A dose-finding and safety study of novel erythropoiesis stimulating protein (NESP) for the treatment of anaemia in patients receiving multicycle chemotherapy

Application of Pharmacokinetic-Pharmacodynamic Modeling in Drug Delivery: Development and Challenges

With the advancement of technology, drug delivery systems and molecules with more complex architecture are developed. As a result, the drug absorption and disposition processes after administration of these drug delivery systems and engineered molecules become exceedingly complex. As the pharmacokinetic and pharmacodynamic (PK-PD) modeling allows for the separation of the drug-, carrier- and pharmacological system-specific parameters, it has been widely used to improve understanding of the in vivo behavior of these complex delivery systems and help their development. In this review, we summarized the basic PK-PD modeling theory in drug delivery and demonstrated how it had been applied to help the development of new delivery systems and modified large molecules. The linkage between PK and PD was highlighted. In particular, we exemplified the application of PK-PD modeling in the development of extended-release formulations, liposomal drugs, modified proteins, and antibody-drug conjugates. Furthermore, the model-based simulation using primary PD models for direct and indirect PD responses was conducted to explain the assertion of hypothetical minimal effective concentration or threshold in the exposure-response relationship of many drugs and its misconception. The limitations and challenges of the mechanism-based PK-PD model were also discussed.

Residues Comprising the Enhanced Aromatic Sequon Influence Protein N-Glycosylation Efficiency

N-Glycosylation is an important co- and/or post-translational modification that occurs on the vast majority of the one-third of the mammalian proteome that traverses the cellular secretory pathway, regulating glycoprotein folding and functions. Previous studies on the sequence requirements for N-glycosylation have yielded the Asn-X-Ser/Thr (NXS/T) sequon and the enhanced aromatic sequons (Phe-X-Asn-X-Thr and Phe-X-X-Asn-X-Thr), which can be efficiently N-glycosylated. To further investigate the influence of sequence variation on N-glycosylation efficiency in the context of a five-residue enhanced aromatic sequon, we used the human CD2 adhesion domain (hCD2ad) to screen the i-2, i-1, i+1, and i+2 residues flanking Asn at the i position. We found that aromatic residues, especially Trp, and sulfur-containing residues at the i-2 position improved N-glycosylation efficiency, while positively charged residues such as Arg suppressed N-glycosylation. Thiol, hydroxyl, and aliphatic-based side chains at the i-1 position had higher N-glycosylation efficiency, and Cys, in particular, compensated for the negative effect of Arg at the i-2 position. Small residues and Ser at the i+1 position increased the likelihood of N-glycosylation, and Thr is better than Ser at the i+2 position. We devised an algorithm for prediction of N-glycosylation efficiency using the SAS software, employing the 120 sequences studied as a training set. We then introduced the optimized-enhanced aromatic sequons into other glycoproteins and observed an enhancement in N-glycan occupancy that was further supported by modeling the high-affinity interaction between the optimized sequence on hCD2ad and a human oligosaccharyltransferase (OST) subunit. The findings in this study provide useful information for enhancing or suppressing N-glycosylation at a site of interest and valuable data for a better understanding of OST-catalyzed N-glycosylation.

Clinical outcomes with use of erythropoiesis stimulating agents in patients with the HeartMate II left ventricular assist device

OBJECTIVES

This study evaluated clinical outcomes associated with erythropoiesis stimulating agent (ESA) use in left ventricular assist devices (LVAD)-supported patients.

BACKGROUND

Use of ESAs in patients with LVADs may minimize blood transfusions and decrease allosensitization. ESAs increase thrombotic events, which is concerning because LVADs are sensitive to pump thrombosis (PT).

METHODS

We retrospectively reviewed 221 patients at our center who received a HeartMate II (Thoratec Corp., Pleasanton, California) LVAD between January 1, 2009 and June 6, 2013. Patients were divided into those who received ESAs during index admission (n = 121) and those who did not (n = 100). Suspected PT was defined as evidence of thrombus in the LVAD or severe hemolysis (lactate dehydrogenase >1,000 mg/dl or plasma-free hemoglobin >40 mg/dl). Outcomes were compared between cohorts using inverse probability-weighted analyses.

RESULTS

During a mean follow-up of 14.2 ± 11.9 months, suspected PT occurred in 37 patients (ESA 23%, no ESA 12%; p =0.03). The ESA cohort received ESAs 13.9 ± 60.9 days after LVAD implantation. At 180 days, event-free rates for suspected PT were ESA 78.6% versus no ESA 94.5% (p < 0.001). ESA use had higher rates of suspected PT (hazard ratio [HR]: 2.35; 95% confidence interval [CI]: 1.38 to 4.00; p = 0.002). For every 100-unit increase in cumulative ESA dosage, the hazard of suspected PT increased by 10% (HR: 1.10; 95% CI: 1.04 to 1.16; p < 0.001). After inverse probability weighting, ESA use was associated with a significantly higher rate of all-cause mortality (HR: 1.62; 95% CI: 1.12 to 2.33; p = 0.01).

CONCLUSIONS

ESA use in LVAD patients is associated with higher rates of suspected PT.

Erythropoietin and the heart: physiological effects and the therapeutic perspective

Erythropoietin (Epo) has been thought to act exclusively on erythroid progenitor cells. The identification of Epo receptor (EpoR) in non-haematopoietic cells and tissues including neurons, astrocytes, microglia, immune cells, cancer cell lines, endothelial cells, bone marrow stromal cells, as well as cells of myocardium, reproductive system, gastrointestinal tract, kidney, pancreas and skeletal muscle indicates that Epo has pleiotropic actions. Epo shows signals through protein kinases, anti-apoptotic proteins and transcription factors. In light of interest of administering recombinant human erythropoietin (rhEpo) and its analogues for limiting infarct size and left ventricular (LV) remodelling after acute myocardial infarction (AMI) in humans, the foremost studies utilising rhEpo are reviewed. The putative mechanisms involved in Epo-induced cardioprotection are related to the antiapoptotic, anti-inflammatory and angiogenic effects of Epo. Thus, cardioprotective potentials of rhEpo are reviewed in this article by focusing on clinical applicability. An overview of non-haematopoietic Epo analogues, which are a reliable alternative to the classic EpoR agonists and may prevent undesired side effects, is also provided.

