Selective Degradation of GSPT1 by Cereblon Modulators Identified via a Focused Combinatorial Library

Abstract

Cereblon (CRBN) is an E3 ligase adapter protein that can be reprogrammed by imide-class compounds such as thalidomide, lenalidomide, and pomalidomide to induce the degradation of neo-substrate proteins. In order to identify additional small molecule CRBN modulators, we implemented a focused combinatorial library approach where we fused an imide-based CRBN-binding pharmacophore to a heterocyclic scaffold, which could be further elaborated. We screened the library for CRBN-dependent antiproliferative activity in the multiple myeloma cell line MM1.S and identified five hit compounds. Quantitative chemical proteomics of hit compounds revealed that they induced selective degradation of GSPT1, a translation termination factor that is currently being explored as a therapeutic target for the treatment of acute myeloid leukemia. Molecular docking studies with CRBN and GSPT1 followed by analogue synthesis identified a possible hydrogen bond interaction with the central pyrimidine ring as a molecular determinant of hit compounds’ selectivity. This study demonstrates that a focused combinatorial library design, phenotypic screening, and chemical proteomics can provide a suitable workflow to efficiently identify novel CRBN modulators.

Acute pharmacological degradation of Helios destabilizes regulatory T cells

“…1b ), suggesting that imide analogs may be able to induce Helios degradation. However, in addition to weak Helios binding, CC-885 degrades GSPT1 14 , 17 , a regulator of translation, and is highly cytotoxic ( Extended Data Fig. 1c , 2c ).…”

Haven't got a glue: Protein surface variation for the design of molecular glue degraders

“…Still, even if apparent specificity is observed in given cell types, many of these compounds appear to be intrinsically polypharmacological (Sievers et al, 2018). For instance, growing out the isoindolinone scaffold of lenalidomide led to the pleiotropic ZF/GSPT1 degrader CC-885 (Matyskiela et al, 2016), and later yielded the more GSPT1-selective compounds CC-90009 (Surka et al, 2020) and ZXH-1-161 (Powell et al, 2020). Small changes in compound structure strongly alter neosubstrate degradation specificity (Figure 2), with a recent report on 5-hydroxythalidomide, a thalidomide metabolite, illustrating how the presence of a single hydroxyl leads to a striking change in degradation selectivity from IKZF1 to SALL4, possibly explaining the ll teratogenicity of thalidomide (Donovan et al, 2018;Furihata et al, 2020).…”

Profiling the Landscape of Drug Resistance Mutations in Neosubstrates to Molecular Glue Degraders

“…For GSPT1 CRISPR-suppressor scanning, the GSPT1 degraders CC-885 and ZXH-1-161 33 were dosed in gradual escalation due to their acute cytotoxicity, starting at the approximate GI 50 values and then gradually escalating to above the GI 90 dose over four weeks ( Figure S1a ). In the case of RBM39 CRISPR-suppressor scanning, E7820 (1 μM) and indisulam (1 μM) were dosed at the approximate GI 90 concentrations for four weeks ( Figure S1b ).…”