Pulsed-focused ultrasound enhances boron drug accumulation in a human head and neck cancer xenograft-bearing mouse model

Purpose: This study aims to demonstrate that pulsed high-intensity focused ultrasound (pulsed-HIFU) may enhance the fructose-conjugated 4-borono-L-phenylalanine (BPA-Fr) accumulation in tumor lesion using ¹⁸F-FBPA-Fr microPET scans. Procedures: To the mice bearing orthotopic SASC03 human tongue squamous carcinoma xenograft, a 2-min pulsed-HIFU was applied to tumor. Immediately after pulsed-HIFU treatment, ¹⁸F-FBPA-Fr was intravenously injected, and biological characterizations including microPET imaging and biodistribution were conducted. Results: Both biodistribution studies and microPET imaging performed after intravenous injection of ¹⁸F-FBPA-Fr revealed higher tumor uptake in HIFU-treated mice than that of the control. CD31 and Ki-67 histochemical staining of tumor sections and H&E staining of nearby normal tissues revealed no significant difference between the pulsed-HIFU-treated mice and the control. Conclusion: This study demonstrated that pulsed-HIFU was beneficial to the accumulation of boron drug in the head and neck tumor lesion and may enhance the therapeutic efficacy of clinical BNCT.