Pure red-cell aplasia and antierythropoietin antibodies in patients treated with recombinant erythropoietin

Treatment for women with postpartum iron deficiency anaemia

BACKGROUND

Postpartum anaemia is associated with breathlessness, tiredness, palpitations and maternal infections. Blood transfusions or iron supplementation have been used in the treatment of iron deficiency anaemia. Recently other anaemia treatments, in particular erythropoietin therapy, have also been used.

OBJECTIVES

To assess the clinical effects of treatments for postpartum anaemia, including oral, intravenous or subcutaneous iron/folate supplementation and erythropoietin administration, and blood transfusion.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group trials register (30 May 2004), the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 1, 2003), MEDLINE (1966 to March 2003), EMBASE (1980 to March 2003), Current Contents and ACP Journal Club (from inception to March 2003).

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing therapy for postpartum iron deficiency anaemia (oral, intravenous or subcutaneous administration of iron, folate, erythropoietin or blood transfusion) with placebo, another treatment or no treatment.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial quality and extracted data.

MAIN RESULTS

Six included RCTs involving 411 women described treatment with erythropoietin or iron as their primary interventions. No RCTs were identified that assessed treatment with blood transfusion. Few outcomes relating to clinical maternal and neonatal factors were reported: studies focused largely on surrogate outcomes such as haematological indices. Overall, the methodological quality of the included RCTs was reasonable; however, their usefulness in this review is restricted by the interventions and outcomes reported. When compared with iron therapy only, erythropoietin increased the likelihood of lactation at discharge from hospital (1 RCT, n = 40; relative risk (RR) 1.90, 95% confidence interval (CI) 1.21 to 2.98). No apparent effect on need for blood transfusions was found, when erythropoietin plus iron was compared to treatment with iron only (2 RCTs, n = 100; RR 0.20, 95% CI 0.01 to 3.92), although the RCTs may have been of insufficient size to rule out important clinical differences. Haematological indices (haemoglobin and haemocrit) showed some increases when erythropoietin was compared to iron only, iron and folate, but not when compared with placebo.

REVIEWERS' CONCLUSIONS

There is some limited evidence of favourable outcomes for treatment of postpartum anaemia with erythropoietin. However, most of the available literature focuses on laboratory haematological indices, rather than clinical outcomes. Further high-quality trials assessing the treatment of postpartum anaemia with iron supplementation and blood transfusions are required. Future trials may also examine the significance of the severity of anaemia in relation to treatment, and an iron-rich diet as an intervention.

Secreted Immunomodulatory Viral Proteins as Novel Biotherapeutics

Many viruses have learned to evade or subvert the host antiviral immune responses by encoding and expressing immunomodulatory proteins that protect the virus from attack by elements of the innate and acquired immune systems. Some of these viral anti-immune regulators are expressed as secreted proteins that engage specific host immune targets in the extracellular environment, where they exhibit potent anti-immune properties. We review here viral immunomodulatory proteins that have been tested as anti-inflammatory reagents in animal models of disease caused by excessive inflammation or hyperactivated immune pathways. The potential for such viral molecules for the development of novel drugs to treat immune-based or inflammatory disorders is discussed.

Enzyme therapy for Fabry disease: Neutralizing antibodies toward agalsidase alpha and beta

BACKGROUND

Fabry disease is an X-linked inherited disorder that is caused by excessive lysosomal globotriaosylceramide (CTH) storage due to a deficiency in alpha-galactosidase A (alpha-Gal A). Two recombinant enzyme preparations have been approved as treatment modality. We studied emergence and properties of alpha-Gal A antibodies in treated patients.

METHODS

During the first 6 to 12 months of intravenous administration of recombinant enzymes (rh-alpha-Gal A) formation of antibodies was studied in 18 adult Fabry patients (two females).

RESULTS

The female patients did not develop detectable amounts of antibodies following enzyme therapy. After 6 months of treatment with either agalsidase alpha or beta, 11/16 male patients showed high titers of immunoglobulin G (IgG) antibodies that cross-react in vitro similarly with both recombinant enzymes. The anti-rh-alpha-Gal A IgG neutralizes rh-alpha-Gal A activity in vitro for 65% to 95%. During infusion with rh-alpha-Gal A, circulating enzyme-antibody complexes are formed and these complexes are taken up by leukocytes in the peripheral blood. After 6 months of treatment all IgG-negative patients showed a significant (P < 0.01) reduction of urinary CTH (1890 +/- 797 to 603 +/- 291 nmol CTH/24hr urine), compared to IgG-positive patients (mean increase from 2535 +/- 988 to 2723 +/- 1212), suggesting a negative effect of circulating antibodies on renal tubular CTH clearance.

