Baseline and on Treatment Biodistribution Variability of 18F-FLT Uptake in Patients With Advanced Melanoma: Brief Communication

Bernies van der Hiel; Else A Aalbersberg; Alfons J M van den Eertwegh; Jitha Fischer; Ronald Boellaard; Filip Y F L de Vos; Marye J Boers-Sonderen; Marcel P M Stokkel; Linda J de Wit-van der Veen; John B A G Haanen

doi:10.1097/RLU.0000000000005281

Baseline and on Treatment Biodistribution Variability of 18F-FLT Uptake in Patients With Advanced Melanoma: Brief Communication

Clin Nucl Med. 2024 May 15. doi: 10.1097/RLU.0000000000005281. Online ahead of print.

Affiliations

¹ From the Department of Nuclear Medicine, Netherlands Cancer Institute-Antoni van Leeuwenhoek, Amsterdam, the Netherlands.
² Departments of Medical Oncology, and.
³ Nuclear Medicine, Amsterdam UMC Location Vrije Universiteit Amsterdam, Amsterdam, the Netherlands.
⁴ Department of Medical Oncology, University Medical Center Utrecht, Utrecht, the Netherlands.
⁵ Department of Medical Oncology, Radboud University Medical Center, Nijmegen, the Netherlands.
⁶ Department of Medical Oncology, Netherlands Cancer Institute-Antoni van Leeuwenhoek, Amsterdam, The Netherlands.

PMID: 38768063
DOI: 10.1097/RLU.0000000000005281

Abstract

Purpose: This prospective study evaluates the biodistribution of 18F-FLT PET in patients with advanced melanoma before and after treatment with BRAF/MEK inhibitors.

Patients and methods: Eighteen BRAF-positive unresectable stage IIIc or IV melanoma patients referred for 18F-FLT PET/CT before (BL) and during (D14) BRAF/MEK inhibition were included. 18F-FLT accumulation in the liver, bone marrow, blood, and muscle was quantified.

Results: Baseline interpatient 18F-FLT uptake had a coefficient-of-variation between 17.5% and 21.5%. During treatment, liver uptake increased (SUVmeanBL = 4.86 ± 0.98, SUVmeanD14 = 6.31 ± 1.36, P < 0.001) and bone marrow uptake decreased (SUVmeanBL = 7.67 ± 1.65, SUVmeanD14 = 6.78 ± 1.19, P < 0.025). Both changes were unrelated to baseline metabolic tumor volume or tumor response.

Conclusions: To assess 18F-FLT PET, both liver and bone marrow uptake may be used as normal tissue references at baseline, but 18F-FLT biodistribution significantly changes in longitudinal response studies when treated with BRAF/MEK inhibitors.