Chemokine receptor-4 targeted PET/CT with 68Ga-Pentixafor in assessment of newly diagnosed multiple myeloma: comparison to 18F-FDG PET/CT.

PURPOSE: 18F-FDG PET/CT has some limitations in the evaluation of multiple myeloma (MM). Since chemokine receptor-4 is overexpressed in MM, we perform a prospective cohort study to compare the performance of 68Ga-Pentixafor and 18F-FDG PET/CT in newly diagnosed MM. METHODS: Thirty patients with newly diagnosed MM were recruited. All patients underwent 68Ga-Pentixafor and18F-FDG PET/CT within 1 week after enrollment. A positive PET/CT was defined as the presence of focal PET-positive lesions in bone marrow or diffuse bone marrow patterns (uptake > liver). Bone marrow uptake values in 68Ga-Pentixafor and18F-FDG PET/CT (total bone marrow glycolysis [TBmGFDG], total bone marrow uptake with 68Ga-Pentixafor [TBmUCXCR4], total bone marrow volume [TBmV], SUVmean, and SUVmax) were obtained by drawing total bone marrow volume of interest on PET/CT. The positive rates of the PET/CT scans were statistically compared, and the correlation between quantitative bone marrow uptake values and clinical characteristics, laboratory findings, and staging was analyzed. RESULTS: 68Ga-Pentixafor PET/CT had a higher positive rate than 18F-FDG PET/CT in recruited patients (93.3 vs. 53.3%, p = 0.0005). In quantitative analysis, bone marrow uptake values in 68Ga-Pentixafor (TBmUCXCR4, SUVmax, and SUVmean) were positively correlated with end organ damage, staging, and laboratory biomarkers related to tumor burden including serum ß2-microglobulin, serum free light chain, and 24-h urine light chain (p < 0.05). In 18F-FDG PET/CT, only the SUVmean of total bone marrow was positively correlated with serum free light chain and 24-h urine light chain (p < 0.05). CONCLUSIONS: 68Ga-Pentixafor PET/CT is promising in assessment of newly diagnosed MM. TRIAL REGISTRATION NUMBER: NCT03436342.