Diffuse B-large cell lymphoma (DVCL) belongs to the group of orphan diseases, is one of the variants of aggressive non-Hodgkin lymphomas of adults. In the Russian Federation, DVCL accounts for approximately 30-40 % of all malignant lymphomas, in 2020, approximately 10112 newly diagnosed malignant lymphomas were registered in Russia, of which about 3000 new cases of DVCL. Over the past two decades, the most common treatment regimen for DVCL, regardless of the morphological variant, immunohistochemical profile and clinical subtype of the tumor, remains the immunochemotherapy regimen with the use of rituximab and its various modifications. Attempts to improve the regime in a wide population of DVKL for 20 years have not shown positive results. This article describes a rare clinical case of DVCL with the use of polatuzumab vedotin, the first in its class conjugate of a monoclonal antibody to CD79b and a cytotoxic agent.