Synthesis and Biological Evaluation of Small Molecules as Potential Anticancer Multitarget Agents

Beyond peptides: Unveiling the design strategies, structure activity correlations and protein-ligand interactions of small molecule inhibitors against PD-1/PD-L1

The landscape of cancer treatment has been transformed by the emergence of immunotherapy, especially through the use of antibodies that target the PD-1/PD-L1 pathway. Recently, there has been a notable increase in interest surrounding immune checkpoint inhibitors for cancer therapy. While antibody-based approaches have drawbacks like high costs and prolonged activity, the approval of monoclonal antibodies such as pembrolizumab and nivolumab has paved the way for a range of alternative therapies, including peptides, peptidomimetics, and small-molecule inhibitors. These smaller molecules, which target the PD-1/PD-L1 interaction, are seen as potential substitutes or supplements to monoclonal antibodies. Our focus in this article is primarily on exploring small molecules designed for PD-1/PD-L1 checkpoint pathway modulation in cancer immunotherapy, along with highlighting current advances in their structural and preclinical/clinical development. The pursuit of therapeutics based on small-molecule inhibitors of the PD-1/PD-L1 axis offers a promising yet intricate avenue for advancing cancer treatment.

Challenging the anticolorectal cancer capacity of quinoxaline-based scaffold via triazole ligation unveiled new efficient dual VEGFR-2/MAO-B inhibitors

Monoamine oxidases (MAOs) and vascular endothelial growth factor receptor-2 (VEGFR-2) are promoters of colorectal cancer (CRC) and central signaling nodes in epithelial-mesenchymal transition (EMT) induced by activating hypoxia-inducible factors (HIFs). Herein, a novel series of rationally designed triazole-tethered quinoxalines were synthesized and evaluated against HCT-116 CRC cells. The tailored scaffolds combine the pharmacophoric themes of both VEGFR-2 inhibitors and MAO inhibitors. All the synthesized derivatives were screened utilizing the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay for their possible cytotoxic effects on normal human colonocytes, then evaluated for their anticancer activities against HCT-116 cells overexpressing MAOs. The hit derivatives 11 and 14 exhibited IC50 = 18.04 and 7.850 µM, respectively, against HCT-116cells within their EC100 doses on normal human colonocytes. Wound healing assay revealed their efficient CRC antimetastatic activities recording HCT-116 cell migration inhibition exceeding 75 %. In vitro enzymatic assays demonstrated that both 11 and 14 efficiently inhibited VEGFR-2 (IC50 = 88.79 and 9.910 nM), MAO-A (IC50 = 0.763 and 629.1 nM) and MAO-B (IC50 = 0.488 and 209.6 nM) with observed MAO-B over MAO-A selectivity (SI = 1.546 and 3.001), respectively. Enzyme kinetics studies were performed for both compounds to identify their mode of MAO-B inhibition. Furthermore, qRT-PCR analysis showed that the hits efficiently downregulated HIF-1α in HCT-116cells by 3.420 and 16.96 folds relative to untreated cells. Docking studies simulated their possible binding modes within the active sites of VEGFR-2 and MAO-B to highlight their essential structural determinants of activities. Finally, they recorded in silico drug-like absorption, distribution, metabolism, excretion, and toxicity (ADMET) profiles as well as ligand efficiency metrics.

Tetrazole derivatives as potent immunomodulatory agents in tumor microenvironment

Twenty-seven compounds bearing a tetrazole ring as a central unit have been designed, synthetized and biologically evaluated. Studies have been performed in order to compare the effect of tetrazole derivatives bearing amine electron-donor or nitro electron-acceptor groups. The antiproliferative activity has been determined in monoculture studies on tumor cell lines HT-29, A-549, MCF-7 and on non-tumor cell line HEK-293 as well as in co-culture studies (HT-29/THP-1). All the compounds have been studied as PD-L1 (Programmed Death Ligand 1), VEGFR-2 (Vascular Endothelial Growth Factor 2), CD-47 (Cluster of Differentiation 47) and c-Myc inhibitors. The effect on TNF-α secretion has also been determined. Bromoderivatives 23, 24 and chloroderivatives 26, 27 have demonstrated an apoptotic effect on HT-29 cancer cells. Compounds bearing an amine group have shown very promising effects as TME immunomodulatory agents.

