Provided are nucleic acid constructs and systems which comprise (i) a first nucleic acid construct encoding a toxin operatively linked to a first promoter and at least one cancer-associated signaling responsive enhancer element and (ii) a second nucleic acid construct encoding an anti-toxin operatively linked to a second promoter, the second promoter being stronger than the first promoter.Also provided are pharmaceutical compositions comprising same and methods of using same for treating cancer.
