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Updated: Feb 13, 2026

Development of a 68Gallium-Labeled D-Peptide PET Tracer for Imaging Programmed Death-Ligand 1 Expression
Published on: February 3, 2023
Reduced Tumour Proportion Scores for Programmed Cell Death Ligand 1 in Stored Paraffin Tissue Sections
Yuki Sato1, Daichi Fujimoto2, Keiichiro Uehara3
1Department of Respiratory Medicine, Kobe City Medical Center General Hospital, Kobe, Japan yuki1130sato@gmail.com.
Background/Aim:
We evaluated the effects of storage of formalin-fixed, paraffin-embedded (FFPE) sections on the tumour proportion score (TPS) for programmed cell death ligand 1 (PD-L1), as indicator in non-small cell lung cancer (NSCLC) tissues of treatment efficacy.
Materials And Methods:
NSCLC postoperative specimens with PD-L1 TPS ≥50% were obtained and cut into five serial sections. One section was stained immediately, and four were stored at 4°C for 2, 4, 6, or 8 weeks. Slides were subjected to PD-L1 immunohistochemistry using the anti-PD-L1 clone 28-8. PD-L1 TPS were blindly evaluated by two independent pathologists.
Results:
Twelve specimens (60 slides) were evaluated. After slide storage for 2, 4, 6, and 8 weeks, a TPS of <50% was obtained in five (41%), four (33%), seven (58%), and eight (67%) patients, respectively.
Conclusion:
TPS values for PD-L1 were reduced by long-term slide storage of FFPE specimens. Sectioned slides should be stained for PD-L1 without delay.
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