CCR5 and neoplasm: However, the EPR effect may vary amongpatients with different stages.60 Our resultsshowed that, compared with liposomes, hybrid exosomes had an activetargeting effect toward melanoma cells and led to higher drug accumulationlevels within tumor tissues, which might be attributed to their surfacefunctional markers, including PD-1 and CCR5, interacting with melanomacells.