Design, synthesis, and mechanistic study of bispecific small molecules-based phenyl pyrazolopyrimidinone scaffold as dual-targeting VEGFR and PD-L1 immune checkpoint in hepatocellular carcinoma.

In this work, a new series of N-arylmethylene/heterylmethylene-2-(4-oxo-1-phenyl-1,4-dihydro-5H-pyrazolo[3,4-d]pyrimidin-5-yl)acetohydrazide 8a-l was synthesized via the condensation reaction of acetohydrazide 6 with various aromatic aldehydes 7a-l. The cytotoxic activity of these compounds was evaluated in vitro using against three human cancer cell lines: hepatocellular carcinoma (HepG2), prostate cancer (PC-3) and colorectal carcinoma (HCT-116). Among the synthesized series, compound 8g exhibited the highest potency, with IC₅₀ values of 3.93 μM, 9.56 μM, and 6.30 μM against HepG2, PC-3, and HCT-116, respectively, surpassing the reference drugs doxorubicin (4.50 μM against HepG2) and sorafenib (9.18 μM against HepG2). Mechanistically, 8g demonstrated strong inhibition of VEGFR2 (IC₅₀ = 0.38 μM), but it outperformed PD-L1 inhibition compared to Bavencio (IC₅₀ = 134.41 pg/mL and 217.74 pg/mL, respectively). In contrast, it enhanced INF-γ secretion in comparison to the reference drug. Cell cycle analysis revealed arrest at G0/G1with apoptosis induction at 29.41%. The apoptotic enzyme assay showed upregulation of BAX and Caspase-3, and downregulation of Bcl-2, confirming the activation of the intrinsic apoptotic pathway. In silico molecular docking and dynamic simulation assisted data strongly correlated with the experimental approach that compound 8g exerts multi-targeted anticancer activity via VEGFR2 and PD-L1 inhibition. In conclusion, 8g is a promising candidate recommended for further therapeutic development.