Changes in levels of serum erythropoietin, serum iron and unsaturated iron binding capacity during chemotherapy for lung cancer

A genetic variation associated with plasma erythropoietin and a non-coding transcript of PRKAR1A in sickle cell disease

Blood erythropoietin (EPO) increases primarily to hypoxia. In sickle cell anaemia (homozygous HBBE6V; HbSS), plasma EPO is elevated due to hemolytic anaemia-related hypoxia. Hydroxyurea treatment reduces haemolysis and anaemia by increasing foetal haemoglobin, which leads to lower hypoxic transcriptional responses in blood mononuclear cells but paradoxically further increases EPO. To investigate this apparent hypoxia-independent EPO regulation, we assessed two sickle cell disease (SCD) cohorts for genetic associations with plasma EPO, by prioritizing 237,079 quantitative trait loci for expression level and/or transcript isoform variations of 12,727 genes derived from SCD blood mononuclear cells. We found an association between the T allele of SNP rs60684937 and increased plasma EPO (n = 567, combined P = 5.5 × 10 − 8 adjusted for haemoglobin and hydroxyurea) and validated it in independent SCD patients (n = 183, P = 0.018). The T allele of rs60684937 was associated with a relatively increased expression of a non-coding transcript of PRKAR1A (cAMP-dependent protein kinase type I-alpha regulatory subunit) in 58 SCD patients (P = 7.9 × 10 − 7) and 58 HapMap Yoruba samples (P = 0.0011). In conclusion, we demonstrate that plasma EPO elevation with hydroxyurea in SCD is independent of hypoxic responses and that genetic variation at SNP rs60684937 may contribute to EPO regulation through a cAMP-dependent protein kinase A pathway.

Pharmacokinetics of Darbepoetin Alfa after Intravenous or Subcutaneous Administration in Patients with Non-myeloid Malignancies Undergoing Chemotherapy

BACKGROUND AND OBJECTIVE

The pharmacokinetics of darbepoetin alfa after intravenous (IV) administration in the oncology setting have not been previously reported. The objective of this study was to evaluate the pharmacokinetics of IV or subcutaneous (SC) darbepoetin alfa in patients with non-myeloid malignancies undergoing multicycle chemotherapy.

METHODS

Fifty-six patients (haemoglobin <or=13.0 g/dL) received weekly darbepoetin alfa 2.25 microg/kg administered either IV (n=27) or SC (n=29) during up to three cycles of chemotherapy. Noncompartmental pharmacokinetic analysis was performed, including analysis of intensive pharmacokinetic profiles collected over 168 hours during week 1 of both the first and third cycles of chemotherapy.

RESULTS

Darbepoetin alfa serum concentrations exhibited a biphasic profile (a rapid distributive phase followed by a slower terminal elimination phase) after IV administration, whereas darbepoetin alfa was slowly absorbed after SC administration. Darbepoetin alfa exhibited limited extravascular distribution after IV administration, with both initial and steady-state mean volumes of distribution (36.1 mL/kg and 55.2 mL/kg, respectively, after a single IV dose) approximating the plasma volume. After a single IV dose, darbepoetin alfa exhibited a mean clearance of 1.05 mL/h/kg, with a mean terminal half-life of 38.8 hours. Similar pharmacokinetic results were observed after single and multiple doses of darbepoetin alfa, for both SC and IV administration.

CONCLUSION

Darbepoetin alfa is cleared slowly after IV administration to patients with cancer receiving chemotherapy, resulting in a terminal half-life of 38.8 hours. No evidence of accumulation and no changes in pharmacokinetic profiles after repeated administration were observed in cancer patients undergoing cyclic chemotherapy, for both IV and SC dosing.

Effects of chemotherapy on endogenous erythropoietin levels and the pharmacokinetics and erythropoietic response of darbepoetin alfa: a randomised clinical trial of synchronous versus asynchronous dosing of darbepoetin alfa

The introduction of longer-acting erythropoietic agents into the practice of oncology has demanded an understanding of the interaction of chemotherapy with the pharmacokinetics and haematological effects of these erythropoietins. We report results of a randomised trial comparing the haematological effects of darbepoetin alfa, 6.75 mug/kg, administered once every 3 weeks to anaemic cancer chemotherapy patients on either an asynchronous (day 15) or synchronous (day 1) schedule relative to their every-3-week chemotherapy. A total of 81 patients were randomised and received the study drug (43 asynchronous; 38 synchronous). No difference was observed between groups in the primary endpoint of mean haemoglobin change after 6 weeks of therapy (P=0.45) and change scores were similar to those observed with standard weekly darbepoetin alfa therapy. In a subset of patients evaluated with intensive pharmacokinetic sampling, an increase in endogenous erythropoietin concentration (up to 4-fold) lasting approximately 1 week following chemotherapy administration was observed in both groups. Synchronous administration of darbepoetin alfa was associated with a 1.3-fold increase in the area under the darbepoetin alfa concentration-time curve compared with asynchronous administration. Our data suggest that darbepoetin alfa is effective administered every 3 weeks regardless of timing of administration with respect to chemotherapy and that receptor-mediated uptake by the erythron may be an important clearance mechanism for erythropoietic proteins.

Erythropoietin response is inadequate in cancer patients receiving chemotherapy

The level of serum erythropoietin (EPO) is inappropriately decreased in cancer patients and has been advocated as the main cause of their anemia. In cancer patients, chemotherapy results in a cumulative anemia severe enough to require transfusion. We investigated the changes in serum EPO, hemoglobin, ceruloplasmin, and copper levels in cancer patients receiving chemotherapy. There was a weak but significant inverse relationship between hemoglobin and log[EPO] (r = -0.41; P < .001). Observed/expected serum EPO ratios decline with repeated chemotherapy indicating inadequate EPO response for the degree of anemia. There was no difference in the severity of anemia and in the degree of EPO response between platinum- and non-platinum-treated patients. Ceruloplasmin, copper, and ferritin levels did not change during chemotherapy. Our results suggest that the EPO response is inadequate for the degree of anemia and justifies the use of recombinant human EPO in cancer patients receiving chemotherapy.

Recombinant human erythropoietin (rhEPO) in the management of anemia and fatigue associated with solid tumors

The anemia that is most common in patients with solid tumors is the anemia of chronic disease, which probably occurs because of im paired production and a diminished response to serum erythropoietin (EPO). A number of trials evaluating recombinant human EPO in anemic cancer patients with a variety of solid tumors have demonstrated effective response rates, with increases in hemoglobin (Hb) concentra tion and reduction or elimination of transfusion requirements. The anemia of certain solid tu mors (eg, lung cancer, prostate cancer) appears to respond better to recombinant human EPO therapy than does the anemia associated with other cancers (eg, colon cancer). Both tumor response and increases in Hb concentrations are important factors in improving the quality of life of patients. The greatest contributor to improved quality of life appears to be the nor malization of Hb levels.