Although the chemokine system has led to only one approved treatment so far (i.e., CCR4 in relapsed/refractory ATLL), it carries a strong therapeutic potential for other oncovirus-associated cancers, as outlined above, but also important pitfalls related to the complex and still incompletely understood biology of the chemokine system and its role in oncogenesis. Here, CCR4 is linked to adult T-cell leukemia/lymphoma.