Indoleamine 2, 3-dioxygenase 1(IDO1) plays a predominant role in the cancer immunotherapy which catalyzes the initial and rate limiting step of the kynurenine pathway as a key enzyme. To explore novel IDO1 inhibitors, 5 erlotinib-linked 1,2,3-triazole derivatives were designed by using structure-based drug design strategy. Drug-target interactions (DTI) were predicted by DeePurpose, an easy-to-use deep learning library that contains more than 50 algorithms. The DTI prediction results suggested that the designed molecules have potential inhibitory activities for IDO1. Chemical synthesis and bioassays showed that compounds exhibited remarkable inhibitory activities against IDO1, among which compound e was the most potent with IC50 value of 0.32±0.07 μM in the Hela cell assay. The docking model and ADME analysis exhibited that the effective interactions of these compounds with iron of heme and better drug-likeness ensured the IDO1 inhibitory activities. The studies suggested that compound e was a novel interesting IDO inhibitor for further development.

In the context of peptide drug development, glycosylation plays a pivotal role. Accordingly, L-type peptides were synthesized predicated upon the PD-1/PD-L1 blocker ^DPPA-1. Subsequent glycosylation resulted in the production of two distinct glycopeptides, D-glu-^LPPA-1 and D-gal-^LPPA-1, by using D-glucose (D-glu) and D-galactose (D-gal), respectively, during glycosylation. Both glycopeptides significantly inhibited the interaction between PD-1 and PD-L1, and the measured half maximal inhibitory concentrations (IC_50s) were 75.5 μM and 101.9 μM for D-glu-LPPA-1 and D-gal-LPPA-1, respectively. Furthermore, D-gal-LPPA-1 displayed a pronounced ability to restore T-cell functionality. In an MC38 tumor-bearing mouse model, D-gal-LPPA-1 demonstrated a significant inhibitory effect. Notably, D-gal-LPPA-1 substantially augmented the abundance and functionality of CD8⁺ T cells in the tumor microenvironment. Additionally, in the lymph nodes and spleens, D-gal-LPPA-1 significantly increased the proportion of CD8⁺ T cells secreting interferon-gamma (IFN-γ). These strong findings position D-gal-LPPA-1 as a potent enhancer of the antitumor immune response in MC38 tumor-bearing mice, underscoring its potential as a formidable PD-1/PD-L1 blocking agent.

In this study, 14 structurally novel gefitinib-1,2,3-triazole derivatives were synthesized using a click chemistry approach and characterized by ¹H NMR, ¹³C NMR and high-resolution mass spectrometry (HRMS). Preliminary cell counting kit-8 results showed that most of the compounds exhibit excellent antitumor activity against epidermal growth factor receptor wild-type lung cancer cells NCI-H1299, A549 and NCI-H1437. Among them, 4b and 4c showed the most prominent inhibitory effects. The half maximal inhibitory concentration (IC₅₀) values of 4b were 4.42 ± 0.24 μM (NCI-H1299), 3.94 ± 0.01 μM (A549) and 1.56 ± 0.06 μM (NCI-1437). The IC₅₀ values of 4c were 4.60 ± 0.18 µM (NCI-H1299), 4.00 ± 0.08 μM (A549) and 3.51 ± 0.05 μM (NCI-H1437). Furthermore, our results showed that 4b and 4c could effectively inhibit proliferation, colony formation and cell migration in a concentration-dependent manner, as well as induce apoptosis in H1299 cells. In addition, 4b and 4c exerted its anti-tumor effects by inducing cell apoptosis, upregulating the expression of cleaved-caspase 3 and cleaved-PARP and downregulating the protein levels of Bcl-2. Based on these results, it is suggested that 4b and 4c be developed as potential new drugs for lung cancer treatment.

A series of 20 novel gefitinib derivatives incorporating the 1,2,3-triazole moiety were designed and synthesized. The synthesized compounds were evaluated for their potential anticancer activity against EGFR wild-type human non-small cell lung cancer cells (NCI-H1299, A549) and human lung adenocarcinoma cells (NCI-H1437) as non-small cell lung cancer. In comparison to gefitinib, Initial biological assessments revealed that several compounds exhibited potent anti-proliferative activity against these cancer cell lines. Notably, compounds 7a and 7j demonstrated the most pronounced effects, with an IC₅₀ value of 3.94 ± 0.17 µmol L⁻¹ (NCI-H1299), 3.16 ± 0.11 µmol L⁻¹ (A549), and 1.83 ± 0.13 µmol L⁻¹ (NCI-H1437) for 7a, and an IC₅₀ value of 3.84 ± 0.22 µmol L⁻¹ (NCI-H1299), 3.86 ± 0.38 µmol L⁻¹ (A549), and 1.69 ± 0.25 µmol L⁻¹ (NCI-H1437) for 7j. These two compounds could inhibit the colony formation and migration ability of H1299 cells, and induce apoptosis in H1299 cells. Acute toxicity experiments on mice demonstrated that compound 7a exhibited low toxicity in mice. Based on these results, it is proposed that 7a and 7j could potentially be developed as novel drugs for the treatment of lung cancer.

Indoleamine 2,3-dioxygenase 1 (IDO1) has received much attention as an immunomodulatory enzyme in the field of cancer immunotherapy. While several IDO1 inhibitors have entered clinical trials, there are currently no IDO1 inhibitor drugs on the market. To explore potential IDO1 inhibitors, we designed a series of compounds with urea and 1,2,3-triazole structures. Organic synthesis and IDO1 enzymatic activity experiments verified the molecular-level activities of the designed compounds, and the IC₅₀ value of compound 3a was 0.75 μM. Molecular docking and quantum mechanical studies further explained the binding mode and reaction potential of compound 3a with IDO1. Our research has resulted in a series of novel IDO1 inhibitors, which is beneficial to the development of drugs targeting IDO1 in numerous cancer diseases.