Provided are methods and compositions for use in therapy, and in particular for treating cancer, preferably drug-resistant cancer, and/or radiation resistant cancer. The compounds may be used for reducing tumor size in a mammalian subject and for inducing apoptosis in a tumor cell. The methods are effective on tumor cells that are resistant to drugs such as temozolomide, doxorubicin, and geldanamycin, as well as non-resistant tumor cells. Further provided are barbiturate and thiobarbiturates diene compounds for use in treating cancer, and uses, methods and compositions relating to these compounds.