Chemotherapy-induced anemia: the story of darbepoetin alfa

BACKGROUND

Prior to the approval of the first erythropoiesis-stimulating agent (ESA) in the early 1990s, red blood cell transfusions were the primary means of treating severe chemotherapy-induced anemia (CIA), with little recourse for those with more mild forms of the condition. The introduction of the ESAs allowed treatment of mild-to-moderate CIA in patients with cancer. It has been a decade since darbepoetin alfa (DA), a second-generation ESA with a longer half-life, became available to patients with CIA.

OBJECTIVE AND METHODS

We present a review of studies on DA in CIA, from its development through to the present day. Medline was searched for randomized clinical trials on DA. Additional trials and meta-analyses on ESAs were incorporated into this review when relevant.

RESULTS

The first publications on DA generally focused on optimal dosing, efficacy and tolerability. In these, it was shown that DA is an effective and well tolerated treatment option to achieve hematopoietic response, regardless of dosing interval. Subsequently, the focus shifted towards meta-analyses on survival data of all ESAs. These reported conflicting results regarding mortality and/or disease progression. However, guidelines for ESA use were updated and, when followed, these make ESAs a well tolerated and effective tool for managing CIA.

CONCLUSIONS

As the past decade has broadened our knowledge on the benefits and risks of CIA management, continued high-quality studies will help to optimize treatment with ESAs in order to maximize quality of life for these patients. The limitation of a literature review of this nature is the complete reliance on previously published research and the availability of these studies using the methodology outlined above.

Effects of exercise on fatigue, sleep, and performance: a randomized trial

PURPOSE/OBJECTIVES

To compare usual care with a home-based individualized exercise program (HBIEP) in patients receiving intensive treatment for multiple myeloma (MM)and epoetin alfa therapy.

DESIGN

Randomized trial with repeated measures of two groups (one experimental and one control) and an approximate 15-week experimental period.

SETTING

Outpatient setting of the Myeloma Institute for Research and Therapy at the Rockfellow Cancer Center at the University of Arkansas for Medical Sciences.

SAMPLE

187 patients with newly diagnosed MM enrolled in a separate study evaluating effectiveness of the Total Therapy regimen, with or without thalidomide.

METHODS

Measurements included the Profile of Mood States fatigue scale, Functional Assessment of Cancer Therapy-Fatigue, ActiGraph® recordings, 6-Minute Walk Test, and hemoglobin levels at baseline and before and after stem cell collection. Descriptive statistics were used to compare demographics and treatment effects, and repeated measures analysis of variance was used to determine effects of HBIEP.

MAIN RESEARCH VARIABLES

Fatigue, nighttime sleep, performance (aerobic capacity) as dependent or outcome measures, and HBIEP combining strength building and aerobic exercise as the independent variable.

FINDINGS

Both groups were equivalent for age, gender, race, receipt of thalidomide, hemoglobin levels, and type of treatment regimen for MM. No statistically significant differences existed among the experimental and control groups for fatigue, sleep, or performance (aerobic capacity). Statistically significant differences (p < 0.05) were found in each of the study outcomes for all patients as treatment progressed and patients experienced more fatigue and poorer nighttime sleep and performance (aerobic capacity).

CONCLUSIONS

The effect of exercise seemed to be minimal on decreasing fatigue, improving sleep, and improving performance (aerobic capacity).

IMPLICATIONS FOR NURSING

Exercise is safe and has physiologic benefits for patients undergoing MM treatment; exercise combined with epoetin alfa helped alleviate anemia.

Erythropoietin or darbepoetin for patients with cancer

BACKGROUND

Anaemia associated with cancer and cancer therapy is an important clinical factor in the treatment of malignant diseases. Therapeutic alternatives are recombinant human erythropoiesis stimulating agents (ESAs) and red blood cell transfusions.

OBJECTIVES

To assess the effects of ESAs to either prevent or treat anaemia in cancer patients.

SEARCH METHODS

This is an update of a Cochrane review first published in 2004. We searched the Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE and other databases. Searches were done for the periods 01/1985 to 12/2001 for the first review, 1/2002 to 04/2005 for the first update and to November 2011 for the current update. We also contacted experts in the field and pharmaceutical companies.

SELECTION CRITERIA

Randomised controlled trials on managing anaemia in cancer patients receiving or not receiving anti-cancer therapy that compared the use of ESAs (plus transfusion if needed).

DATA COLLECTION AND ANALYSIS

Several review authors assessed trial quality and extracted data. One review author assessed quality assessment and extracted data, a second review author checked for correctness.

MAIN RESULTS

This update of the systematic review includes a total of 91 trials with 20,102 participants. Use of ESAs significantly reduced the relative risk of red blood cell transfusions (risk ratio (RR) 0.65; 95% confidence interval (CI) 0.62 to 0.68, 70 trials, N = 16,093). On average, participants in the ESAs group received one unit of blood less than the control group (mean difference (MD) -0.98; 95% CI -1.17 to -0.78, 19 trials, N = 4,715). Haematological response was observed more often in participants receiving ESAs (RR 3.93; 95% CI 3.10 to 3.71, 31 trials, N = 6,413). There was suggestive evidence that ESAs may improve Quality of Life (QoL). There was strong evidence that ESAs increase mortality during active study period (hazard ratio (HR) 1.17; 95% CI 1.06 to 1.29, 70 trials, N = 15,935) and some evidence that ESAs decrease overall survival (HR 1.05; 95% CI 1.00 to 1.11, 78 trials, N = 19,003). The risk ratio for thromboembolic complications was increased in patients receiving ESAs compared to controls (RR 1.52, 95% CI 1.34 to 1.74; 57 trials, N = 15,498). ESAs may also increase the risk for hypertension (fixed-effect model: RR 1.30; 95% CI 1.08 to 1.56; random-effects model: RR 1.12; 95% CI 0.94 to 1.33, 31 trials, N = 7,228) and thrombocytopenia/haemorrhage (RR 1.21; 95% CI 1.04 to 1.42; 21 trials, N = 4,507). There was insufficient evidence to support an effect of ESA on tumour response (fixed-effect RR 1.02; 95% CI 0.98 to 1.06, 15 trials, N = 5,012).

