Erythropoiesis-stimulating agents (ESAs), such as erythropoietin (EPO) and darbepoetin, may alleviate anemia in diffuse large B-cell lymphoma (DLBCL) patients. However, many cancer cells express EPO receptors (EPOR), through which exogenously administered ESAs potentially promote cancer cell growth. We conducted preclinical/phase II studies to investigate the safety and efficacy of ESAs for managing chemotherapy-related anemia in DLBCL patients. We examined EPOR expression in germinal center B-cell (GCB)- and activated B-cell (ABC)-DLBCL cell lines, and investigated the effects of ESAs on cell proliferation, and rituximab-mediated complement-dependent cytotoxicity (CDC). The clinical study enrolled 50 histologically confirmed DLBCL patients receiving rituximab/cyclophosphamide/doxorubicin/vincristine/prednisolone (R-CHOP) who had hemoglobin levels <10.0 g/dl after a maximum of three R-CHOP cycles and received ≥4 doses of fixed-dose darbepoetin (360 μg) once every 3 weeks. EPOR mRNA was detected in all GCB-DLBCL cell lines, but little/none was detected in ABC-DLBCL cell lines. GCB-DLBCL and ABC-DLBCL cell proliferation was unaffected by EPO or darbepoetin. Rituximab-mediated CDC of DLBCL cell lines with/without EPOR expression was not affected adversely by EPO. In the clinical study, baseline mean hemoglobin was 9.19 g/dl; the overall mean change in hemoglobin was 1.59 ± 1.3 g/dl (16 weeks). Forty-eight percent of enrolled patients achieved a hematopoietic response. Our study shows that ESAs do not affect the growth of DLBCL cells or rituximab-mediated CDC under the experimental conditions that we used, and the appropriate use of ESAs may be effective and safe for DLBCL patients with anemia after R-CHOP.
Keywords: EPO receptor; diffuse large B-cell lymphoma; erythropoiesis-stimulating agents; erythropoietin.
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