Design, Synthesis, and Evaluation of o-(Biphenyl-3-ylmethoxy)nitrophenyl Derivatives as PD-1/PD-L1 Inhibitors with Potent Anticancer Efficacy In Vivo

Abstract

Two series of novel o-(biphenyl-3-ylmethoxy)­nitrophenyl compounds (A1–31 and B1–17) were designed as programmed cell death protein 1 (PD-1)/PD-ligand 1 (PD-L1) inhibitors. All compounds showed significant inhibitory activity with IC50 values ranging from 2.7 to 87.4 nM except compound A17, and compound B2 displayed the best activity. Further experiments showed that B2 bound to the PD-L1 protein without obvious toxicity in Lewis lung carcinoma (LLC) cells. Furthermore, B2 significantly promoted interferon-gamma secretion in a dose-dependent manner in vitro and in vivo. Especially, B2 exhibited potent in vivo anticancer efficacy in an LLC-bearing allograft mouse model at a low dose of 5 mg/kg, which was more active than BMS-1018 (tumor growth inhibition rate: 48.5% vs 17.8%). A panel of immunohistochemistry and flow cytometry assays demonstrated that B2 effectively counteracted PD-1-induced immunosuppression in the tumor microenvironment, thereby triggering antitumor immunity. These results indicate that B2 is a promising PD-1/PD-L1 inhibitor worthy of further development.

Design, Synthesis, and Pharmacological Evaluation of Biaryl-Containing PD-1/PD-L1 Interaction Inhibitors Bearing a Unique Difluoromethyleneoxy Linkage

“…As shown in Table , by incorporating the difluoromethyleneoxy motif as an unusual bioisosteric replacement of the methoxy linkage and retaining other structural components intact, compound 25 displayed an IC 50 of 31.87 nM against the PD-1/PD-L1 interaction, which is slightly more potent than reference compound 2 (IC 50 = 48.2 nM). A quick screening of a small set of alkylamino alcohols/acids widely used in the literature ,,− as the solvent interaction structural motif indicated that all the resulting compounds 26–28 retained high inhibitory activity against the PD-1/PD-L1 interaction, and compound 28 bearing a 2-amino-2-methylpropane-1,3-diol component showed more increased potency with an IC 50 value of 16.31 nM. Keeping the 2-amino-2-methylpropane-1,3-diol component intact and changing the substitution pattern of the central tetra-substituted phenyl ring from 3-methyl to the 4-chloro pattern led to compound 29 , showing a much improved potency with an IC 50 value of 5.93 nM.…”

“…By taking advantage of the interaction profile of the biaryl core component, Hu and Holak reported a series of C 2 -symmetric 2,2′-dimethyl-3,3′-bis­(aryloxymethyl)-1,1′-biphenyl analogues, among which compound 3 (Figure ) exhibited an IC 50 value of 3.0 nM in the HTRF assay . A ring fusion strategy was conducted by Gong’s and Wang’s groups, and the representative compounds [1,2,4]­triazolo­[4,3-α]­pyridine 4 and indolin 5 showed IC 50 values of 92.3 and 11.2 nM, respectively. , More recently, Lai and co-workers reported a series of nitrophenyl derivatives, and compound 6 showed an IC 50 value of 2.7 nM . In addition, optimization of the methoxy (−CH 2 O−) linker was conducted by two groups.…”

Small Molecule Agents Targeting PD-1 Checkpoint Pathway for Cancer Immunotherapy: Mechanisms of Action and Other Considerations for Their Advanced Development

“…In a peripheral blood mononuclear cell (PBMC)-based assay, BMS-202, one of the early biphenyl compounds with poor cellular activity in the NFAT reporter assay ( 53 ), showed significant rescue of interferon gamma (IFN-γ) secretion inhibited by PD-L1 at a lower concentration (100 nM) similar to another biphenyl compound, Compound 58 ( 54 ). The biphenyl compound B2 has been shown to induce IFN-γ secretion from the lymph node T cells co-cultured with LLC cells and rescue the inhibition of IFN-γ secretion from PD-L1 of PBMC treated with anti-CD3/anti-CD28, with a potency similar to that observed in biochemical assay for the disruption of PD-1/PD-L1 interaction ( 56 ). During the discovery of amino-acid-inspired interface mimic CA-170, a PBMC-based function assay monitoring the rescue of T cells from the inhibitory activity of PD-L1 in inducing proliferation and cytokine secretion was extensively used.…”

“…A number of reports are also emerging recently from the industry and academia using the privileged structure of biphenyl-containing compounds and their various derivatives to improvise the druggability of the molecules. This includes scaffold based on nicotinyl alcohol ether derivative ( 45 – 47 ), resorcinol dibenzyl ether ( 48 ), 4-phenylindoline derivatives ( 49 ), combining two privileged scaffolds such as biphenyl backbone structure and 2-amino-pyrimidine structure ( 50 ), biphenyl-4-carboxamide derivatives ( 51 ), incorporating taurine moieties ( 52 ), 1-methyl-1H-pyrazolo[4,3-b] pyridine derivatives ( 53 ), replacing the linker connecting aryl group and biaryl core with a novel amine linker ( 54 ), a series of novel biphenyl pyridines derivatives lacking linker ( 55 ), biphenyl methyl nitrophenyl core unit ( 56 ), and terphenyl scaffold derived from the rigidified biphenyl inspired structure ( 57 ). Representative structures of the compounds disclosed are presented in Figure 3 .…”

“…In this assay, CA-170 shows the Emax and potency similar to those observed with an anti-PD1 antibody ( 19 ). A functional assay in a similar format was recently employed to establish equipotent functional activity as in biochemical assays of modified biphenyl compound, Compound B2, from researchers of Nanjing University and China Pharmaceutical University ( 56 ).…”