AUTHORS' CONCLUSIONS

ESAs reduce the need for red blood cell transfusions but increase the risk for thromboembolic events and deaths. There is suggestive evidence that ESAs may improve QoL. Whether and how ESAs affects tumour control remains uncertain. The increased risk of death and thromboembolic events should be balanced against the potential benefits of ESA treatment taking into account each patient's clinical circumstances and preferences. More data are needed for the effect of these drugs on quality of life and tumour progression. Further research is needed to clarify cellular and molecular mechanisms and pathways of the effects of ESAs on thrombogenesis and their potential effects on tumour growth.

Alexithymia in oncologic disease: association with cancer invasion and hemoglobin levels

BACKGROUND

The literature suggests that alexithymia is the result of individual differences and/or biological mechanisms. Both individual differences and disease mechanisms may play a role among individuals with medical or surgical conditions. The relative weight of clinical and individual differences factors related to alexithymia has not been studied in patients with cancer. The purpose of this study was to examine the extent to which individual differences in perceived stress and biological markers of illness severity are associated with alexithymia among patients with cancer.

METHODS

Treated oncologic outpatients (N = 37) were assessed using the 20-item Toronto Alexithymia Scale and Perceived Stress Scale. Alexithymia was examined in relation to perceived stress, tumor staging, and hemoglobin levels.

RESULTS

Among the patients studied, 34.2% endorsed the established cutoff score (≥61) for alexithymia. Higher alexithymia scores were found in patients with more advanced stages of cancer invasion. Alexithymia correlated directly with perceived stress and indirectly with hemoglobin levels. Hemoglobin levels and cancer invasion significantly correlated with alexithymia when controlling for perceived stress.

CONCLUSIONS

A significant component of alexithymia in cancer patients may be construed as acquired. But awareness of health status influencing perceived stress might partially mediate the role of cancer invasion and hemoglobin on alexithymia.

Pharmacokinetic study of darbepoetin alfa: absorption, distribution, and excretion after a single intravenous and subcutaneous administration to rats

KRN321 is a hyperglycosylated analogue of recombinant human erythropoietin (rHuEPO, epoetin alfa), and its absorption, distribution, and excretion have been studied after a single intravenous and subcutaneous administration of 125I-KRN321 at a dose of 0.5 microg kg-1 to male rats. The half-lives of immunoreactive radioactivity in the terminal phase after intravenous and subcutaneous administration were 14.05 and 14.36 h, respectively, and the bioavailability rate after subcutaneous administration was 47%. The total radioactivity in tissues was lower than that in the serum in all tissues excluding the thyroid gland and skin at the injection site (subcutaneous administration). The maximum concentrations were observed in the bone marrow or skin at the injection site followed by the thyroid gland, kidneys, adrenal glands, spleen, lungs, stomach and bladder. The radioactivity found in trichloroacetic acid-precipitated fractions suggested that a high-molecular weight compound, unchanged or mixed with endogenous protein, distributed to the tissues after administration. The whole-body autoradiographic findings in both groups were in agreement with the tissue distribution mentioned above. The blood cell uptake of KRN321 was low for both groups. The excretion ratios of radioactivity into urine and faeces up to 168 h were 71.4 and 14.1% after the intravenous administration and 74.9 and 12.0% after the subcutaneous administration. There was no difference in the excretion profile of radioactivity between the two groups.

Sialic acids: carbohydrate moieties that influence the biological and physical properties of biopharmaceutical proteins and living cells

Sialic acids are structurally diverse molecules that have important roles in the physiological reactions and characteristics of prokaryotes and eukaryotes. These include the ability to mask epitopes on underlying glycan chains and to repulse negatively charged moieties. Here, we describe the metabolism and immunological relevance of sialic acids and outline how their properties have been exploited by the pharmaceutical industry to enhance the therapeutic properties of proteins such as asparaginase and darbepoetin alpha.

Erythropoietin or darbepoetin for patients with cancer

BACKGROUND

Anaemia associated with cancer and cancer therapy is an important clinical factor in the treatment of malignant diseases. Therapeutic alternatives are recombinant human erythropoietin (Epo), darbepoetin (Darbepo) and red blood cell transfusions.

OBJECTIVES

The aim of this systematic review was to assess the effects of Epo or Darbepo to either prevent or treat anaemia in cancer patients.

SEARCH STRATEGY

We searched the Central Register of Controlled Trials, MEDLINE and EMBASE and other data bases. Searches were done for the periods 01/1985 to 12/2001 for the first review and 1/2002 to 04/2005 for the update. We also contacted experts in the field and pharmaceutical companies.

SELECTION CRITERIA

Randomised controlled trials on managing anaemia in cancer patients that compared the use of Epo/Darbepo (plus transfusion if needed) with observation until red blood cell transfusion was required.

DATA COLLECTION AND ANALYSIS

Several reviewers independently assessed trial quality and extracted data.

MAIN RESULTS

This update of the systematic review included a total of 57 trials with 9,353 patients. Of these, 27 trials with 3,287 adults were also included in the first Cochrane Review. Thirty trials with 6,066 patients were added during the update process. Use of Epo/Darbepo significantly reduced the relative risk of red blood cell transfusions (RR 0.64; 95% CI 0.60 to 0.68, 42 trials, n = 6,510). On average participants in the Epo/Darbepo group received one unit of blood less than the control group (WMD -1.05; 95% CI -1.32 to -0.78, 14 trials, n = 2,353). For participants with baseline haemoglobin below 12 g/dL haematological response was observed more often in participants receiving Epo/Darbepo (RR 3.43; 95% CI 3.07 to 3.84, 22 trials, n = 4,307). There was suggestive evidence that Epo/Darbepo may improve Quality of Life (QoL). The relative risk for thrombo embolic complications was increased in patients receiving Epo/Darbepo compared to controls (RR 1.67, 95% CI 1.35 to 2.06; 35 trials, n = 6,769). Uncertainties remain whether and how Epo/Darbepo effects tumour response (fixed effect RR 1.12; 95% CI 1.01 to 1.23, 13 trials, n = 2,833; random effects: RR 1.09; 95% CI 0.94 to 1.26) or overall survival (unadjusted and adjusted data: HR 1.08; 95% CI 0.99 to 1.18; 42 trials, n = 8,167).

