PD-1/PD-L1 (IC50 = 18 nM); PD-1/PD-L1 (KD = 8 μM)

BMS-202 (0-100 μM; 4 days; SCC-3 or Jurkat cells) treatment prevents the proliferation of strongly PD-L1 positive SCC-3 cells (IC50 of 15 μM) and anti-CD3 antibody-activated Jurkat cells (IC50 10 μM) in vitro[2]. BMS-202 specifically induces PD-L1 thermal stabilization. BMS-202 causes PD-L1 dimerization in solution. At the homodimer's core, BMS-202 fills a large hydrophobic pocket, facilitating numerous additional interactions between the monomers. PD-1/PD-L1 interaction is physiologically mediated by hydrophobic surfaces, and BMS-202 interacts with both PD-L1 molecules on these surfaces[1].

BMS-202 (20 mg/kg; intraperitoneal injection; daily; for 9 days; NOG-dKO mice) treatment exhibits a distinct antitumor effect in comparison to the controls, in humanized MHC- dKO NOG mice[2].

All binding studies are performed in an HTRF assay buffer consisting of dPBS supplemented with 0.1% (with v) bovine serum albumin and 0.05% (v/v) Tween-20. For the PD-l-Ig/PD-Ll-His binding assay, inhibitors are pre-incubated with PD-Ll-His (10 nM final) for 15 m in 4 μL of assay buffer, followed by addition of PD-l-Ig (20 nM final) in 1 μL of assay buffer and further incubation for 15 m. PD-L1 from either human, cyno, or mouse are used. HTRF detection is achieved using europium crypate-labeled anti- Ig (1 nM final) and allophycocyanin (APC) labeled anti-His (20 nM final). Antibodies are diluted in HTRF detection buffer and 5 μL is dispensed on top of binding reaction. The reaction mixture is allowed to equilibrate for 30 minutes and signal (665 nm/620 nm ratio) is obtained using an En Vision fluorometer. Additional binding assays are established between PD-1-Ig/PD-L2-His (20, 5 nM, respectively), CD80-His/PD-Ll-Ig (100, 10 nM, respectively) and CD80-His/CTLA4-Ig (10, 5 nM, respectively).

The programmed death-1/programmed death-ligand 1 (PD-1/PD-L1) interaction plays a dominant role in the suppression of T cell responses, especially in a tumor microenvironment, protecting tumor cells from lysis. PD-1/PD-L1 inhibitor 2 is reported to prevent the interaction of PD-L1 with PD-1 with an IC50 value of 18 nM.

In an in vivo study using humanized MHC-double knockout (dKO) NOG mice, BMS-202 showed a clear antitumor effect compared with the controls; however, a direct cytotoxic effect was revealed to be involved in the antitumor mechanism, as there was no lymphocyte accumulation in the tumor site. These results suggest that the antitumor effect of BMS-202 might be partly mediated by a direct off-target cytotoxic effect in addition to the immune response-based mechanism. Also, the humanized dKO NOG mouse model used in this study was shown to be a useful tool for the screening of small molecule inhibitors of PD-1/PD-L1 binding that can inhibit tumor growth via an immune-response-mediated mechanism[2].

[1]. Structural basis for small molecule targeting of the programmed death ligand 1 (PD-L1). Oncotarget. 2016 May 24;7(21):30323-35.

[2]. Antitumor activity of the PD-1/PD-L1 binding inhibitor BMS-202 in the humanized MHC-double knockout NOG mouse. Biomed Res. 2019;40(6):243-250.

Targeting the PD-1/PD-L1 immunologic checkpoint with monoclonal antibodies has provided unprecedented results in cancer treatment in the recent years. Development of chemical inhibitors for this pathway lags the antibody development because of insufficient structural information. The first nonpeptidic chemical inhibitors that target the PD-1/PD-L1 interaction have only been recently disclosed by Bristol-Myers Squibb. Here, we show that these small-molecule compounds bind directly to PD-L1 and that they potently block PD-1 binding. Structural studies reveal a dimeric protein complex with a single small molecule which stabilizes the dimer thus occluding the PD-1 interaction surface of PD-L1s. The small-molecule interaction "hot spots" on PD-L1 surfaces suggest approaches for the PD-1/PD-L1 antagonist drug discovery.[1]

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Recently, the first series of small molecule inhibitors of PD-1/PD-L1 were reported by Bristol-Myers Squibb (BMS), which were developed using a homogeneous time-resolved fluorescence (HTRF)-based screening investigation of the PD-1/PD-L1 interaction. Additional crystallographic and biophysical studies showed that these compounds inhibited the interaction of PD-1/PD-L1 by inducing the dimerization of PD-L1, in which each dimer binds one molecule of the stabilizer at its interface. However, the immunological mechanism of the antitumor effect of these compounds remains to be elucidated. In the present study, we focused on BMS-202 (a representative of the BMS compounds) and investigated its antitumor activity using in vitro and in vivo experiments. BMS-202 inhibited the proliferation of strongly PD-L1-positive SCC-3 cells (IC50 15 μM) and anti-CD3 antibody-activated Jurkat cells (IC50 10 μM) in vitro. Additionally, BMS-202 had no regulatory effect on the PD-1 or PD-L1 expression level on the cell surface of these cells. In an in vivo study using humanized MHC-double knockout (dKO) NOG mice, BMS-202 showed a clear antitumor effect compared with the controls; however, a direct cytotoxic effect was revealed to be involved in the antitumor mechanism, as there was no lymphocyte accumulation in the tumor site. These results suggest that the antitumor effect of BMS-202 might be partly mediated by a direct off-target cytotoxic effect in addition to the immune response-based mechanism. Also, the humanized dKO NOG mouse model used in this study was shown to be a useful tool for the screening of small molecule inhibitors of PD-1/PD-L1 binding that can inhibit tumor growth via an immune-response-mediated mechanism.[2]

C25H29N3O3

419.52

419.22

C, 71.57; H, 6.97; N, 10.02; O, 11.44

1675203-84-5

N-deacetylated BMS-202;2310135-18-1

117951478

White to off-white solid powder

1.1±0.1 g/cm3

611.4±55.0 °C at 760 mmHg

323.6±31.5 °C

0.0±1.8 mmHg at 25°C

1.575

3.99

2

5

10

31

526

0

O(C1C([H])=C([H])C(=C(N=1)OC([H])([H])[H])C([H])([H])N([H])C([H])([H])C([H])([H])N([H])C(C([H])([H])[H])=O)C([H])([H])C1C([H])=C([H])C([H])=C(C2C([H])=C([H])C([H])=C([H])C=2[H])C=1C([H])([H])[H]

JEDPSOYOYVELLZ-UHFFFAOYSA-N

InChI=1S/C25H29N3O3/c1-18-22(10-7-11-23(18)20-8-5-4-6-9-20)17-31-24-13-12-21(25(28-24)30-3)16-26-14-15-27-19(2)29/h4-13,26H,14-17H2,1-3H3,(H,27,29)

2-[2,6-dichloro-4-(3,5-dimethyl-1,2-oxazol-4-yl)anilino]-N-hydroxybenzamide

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Solubility in Formulation 1: ≥ 2.5 mg/mL (5.96 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (5.96 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (5.96 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 4: 4.05 mg/mL (9.65 mM) in 45% PEG300 5% Tween-80 50% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution; with ultrasonication.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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 (Please use freshly prepared in vivo formulations for optimal results.)