@article {Ribas340, author = {Antoni Ribas and Matthias R. Benz and Martin S. Allen-Auerbach and Caius Radu and Bartosz Chmielowski and Elizabeth Seja and John L. Williams and Jesus Gomez-Navarro and Timothy McCarthy and Johannes Czernin}, title = {Imaging of CTLA4 Blockade{\textendash}Induced Cell Replication with 18F-FLT PET in Patients with Advanced Melanoma Treated with Tremelimumab}, volume = {51}, number = {3}, pages = {340--346}, year = {2010}, doi = {10.2967/jnumed.109.070946}, publisher = {Society of Nuclear Medicine}, abstract = {Preclinical models predict that blockade of the coinhibitory molecule cytotoxic T lymphocyte{\textendash}associated antigen 4 (CTLA4) on lymphocytes results in the release of a cell cycle inhibitory checkpoint, allowing lymphocyte proliferation, tumor targeting, and regression. However, there is a paucity of data demonstrating that lymphocyte proliferation does occur in humans treated with CTLA4-blocking antibodies. Methods: We tested the role of whole-body molecular imaging in patients with advanced melanoma receiving the CTLA4-blocking antibody tremelimumab, allowing the analysis of changes in glucose metabolism using the PET probe 18F-FDG and cell replication with the PET probe 3'-deoxy-3'-18F-fluorothymidine (18F-FLT). Results: PET/CT scans obtained at a median of 2 mo after initial dosing did not demonstrate significant changes in lesion size or 18F-FDG or 18F-FLT uptake when focusing on metastatic lesions. Similarly, there was no difference in 18F-FDG uptake in the non{\textendash}melanoma-involved spleen. However, there were significant increases in standardized uptake values for 18F-FLT in the spleen using post- and pretremelimumab treatment scans. Conclusion: Molecular imaging with the PET probe 18F-FLT allows mapping and noninvasive imaging of cell proliferation in secondary lymphoid organs after CTLA4 blockade in patients with metastatic melanoma.}, issn = {0161-5505}, URL = {https://jnm.snmjournals.org/content/51/3/340}, eprint = {https://jnm.snmjournals.org/content/51/3/340.full.pdf}, journal = {Journal of Nuclear Medicine} }