Imipridones has been found to selectively modulate Class A G protein-coupled receptors (GPCRs), such as the D2-like subfamily of dopamine receptors, and to be useful for the treatment of conditions and disorders in need of such modulation, such as cancers, psychiatric disorders, and bacterial infections. In addition, methods of identifying whether a subject having these condition, is likely to be responsive to a treatment regimen, such as administration of an imipridone, are provided. Furthermore, methods of assessing the effectiveness of a treatment regimen, such as administration of an imipridone, monitoring, or providing a prognosis for a subject with these condition are also provided.