Source: European Medicines Agency (EU) Revision Year: 2022 Publisher: ratiopharm GmbH, Graf-Arco-Straße 3, 89079 Ulm, Germany
Pharmacotherapeutic group: Other antianemic preparations
ATC code: B03XA01
Human erythropoietin is an endogenous glycoprotein hormone that is the primary regulator of erythropoiesis through specific interaction with the erythropoietin receptor on the erythroid progenitor cells in the bone marrow. It acts as a mitosis-stimulating factor and differentiation hormone. The production of erythropoietin primarily occurs in and is regulated by the kidney in response to changes in tissue oxygenation. Production of endogenous erythropoietin is impaired in patients with chronic renal failure and the primary cause of their anaemia is erythropoietin deficiency. In patients with cancer receiving chemotherapy the aetiology of anaemia is multifactorial. In these patients, erythropoietin deficiency and a reduced response of erythroid progenitor cells to endogenous erythropoietin both contribute significantly towards their anaemia.
Epoetin theta is identical in its amino acid sequence and similar in its carbohydrate composition (glycosylation) to endogenous human erythropoietin.
The biological efficacy of epoetin theta has been demonstrated after intravenous and subcutaneous administration in various animal models in vivo (mice, rats, dogs). After administration of epoetin theta, the number of erythrocytes, the haematocrit values and reticulocyte counts increase.
Data from correction phase studies in 284 chronic renal failure patients show that the haemoglobin response rates (defined as haemoglobin levels above 11 g/dl at two consecutive measurements) in the epoetin theta group (88.4% and 89.4% in studies in patients on dialysis and not yet undergoing dialysis, respectively) were comparable to epoetin beta (86.2% and 81.0%, respectively). The median time to response was similar in the treatment groups with 56 days in haemodialysis patients and 49 days in patients not yet undergoing dialysis.
Two randomised controlled studies were conducted in 270 haemodialysis patients and 288 patients not yet undergoing dialysis, who were on stable treatment with epoetin beta. Patients were randomised to continue their current treatment or to be converted to epoetin theta (same dose as epoetin beta) in order to maintain their haemoglobin levels. During the evaluation period (weeks 15 to 26), the mean and median level of haemoglobin in patients treated with epoetin theta was virtually identical to their baseline haemoglobin level. In these two studies, 180 haemodialysis patients and 193 patients not undergoing dialysis were switched from maintenance phase treatment with epoetin beta to treatment with epoetin theta for a period of six months showing stable haemoglobin values and a similar safety profile as epoetin beta. In the clinical studies, patients not yet undergoing dialysis (subcutaneous administration) discontinued the study more frequently than haemodialysis patients (intravenous administration) as they had to terminate the study when starting dialysis.
In two long-term studies, the efficacy of epoetin theta was evaluated in 124 haemodialysis patients and 289 patients not yet undergoing dialysis. The haemoglobin levels remained within the desired target range and epoetin theta was well tolerated over a period of up to 15 months.
In the clinical studies, pre-dialysis patients were treated once-weekly with epoetin theta, 174 patients in the maintenance phase study and 111 patients in the long-term study.
Pooled post-hoc analyses of clinical studies of epoetins have been performed in chronic renal failure patients (on dialysis, not on dialysis, in diabetic and non-diabetic patients). A tendency towards increased risk estimates for all-cause mortality, cardiovascular and cerebrovascular events associated with higher cumulative epoetin doses independent of the diabetes or dialysis status was observed (see sections 4.2 and section 4.4).
409 cancer patients receiving chemotherapy were included in two prospective, randomised double-blind, placebo-controlled studies. The first study was conducted in 186 anaemic patients with non-myeloid malignancies (55% with haematological malignancies and 45% with solid tumours) receiving non-platinum chemotherapy. The second study was conducted in 223 patients with various solid tumours receiving platinum-containing chemotherapy. In both studies, treatment with epoetin theta resulted in a significant haemoglobin response (p<0.001), defined as an increase in haemoglobin of ≥2 g/dl without transfusion, and a significant reduction in transfusion requirements (p<0.05) in comparison to placebo.
Erythropoietin is a growth factor that primarily stimulates red cell production. Erythropoietin receptors may be expressed on the surface of a variety of tumour cells.
