Discovery and biological evaluation of phthalazines as novel non-kinase TGFβ pathway inhibitors

Synthesis and biological evaluation of 4-((3-(tetrahydro-2H-pyran-4-yl)-1H-pyrazol-4-yl)oxy)quinoline derivatives as novel potential transforming growth factor-β type 1 receptor inhibitors for hepatocellular carcinoma

The transforming growth factor β (TGF-β) type 1 receptor (ALK5) plays a key role in tumor microenvironment. Small-molecule inhibitors of TGFβR1 provides a prospective approach for the treatment of malignant tumors. In this study, a series of 4-((3-(tetrahydro-2H-pyran-4-yl)-1H-pyrazol-4-yl)oxy)quinoline derivatives were identified as novel, potential TGFβR1 inhibitors. The most potent compound 16w inhibited SMAD2/3 phosphorylation and H22 cell viability with IC50 values of 12 and 65 nM, respectively. Further, compound 16w exhibited reasonable pharmacokinetic profiles and exhibited significant anti-tumor efficacy in a xenograft model of H22 cells, with TGI of 79.6 %. Additionally, compound 16w also showed a strong synergistic proapoptotic effect in combination with sorafenib, which provided a promising lead for further development of novel anticancer drugs.

Discovery of 4-aminoquinolines as highly selective TGFβR1 inhibitors with an attenuated MAP4K4 profile for potential applications in immuno-oncology

The tumor microenvironment contains high concentrations of TGFβ, a crucial immunosuppressive cytokine. TGFβ stimulates immune escape by promoting peripheral immune tolerance to avoid tumoricidal attack. Small-molecule inhibitors of TGFβR1 are a prospective method for next-generation immunotherapies. In the present study, we identified selective 4-aminoquinoline-based inhibitors of TGFβR1 through structural and rational-based design strategies. This led to the identification of compound 4i, which was found to be selective for TGFβR1 with the exception of MAP4K4 in the kinase profiling assay. The compound was then further optimized to remove MAP4K4 activity, since MAP4K4 is vital for proper T-cell function and its inhibition could exacerbate tumor immunosuppression. Optimization efforts led to compound 4s that inhibited TGFβR1 at an IC₅₀ of 0.79 ± 0.19 nM with 2000-fold selectivity against MAP4K4. Compound 4s represents a highly selective TGFβR1 inhibitor that has potential applications in immuno-oncology.