CONCLUSION

Emergence of antibodies with in vivo neutralizing capacities is frequently encountered in treated Fabry disease patients. Complete cross-reactivity of these antibodies suggests that it is unlikely that switching from one to the other recombinant protein prevents the immune response and related effects. Further studies on the clinical implications of alpha-Gal A antibodies are essential.

EORTC guidelines for the use of erythropoietic proteins in anaemic patients with cancer

Anaemia is frequently diagnosed in patients with cancer, yet it is difficult to identify a single cause due to its multifactorial aetiology. We conducted a systematic literature review (1996-2003) to produce evidence-based guidelines on the use of erythropoietic proteins in anaemic patients with cancer (see ). Level I evidence exists for a positive impact of erythropoietic proteins on haemoglobin (Hb) levels when administered to patients with chemotherapy-induced anaemia or anaemia of chronic disease, when used to prevent cancer anaemia, in patients undergoing cancer surgery and following allogeneic bone marrow transplantation. The Hb level at which erythropoietic protein therapy should be initiated is difficult to determine as it varied between studies; a large number of Level I studies in patients with chemotherapy-induced anaemia or anaemia of chronic disease enrolled patients with a Hb concentration </=105 g/L, but none compared the effect of different baseline Hb levels on the response to treatment. Similarly, several studies defined the target Hb concentration as 120-130 g/L following treatment with erythropoietic proteins, but none specifically addressed the correlation between target Hb level and clinical benefit in a randomised fashion. Level I evidence shows that red blood cell (RBC) transfusion requirements are significantly reduced with erythropoietic protein therapy in patients with chemotherapy-induced anaemia or when used to prevent cancer anaemia (approximately 20% reduction compared with controls). We found indirect Level I and III evidence that patients with chemotherapy-induced anaemia or anaemia of chronic disease initially classified as non-responders to standard doses proceed to respond to treatment following a dose increase (absolute increases in response rate ranged from 8% to 18%). However, none of these studies examined the effect on response rates of a longer treatment period at the lower dose, or performed a randomised comparison of a dose increase versus an unchanged dose. There is Level I evidence to show that quality-of-life (QOL) is significantly improved in patients with chemotherapy-induced anaemia and in those with anaemia of chronic disease, particularly in patients achieving a Hb response to erythropoietic protein therapy. There are insufficient data to determine the effect on survival following treatment with erythropoietic proteins in conjunction with chemotherapy or radiotherapy. There is Level I evidence that dosing of erythropoietic proteins less frequently than three times per week (TIW) is efficacious when used to treat chemotherapy-induced anaemia or prevent cancer anaemia. There is Level III evidence that initial doses of erythropoietic proteins considered to be higher than current standard practice produce higher haematological responses in patients with chemotherapy-induced anaemia or anaemia of chronic disease. Level I evidence demonstrates that several baseline patient parameters (e.g., low endogenous erythropoietin [EPO] concentration, age <60 years, Hb concentration >/=90 g/L) impact upon the response to erythropoietic proteins when used to treat chemotherapy-induced anaemia or prevent cancer anaemia. Evidence indicates that endogenous EPO concentration impacts on response in patients with lymphoproliferative malignancies, but is not a valid parameter in patients with solid tumours. There is Level I evidence that fixed doses of erythropoietic proteins can be used at the start of therapy to treat patients with chemotherapy-induced anaemia, but maintenance doses should be titrated individually. There is no evidence that pure red cell aplasia (PRCA) occurs following treatment with erythropoietic proteins in patients with chemotherapy-induced anaemia or when used prophylactically in patients with cancer. There is Level I evidence that the risk of thromboembolic events and hypertension are slightly elevated in patients with chemotherapy-induced anaemia receiving erythropoietic proteins. Level I evidence supports the effectiveness of erythropoietic proteins to prevenroteins to prevent anaemia in non-anaemic cancer patients receiving chemotherapy or radiotherapy or in those undergoing cancer surgery. However, these are non-licensed indications and we do not currently recommend the prophylactic use of erythropoietic proteins to prevent anaemia in patients who have normal Hb values at the start of treatment. Additional trials are warranted, especially on the issues of iron replacement and cost-effectiveness of erythropoietic protein therapy, as well as on tumour response/progression and survival.

