INDOLE DERIVATIVE AND USE FOR TREATMENT OF CANCER

The present invention relates to a compound represented by the formula wherein A is a benzene ring optionally having substituents, R1, R2a and R3 are each a hydrogen atom, a hydrocarbon group optionally having substituents or a heterocyclic group optionally having substituents, R1 and R2a may form a ring via X, when R1 and R2a form a ring via X, R1 and R2a are each a bond or a divalent C1-5 acyclic hydrocarbon group optionally having substituents, and X is a bond, an oxygen atom, an optionally oxidized sulfur atom or an imino group optionally having a substituent, provided that R1, R2a and X are not bonds at the same time, or a salt thereof, and an agent for inhibiting kinase (phosphorylation enzyme), which contains this compound or a prodrug thereof. The compound of the present invention has an inhibitory activity against kinase such as a vascular endothelial growth factor receptor (VEGFR) and the like, and is useful as an agent for the prophylaxis or treatment of cancer and the like.