open access: British Journal of Cancer - Effects of erythropoietin receptors and erythropoiesis-stimulating agents on disease progression in cancer (safety, adverse events, disease progression, conflicting research.....)

Blogger's Note: note ties to industry
          
                 `````````````````````````````````

"Erythropoiesis-stimulating agents (ESAs) increase red blood cell (RBC) production in bone marrow by activating the erythropoietin receptor (EpoR) on erythrocytic-progenitor cells. Erythropoiesis-stimulating agents are approved in the United States and Europe for treating anaemia in cancer patients receiving chemotherapy based on randomised, placebo-controlled trials showing that ESAs reduce RBC transfusions.

Erythropoiesis-stimulating agent-safety issues include thromboembolic events and concerns regarding whether ESAs increase disease progression and/or mortality in cancer patients. Several trials have reported an association between ESA use and increased disease progression and/or mortality, whereas other trials in the same tumour types have not provided similar findings.

This review thoroughly examines available evidence regarding whether ESAs affect disease progression. Both clinical-trial data on ESAs and disease progression, and preclinical data on how ESAs could affect tumour growth are summarised. Preclinical topics include (i) whether tumour cells express EpoR and could be directly stimulated to grow by ESA exposure and (ii) whether endothelial cells express EpoR and could be stimulated by ESA exposure to undergo angiogenesis and indirectly promote tumour growth.

Although assessment and definition of disease progression vary across studies, the current clinical data suggest that ESAs may have little effect on disease progression in chemotherapy patients, and preclinical data indicate a direct or indirect effect of ESAs on tumour growth is not strongly supported."

"This review summarised results from clinical and preclinical studies that evaluated whether ESAs affect disease progression. Although there are important limitations on the quality and assessment of disease progression in these studies, the current meta-analyses suggest no overall effect of ESAs on disease progression. Several individual studies have shown a potential trend associating ESA use with increased disease progression. This suggests that ESAs may affect disease progression in particular cancer patient populations (e.g., head and neck cancer patients receiving radiotherapy only) and that additional research is needed to define these populations and how ESAs mediate this effect. Although indirect effects on tumours induced by increased RBC production are theoretically possible, preclinical data to date suggest that tumour cells either do not express EpoR or express low levels of EpoR molecules that are non-functional and/or are not present at the cell surface. Overall, the balance of current evidence does not support an effect of ESAs on either activating EpoR on tumour cells or indirectly stimulating disease progression via angiogenesis. Future clinical trials, meta-analyses, and preclinical research should provide additional data to guide evidence-based use of ESAs in cancer patients."