Cerenkov luminescence imaging is an effective preclinical tool for assessing colorectal cancer PD-L1 levels in vivo

Abstract

Background: Preclinical and clinical studies have demonstrated that immunotherapy has effectively delayed tumor progression, and the clinical outcomes of anti-PD-1/PD-L1 therapy were related to PD-L1 expression level in the tumors. A 131 I-labeled anti-PD-L1 monoclonal antibody tracer, 131 I-PD-L1-Mab, was developed to study the target ability of noninvasive Cerenkov luminescence imaging in colorectal cancer xenograft mice. Method: Anti-PD-L1 monoclonal antibody labeled with 131 I (131 I-PD-L1-Mab), and in vitro binding assays were used to evaluate the affinity of 131 I-PD-L1-Mab to PD-L1 and their binding level to different colorectal cancer cells, and compared with flow cytometry, Western blot analysis, and immunofluorescence staining. The clinical application value of 131 I-PD-L1-Mab was evaluated through biodistribution and Cerenkov luminescence imaging, and different tumor-bearing models expressing PD-L1 were evaluated. Results: 131 I-PD-L1-Mab showed high affinity to PD-L1, and the equilibrium dissociation constant was 1.069 × 10-9 M. The competitive inhibition assay further confirmed the specific binding ability of 131 I-PD-L1-Mab. In four different tumor-bearing models with different PD-L1 expression, the biodistribution and Cerenkov luminescence imaging showed that the RKO tumors demonstrated the highest uptake of the tracer 131 I-PD-L1-Mab, with a maximum uptake of 1.613 ± 0.738% IA/g at 48 h. Conclusions: There is a great potential for 131 I-PD-L1-Mab noninvasive Cerenkov luminescence imaging to assess the status of tumor PD-L1 expression and select patients for anti-PD-L1 targeted therapy.

Electrostimulus-associated PD-L1 expression on cell membrane revealed by immune SERS nanoprobes

“…19 Researchers from the same team also used Cerenkov luminescence imaging to evaluate PD-L1 levels in different tumour cells. 20 Our results exhibit a consistent trend of PD-L1 expression with these publications.…”

“…Firstly, the MCF-7 cells (human breast cancer cells) were cultured on indium tin oxide (ITO) glass slides for 12 h. Then, the cells were washed thrice using cold PBS. Subsequently, the cells were incubated with the immune SERS tag (5.0 pM) for different periods (10,20,30, and 40 min), while the control experiments were carried out by incubating the cells with Ag NPs (5.0 pM) and 4-MBA-Ag NP (5.0 pM), respectively. After that, the cells were cleaned three times with cold PBS, and they were observed using an inverted Leica DMI6000B microscope equipped with a dark-field condenser (Leica 0.90 S1).…”

Development of Radiotracers for Imaging of the PD-1/PD-L1 Axis

“…Licor 800 NIRF 0.43 nM 2 (human) 0.13 nM 1 (mouse) [34,35] 111 In SPECT 64 Cu PET [36] 89 Zr [37][38][39] 99m Tc SPECT 111.8 ± 17.85 nM [40] mAb NOTA-MX001 64 Cu PET 5.40 ± 2.30 nM [41] mAb [ 89 Zr]Zr-DFO-anti-PD-L1 mAb 89 Zr PET n.a. [42] mAb Df-KN035 89 Zr PET 2.86 ± 0.23 nM [43,44] mAb PD-L1-Mab 131 I Cherenkov Luminescence 1.069 nM [45] mAb PD-L1 mAb 131 I Optical n.a. [46] mAb NIR-PD-L1-mAb Licor 800 NIRF n.a.…”

“…Zhao et al published an antibody-based radiotracer for the detection of PD-L1 via Cerenkov luminescence imaging (CLI) [45]. This imaging method is inferior in terms of spatial resolution, biological penetration, and signal specificity compared to the PET and SPECT imaging methods but offers a cheaper and simpler operation, allowing for a higher throughput, which can be beneficial for preclinical studies.…”

Development of an Immuno-SPECT/Fluorescent Bimodal Tracer Targeting Human or Murine PD-L1 on Preclinical Models

“…30,31 At present, the development of bimodal organic probes enabling dual imaging in a single injection for PD-L1 imaging remains relatively limited. 32,33 In light of these considerations, we set out to create a bimodal imaging agent combining fluorescence and SPECT imaging. The aim of this approach is to provide a deeper understanding of biological mechanisms involving PD-1/PD-L1.…”