Presentation A novel PET radiotracer for visualizing in vivo action of immune checkpoint blocker anti-CTLA4 mAb

Jiang, Cuiping  ,  Xie, Lin  ,  Hanyu, Masayuki  ,  Zhang, Yiding  ,  Azuma, Rikako  ,  Suzuki, Hisashi  ,  Shimokawa, Takashi  ,  Wakizaka, Hidekatsu  ,  Zang, Shiming  ,  Wang, Feng  ,  Ming-Rong, Zhang

Purpose: Immune checkpoint blocker CTLA4 mAb has revolutionized cancer therapy. However, this therapy development is challenged by incomplete understanding of its action. Here, we sought to label CTLA4 with 64Cu, and to evaluate the in vivo potential of [64Cu]CTLA4 ([64Cu]1) as a novel PET tracer.Method: [64Cu]1 was synthesized by labeling DOTA-CTLA4 with 64Cu. PET scans and biodistribution were performed at 24 h, 48 h after [64Cu]1 injection for immunocompetent C57BL/6 mice bearing B16F10 melanomas.Result: PET showed high uptake of radioactivity in the spleen and gut-associated lymphoid tissue at 24 h (3.44 % ID/g, 2.61 % ID/g), 48 h (3.47 % ID/g, 2.49 %ID/g) after [64Cu]1 injection. B16F10 tumors also showed high uptake at 24 h (4.25 % ID/g) and retention at 48 h (3.74 % ID/g) after administration. Biodistribution data supported the PET imaging. Conclusion: PET with [64Cu]1 permitted to noninvasively track and quantify in vivo action of anti-CTLA-4 mAb, which would be helpful for facilitating the development of anti-CTLA4 mAb immunotherapy.
The12th asia Oceania Congress of Nuclear Medicine and Biology

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