Aryl azoles based scaffolds for disrupting tumor microenvironment

Thirty-nine aryl azoles, thirteen triazoles and twenty-seven tetrazoles, have been synthetized and biologically evaluated to determine their activity as tumor microenvironment disruptors. Antiproliferative studies have been performed on tumor cell lines HT-29, A-549 and MCF-7 and on non-tumor cell line HEK-293. It has been studied in HT-29 the expression levels of biological targets which are involved in tumor microenvironment processes, such as PD-L1, CD-47, c-Myc and VEGFR-2. In addition, antiproliferative activity was evaluated when HT-29 were co-cultured with THP-1 monocytes and the secretion levels of IL-6 were also determined in these co-cultures. The angiogenesis effect of some selected compounds on HMEC-1 was also evaluated as well as their action against vasculogenic mimicry on HEK-293. Compounds bearing an amino group in the phenyl ring and a halogen atom in the benzyl ring showed promising results as tumor microenvironment disrupting agents. The most outstanding compound decrease dramatically the population of HT-29 cells when co-cultured with THP-1 monocytes and the levels of IL-6 secreted, as well as it showed moderate effects over PD-L1, CD-47 and c-Myc.

Unveiling the Potential of BenzylethyleneAryl-Urea Scaffolds for the Design of New Onco Immunomodulating Agents

This work focuses on the development of thirteen benzylethylenearyl ureas and one carbamate. After the synthesis and purification of the compounds, we studied their antiproliferative action on cell lines, such as HEK-293, and cancer ones, such as HT-29, MCF-7 or A-549, on the immune Jurkat T-cells and endothelial cells HMEC-1. Compounds C.1, C.3, C.12 and C.14 were selected for further biological studies to establish their potential as immunomodulating agents. Some of the derivatives exhibited significant inhibitory effects on both targets: PD-L1 and VEGFR-2 in the HT-29 cell line, showing that urea C.12 is active against both targets. Some compounds could inhibit more than 50% of cancer cell proliferation compared to non-treated ones when assessed in co-cultures using HT-29 and THP-1 cells. In addition, they significantly reduced CD11b expression, which is a promising target for immune modulation in anticancer immunotherapies.

Exploring BenzylethoxyAryl Urea Scaffolds for Multitarget Immunomodulation Therapies

Thirteen benzylethoxyaryl ureas have been synthesized and biologically evaluated as multitarget inhibitors of VEGFR-2 and PD-L1 proteins to overcome resistance phenomena offered by cancer. The antiproliferative activity of these molecules on several tumor cell lines (HT-29 and A549), on the endothelial cell line HMEC-1, on immune cells (Jurkat T) and on the non-tumor cell line HEK-293 has been determined. Selective indexes (SI) have been also determined and compounds bearing p-substituted phenyl urea unit together with a diaryl carbamate exhibited high SI values. Further studies on these selected compounds to determine their potential as small molecule immune potentiators (SMIPs) and as antitumor agents have been performed. From these studies, we have concluded that the designed ureas have good tumor antiangiogenic properties, exhibit good inhibition of CD11b expression, and regulate pathways involved in CD8 T-cell activity. These properties suggest that these compounds could be potentially useful in the development of new cancer immune treatments.

Synthesis and Biological Evaluation of Potential Oncoimmunomodulator Agents

Fourteen triazole-scaffold derivatives were synthetized and biologically evaluated as potential oncoimmunomodultator agents by targeting both PD-L1 and c-Myc. First, the antiproliferative activity of these molecules on the monocultures of several tumor cell lines (HT-29, A-549, and MCF-7) and on the non-tumor cell line HEK-293 was studied. Then, the effects on the mentioned biological targets were also evaluated. Finally, the effect on cancer cell viability when the molecules were co-cultured with immune cells (Jurkat T cells or THP-1) was also determined. Compounds bearing a bromoophenyl group were selected because of their excellent results, and their effect on IL-6 secretion was also studied. In conclusion, we found compounds that are capable of downregulating c-Myc, as well as influencing and altering the distribution of PD-L1 in tumor cells; the compounds are thus capable of influencing the behavior of defensive cells towards cancer cells. p-Bromophenyltriazol 3 is the most active of these as a PD-L1 and c-Myc downregulator and as a potential immunomodulator agent. Moreover, it exhibits an interesting action on inflammation-related cytokine IL-6.