AUTHORS' CONCLUSIONS

There is consistent evidence that administration of Epo/Darbepo reduces the relative risk for blood transfusions and the number of units transfused in cancer patients. For patients with baseline haemoglobin below 12 g/dL (mild anaemia) there is strong evidence that Epo/Darbepo improves haematological response. There is suggestive evidence that Epo/Darbepo may improve QoL. However, there is strong evidence that Epo/Darbepo increases the relative risk for thrombo embolic complications. Whether and how Epo/Darbepo effects tumour response and overall survival remains uncertain.

Anemia in the elderly—Clinical findings and impact on health

Anemia is common in older people and it becomes more so with advancing decades. Because the older population is increasing, the prevalence of anemia and consequently its impact on health and healthcare expenditure is expected to rise. Although the causes and consequences of anemia have not been fully elucidated and its etiology is occasionally elusive, clinical evidence has indicated that anemia itself is a cause of morbidity and it can complicate other health conditions. The clinical approach to anemia is evolving. In the past, anemia was mainly seen as a sign of underlying disease; today, anemia is considered to be a cause of severe deterioration of quality of life, morbidity, and decline in physical function, and a risk factor for death. A better understanding of anemia in the elderly will lead to improved treatment strategies, including the more judicious use of transfusion and appropriate use of erythropoietic agents.

Darbepoetin Alfa Administered Every Three Weeks Is Effective for the Treatment of Chemotherapy‐Induced Anemia

Patients with cancer receiving chemotherapy often have chemotherapy-induced anemia (CIA) and reduced quality of life. Darbepoetin alfa can effectively treat CIA when administered at an extended dosing interval of once every 3 weeks (Q3W). Darbepoetin alfa administered Q3W may allow synchronization of darbepoetin alfa therapy with chemotherapy administered Q3W. This multicenter, open-label, 16-week study evaluated the effectiveness and safety of darbepoetin alfa administered as a fixed dose (300 mug) Q3W in patients with CIA. Eligible patients (> or =18 years) were anemic (hemoglobin <11g/dl), had a nonmyeloid malignancy, and were receiving multicycle chemotherapy. This analysis includes 1,493 patients who received at least one dose of darbepoetin alfa. The effect of baseline hemoglobin (<10 or > or =10 g/dl) on clinical outcomes was evaluated. Patients in the > or =10-g/dl stratum achieved the hemoglobin target range (11-13 g/dl)in less time than patients in the <10-g/dlstratum (3 weeks vs. 9 weeks). More patients in the > or =10-g/dl stratum achieved the hemoglobin target range (87% vs. 66%); however, similar proportions of patients in both strata maintained hemoglobin within the target range (73% vs. 71%). Fewer patients in the > or =10-g/dl stratum received RBC transfusions from week 5 to the end of the study (12% vs. 28%). Over 50% of patients in both strata reported clinically significant improvements (> or =3-point increase) in Functional Assessment of Cancer Therapy-Fatigue score. Twenty-eight percent of patients reported serious adverse events; 3% of all patients had a venous or arterial thrombotic event. This study demonstrates that darbepoetin alfa Q3W is well tolerated and effective for treating CIA.

Management of cancer-related anemia with erythropoietic agents: doubts, certainties, and concerns

The management of cancer-related anemia with erythropoietic agents presents many unresolved issues. We reviewed the literature relating to epoetin alfa (Eprex)/Epypo); Ortho Biotech/Janssen-Cilag, High Wycombe, United Kingdom, http://www.orthobiotech.co.uk; Procrit); Ortho Biotech Products, L.P., Bridgewater, NJ, http://www.orthobiotech.com), epoetin beta (NeoRecormon); Hoffman-La Roche, Basel, Switzerland, http://www.roche.com), and darbepoetin alfa (Aranesp); Amgen Inc., Thousand Oaks, CA, http://www.amgen.com) highlighting the results of published clinical trials, safety, and cost-effectiveness. Studies were identified through MEDLINE and the bibliographies of relevant articles. Epoetin alfa, epoetin beta, and darbepoetin alfa have differing pharmacokinetic and pharmacodynamic profiles. They are all effective at reducing transfusion requirements and improving health-related quality-of-life parameters, irrespective of tumor response. A direct comparison between epoetin alfa and darbe poetin alfa is based on limited evidence, which does not allow definitive conclusions about relative efficacy and cost-effectiveness. No predictive factors for response to erythropoietic agents have been validated in prospective trials. The most consistent adverse events are thrombotic and may occur irrespective of an increase in hemoglobin. Recent research indicates that the erythropoietin receptor is expressed in several cancer cell lines, raising the concern of possible stimulation of tumor cell growth by these drugs. Studies on the cost-effectiveness of erythropoietins, particularly compared with transfusion therapy, have been challenging to conduct and analyze and have generated ambiguous results. The use of erythropoietins needs to be optimized in terms of cost-effectiveness, and issues surrounding safety need to be clarified. A stronger methodology for clinical studies and the design of new, randomized, clinical trials is a major priority.

Evaluating erythropoietic agents for the treatment of anaemia in the oncology setting

Anaemia is a common complication of cancer and its treatment. It is also associated with substantial impairment of patient quality of life (QOL). Erythropoietic agents are primary treatment options for cancer-related anaemia (CRA). This review summarises evidence supporting clinical use of the approved erythropoietic agents (epoetin alfa, epoetin beta, darbepoetin alfa). A MEDLINE((R)) search from January 2000 to September 2004 using the search terms "epoetin alfa," "epoetin beta," "darbepoetin alfa," "erythropoietin," and "anaemia" was conducted to identify studies evaluating erythropoietic agents in the treatment of CRA. Recent presentations at professional meetings were also included. Erythropoietic agents increase haemoglobin levels, decrease transfusion requirements, and improve QOL in patients with CRA. However, variations in study design, patient populations, dose titration schedules, and outcome measures among available studies make data comparisons between clinical trials difficult. Head-to-head trials are comparing erythropoietic agents in a randomised setting; other trials are evaluating optimal dosage schedules. Clinically relevant differences among approved erythropoietic agents have not been determined in direct comparative trials; however, epoetin alfa appears to be at least as effective as darbepoetin alfa in treatment of CRA.