Pure red-cell aplasia and epoetin therapy

BACKGROUND

Between 1988 and 1998, antibody-associated pure red-cell aplasia was reported in three patients who had undergone treatment with recombinant human erythropoietin (epoetin). Between 1998 and 2000, 13 such cases were reported from France--12 in patients who had received the Eprex formulation of epoetin alfa and 1 in a patient who had received Neorecormon (a formulation of epoetin beta); both are products that are marketed outside the United States.

METHODS

We obtained reports of epoetin-associated pure red-cell aplasia from the Food and Drug Administration and from the manufacturers of Eprex, Epogen (another formulation of epoetin alfa), and Neorecormon. The numbers of case reports and estimates of exposure-adjusted incidence were analyzed according to the product, the cause of anemia, the route of administration, the country in which pure red-cell aplasia was identified, and the date on which pure red-cell aplasia was reported.

RESULTS

Between January 1998 and April 2004, 175 cases of epoetin-associated pure red-cell aplasia were reported for Eprex, 11 cases for Neorecormon, and 5 cases for Epogen. Over half these cases had occurred in France, Canada, the United Kingdom, and Spain. Between 2001 and 2003, the estimated exposure-adjusted incidence was 18 cases per 100,000 patient-years for the Eprex formulation without human serum albumin, 6 per 100,000 patient-years for the Eprex formulation with human serum albumin, 1 case per 100,000 patient-years for Neorecormon, and 0.2 case per 100,000 patient-years for Epogen. After procedures were adopted to ensure appropriate storage, handling, and administration of Eprex to patients with chronic kidney disease, the exposure-adjusted incidence decreased by 83 percent worldwide.

CONCLUSIONS

After the peak incidence of Eprex-associated pure red-cell aplasia was reached in 2001, interventions designed in response to drug-monitoring programs worldwide resulted in a reduction of more than 80 percent in the incidence of pure red-cell aplasia due to Eprex.

Phase III, randomized, double-blind study of epoetin alfa compared with placebo in anemic patients receiving chemotherapy

PURPOSE

To determine whether weekly epoetin alfa could improve hemoglobin (HgB) levels, reduce RBC transfusions, and improve quality of life (QOL) in patients with advanced cancer and with anemia after receiving myelosuppressive chemotherapy.

PATIENTS AND METHODS

This double-blind, placebo-controlled study randomly assigned patients to placebo or epoetin alfa (Ortho Biotech, Bridgewater, NJ) 40,000 U subcutaneous weekly for 16 weeks. QOL, HgB, and RBC transfusions were measured pretreatment and monthly.

RESULTS

The study accrued 344 patients; 330 were assessable for efficacy and 305 were assessable for QOL. Placebo-treated patients had a mean increase in HgB of 0.9 g/dL (range, -3.8 to +5.3) compared with 2.8 g/dL (range, -2.2 to +7.5) for epoetin-treated patients (P < .0001). During the study, 31.7% of placebo-treated patients achieved a > or = 2 g/dL HgB increase compared with 72.7% of epoetin-treated patients (P < .0001). The incidence of RBC transfusion for placebo and epoetin treatment arms was 39.6% and 25.3% (P = .005), respectively. The placebo group received 256 units of RBCs compared with 127 units in the epoetin group (P < .0001). The incidence of toxicity in the groups was similar. Changes in the average QOL scores from baseline to the end of the study were similar in the two groups (P = not significant). The HgB responders (irrespective of treatment arm) had a mean change in Functional Assessment of Cancer Therapy (FACT) fatigue score from a baseline of +5.1 compared with -2.1 for the nonresponders (P = .006).

CONCLUSION

Epoetin alfa significantly improved HgB and reduced transfusions in this patient population. These results support the use of weekly epoetin alfa as an ameliorative agent for cancer-related anemia.

