Pharmaceutical compositions containing organic compounds or salts thereof that serve as modulators for the SDF-1 or I-TAC chemokines are disclosed. The compounds and compositions are useful in the treatment of cancer, especially in the inhibition of cancer proliferation, growth, and metastasis. Methods of interfering with SDF-1 and/or I-TAC binding to the CCXCKR2 receptor and treating cancer using the compounds and pharmaceutical compositions of the present invention are also disclosed.