Correlation between L-amino acid transporter 1 expression and 4-borono-2-¹⁸F-fluoro-phenylalanine accumulation in humans

Background: The correlation between L-type amino acid transporter 1 (LAT1) expression and 4-borono-2-F-18-fluoro-phenylalanine (F-18-FBPA) accumulation in humans remains unclear. This study aimed to investigate the correlation between LAT1 expression in tumor tissues and F-18-FBPA accumulation in patients with head and neck cancer who participated in a clinical trial of F-18-FBPA positron emission tomography (PET).Methods: Altogether, 28 patients with head and neck cancer who participated in a clinical trial of F-18-FBPA PET at our institution between March 2012 and January 2018 were included. Correlations between standardized uptake values (SUVs); the maximum SUV (SUVmax), the mean SUV within a 1 cm(3) sphere centered at a single point, that is, the SUVmax (SUVpeak), the minimum SUV (SUVmin), and the intensity of LAT1 expression (maximum and minimum LAT1 expressions) were investigated.Results: Weak correlations were identified between SUVmax and LAT1 maximum score, SUVmin and LAT1 maximum score, and SUVmin and LAT1 minimum score (rho = 0.427, 0.362, and 0.330, respectively). SUVmax and LAT1 minimum score, SUVpeak and LAT1 maximum score, and SUVpeak and LAT1 minimum score demonstrated moderate correlations (rho = 0.535, 0.556, and 0.661, respectively). Boron neutron capture therapy (BNCT) was performed in 2 of the 4 patients with discrepancies between F-18-FBPA accumulation and intensity of LAT1 expression, and the intensity of LAT1 expression was a better predictor of treatment response.Conclusion: F-18-FBPA accumulation and the intensity of LAT1 expression demonstrated a moderate correlation; however, LAT1 expression may be a better predictor of treatment response of BNCT in patients with discrepancies.