⁶⁴Cu-daratumumab uptake as a result of increasing doses of unlabeled daratumumab. (A) PET/CT scan of 1 representative patient from each cohort treated with ⁶⁴Cu-daratumumab and increasing concentrations of preinfused unlabeled antibody (0, 10, 45, and 95 mg) showing higher liver and spleen uptake in patients who did not receive any unlabeled daratumumab (0 mg) compared with the 10-, 45-, and 95-mg cohort of patients. Increased BM uptake was instead observed in the 10- and 45-mg cohort compared with both the 0- and the 95-mg cohorts. Coronal and axial images through these PET scans are also shown for visualizing relative organ uptake between the cohorts. Color bar is shared between all coronal and axial images. (B) Bar graphs showing the SUV_mean values for each cohort in the organs of interest. The BM uptake of the plasmacytoma patient in the 45-mg cohort was not included in the graph. Two-way analysis of variance Tukey multiple comparison test was used to calculate the significance in liver and spleen uptake among treatment cohorts. (C) Dot plots showing radiotracer concentration in the whole blood of the different cohorts at early (1 to 3 hours) and late time points (25 to 27 hours). One-way analysis of variance Tukey multicomparison test was conducted. MIP, maximum intensity projection.