Treatment of cancer-related anemia with epoetin alfa: a review

Erythropoietin (EPO) is a hematopoietic growth hormone that regulates survival, proliferation, and differentiation of erythroid progenitor cells. A reduction in tissue oxygenation stimulates EPO production, through a complex feedback mechanism. Patients with cancer-related anemia have an inadequate EPO response that is further impaired by cancer treatments such as chemotherapy. Cancer-related anemia substantially impairs patient functioning and may contribute to poor treatment outcomes. A significant number of studies demonstrates that treatment of anemia in cancer patients using recombinant human EPO (rHuEPO, epoetin alfa) significantly increases haemoglobin (Hb) levels, reduces transfusion requirements, and improves quality of life, particularly by relieving fatigue. Recent data also show that epoetin alfa therapy may improve cognitive function in patients receiving chemotherapy. In addition, the correction of anemia may prolong survival by enhancing tumor oxygenation, thus increasing tumor sensitivity to chemotherapy or radiation. The indicated dose of epoetin alfa is 150-300 IU/kg three times per week, but it is commonly dosed at 40,000-60,000 IU once weekly based on trial data and extensive clinical use. Determining the timing of initiation of epoetin alfa is a clinical judgement; however, data suggest that patient functioning declines and the risk of transfusion increases when the Hb level falls under 12 g/dL.

High prevalence in Switzerland of pure red-cell aplasia due to anti-erythropoietin antibodies in chronic dialysis patients: report of five cases

BACKGROUND

Pure red-cell aplasia (PRCA) after erythropoietin (Epo) administration due to the appearance of neutralizing anti-Epo antibodies has been reported in over 200 cases between 1998 and 2002. However, large intercountry disparities were observed in the occurrence of this syndrome.

METHODS

On behalf of the Swiss Society of Nephrology, a survey was conducted in all the dialysis units of Switzerland in order to collect information on the occurrence, diagnostic and evolution data of the cases observed. A questionnaire was send to the nephrologists in charge of each of the 69 dialysis units in January 2003. The clinical and biological data of the suspected cases were analysed and compared with the data provided to health authorities and pharmaceutical companies.

RESULTS

A total of five cases were identified as true PRCA with demonstrated positive anti-Epo antibodies. They occurred between November 1998 and February 2002, were all treated by haemodialysis and had received Epo subcutaneously. The median appearance time of refractory anaemia after Epo initiation was 10 months (range: 7-54 months). Two cases had been treated exclusively with epoietin-alpha, one solely with epoietin-beta and the two others with a combination of both. With five cases out of a total of about 2500 dialysis patients and 2300 Epo-treated dialysis patients or an exposure rate to Epo of 9900 dialysis patient-years during a 4.3 year period, this prevalence is among the highest of those reported in European countries.

CONCLUSIONS

The prevalence of PRCA after Epo administration in dialysis patients appears particularly high in Switzerland. Among the potential explanations, the most plausible are the high percentage of dialysis patients treated with Epo, the almost exclusive subcutaneous administration, the larger market distribution of the epoietin-alpha brand, the eventual disruption of the cold chain and the setting-up of a systematic national survey.

Modifying an immunogenic epitope on a therapeutic protein: a step towards an improved system for antibody-directed enzyme prodrug therapy (ADEPT)

Carboxypeptidase G2 (CP) is a bacterial enzyme, which is targeted to tumours by an antitumour antibody for local prodrug activation in antibody-directed enzyme prodrug therapy (ADEPT). Repeated cycles of ADEPT are desirable but are hampered by human antibody response to CP (HACA). To address this, we aimed to identify and modify clinically important immunogenic sites on MFECP, a recombinant fusion protein of CP with MFE-23, a single chain Fv (scFv) antibody. A discontinuous conformational epitope at the C-terminus of the CP previously identified by the CM79 scFv antibody (CM79-identified epitope) was chosen for study. Modification of MFECP was achieved by mutations of the CM79-identified epitope or by addition of a hexahistidine tag (His-tag) to the C-terminus of MFECP, which forms part of the epitope. Murine immunisation experiments with modified MFECP showed no significant antibody response to the CM79-identified epitope compared to A5CP, an unmodified version of CP chemically conjugated to an F(ab)(2) antibody. Success of modification was also demonstrated in humans because patients treated with His-tagged MFECP had a significantly reduced antibody response to the CM79-identified epitope, compared to patients given A5CP. Moreover, the polyclonal antibody response to CP was delayed in both mice and patients given modified MFECP. This increases the prospect of repeated treatment with ADEPT for effective cancer treatment.

