The present invention relates to fused pyrimidine-based hydroxamate compounds of formula (I), comprising a hydroxamate group, that are inhibitors of histone deacetylase (HDAC) and kinases. More particularly, the present invention relates to hydroxamate substituted purine or 5H-pyrrolo[3,2-d]pyrimidine derivatives, methods for their preparation, pharmaceutical compositions containing these compounds and uses of these compounds in the treatment of disorders/conditions/diseases involving, relating to or associated with enzymes having histone deacetylase, non-histone deacetylase and kinase activities/functions and/or via unspecified/multi-targeted mechanisms.