Kinase experiment:

Various kinase activities are assayed by measuring the incorporation of radiolabeled ATP into a peptide or protein substrate. The reactions are performed in 96-well plates and included the relevant kinase, substrate, ATP, and appropriate cofactors. The reactions are incubated and then stopped by the addition of phosphoric acid. Substrate is captured onto a phosphocellulose filter, which is washed free of unreacted ATP. The counts incorporated are determined by counting on a microplate scintillation counter. The ability of SD-208 to inhibit the respective kinase is determined by comparing counts incorporated in the presence of compound with those incorporated in the absence of compound.

Cell experiment:

Glioma cells are cultured in the absence or presence of SD-208 (1 μM) for 48 hours. The cells are pulsed for the last 24 hours with [methyl-3H]thymidine (0.5 μCi) and harvested, and incorporated radioactivity is determined in a liquid scintillation counter.

Animal experiment:

VM/Dk mice are purchased from the TSE Resource Center. Mice of 6 to 12 weeks of age are used for the survival experiments. Groups of eight mice are anesthesized before all intracranial procedures and placed in a stereotaxic fixation device. A burr hole is drilled in the skull 2 mm lateral to the bregma. The needle of a Hamilton syringe is introduced to a depth of 3 mm. SMA-560 cells [5×103cells] resuspended in a volume of 2 μL of PBS are injected into the right striatum. Three days later, the mice are allowed to drink SD-208 at 1 mg/mL in deionized water. The mice are observed daily and, in the survival experiments, sacrificed on development of neurologic symptoms.

SD-208 Description:
EC50: SD-208 inhibits the growth inhibition of TGF-β–sensitive CCL64 cells at an EC50 of 0.1 μmol/L .
The cytokine transforming growth factor (TGF)-β has become a major target for the experimental treatment of human malignant gliomas. SD-208, a novel transforming growth factor β receptor I kinase inhibitor, inhibits growth and invasiveness and enhances immunogenicity of murine and human Glioma cells both in vitro and in vivo.
In vitro: SD-208 inhibits the growth inhibition of TGF-β–sensitive CCL64 cells mediated by recombinant TGF-β1 or TGF-β2 or of TGF-β–containing glioma cell supernatant at an EC50 of 0.1 μmol/L. SD-208 also blocks autocrine and paracrine TGF-β signaling in glioma cells as detected by the phosphorylation of Smad2 or TGF-β reporter assays and strongly inhibits constitutive and TGF-β–evoked migration and invasion, but not viability or proliferation. Moreover, SD-208 restores the lytic activity of polyclonal natural killer cells against glioma cells in the presence of recombinant TGF-β or of TGF-β–containing glioma cell supernatant. [1].
In vivo: The oral bioavailability of SD-208 was verified by demonstrating the inhibition of TGF-β–induced Smad phosphorylation in spleen and brain. Systemic SD-208 treatment initiated 3 days after the implantation of SMA-560 cells into the brains of syngeneic VM/Dk mice prolongs their median survival from 18.6 to 25.1 days. Histologic analysis revealed no difference in blood vessel formation, proliferation, or apoptosis. However, animals responding to SD-208 showed an increased tumor infiltration by natural killer cells, CD8 T cells, and macrophages. These data define TGF-β receptor I kinase inhibitors such as SD-208 as promising novel agents for the treatment of human malignant glioma and other conditions associated with pathological TGF-β activity [1].
Clinical trial: Up to now, SD-208 is still in the preclinical development stage.
Reference:
[1] Leung SY, Niimi A, Noble A, Oates T, Williams AS, Medicherla S, Protter AA, Chung KF. Effect of transforming growth factor-beta receptor I kinase inhibitor 2,4-disubstituted pteridine (SD-208) in chronic allergic airway inflammation and remodeling. J Pharmacol Exp Ther. 2006;319(2):586-94.