Indications et limites de l'utilisation d'érythropoïétine recombinée en réanimation

OBJECTIVE

To analyze the data from the literature on erythropoietin and the future indications of recombinant human erythropoietin in intensive care unit (ICU) patients.

DATA SOURCE

References were obtained from computerized bibliographic research (Pubmed) from 1986 to 2003, except for some physiologic data.

DATA SELECTION

Original articles, reviews, and letters to editor in French and English were selected and analyzed.

DATA SYNTHESIS

An anemia is often observed in patients hospitalized in ICU. This anemia may be due to many reasons. The management of anemia consists on the treatment of the underlying disease associated with the transfusion of red blood cells. Recent studies provided evidence of an association between transfusions and mortality in ICU patients. The anemia of ICU patients is compared to the anemia of chronic diseases, which is characterized by a blunted erythropoietin. A treatment with rHuEPO may be a future therapeutic of the anemia in such patients. A multicentric study shows the efficacy of recombinant erythropoietin therapy on a decrease in the use of red blood cell, and another clinical trial highlights a decrease of the proportion of ICU patients receiving red blood cell. Recombinant erythropoietin could be an alternative to transfusion in certain conditions and certain ICU patients. Further studies are needed to determine the consequences on mortality rate and to clarify the place of this therapy in ICU patients.

Does erythropoietin protect the preterm brain?

There is a high incidence of hypoxic-ischaemic brain injury and intraventricular haemorrhage in newborn infants, particularly those born preterm. Many die during the newborn period or suffer permanent neurodevelopmental handicaps. Hypoxic brain injury develops over several hours and could potentially be influenced by intervention. At present, no drug exists that effectively prevents infant brain injury or ameliorates detrimental neurodevelopmental effects. The hypothesis is put forward that systemic administration of recombinant human erythropoietin positively affects the neurodevelopmental outcome of high risk preterm infants affected by brain injury. A multicentre, randomised, placebo controlled study is proposed to prospectively test this hypothesis.

Autoantibodies against granulocyte-macrophage colony stimulating factor and interleukin-3 are rare in patients with Felty's syndrome

OBJECTIVES

Antibodies against granulocyte colony stimulating factor are frequently found in patients with Felty's syndrome (FS). In this study, we examined the prevalence of antibodies against two other granulopoietic cytokines: granulocyte-macrophage colony stimulating factor (GM-CSF) and interleukin-3 (IL3).

METHODS

Sera of 32 patients with FS, 20 normocytic patients with rheumatoid arthritis (RA), and 72 healthy individuals were screened for the presence of antibodies against GM-CSF and IL3 by ELISA and bioassays, using the human erythroleukaemia cell line TF-1.

RESULTS

In two of the 32 patients with FS, antibodies to GM-CSF and IL3 were detectable by ELISA. Binding anti-GM-CSF antibodies were also detected in one of the 72 healthy controls, while in another healthy subject and in one of the patients with normocytic RA, anti-IL3 antibodies were present. Serum from one of the two patients with FS who tested positive for anti-IL3 and anti-GM-CSF antibodies by ELISA showed strong neutralising capacity to the biological effect of IL3, but not to GM-CSF in vitro. Patients with FS had significantly higher serum levels of GM-CSF (median; 2.82 pg/mL; interquartile range 2.64-3.19 pg/mL) compared with patients with RA (2.52 pg/mL; 2.28-2.72 pg/mL; p = 0.012) and healthy controls (2.23 pg/mL; 2.04-2.52; p<0.001). In addition, serum levels of IL3 in patients were significantly higher in FS (10.05 pg/mL; 8.94-11.98) compared with controls (4.79 pg/mL; 3.72-7.22; p<0.001), but not compared with RA patients (9.52 pg/mL; 8.32-10.42; p = 0.17).

CONCLUSIONS

Antibodies to GM-CSF and IL3 are rare in patients with FS and RA and in healthy subjects. In individual patients with FS, the presence of neutralising anti-IL3 antibodies may contribute to the development of cytopenia.

