Optimization of programmed death Ligand-1 73-10 clone immunohistochemical protocol on urothelial carcinomas
Abstract
Background
In urothelial carcinomas, Programmed Death Ligand-1 (PD-L1) expression assessed by immunohistochemistry is essential in order to predict the response of patients to immunotherapy.
Objective
The aims of our study were (1) to optimize the automated immunohistochemistry staining technique for the PD-L1 antibody 73-10 clone (Leica Biosystems), using a control tissue, on the Leica BOND-MAX immunostaining platform at the Center for Advanced Medical and Pharmaceutical Research – Laboratory of Normal and Pathological Morphology (MORPHO) and (2) to validate the technique by applying it on a series of 40 urothelial carcinomas.
Methods
The cases included in our study corresponded to muscle-invasive urothelial carcinomas diagnosed on radical cystectomy specimens. The cases were retrieved from the Pathology Department of Targu-Mures Emergency County Hospital database (between 2011-2018). The immunohistochemical staining was optimized according to the producer’s recommendation and adapted to our laboratory. Palatine tonsil specimen served as positive control tissue. PD-L1 positivity was assessed in all urothelial carcinoma cases either by evaluating the tumor and immune cells, or by applying the Combined Positive Score.
Results
Our technique enabled us to obtain a well-optimized, high quality immunohistochemical PD-L1 staining on the control tissue, which was further successfully applied on the urothelial carcinoma cases. By assessing the PD-L1-positive tumor cells and/or immune cells percentages, 15 cases were considered PD-L1 positive. Using the Combined Positive Score, 16 cases were evaluated as positive.
Conclusion
Through the optimization process we achieved an excellent staining reaction for the PD-L1 73-10 antibody, that can be used successfully when assessing urothelial carcinoma cases.
© 2026 Lorena Solovăstru, Ioan Alin Nechifor-Boilă, Angela Borda, Andrada Loghin, Adela Nechifor-Boilă, published by University of Medicine, Pharmacy, Science and Technology of Targu Mures
This work is licensed under the Creative Commons Attribution 4.0 License.