Page 168 - 89Zr-Immuno-PET:Towards a Clinical Tool to Guide Antibody-based Therapy in Cancer

Chapter 8
Figure 4 Tissue-to-blood AUC ratio of RG7356 as a function of antibody dose. Data is presented as mean, error bars represent SD.
89Zr-RG7356 PET: tumor uptake
Assessment of tumor uptake of 89Zr-RG7356 at 96 hours p.i. per tumor lesion is shown in Table 2. In all patients receiving ≥ 450 mg RG7356 (n=7) tumor uptake was observed. An example image of visible tumor uptake is shown in Figure 5. For this patient, the time activity curves for blood pool, normal tissues and tumor are provided as an example (Figure 2S in Supplementary Data). In 1 out of 6 patients receiving ≤ 200 mg RG7356, diffuse uptake of 89Zr-labeled-RG7356 was observed in the lung, indicating diffuse tumor localisation. Quantification was not feasible due to the diffuse localization. Quantification of mAb uptake in focal tumor lesions resulted in an average SUVpeak of 3.7 ± 1.7 for the 450 mg cohort and 6.5 ± 1.3 for the 675 mg cohort. Average tumor AUC was 1.5 ± 0.5 mg·h/mL in the 450 mg cohort and 3.2 ± 0.5 mg·h/mL for the 675 mg cohort. Average tumor to blood AUC ratio was 0.46 ± 0.15 in the 450 mg cohort and 0.65 ± 0.07 for the 675 mg cohort. For the 675mg cohort, the average tumor blood volume fraction was 67%.
Figure 5. Example of tumor uptake of 89Zr-RG7356 at 96 h p.i.. Tumor lesion mediastinal/in the aorta- pulmonary window (patient 8, 450 mg cohort). (a) low dose CT (b) attenuation corrected PET (c) fused image.
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