Optimising the management of anaemia in patients with cancer with practice guidelines using erythropoiesis-stimulating proteins

Anaemia, a common problem in patients with cancer, usually leads to severe fatigue, which can dramatically impair patients' quality of life (QOL). Nurses are in the ideal position to assess and monitor cancer patients at risk of anaemia and recommend appropriate supportive care measures to alleviate anaemia-related symptoms. Erythropoiesis-stimulating proteins (ESPs) can increase haemoglobin levels, reduce the need for red blood cell transfusions, and improve QOL in patients with cancer and anaemia. Evidence-based guidelines published by national and international organisations make specific recommendations for the appropriate use of ESPs. Nurses are key members of the multidisciplinary teams that develop practice-specific protocols, which are based on the national guidelines. The practice guidelines should describe protocols to identify patients at risk for anaemia and interventions to correct anaemia, with specific details on the choice of ESP and when such interventions should be initiated and halted. In addition, nurses should also recommend strategies to reduce patient burden, such as patient self-administration with prefilled pens or synchronisation of visits for ESPs with chemotherapy visits, which is made possible with the once-every-3-weeks extended dosing with darbepoetin alfa. The implementation of such practice guidelines should improve the quality of care provided to patients.

Long-acting erythropoietin: clinical studies and potential uses in neonates

Aranesp (darbepoietin alfa) is a biologically modified form of recombinant human erythropoietin (rHuEpo). Two additional carbohydrate-binding sites give Aranesp a half-life about three times that of rHuEpo. Extensive studies in adults and early studies in children indicate that Aranesp can be administered far less frequently than rHuEpo with an equivalent erythropoietic effect. This article reviews these studies and reports on the in vitro effects of Aranesp on human fetal and neonatal erythroid progenitors.

Clinical and economic comparison of epoetin alfa and darbepoetin alfa

BACKGROUND

The pharmacoeconomics of erythropoietic therapy for the treatment of anemia is receiving renewed attention due to the current availability of two agents. Epoetin alfa has been the standard of therapy for patients with renal disease and cancer-related anemia for more than a decade. Darbepoetin alfa, an alternative agent, is now approved for anemia resulting from renal disease and cancer chemotherapy.

METHODOLOGY

Although direct comparative trials have not been performed with these agents, information published in the last several years regarding their clinical efficacy, safety, and dosing is sufficient, in most cases, to compare costs. With the disclaimer that any efficacy comparison of competing products using published reports has certain limitations, a cost-minimization approach from a provider's perspective was conducted.

RESULTS

To provide background for the economic evaluation, pharmacokinetic and pharmacodynamic data for these two agents are discussed. Recent clinical trials in the nephrology and oncology therapeutic areas are summarized, highlighting study designs, dosing regimens, patient entry criteria, study endpoints, and published results. Cost data, based on average wholesale prices (AWP) in 2003, are compared and calculated from available clinical data with an emphasis on efficacy.

CONCLUSION

These evaluations largely conclude that epoetin alfa is the better pharmacoeconomic value of the two currently available erythropoietic agents.

The development of supportive-care agents for patients with cancer

As the population ages, a dramatic increase in the number of cases of cancer is expected and the need for supportive-care agents, those used to ameliorate some of the side effects of cancer or its treatment, becomes more urgent. At present, supportive-care products are available and new agents are being developed with novel mechanisms of action or modifications of existing agents that improve performance. Because of the urgent need for such products, efficient development is required to deliver useful products to patients as rapidly as possible. This chapter uses actual examples to illustrate the stages of drug development, phase I through phase 3.

Impact of Long-Acting Growth Factors on Practice Dynamics and Patient Satisfaction

OBJECTIVE

To quantify time expended, patient satisfaction, and econometrics associated with short-acting (sargramostim, epoetin alfa) and long-acting (darbepoetin alfa, pegfilgrastim) growth factors.

DESIGN

Retrospective resource utilization and prospective two-phase observational study.

METHODS

During week 1, time-motion measurements related to patient treatment and drug preparation were collected for scheduling; check-in; phlebotomy; laboratory; and drug preparation, administration, and recording. Drug utilization for one chemotherapy cycle during weeks 2 and 3 was assessed for sargramostim, pegfilgrastim, epoetin alfa, darbepoetin alfa, sargramostim plus epoetin alfa, and pegfilgrastim plus darbepoetin alfa. Patients completed a satisfaction survey.

RESULTS

Among 140 patients (mean age 58 yrs), mean chemotherapy cycle duration was 19 days. A total of 268 events were observed. Mean total staff time/patient visit for drug administration was 22.1 minutes, with most time spent on scheduling (5.5 min) and drug preparation, administration, recording (5.2 min). For sargramostim only versus pegfilgrastim only, pegfilgrastim resulted in a 37% reduction (p < 0.01) in all visits and an 85% reduction (p < 0.01) in mean number of doses. For epoetin alfa only versus darbepoetin alfa only, darbepoetin alfa resulted in a 48% reduction (p < 0.01) in mean number of doses. The most common dosage of epoetin alfa was 40,000 U/week (63.6%) and that of darbepoetin alfa was 200 microg every other week (92%), but complete blood counts were obtained weekly. For pegfilgrastim plus darbepoetin alfa versus sargramostim plus epoetin alfa, a 45% reduction (p < 0.01) in total visits and a 77% reduction (p < 0.01) in mean number of doses were noted in the former group. In 69 patients converted to long-acting drugs, 65 actual hours for a single treatment cycle were saved. For patients receiving pegfilgrastim plus darbepoetin alfa, there was a 45% reduction in total clinic visits, 77% reduction in doses, and staff time savings of 1.9 hours/patient/cycle of chemotherapy. Fifty-four patients completed the survey and trended toward neutral in their responses, with moderate disagreement that receiving injections is painful.

CONCLUSION

Long-acting growth factors resulted in significant time savings for staff and providers by reducing the number of necessary office visits for drug administration. These time savings can significantly improve the quality of life for patients, as well as nurses, physicians, and caregivers.

Cancer-related fatigue: evolving concepts in evaluation and treatment

BACKGROUND

Although fatigue is one of the most common complaints of patients with cancer, it went unrecognized or overlooked for many years, until clinicians achieved better control over the more acute symptoms of nausea, emesis, and pain. A number of treatment-related and disease-related factors may contribute to the development of fatigue, but its physiologic basis remains poorly understood, and many proposed interventions have not been studied systematically. The lack of a standard of care for the assessment or treatment of fatigue in patients with cancer has limited research in this field. A critical appraisal of these issues is presented in this review.

METHODS

The published literature was reviewed for definition, prevalence, causes, and means of managing cancer-related fatigue (CRF).

