The present invention relates to an inhibitor of MELK and/or ROR2, preferably for use in the treatment of diffuse intrinsic pontine glioma (DIPG), wherein said DIPG is preferably characterized by overexpression of MELK and/or overexpression of ROR2. The inhibitor may be combined with a P-glycoprotein inhibitor, an Abcb1a inhibitor, Abcb1b inhibitor, mannitol, or an Abcg2 inhibitor.