Background. Urothelial cancer ranks 7th and 17th of all the malignant tumors in males and females, respectively. Development of new immunotherapeutic drugs provides new possibilities in treatment of such patients, especially the patient population in whom platinum‑based therapy is contraindicated. Administration of immunooncology drugs requires determination of PD-L1, for which various diagnostic systems are used. The question regarding correlation of results of determination of PD-L1

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... remains of concern.Materials and Methods. The study was performed on 100 samples of surgical and biopsy samples of urothelial cancer. Two clones of 22C3 and SP142 with corresponding detection systems were used for the study. PD-L1 expression was assessed in tumor and immune cells.Results. The study demonstrated a high correlation of negative PD-L1 tumor status determined using both diagnostic agents (92 % and 97 %) and low correlation of results of positive PD-L1 status (67 % and 43 %).Conclusions. Thus, if a negative result of PD-L1 status of urothelial cancer is obtained using any of the diagnostic agents studied, repeated test with the other antibody is not required. If positive status is obtained in one test, the patient may have a negative status in the other test, which allows recommending a repeated testing in borderline cases using a test, recommended for the medicinal product untended for treatment.