Structure-activity relationship analysis of novel GSPT1 degraders based on benzotriazinone scaffold and its antitumor effect on xenograft mouse model.

Molecular glue degraders, such as lenalidomide and pomalidomide, bind to cereblon (CRBN) E3 ligase and subsequently recruit neosubstrate proteins, Ikaros (IKZF1) and Aiolos (IKZF3), for the ubiquitination-proteasomal degradation process. In this study, we explored structure-activity relationship analysis for novel GSPT1 degraders utilizing a benzotriazinone scaffold previously discovered as a novel CRBN binder. In particular, we focused on the position of the ureido group on the benzotriazinone scaffold, substituent effect on the phenylureido group, and methyl substitution on the benzylic position of benzotriazinone. As a result, we identified 34f (TD-522), which exhibits strong anti-proliferative effects in both KG-1 (EC50 = 0.5 nM) and TMD-8 (EC50 = 5.2 nM) cell lines. Compound 34f effectively induced GSPT1 degradation with a DC50 of 0.269 nM and Dmax of >95 % at 10 nM concentration in KG-1 cells. An in vivo xenograft study showed that compound 34f effectively suppressed TMD8-driven tumor growth, suggesting a potential role in the development of novel GSPT1 degraders.

Design and characterization of cereblon-mediated androgen receptor proteolysis-targeting chimeras.

Proteolysis-targeting chimera (PROTAC)-mediated protein degradation is a rapidly emerging therapeutic intervention that induces the degradation of targeted proteins. Herein, we report the design and biological evaluation of a series of androgen receptor (AR) PROTAC degraders for the treatment of metastatic castration-resistant prostate cancer. Predominantly, instead of thalidomide, we utilized the TD-106 scaffold, a novel cereblon (CRBN) binder that was identified in our previous study. Our results suggest that the linker position in the TD-106 CRBN binder is critical for the efficiency of AR degradation. The compounds attached to the 6-position of TD-106 promoted better degradation of AR than those at the 5- and 7-positions. Among the synthesized AR PROTACs, the representative degrader 33c (TD-802) effectively induced AR protein degradation, with a degradation concentration 50% of 12.5 nM and a maximum degradation of 93% in LNCaP prostate cancer cells. Additionally, most AR PROTAC degraders, including TD-802, displayed good liver microsomal stability and in vivo pharmacokinetic properties. Finally, we showed that TD-802 effectively inhibited tumor growth in an in vivo xenograft study.