Abstract: Compounds of formula (I): or a pharmaceutically acceptable salt thereof, wherein: W is arylene, heteroarylene or formula (a) each L is independently alkylene, alkenylene, alkynylene, a direct bond, arylene, cycloalkylene, alkylene-arylene, alkylene-C?O or —C?O; each X is independently an N-containing heteroarylene, N-containing cycloalkylene or NR; Y is N-containing heteroaryl, N-containing cycloalkyl, NR2, OR1, CN or CO2R; Z1 is formula (b); are useful in therapy, particularly in the therapy of neurodegeneration and cancer.