of mRNA requires direct interaction between the cap structure and the eukaryotic translation initiation factor eIF4E. Biophysical studies of the association between eIF4E and various cap analogs have demonstrated that m(7)GTP binds to the protein ca. -5.0 kcal/mol more favorably than unmethylated GTP. In this work, a thermodynamic analysis of the binding process between eIF4E and several cap analogs has been conducted using Monte Carlo (MC) simulations in conjunction with free energy perturbation (FEP) calculations. To address the role of the 7-methyl group in the eIF4E/m7GpppX cap interaction, binding free energies have been computed for m(7)GTP, GTP, protonated GTP at N(7), the 7-methyldeazaguanosine 5'-triphosphate (m(7)DTP), and 7-deazaguanosine 5'-triphosphate (DTP) cap analogs. The MC/FEP simulations for the GTP-->m(7)DTP transformation demonstrate that half of the binding free energy gain of m(7)GTP with respect to GTP can be attributed to favorable van der Waals interactions with Trp166 and reduced desolvation penalty due to the N(7) methyl group. The methyl group both eliminates the desolvation penalty of the N(7) atom upon binding and creates a larger cavity within the solvent that further facilitates the desolvation step. Analysis of the pair m(7)GTP-m(7)DTP suggests that the remaining gain in affinity is related to the positive charge created on the guanine moiety due to the N(7) methylation. The charge provides favorable cation-pi interactions with Trp56 and Trp102 and decreases the negative molecular charge, which helps the transfer from the solvent, a more polar environment, to the protein.