The low number of intratumoral macrophages observed in our study after 10 mg/kg of [89Zr]Zr-DFO-N-suc-CSF1R-mAb administration can explain the lack of specific tumor uptake of [89Zr]Zr-DFO-N-suc-CSF1R-mAb. Here, CSF1R is linked to neoplasm.