Homing of cytokine-induced killer cells during the treatment of acute promyelocytic leukemia

Cytokine-induced killer (CIK) cells have been shown to be an effective immunotherapy for malignancies. However, their clinical application has been limited due to lack of knowledge on their in vivo kinesis. In this study, we explored their biodistribution by labeling CIK cells with 18 F-FDG and tracking their in vivo migration by PET/CT imaging. In the nine refractory APL patients enrolled in this study, pre-treatment PET/CT scans revealed leukemia burdens in vertebrae, and the bones of the pelvis and limbs. Post-treatment serial PET/CT tracked the localization of CIK cells over time: at 1 h, the majority of these cells accumulated diffusely in the lungs, while the first minor cell activities were observed in brain, liver and spleen; at 4 and 8 h, they not only migrated to the heart, spleen, and liver, but also showed tendencies to accumulate in bone marrow and brain. This specific cell migration route suggested that CIK cells show in vivo functional kinesis and potency as a targeted immunotherapy. The clinical outcome of this small cohort of nine patients supported the efficacy of this regimen: two patients achieved rapid complete remission after three-cycle treatment, and six patients remained stable, subsequently became sensitive to conventional therapy, and also achieved complete remission.