RESULTS

Fatigue was reportedly present at the time of diagnosis in approximately 50-75% of cancer patients. The prevalence of CRF increased to 80-96% in patients undergoing chemotherapy and to 60-93% in patients receiving radiotherapy. Two tested interventions that showed consistent effects to alleviate CRF were treatment of cancer-related anemia with erythropoietin agents (recombinant human erythropoietin and darbepotin alpha) and aerobic exercise.

CONCLUSIONS

Several lines of research are needed to bridge the specific gaps in the current knowledge of CRF. These involve the pathophysiology of the symptom, the validation of diagnostic criteria, and specific therapeutic interventions. Current practice guidelines are based on a combination of research and expert clinical judgment and should be used to guide care with the expectation that they will evolve to incorporate the results of studies currently underway.

Kinetics of haematopoietic recovery after dose-intensive chemo/radiotherapy in mice: optimized erythroid support with darbepoetin alpha

Despite its frequency and impact on clinical outcomes, anaemia in cancer patients remains poorly understood and suboptimally treated. The definition of optimum treatment schedules with erythropoietic agents requires a suitable model of chemotherapy-induced progressive anaemia. This study investigated novel strategies such as once-per-chemotherapy-cycle dosing, synchronization between erythroid supportive care and chemotherapy, and definition of the optimum timing of erythroid support. A murine model of carboplatin chemotherapy/radiotherapy (CRT)-induced anaemia was used, which caused progressive anaemia across multiple cycles. Weekly administration of recombinant human erythropoietin (rHuEPO) was effective, but the longer-acting darbepoetin alpha resulted in superior responses. In all animals, anaemia became progressive and more refractory across cycles because of accumulated bone marrow damage. Exploiting a specific enzyme-linked immunosorbent assay, which could distinguish between darbepoetin alpha and endogenous erythropoietin, the effect of CRT upon the pharmacokinetics of darbepoetin alpha showed that clearance of darbepoetin alpha, and presumably erythropoietin, was at least partially dependent on a chemotherapy-sensitive pathway. Scheduling data suggested that administration of erythropoietic agents prior to chemotherapy was more effective than administration after chemotherapy. There was no evidence that erythropoietic agents exacerbated anaemia, even when administered immediately prior to CRT in an attempt to "prime" erythroid cells for the effects of CRT.

Recombinant erythropoietin in clinical practice

The introduction of recombinant human erythropoietin (RHuEPO) has revolutionised the treatment of patients with anaemia of chronic renal disease. Clinical studies have demonstrated that RHuEPO is also useful in various non-uraemic conditions including haematological and oncological disorders, prematurity, HIV infection, and perioperative therapies. Besides highlighting both the historical and functional aspects of RHuEPO, this review discusses the applications of RHuEPO in clinical practice and the potential problems of RHuEPO treatment.

Enhancement of therapeutic protein in vivo activities through glycoengineering

Delivery of protein therapeutics often requires frequent injections because of low activity or rapid clearance, thereby placing a burden on patients and caregivers. Using glycoengineering, we have increased and prolonged the activity of proteins, thus allowing reduced frequency of administration. Glycosylation analogs with new N-linked glycosylation consensus sequences introduced into the protein were screened for the presence of additional N-linked carbohydrates and retention of in vitro activity. Suitable consensus sequences were combined in one molecule, resulting in glycosylation analogs of rHuEPO, leptin, and Mpl ligand. All three molecules had substantially increased in vivo activity and prolonged duration of action. Because these proteins were of three different classes (rHuEPO is an N-linked glycoprotein, Mpl ligand an O-linked glycoprotein, and leptin contains no carbohydrate), glycoengineering may be generally applicable as a strategy for increasing the in vivo activity and duration of action of proteins. This strategy has been validated clinically for glycoengineered rHuEPO (darbopoetin alfa).

Planning for hemorrhage. Steps an anesthesiologist can take to limit and treat hemorrhage in the obstetric patient

Obstetric hemorrhage continues to be a significant cause of maternal mortality and morbidity. Blood transfusion in such circumstances may be life saving but involves exposing the patient to additional risks. Limiting blood transfusion and using autologous blood when possible may reduce some of these risks. This article outlines the techniques that may be used to limit and more effectively treat hemorrhage in the obstetric patient, with particular attention paid to reducing the use of allogeneic blood transfusion.

A randomized, active-control, pilot trial of front-loaded dosing regimens of darbepoetin-alfa for the treatment of patients with anemia during chemotherapy for malignant disease

BACKGROUND

Anemia in patients receiving chemotherapy can be ameliorated with recombinant human erythropoietin (rHuEPO), which is administered one to three times per week. Darbepoetin alpha, a new erythropoietic agent, has longer serum residence time, allowing it to be administered less frequently.

METHODS

Patients (n = 127) were randomized to receive study drug for 12 weeks: either rHuEPO 40,000 U with escalations to 60,000 U for nonresponders or darbepoetin alpha at doses of 4.5 microg/kg per week until hemoglobin concentration >or= 12 g/dL, then 1.5 microg/kg per week (Group 1); 4.5 microg/kg per week for 4 weeks, then 2.25 microg/kg per week for 8 weeks (Group 2); or 4.5 microg/kg per week for 4 weeks, then 3.0 microg/kg every 2 weeks (Group 3). Efficacy was measured using the mean change in hemoglobin level, the proportion of patients achieving a hemoglobin response, the time to response, and the mean change in Functional Assessment of Cancer Therapy-Fatigue Scale scores. Safety was assessed by reports of adverse events.

RESULTS

Overall, after 4 weeks of treatment, the mean change (95% confidence interval [95%CI]) in hemoglobin concentration was 0.53 g/dL (95%CI, 0.05-1.02 g/dL), 0.70 g/dL (95%CI, 0.11-1.29 g/dL), and 0.90 g/dL (95%CI, 0.47-1.33 g/dL) in darbepoetin alpha Groups 1, 2, and 3, respectively, and 0.39 g/dL (95%CI, - 0.22-1.00 g/dL) in the rHuEPO group. By the end of the study, the mean change (95%CI) in hemoglobin concentration was 1.35 g/dL (95%CI, 0.67-2.02 g/dL), 1.35 g/dL (95%CI, 0.57-2.12 g/dL), and 1.28 g/dL (95%CI, 0.84-1.73 g/dL) in darbepoetin alpha Groups 1, 2, and 3, respectively, and 1.03 g/dL (95%CI, 0.53-1.53 g/dL) in the rHuEPO group. The early erythropoietic response in patients who were treated with darbepoetin alpha was associated with an early and maintained reduction in patient-reported fatigue. The adverse event profile was comparable with all doses of darbepoetin alpha and rHuEPO.