Pure red cell aplasia--a rare disease with multiple causes

Pure red cell aplasia (PRCA) is a relatively rare disease although multiple factors are implied in the pathogenesis of its development. A slow progressive normocytic-normochromic anemia and reticulocytopenia, without leukopenia and thrombocytopenia in a patient who, except pallor, does not show abnormal findings on physical examination, should arise the suspicion that he has PRCA. Search for underlying diseases or infections and intake of drugs may help for the establishment of the diagnosis of acquired PRCA. Lack of erythroblasts in the bone marrow with normal development of the other hemopoietic series, as well as high level of serum erythropoietin are important clues for the diagnosis. Elimination of potentially causative factors, administration of immunosuppressive agents and/or recombinant erythropoietin, preferably epoetin beta, may induce remission and complete recovery.

Treatment of beta-thalassemia patients with recombinant human erythropoietin: effect on transfusion requirements and soluble adhesion molecules

The most common single genetic disorder and a major public health issue in Greece and other Mediterranean countries is beta-thalassemia. Current therapeutic approaches for homozygous beta-thalassemia entail blood transfusions and iron chelation therapy with deferoxamine or deferiprone for preventing tissue hemosiderosis. Recently, much effort has focused on various inducers of fetal hemoglobin (HbF) such as recombinant human erythropoietin (rHuEPO), especially in beta-thalassemia intermedia. Ten adult patients, 5 with beta-thalassemia major and 5 with beta-thalassemia intermedia, received 150 IU/kg rHuEPO (epoetin-alpha) subcutaneously three times a week. Seven patients were transfused every 14-30 days and 3 with beta-thalassemia intermedia were only occasionally transfused. The minimum duration of treatment was 12 weeks in order to define if there was any response. Transfusion intervals were modified according to the rHuEPO response to maintain stable Hb values. Lower transfusion requirements were observed in 5 patients after rHuEPO treatment (p = 0.028). In the 3 non-transfused patients, Hb values increased, and the patients are still being treated and followed up for a period ranging from 14 weeks to 2 years. Two patients with thalassemia major discontinued treatment after 12 weeks, as they did not achieve any response regarding transfusion requirements or Hb values. Pretreatment serum transferrin receptor levels were higher than in controls (p < 0.001) and significantly increased following rHuEPO treatment (p = 0.027). Patients had higher serum endothelin-3, sICAM-1 and sE-selectin values before rHuEPO treatment compared to controls (p < 0.001, p < 0.001 and p = 0.016, respectively), but these values were not altered during treatment. HbF values presented a slight, non-significant increase. rHuEPO treatment has a beneficial effect in transfusion-dependent beta-thalassemia patients. Although a slight increase in HbF levels was observed, other possible mechanisms are probably involved. None of our patients experienced thrombotic complications and a rise in blood pressure.

Role of iron in anaemic critically ill patients: it's time to investigate!

Anaemia is a common problem in critically ill patients admitted to intensive care units. Many factors can be involved in its development, including rapid alterations of iron metabolism. Maintenance of iron homeostasis is a prerequisite for many essential biological processes and a central element for the development of erythroid precursors and mature red blood cells. With the inflammatory process, iron distribution is disturbed, with decreased serum iron levels and increased iron stores. Little information is available on the precise role of alterations of iron metabolism in the development of iron anaemia in critically ill patients.

Haemoglobin response to subcutaneous versus intravenous epoetin alfa administration in iron-replete haemodialysis patients

BACKGROUND

Numerous prior studies have reported that a substantially higher dose of epoetin is required to maintain haemoglobin (Hb) concentration when patients are switched from a subcutaneous (s.c.) to intravenous (i.v.) route of administration. Many of the reported trials, however, involved patients who did not have adequate serum iron levels. It was hypothesized that patients with adequate iron stores who are switched from one route of administration to the other without a change in dose will experience substantially less change in their Hb concentration.

METHODS

Haemodialysis patients who were iron replete (ferritin 300-800 microg/L, transferrin saturation (TSAT) 25-50%) participated in a prospective, randomized cross-over trial receiving epoetin for 3 months either by s.c. or i.v. injection followed by a further 3 months of epoetin via the other route. The principal aim was to determine changes in Hb concentration without altering the weekly epoetin dose. The secondary aim was to assess whether the frequency of dosing (once, twice or thrice weekly) influenced the Hb concentration response.

