PD-1/PD-L1 inhibitor 1 (BMS-1) (Synonyms: BMS-1, Programmed Cell Death 1/Programmed Cell Death-Ligand 1 Inhibitor 1)

PD-1/PD-L1 inhibitor 1 is a PD-1/PD-L1 interaction inhibitor with an IC₅₀ value between 6 and 100 nM^[1]. PD-1 / PD-L1 regulates cell signaling pathways and epigenetic modifications, thereby inhibiting T cell and B cell proliferation and effector functions. Lack of tumor antigen and effective antigen presentation, abnormal activation of carcinogenic pathway, IFN- γ Signal mutation, immunosuppressive tumor microenvironment (such as regulatory T cells, myeloid derived inhibitory cells, M2 macrophages, and immunosuppressive cytokines) can lead to resistance to PD-1 / PD-L1 blockade.

PD-1/PD-L1 inhibitor 1 has been identified to be a potent and selective small molecule inhibitor blocking the interaction of programmed cell death protein 1 (PD-1) with its ligand protein (PD-L1) ^[3]. PD-1/PD-L1 inhibitor 1 was also found to act as an immunomodulator. In preclinical studies, PD-1/PD-L1 inhibitor 1 was able to block PD-1/PD-Ll interactions with an IC₅₀ value between 6 and 100 nM, which was measured by a homogenous time-resolved fluorescence (HTRF) binding assay. Thus, PD-1/PD-L1 inhibitor 1 might potentially be used for the treatment of cancer as well as infectious diseases, such as hepatitis C ^[2].

PD-1/PD-L1 inhibitor 1 +LPS treatment decreased PD-1 mRNA and protein expression in MH-S cells. BMS-1 treatment reduced TNF in LPS induced MH-S cells- α、 IL-1 β and IL-6, while IL-10 increased significantly. PD-1/PD-L1 inhibitor 1 pathway has anti apoptotic and anti-inflammatory effects on LPS stimulated MH-S cells^[3].

PD-1/PD-L1 inhibitor 1 is a small molecule inhibitor of PD-1 delivered by coated patch. After 14 days, the new intima in the PD-1/PD-L1 inhibitor 1 coated patch was thinner than the control patch. In addition, compared with the control patch, the number of PD-1, CD3, CD68, CD45 and PCNA positive cells in the PD-1/PD-L1 inhibitor 1 coated patch was also significantly reduced, with a similar number of cut caspase control and three positive cells in the PD-1/PD-L1 inhibitor 1 coated patch. These data confirm that inhibition of PD-1 can reduce the thickness of new intima and the accumulation of inflammatory cells in the new intima formed after patch angioplasty (day 14) in rats^[4].

The factors that lead to resistance to PD-1 blockade include PD-L1 expression, tumor neoantigens expression and presentation, cellular signaling pathways (PI3K, WNT, IFN-γ, MAPK), tumor microenvironment (TME) (exhausted T cell, Treg, MDSC, TAM, other chemokines), and related immune genes (IPRES). The inhibitors against target molecules are indicated, which could enhance antitumor responses in in mouse models when combined with PD-1/PD-L1 blockade^[1].

References:
[1] Bai J , Gao Z , Li X , et al. Regulation of PD-1/PD-L1 pathway and resistance to PD-1/PDL1 blockade[J]. Oncotarget, 2017, 8(66).
[2] https://www. google.com/patents/WO2015034820A1
[3] Jia L, Liu K, Fei T, et al. Programmed cell death‑1/programmed cell death‑ligand 1 inhibitors exert antiapoptosis and antiinflammatory activity in lipopolysaccharide stimulated murine alveolar macrophages[J]. Experimental and Therapeutic Medicine, 2021, 21(4): 1-7.
[4] Bai H, Wang Z, Li M, et al. Inhibition of programmed death‐1 decreases neointimal hyperplasia after patch angioplasty[J]. Journal of Biomedical Materials Research Part B: Applied Biomaterials, 2021, 109(2): 269-278.