Design, Synthesis, Biological Studies and Putative Binding Mode of Novel Benzotriazolothalidomide Derivatives as...

Targeted protein degradation (TPD) represents a new paradigm in drug discovery, encompassing several innovative strategies like proteolysis targeting chimeras (PROTACs). PROTACs work by linking the target protein of interest (POI) to an E3 ubiquitin ligase, marking it for ubiquitination, and subsequent degradation by the proteasome. The ligand space of E3 ligase cereblon (CRBN) mostly includes phthalimide-based thalidomide 1 and its analogs, commonly known as cereblon E3 ligase modulators (CELMoDs) which have been approved for the treatment of multiple subtypes of non-Hodgkin's lymphoma (NHL). Recently, benzotriazolo thalidomide (4) was reported which displayed similar binding mode like thalidomide, having relatively stronger binding affinity. Towards our aim of identifying new generation CRBN binding ligands, which can have use either in PROTAC or CELMoD chemical space, systematic design and SAR studies around 4, synthesis, biological, and docking experiments to understand putative binding mode have been carried out. As a result, a few compounds were identified as potent CRBN ligands, including compound 13 having an IC₅₀ value of 198 ± 7 nM. Cell viability assay of benzotriazolothalidomide 13 in human embryonic kidney cells (HEK293) suggest a high level of safety profile (SI = > 500). To showcase the drug likeness of this compound, it was tested in preliminary ADME assays, revealing its excellent aqueous solubility (161.87 ± 0.96 μM), and high in vitro metabolic stability in human liver microsome (CL_int, app = 16.57 ± 0.19 μL/min/mg of protein; T_1/2 = 104.57 ± 1.22 min) and thus offers the scope for further optimization of the compound.