성균관의대 / 정경호, 이경한*
Abstract
We developed an 89Zr-labeled anti-programmed death ligand 1 (anti-PD-L1) immune PET that can monitor chemotherapy-mediated modulation of tumor PD-L1 expression in living subjects. Methods: Anti-PD-L1 underwent sulfohydryl moiety-specific conjugation with maleimide-deferoxamine followed by 89Zr radiolabeling. CT26 colon cancer cells and PD-L1-overexpressing CT26/PD-L1 cells underwent binding assays, flow cytometry, and Western blotting. In vivo pharmacokinetics, biodistribution, and PET imaging were evaluated in mice. Results: 89Zr-anti-PD-L1 synthesis was straightforward and efficient. Sodium dodecyl sulfate polyacrylamide gel electrophoresis showed that reduction produced half-antibody fragments, and matrix-assisted laser desorption ionization time-of-flight analysis estimated 2.18 conjugations per antibody, indicating specific conjugation at the hinge-region disulfide bonds. CT26/PD-L1 cells showed 102.2 ± 6.7-fold greater 89Zr-anti-PD-L1 binding than that of weakly expressing CT26 cells. Excellent target specificity was confirmed by a drastic reduction in binding by excess cold antibody. Intravenous 89Zr-anti-PD-L1 followed biexponential blood clearance. PET/CT image analysis demonstrated decreases in major organ activity over 7 d, whereas high CT26/PD-L1 tumor activity was maintained. Again, this was suppressed by excess cold antibody. Treatment of CT26 cells with gemcitabine for 24 h augmented PD-L1 protein to 592.4% ± 114.2% of the control level and increased 89Zr-anti-PD-L1 binding, accompanied by increased AKT (protein kinase B) activation and reduced phosphatase and tensin homolog (PTEN). In CT26 tumor-bearing mice, gemcitabine treatment substantially increased tumor uptake from 1.56% ± 0.48% to 6.24% ± 0.37% injected dose per gram (tumor-to-blood ratio, 34.7). Immunoblots revealed significant increases in tumor PD-L1 and activated AKT and a decrease in PTEN. Conclusion: 89Zr-anti-PD-L1 showed specific targeting with favorable imaging properties. Gemcitabine treatment upregulated cancer cell and tumor PD-L1 expression and increased 89Zr-anti-PD-L1 uptake. 89Zr-anti-PD-L1 PET may thus be useful for monitoring chemotherapy-mediated tumor PD-L1 modulation in living subjects.
Affiliations
Kyung-Ho Jung 1 2 , Jin Won Park 3 , Jin Hee Lee 1 2 , Seung Hwan Moon 1 , Young Seok Cho 1 , Kyung-Han Lee 4 2
1 Department of Nuclear Medicine, Samsung Medical Center, Seoul, Korea.
2 Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University School of Medicine, Seoul, Korea; and.
3 Scripps Korea Antibody Institute, Chuncheon-si, Gangwon-do, Korea.
4 Department of Nuclear Medicine, Samsung Medical Center, Seoul, Korea khleenm@naver.com.
편집위원
방사성핵종 표지 Anti-PD-L1 항체 영상을 이용하여 종양의 PD-L1 발현을 비침습적으로 평가할 수 있는 것을 보여준 연구결과임. 면역치료에 관심이 있는 연구자 및 종양 핵의학 임상가에게 관심을 끌 연구로 생각됨.
2021-06-30 16:09:18