CXCR7 antagonist-1 hydrochloride is a CXCR7 antagonist that inhibits the binding of the SDF-1 chemokine (also known as the CXCL12 chemokine) or I-TAC (also known as CXCL11) to the chemokine receptor CXCR7. CXCR7 antagonist-1 hydrochloride is useful in preventing tumor cell proliferation, tumor formation, inflammatory diseases, and many other diseases (extracted from patent WO2014085490A1, compound 1.128).