Semi-quantitative measurements of chemokine receptor 4-targeted Ga-pentixafor PET/CT in response assessment of Waldenström macroglobulinemia/lymphoplasmacytic lymphoma.

Purpose: Ga-pentixafor PET/CT was reported to have a high sensitivity in detecting tumor involvement of Waldenström macroglobulinemia/lymphoplasmacytic lymphoma (WM/LPL) in our previous study. We aimed to further investigate the semi-quantitative measurements of Ga-pentixafor PET/CT in response assessment in WM/LPL.

Methods: Fifteen patients with WM/LPL were recruited in a prospective cohort study and underwent both Ga-pentixafor and F-FDG PET/CT at baseline and post-treatment. PET/CT-based responses were analyzed with semi-quantitative assessments of metabolic tumor volume (MTV) and total lesions glycolysis/uptake (TLG and TLU), and the correlation between PET/CT-based response and clinical response, monoclonal protein and IgM response was analyzed.

Results: After chemotherapy, 5 patients had complete response or very good partial response, 8 had partial response or minimal response and 2 had progressive disease. In quantitative analysis, Ga-pentixafor PET/CT-based response (measured in ∆TLU%, ∆MTV%, ∆SUVpeak%) showed a significant direct correlation with clinical response, monoclonal protein and IgM response (p < 0.01). However, F-FDG PET/CT-based response was independent from clinical response (p > 0.05).

Conclusions: The semi-quantitative measurements of Ga-pentixafor PET/CT outperformed F-FDG PET/CT in response assessment of WM/LPL.