Abstract: Disclosed are methods of enhancing the chemotherapeutic treatment of tumor cells, reducing resistance of a cancer cell to a chemotherapeutic agent, a method of inhibiting ABCG2, Pgp, or MRP1 in a mammal afflicted with cancer, and a method of increasing the bioavailability of an ABCG2 substrate drug in a mammal. The methods comprise administering effective amounts of certain compounds to the mammal, for example, a compound of the formula (I): wherein R1, R2, R3, X1, X2, X3, a, and b are as described herein. Uses of these compounds in the preparation of a medicament are also disclosed. Also disclosed are compounds of formula (II), pharmaceutical compositions comprising such compounds and uses thereof.

Abstract: Disclosed are methods of enhancing the chemotherapeutic treatment of tumor cells, reducing resistance of a cancer cell to a chemotherapeutic agent, a method of inhibiting ABCG2, Pgp, or MRP1 in a mammal afflicted with cancer, and a method of increasing the bioavailability of an ABCG2 substrate drug in a mammal. The methods comprise administering effective amounts of certain compounds to the mammal, for example, a compound of the formula (I): wherein R1, R2, R3, X1, X2, X3, a, and b are as described herein. Uses of these compounds in the preparation of a medicament are also disclosed. Also disclosed are compounds of formula (II), pharmaceutical compositions comprising such compounds and uses thereof.

Abstract: Disclosed are methods of enhancing the chemotherapeutic treatment of tumor cells, reducing resistance of a cancer cell to a chemotherapeutic agent, a method of inhibiting ABCG2, Pgp, or MRP1 in a mammal afflicted with cancer, and a method of increasing the bioavailability of an ABCG2 substrate drug in a mammal. The methods comprise administering effective amounts of certain compounds to the mammal, for example, a compound of the formula (I): Formula (I), wherein R1, R2, R3, X1, X2, X3, a, and b are as described herein. Uses of these compounds in the preparation of a medicament are also disclosed. Also disclosed are compounds of formula (II), pharmaceutical compositions comprising such compounds and uses thereof.

Abstract: Disclosed are methods of enhancing the chemotherapeutic treatment of tumor cells, reducing resistance of a cancer cell to a chemotherapeutic agent, a method of inhibiting ABCG2, Pgp, or MRP1 in a mammal afflicted with cancer, and a method of increasing the bioavailability of an ABCG2 substrate drug in a mammal. The methods comprise administering effective amounts of certain compounds to the mammal, for example, a compound of the formula (I): Formula (I), wherein R1, R2, R3, X1, X2, X3, a, and b are as described herein. Uses of these compounds in the preparation of a medicament are also disclosed. Also disclosed are compounds of formula (II), pharmaceutical compositions comprising such compounds and uses thereof.