Used primarily in research settings as a potent and selective antagonist of the CXCR4 chemokine receptor. This compound is valuable in studies related to cancer biology, particularly in investigating mechanisms of tumor metastasis, as CXCR4 signaling plays a key role in cancer cell migration and homing to distant organs. It is also employed in hematopoiesis research due to CXCR4's involvement in stem cell mobilization and retention in bone marrow. Additionally, CCG-203971 has been explored in inflammatory disease models and viral infection studies, including HIV, where CXCR4 acts as a co-receptor for viral entry. Its high selectivity makes it a useful tool for dissecting CXCR4-mediated pathways without significant off-target effects.