Survival and tumour progression have been examined in five large controlled studies involving a total of 2,833 patients, of which four were double-blind placebo-controlled studies and one was an openlabel study. Two of the studies recruited patients who were being treated with chemotherapy. The target haemoglobin concentration in two studies was >13 g/dl; in the remaining three studies it was 12-14 g/dl. In the open-label study there was no difference in overall survival between patients treated with recombinant human erythropoietin and controls. In the four placebo-controlled studies the hazard ratios for overall survival ranged between 1.25 and 2.47 in favour of controls. These studies have shown a consistent unexplained statistically significant excess mortality in patients who have anaemia associated with various common cancers who received recombinant human erythropoietin compared to controls. Overall survival outcome in the trials could not be satisfactorily explained by differences in the incidence of thrombosis and related complications between those given recombinant human erythropoietin and those in the control group.
Data from three placebo-controlled clinical studies in 586 anaemic cancer patients conducted with epoetin theta, showed no negative effect of epoetin theta on survival. During the studies, mortality was lower in the epoetin theta group (6.9%) compared to placebo (10.3%).
A systematic review has also been performed involving more than 9,000 cancer patients participating in 57 clinical trials. Meta-analysis of overall survival data produced a hazard ratio point estimate of 1.08 in favour of controls (95% CI: 0.99, 1.18; 42 trials and 8,167 patients). An increased relative risk of thromboembolic events (RR 1.67, 95% CI: 1.35, 2.06; 35 trials and 6,769 patients) was observed in patients treated with recombinant human erythropoietin. There is therefore consistent evidence to suggest that there may be significant harm to patients with cancer who are treated with recombinant human erythropoietin. The extent to which these outcomes might apply to the administration of recombinant human erythropoietin to patients with cancer, treated with chemotherapy to achieve haemoglobin concentrations less than 13 g/dl, is unclear because few patients with these characteristics were included in the data reviewed.
A patient-level data analysis has also been performed on more than 13,900 cancer patients (chemo-, radio-, chemoradio- or no therapy) participating in 53 controlled clinical trials involving several epoetins. Meta-analysis of overall survival data produced a hazard ratio point estimate of 1.06 in favour of controls (95% CI: 1.00, 1.12; 53 trials and 13,933 patients) and for cancer patients receiving chemotherapy, the overall survival hazard ratio was 1.04 (95% CI: 0.97, 1.11; 38 trials and 10,441 patients). Meta-analyses also indicate consistently a significantly increased relative risk of thromboembolic events in cancer patients receiving recombinant human erythropoietin (see section 4.4).
The pharmacokinetics of epoetin theta have been examined in healthy volunteers, in patients with chronic renal failure and in cancer patients receiving chemotherapy. The pharmacokinetics of epoetin theta are independent of age or gender.
Following subcutaneous injection of 40 IU/kg body weight epoetin theta at three different sites (upper arm, abdomen, thigh) in healthy volunteers, similar plasma level profiles were observed. The extent of absorption (AUC) was slightly greater after injection in the abdomen in comparison to the other sites. The maximum concentration is reached after an average of 10 to 14 hours and the average terminal half-life ranges from approximately 22 to 41 hours.
Average bioavailability of epoetin theta after subcutaneous administration is approximately 31% compared with intravenous administration.
In pre-dialysis patients with chronic renal failure following subcutaneous injection of 40 IU/kg body weight, the protracted absorption results in a concentration plateau, whereby the maximum concentration is reached after an average of approximately 14 hours. The terminal half-life is higher than after intravenous administration, with an average of 25 hours after single dosing and 34 hours in steady state after repeated dosing three times weekly, without leading to an accumulation of epoetin theta.
In cancer patients receiving chemotherapy, after repeated subcutaneous administration of 20,000 IU epoetin theta once-weekly, the terminal half-life is 29 hours after the first dose and 28 hours in steady state. No accumulation of epoetin theta was observed.
In patients with chronic renal failure undergoing haemodialysis, the elimination half-life of epoetin theta is 6 hours after single dosing and 4 hours in steady state after repeated intravenous administration of 40 IU/kg body weight epoetin theta three times weekly. No accumulation of epoetin theta was observed. Following intravenous administration, the volume of distribution approximates to total blood volume.
Non-clinical data with epoetin theta reveal no special hazard for humans based on conventional studies of safety pharmacology and repeated dose toxicity.
Non-clinical data with other epoetins reveal no special hazard for humans based on conventional studies of genotoxicity and toxicity to reproduction.
In reproductive toxicity studies performed with other epoetins, effects interpreted as being secondary to decreased maternal body weight were observed at doses sufficiently in excess to the recommended human dose.
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