The present invention provides compounds of formula (I) and pharmaceutically acceptable salts thereof in which m, n, W, X, Y, Z, R1, R2, R3 and R4 are as defined in the specification, for use in therapy.本發明提供式(I)化合物及其醫藥可接受鹽其中m、n、W、X、Y、Z、R1、R2、R3及R4係於說明書中所定義,其係用於治療。