Immuno-PET/CT Imaging of Trop2 with [18F]AlF-RESCA-T4 Differentiates Lung Cancer from Inflammation

Wei Huang; Min Cao; Yanfei Wu; You Zhang; Shuxian An; Xinbing Pan; Xinyuan Zhou; Hongda Shao; Yihui Guan; Gang Huang; Fabrizia Gelardi; Arturo Chiti; Fang Xie; Jianjun Liu; Weijun Wei

doi:10.2967/jnumed.124.268751

Immuno-PET/CT Imaging of Trop2 with [¹⁸F]AlF-RESCA-T4 Differentiates Lung Cancer from Inflammation

J Nucl Med. 2024 Nov 14:jnumed.124.268751. doi: 10.2967/jnumed.124.268751. Online ahead of print.

Authors

Wei Huang¹, Min Cao², Yanfei Wu³, You Zhang¹, Shuxian An¹, Xinbing Pan¹, Xinyuan Zhou¹, Hongda Shao¹, Yihui Guan³, Gang Huang¹, Fabrizia Gelardi^{4

5}, Arturo Chiti^{4

5}, Fang Xie³, Jianjun Liu⁶, Weijun Wei⁶

Affiliations

¹ Department of Nuclear Medicine, Institute of Clinical Nuclear Medicine, School of Medicine, Renji Hospital, Shanghai Jiao Tong University, Shanghai, China.
² Department of Thoracic Surgery, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
³ Department of Nuclear Medicine and PET Center, Huashan Hospital, Fudan University, Shanghai, China.
⁴ Università Vita-Salute San Raffaele, Milan, Italy; and.
⁵ Nuclear Medicine Department, IRCCS San Raffaele, Milano, Italy.
⁶ Department of Nuclear Medicine, Institute of Clinical Nuclear Medicine, School of Medicine, Renji Hospital, Shanghai Jiao Tong University, Shanghai, China; wwei@shsmu.edu.cn ljjsh@sjtu.edu.cn.

PMID: 39542697
DOI: 10.2967/jnumed.124.268751

Abstract

Immuno-PET/CT imaging, a branch of molecular imaging, can noninvasively and specifically visualize biomarker expression across the body. Trophoblast cell surface antigen 2 (Trop2) is a pan-cancer biomarker and plays a crucial role in tumorigenesis through multiple signaling pathways. The study aims to develop and translate novel Trop2 single-domain antibody (sdAb) tracers for clinical use. Methods: Two sdAbs (i.e., His-tagged T4 and His-tag-free RT4) are recombinantly expressed in Chinese hamster ovary cells. The purities and binding kinetics are determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis, high-performance liquid chromatography, and surface plasmon resonance assays. The AlF restrained complexing agent (RESCA) method is applied to develop ¹⁸F-labeled sdAb tracers ([¹⁸F]AlF-RESCA-T4 and [¹⁸F]AlF-RESCA-RT4), followed by thorough preclinical imaging and blocking studies on tumor-bearing mice and a pilot clinical trial evaluating the clinical imaging safety and feasibility of [¹⁸F]AlF-RESCA-T4 immuno-PET/CT. Results: [¹⁸F]AlF-RESCA-T4 and [¹⁸F]AlF-RESCA-RT4 possess high radiochemical purities. Preclinical imaging in the T3M-4 tumor model revealed prominent uptake (percentage injected dose/g) of [¹⁸F]AlF-RESCA-T4 (11.13 ± 1.53, n = 4) and [¹⁸F]AlF-RESCA-RT4 (8.83 ± 1.22, n = 4), which were significantly reduced by coinjection of unlabeled T4 and RT4 in blocking studies. The His-tag removal strategy further optimized the probe's in vivo pharmacokinetics and reduced renal radioactivity accumulation without significantly decreasing tumor uptake. In a pilot clinical trial, [¹⁸F]AlF-RESCA-T4 immuno-PET/CT showed promising potency in annotating Trop2 expression and differentiating tumors from inflammatory diseases such as tuberculosis. Conclusion: [¹⁸F]AlF-RESCA-T4 and [¹⁸F]AlF-RESCA-RT4 can specifically annotate Trop2 expression. Clinical [¹⁸F]AlF-RESCA-T4 immuno-PET/CT imaging can screen patients for Trop2-targeted therapies and differentiate lung inflammation from cancer.

Keywords: Trop2; companion diagnostics; immuno-PET; single-domain antibody.