Erythropoietin beyond red blood cells: Systemic and oncological functions (Review)

Erythropoietin (Epo) is widely recognized as the primary regulator of haematopoiesis, managing red blood cell production via erythropoietin receptor (EPOR) expressed on erythroid progenitors. Beyond erythropoiesis, Epo functions as a pleiotropic cytokine, exhibiting marked tissue‑protective effects across various non‑haematopoietic systems, including neuroprotection, cardioprotection, anti‑inflammatory effects and promotion of angiogenesis. Clinically, recombinant Epo is widely used to alleviate cancer‑related anaemia and improve haemoglobin levels. However, the presence of EPOR in malignant tissues may directly influence tumour progression or angiogenesis. The aim of the present review is to summarize current knowledge on Epo signalling across multiple organ systems, to discuss the possible applications of Epo derivatives, and to refer to emerging evidence suggesting that Epo may affect tumour biology and modulate the efficacy of chemotherapy. The review provides a comprehensive overview of current and emerging therapeutic concepts involving Epo derivatives, while emphasizing that most non‑haematopoietic applications remain under preclinical or early clinical investigation.