Abstract: The present invention provides a composition comprising a therapeutic agent and a C-X-C chemokine receptor type 4 (CXCR4) antagonist, and methods for using the same. Compositions and methods of the invention can be used to treat cancer, viral infection, immune disorders (e.g., rheumatoid arthritis), pulmonary fibrosis, or any other clinical condition associated with abnormal expression (e.g., overexpression and/or upregulation) of CXCR4. Compounds of the invention can also be used in stem cell therapeutics.

Abstract: The present invention provides a compound that can be used for targeted drug delivery, imaging a patient, or diagnosing a subject for a clinical condition which is believed to be associated with overexpression and/or upregulation of CXCR4. In particular, the present invention provides a high affinity CXCR4 selective binding ligand peptide conjugate (PC) of the Formula: P-(L-A)n (I) or a pharmaceutically acceptable salt thereof, and a method for using and producing the same. The high affinity CXCR4 selective binding ligand peptide conjugate (PC) of the invention is useful in diagnosing, treating or imaging a patient. In compound of Formula (I), n is an integer from 1 to the sum of (the total number of amino acid resides in P and the total number of side-chain functional group in the amino acid residue of P); each A is independently a diagnostic agent, a therapeutic agent, or an imaging agent; L is a linker or absent; and P is a high affinity CXCR4 selective binding peptidyl ligand.