This invention relates to combination therapies for the treatment of breast cancer comprising administering to a subject in need thereof a compound of Formula I or a pharmaceutically acceptable salt thereof and an anti-estrogenic agent (e.g., an aromatase inhibitor, a SERM that is not the SERM of Formula I, a GNRH agonist, a GNRH antagonist, or an estrogen receptor downregulator) and to compositions (e.g., pharmaceutical compositions) comprising a compound of Formula I or a pharmaceutically acceptable salt thereof and an anti-estrogenic agent. This invention also relates to a method of treating the side effects (e.g., vasomotor disturbances, osteoporosis and musculoskeletal complaints) associated with anti-estrogen therapy in a subject treated with one or more anti-estrogenic agents (e.g., an aromatase inhibitor, a SERM that is not the SERM of Formula I, a GNRH agonist, a GNRH antagonist or an estrogen receptor downregulator). The method comprises administering to the subject an effective amount of a compound of formula I or a pharmaceutically acceptable salt thereof.