CONCLUSIONS

Darbepoetin alpha, given as a front-loaded dose for 4 weeks and followed by lower and/or less frequent doses, appears to be efficacious and may decrease the time to response relative to treatment with rHuEPO.

Use of epoetin in patients with cancer: evidence-based clinical practice guidelines of the American Society of Clinical Oncology and the American Society of Hematology

Anemia resulting from cancer, or its treatment, is an important clinical problem increasingly treated with the recombinant hematopoietic growth factor erythropoietin. To address uncertainties regarding indications and efficacy, the American Society of Clinical Oncology and the American Society of Hematology developed an evidence-based clinical practice guideline for the use of epoetin in patients with cancer. The guideline panel found good evidence to recommend use of epoetin as a treatment option for patients with chemotherapy-associated anemia with a hemoglobin level less than 10 g/dL. Use of epoetin for patients with less severe anemia (hemoglobin < 12 g/dL but never below 10 g/dL) should be determined by clinical circumstances. Good evidence from clinical trials supports the use of subcutaneous epoetin thrice weekly (150 U/kg tiw) for a minimum of 4 weeks. Less strong evidence supports an alternative weekly (40,000 U/wk) dosing regimen, based on common clinical practice. With either administration schedule, dose escalation should be considered for those not responding to the initial dose. In the absence of response, continuing epoetin beyond 6 to 8 weeks does not appear to be beneficial. Epoetin should be titrated once the hemoglobin concentration reaches 12 g/dL. Evidence from one randomized controlled trial supports use of epoetin for patients with anemia associated with low-risk myelodysplasia not receiving chemotherapy; however, there are no published high-quality studies to support its use for anemia in other hematologic malignancies in the absence of chemotherapy. Therefore, for anemic patients with hematologic malignancies, it is recommended that physicians initiate conventional therapy and observe hematologic response before considering use of epoetin.

An overview of the pharmacokinetic disposition of darbepoetin alfa

Darbepoetin alfa is a new erythropoiesis-stimulating protein that has five carbohydrate chains compared with three in recombinant human erythropoietin (r-HuEPO, epoetin alfa). Owing to its increased carbohydrate content, the terminal half-life of darbepoetin alfa is 2-3-fold greater than that of r-HuEPO in patients with chronic kidney disease or cancer. This pharmacokinetic property may allow for less frequent administration of darbepoetin alfa compared with r-HuEPO. Although several regimens are still being tested, a predictable increase was observed in serum concentrations of darbepoetin alfa and no clinically relevant accumulation was seen with once-weekly administration for up to 48 weeks. Preliminary data in patients with cancer suggest that concurrent chemotherapy may influence the pharmacokinetics of darbepoetin alfa. Therefore, the timing of dosing relative to chemotherapy may be important. Darbepoetin alfa, through its potential for less frequent dosing, offers a more convenient treatment option than r-HuEPO for patients with anemia secondary to cancer or kidney disease.

Overview of cancer-related anemia: focus on the potential role of darbepoetin alfa

Cancer-associated anemia is common and has many causes, including the effects of the underlying disease and cancer treatment. The effect of anemia on patients with cancer was not appreciated fully until relatively recently. Several well-designed studies have demonstrated the relationship between anemia and fatigue, and the effect of fatigue on quality of life. These data have resulted in a greater awareness of anemia in cancer and have increased the use of recombinant human erythropoietin (r-HuEPO, epoetin alfa) therapy for the treatment of anemia. Recombinant HuEPO produces a hemoglobin response in 50-60% of patients with cancer; however, to obtain this response rate, frequent dosing is required. Darbepoetin alfa, a recently developed erythropoietic protein, has a longer half-life than that of r-HuEPO, enabling less frequent dosing, and has a greater in vivo activity. In studies of patients with cancer who develop anemia, darbepoetin alfa has proved to be well tolerated and effective, and its advantages make it a potential improved treatment option for anemia in these patients.

Darbepoetin alfa given every 1 or 2 weeks alleviates anaemia associated with cancer chemotherapy

In part A of this study, patients were randomised to cohorts receiving darbepoetin alfa at doses of 0.5 to 8.0 m.c.g x kg(-1) x wk(-1) or to a control group receiving epoetin alfa at an initial dose of 150 U x kg(-1) three times weekly. In part B, the cohorts were darbepoetin alfa 3.0 to 9.0 m.c.g x kg(-1) every 2 weeks or epoetin alfa, initial dose 40 000 U x wk(-1). Safety was assessed by adverse events, changes in blood pressure, and formation of antibodies to darbepoetin alfa. Efficacy was assessed by several haematologic endpoints, including change in haemoglobin from baseline. The adverse event profile of darbepoetin alfa was similar to that of epoetin alfa. No relationship between the rapidity of haemoglobin response and any adverse event was observed. No antibodies to darbepoetin alfa were detected. Higher doses of darbepoetin alfa increased the proportion of patients with a haemoglobin response and decreased the median time to response. The overall dose of darbepoetin alfa required to produce a mean increase in haemoglobin does not increase when the dosing interval is increased from 1 to 2 weeks. Therapy with darbepoetin alfa is safe and effective in producing a dose-related increase in haemoglobin levels in patients with cancer receiving chemotherapy.

Darbepoetin alfa: a novel erythropoiesis-stimulating protein

OBJECTIVE

To review the pharmacology, pharmacokinetics, clinical efficacy, and safety of darbepoetin alfa.

DATA SOURCES

Pertinent references were identified by a MEDLINE search (1995-January 2001) of the medical literature, review of English-language literature and references of these articles, product information, and abstracts from professional meetings.

STUDY SELECTION

Clinical efficacy data were gathered from all available trial data citing darbepoetin alfa. Additional information concerning pharmacology, pharmacokinetics, and safety was also reviewed.

