Design, Synthesis, and Biological Evaluation of HDAC Degraders with CRBN E3 Ligase Ligands.

Histone deacetylases (HDACs) play important roles in cell growth, cell differentiation, cell apoptosis, and many other cellular processes. The inhibition of different classes of HDACs has been shown to be closely related to the therapy of cancers and other diseases. In this study, a series of novel CRBN-recruiting HDAC PROTACs were designed and synthesized by linking hydroxamic acid and benzamide with lenalidomide, pomalidomide, and CC-220 through linkers of different lengths and types. One of these PROTACs, denoted 21a, with a new benzyl alcohol linker, exhibited comparably excellent HDAC inhibition activity on different HDAC classes, acceptable degradative activity, and even better in vitro anti-proliferative activities on the MM.1S cell line compared with SAHA. Moreover, we report for the first time the benzyl alcohol linker, which could also offer the potential to be used to develop more types of potent PROTACs for targeting more proteins of interest (POI).

Design and synthesis of new lenalidomide analogs via Suzuki cross-coupling reaction.

Lenalidomide is a cereblon modulator known for its antitumor, anti-inflammatory, and immunomodulatory properties in clinical applications. Recently, some reported lenalidomide analogs could exhibit a significant bioactivity through various modifications in the isoindolinone ring. In this study, we designed and synthesized a series of novel lenalidomide analogs on the basis of the installation of a methylene chain at the C-4 position of isoindolinone via the Suzuki cross-coupling reaction. These new compounds were further evaluated for their in vitro antiproliferative activities against two tumor cell lines (MM.1S and Mino). Specifically, compound 4c displayed the strongest antiproliferative activity against the MM.1S (IC50 = 0.27 ± 0.03 µM) and Mino (IC50 = 5.65 ± 0.58 µM) tumor cell lines. In summary, we have developed a new synthetic strategy for C-4 derivatization of lenalidomide, providing a bioactive scaffold that could be used to discover further potential antitumor lead compounds in pharmaceutical research.

Design, synthesis, and biological evaluation of Wee1 kinase degraders.

Proteolysis targeting chimera (PROTAC) technology has received widespread attention in recent years as a promising strategy for drug development. Herein, we report a series of novel Wee1 degraders, which were designed and synthesized based on PROTAC technology by linking AZD1775 with CRBN ligands through linkers of different lengths and types. All degraders could effectively and completely degrade cellular Wee1 protein in MV-4-11 cell line at IC50 concentrations. Preliminary assessments identified 42a as the most active degrader, which possessed potent antiproliferative activity and induced CRBN- and proteasome-dependent degradation of Wee1. Moreover, 42a also exhibited a time- and concentration-dependent depletion manner and inducing cell cycle arrest in G0/G1 phase and cancer cell apoptosis. More importantly, 42a showed acceptable in vitro and in vivo pharmacokinetic properties and displayed rapid and sustained Wee1 degradation ability in vivo. Taken together, these findings contribute to understanding the development of PROTACs and demonstrate that our Wee1-targeting PROTAC strategy has potential novel applications in cancer therapy.

Design, synthesis and biological evaluation of the thioether-containing lenalidomide analogs with anti-proliferative activities.

Lenalidomide and its analogs have exhibited extensive anti-tumor, anti-inflammatory and immunomodulatory properties in pharmaceutical research. In this work, a series of novel thioether-containing lenalidomide analogs were designed and synthesized for biological evaluation. Lenalidomide showed significant anti-proliferative activity against the MM.1S cell line (IC50 = 50 nM) while it displayed no anti-proliferative activity against other treated tumor cell lines. Compared with lenalidomide, compound 3j exhibited preferable anti-proliferative activity against the MM.1S (IC50 = 1.1 nM), Mino (IC50 = 2.3 nM) and RPMI 8226 cell lines (IC50 = 5.5 nM). In addition, compound 3j displayed selective anti-proliferative activity against several tumor cell lines, including various B-NHL, MM and AML cell lines, and showed no cytotoxicity on the normal human cell line PBMC, suggesting a good safety profile. Following oral administration, compound 3j achieved a Cmax of 283 ng/mL at 0.83 h, and had a higher relative oral bioavailability value (F = 39.2%) than that of CC-220 (F = 22.8%), but its oral exposure in vivo was somewhat low (AUC = 755 h ng/mL). Furthermore, it was found that oral administration of compound 3j at dosages of 60 mg/kg could delay RPMI 8226 tumor growth in the female CB-17 SCID mice. The current work confirmed that installing thioether moiety at the 4-position of isoindolinone is an effective strategy for identifying new promising lenalidomide analogs with anti-tumor activities in preclinical study.