Chemokine receptor 1 (CCR1) is a receptor on the surface of various immune cells (e.g. monocytes and T-cells) that bind multiple chemokines and directly mediates inflammatory responses through leukocyte chemotaxis and cytokine balance. Small molecule antagonists of CCR1 may have therapeutic potential for the treatment of multiple immunological disorders which have the potential to be managed by regulation of inflammatory chemokines, such as rheumatoid arthritis and the treatment of bone lesions associated with multiple myeloma. Ligand has identified potent, orally-bioavailable, small-molecule CCR1 antagonists with an excellent profile for clinical candidate selection and are structurally distinct from other known CCR1 antagonists.