DATA SYNTHESIS

Darbepoetin alfa is a new erythropoiesis-stimulating protein with a threefold longer half-life than recombinant human erythropoietin (r-HuEPO). Darbepoetin alfa is approved for intravenous and subcutaneous administration in patients requiring and not requiring dialysis. Clinical studies in patients with chronic kidney disease (CKD) have shown darbepoetin alfa to be equivalent to r-HuEPO in terms of increases in hemoglobin concentration, percentage of patients obtaining target hemoglobin, and average time to reach target hemoglobin concentration. Trials are currently ongoing in patients receiving cancer chemotherapy. The adverse event profile appears to be similar between the 2 agents.

CONCLUSIONS

The equivalent efficacy and safety profile, as well as the longer half-life, may make darbepoetin alfa an attractive alternative to r-HuEPO in patients with CKD. Since these patients need to receive r-HuEPO 1-3 times weekly at the expense of increased healthcare utilization to improve their hemoglobin, agents such as darbepoetin alfa, with longer durations of action, may reduce healthcare expenses. In addition, enhanced patient compliance may be realized with once-weekly or once every-other-week administration.

Darbepoetin Alfa

Each month, subscribers to The Formulary® Monograph Service receive five to six well-documented monographs on drugs that are newly released or are in late Phase III trials. The monographs are targeted to your Pharmacy and Therapeutics Committee. Subscribers also receive monthly one-page summary monographs on the agents that are useful for agendas and pharmacy/nursing in-services. A comprehensive target drug utilization evaluation (DUE) is also provided each month. The monographs are published in printed form and on diskettes that allow customization. Subscribers to the The Formulary Monograph Service also receive access to a pharmacy bulletin board, The Formulary Information Exchange (The F.I.X). All topics pertinent to clinical and hospital pharmacy are discussed on The F.I.X.

Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. If you would like information about The Formulary Monograph Service or The F.I.X., call The Formulary at 800-322-4349. The December 2001 Formulary monograph topics are budesonide modified-release capsules, tenofovir disoproxil fumarate, pegfilgrastim, fulvestrant, and etonogestrol/ethinyl estradiol vaginal ring. The DUE is on budesonide modified-release capsules.

Erythropoietin therapy versus red cell transfusion

Erythropoietin therapy was approved for use as a blood conservation intervention beginning in 1989 for patients with medical anemia and in 1997 for surgical patients. The adoption of this strategy has been rapid in some settings (such as renal failure patients), progressive in others ( eg, cancer patients), and slow in others (surgery patients, for instance). At the same time, the risks of blood transfusion have declined substantially whereas the costs of blood transfusion have increased significantly. The evolution of new techniques such as acute normovolemic hemodilution (ANH) and the novel erythropoiesis-stimulating protein (NESP) bring new options to allogeneic blood transfusion. Erythropoietin therapy, with or without autologous blood procurement, is undergoing new scrutiny as an alternative to blood transfusion. This is not only because of traditional concerns regarding blood risks but because of new blood inventory and cost considerations.

Pharmacokinetics of novel erythropoiesis stimulating protein (NESP) in cancer patients: preliminary report

Anaemia is a common occurrence in patients with cancer, and currently can be treated in several ways. Novel erythropoiesis stimulating protein (NESP, darbepoetin alfa) was created using site-directed mutagenesis to have 8 more sialic acid side chains than recombinant human erythropoietin (rHuEPO). The additional sialic acid content has resulted in an approximately 3-fold greater half-life relative to rHuEPO in patients with chronic renal failure. This study evaluates the pharmacokinetic profile of NESP in patients receiving multiple cycles of chemotherapy. Anaemic patients (haemoglobin < or = 11.0 g dl(-1)) who had non-myeloid malignancies received NESP weekly (2.25 mcg kg(-1) wk(-1)) under the supervision of a physician, starting on day 1 of chemotherapy for 3 chemotherapy cycles given at 3-week intervals. Blood samples were collected during chemotherapy cycles 1 and 3 for pharmacokinetic analysis. All patients were followed for 4 weeks after treatment. NESP was well tolerated by all patients. After a single dose during chemotherapy cycle 1, pharmacokinetic parameters (mean (SD), n) for the first 15 patients were: T(max)86.1 (22.8) h (n = 14); C(max)9.0 (5.1) ng ml(-1)(n = 14); t(1/2,z)32.6 (11.8) h (n = 7); CL/F 3.7 (1.0) ml h(-1) kg(-1)(n = 7). The subjects for whom all parameters could be calculated may represent a sub-group of the entire population. Similar results were obtained in cycle 3. In addition, haemoglobin response data suggests that, in this patient population, dosing less frequently than the 3 times weekly doses used for rHuEPO may be possible while improving anaemia.

Anaemia and its functional consequences in cancer patients: current challenges in management and prospects for improving therapy

Anaemia is a common occurrence in patients with cancer and contributes to the clinical symptomatology and reduced quality of life (QOL) seen in cancer patients. Many aspects of reduced QOL, including fatigue, are known to be associated with suboptimally low levels of haemoglobin. Even mild-to-moderate anaemia adversely affects patient-reported QOL parameters. Red blood cell transfusions are associated with many real and perceived risks, inconveniences, costs, and only temporary benefits. Recombinant human erythropoietin (rHuEPO) is an effective therapy to increase haemoglobin values in over half of anaemic cancer patients receiving concurrent chemotherapy. These increased haemoglobin values are closely correlated with improvements in QOL. Despite these objectively defined benefits, less than 50% of anaemic patients undergoing cytotoxic chemotherapy receive rHuEPO, in contrast to patients with chronic renal failure on dialysis, where anaemia is universally and aggressively treated to more optimal haemoglobin values. However, there are several barriers that may limit more widespread use of rHuEPO. These include inconvenience associated with frequent dosing; failure of a large proportion (40 to 50%) of patients to respond; relatively slow time to response; absence of reliable early indicators of response; and current lack of rigorous pharmacoeconomic data demonstrating cost-effectiveness. Darbepoetin alfa is a novel erythropoiesis stimulating protein (NESP) that is biochemically distinct from rHuEPO, and which has been proven to stimulate red blood cell production. The molecule has a 3-fold longer half-life and increased biological activity that will allow less frequent dosing, facilitating improved management of the anaemia of cancer. With this new option for therapy, further avenues of investigation should lead to renewed interest in the clinical benefits of optimal haemoglobin levels for patients with cancer.