or a pharmaceutically acceptable salt thereof, wherein R is hydrogen or an acyl group； and (b) a BCL-2 inhibitor； wherein the compound of Formula I or pharmaceutically acceptable salt thereof and a BCL-2 inhibitor are administered in amounts which in combination are therapeutically effective. The invention further provides a pharmaceutical composition comprising a compound of Formula I or a pharmaceutically acceptable salt thereof, a BCL-2 inhibitor and a pharmaceutically acceptable carrier or excipient.
