An orally bioavailable small-molecule inhibitor of CK2 with potential antineoplastic activity. Silmitasertib selectively binds to and inhibits the enzyme casein kinase II (CK2), which may lead to an inhibition of cellular proliferation. CK2, a protein kinase often overexpressed in a variety of cancer cell types, appears to be correlated with malignant transformation, tumor growth and survival.