RESULTS

Eighty-one patients (mean age 62 years, 60% male) entered the study and 15 withdrew prior to study completion. Forty-three patients began s.c. epoetin alfa administration (group A) and 38 on i.v. (group B). Median ferritin and TSAT at entry for groups A and B were 409 and 394 microg/L (NS) and 31 and 32% (NS), respectively, which remained within the target range during the study. Median epoetin doses for groups A and B were similar (90 vs 93 IU/kg per week, NS). After 3 months, the mean Hb concentration rose for group A (SC; 118.7-121.9 g/L (P = 0.03)) but it fell for group B (i.v.; 119.1-116.0 g/L (P = 0.019)). Following the change in route of administration, the Hb concentration for group A (i.v.) fell by 5.1% over 3 months (121.9-115.4, P < 0.001) and rose by 2.8% for group B (s.c.) over 3 months (116.0-119.7, P = 0.001). Similar significant changes in the Hb concentration were seen at different dosing frequencies.

CONCLUSION

Subcutaneous administration of epoetin produces a significant, although slight clinical change in Hb concentration compared with i.v. administration in stable, iron replete, haemodialysis patients. A similar effect appears to prevail regardless of the frequency of injections given.

Treatment of erythropoietin-induced pure red cell aplasia: a retrospective study

BACKGROUND

Recombinant human erythropoietin is the standard treatment for anaemia related to chronic kidney disease, and its widespread use has been favoured by a very high therapeutic index. However, since 1998, more than 200 patients worldwide with chronic kidney disease treated in this way have developed neutralising antibodies to erythropoietin, causing pure red cell aplasia. We aimed to collate clinical and pathological features in patients unequivocally shown to have erythropoietin-induced pure red cell aplasia.

METHODS

We retrospectively obtained data from the files of 47 patients with pure red cell aplasia. We assessed treatment and outcome of patients and defined recovery from pure red cell aplasia as an increase in reticulocyte counts to more than 20 000 per microL in patients who were no longer transfusion-dependent.

FINDINGS

When patients developed pure red cell aplasia, all were receiving erythropoietin subcutaneously, and the product most typically prescribed was epoetin alfa (Eprex, Ortho Biotech). The median delay between start of erythropoietin treatment and occurrence of pure red cell aplasia was 11 months (IQR 7.5-14). Nine patients received no immunosuppressive treatment, and none of these recovered. Of 37 patients who received immunosuppressive therapy, 29 (78%) recovered. All six patients who received a kidney transplant recovered within 1 month, and recovery rates were between 56% and 88% in patients treated with corticosteroids, corticosteroids plus cyclophosphamide, or ciclosporin. No relapse of pure red cell aplasia happened after stopping immunosuppressive treatment, but no patient was rechallenged with erythropoietin.

INTERPRETATION

Immunosuppressive treatment accelerates recovery from erythropoietin-induced pure red cell aplasia.

Evaluation of methods to detect and characterize antibodies against recombinant human erythropoietin

BACKGROUND

From May 1998 to November 2000, 13 European patients developed antibody-mediated pure red cell aplasia during treatment with recombinant human erythropoietin (rHuEPO), reinforcing the need for analytical testing for antibodies against erythropoietic agents. Specimens from 8 patients were provided for further antibody testing and characterization.

METHODS

We evaluated 4 analytical methods with these sera: radioimmune precipitation (RIP), enzyme-linked immunosorbent assay (ELISA), biosensor immunoassay, and a bioassay for identification of neutralizing antibodies.

RESULTS

The RIP, biosensor immunoassay, and biological assay performed equally to detect and quantify anti-rHuEPO antibodies. The ELISA failed to detect antibodies in 2 patient samples. The biosensor immunoassay could determine antibody isotypes, subclasses, and dissociation rates and the bioassay could determine whether these antibodies were able to neutralize the biological effect of the drug; the other assays could not make this determination.

CONCLUSION

We recommend the use of the biosensor immunoassay followed by a bioassay to best identify and characterize anti-rHuEPO antibodies. The biosensor immunoassay allows for identification of all classes and subclasses of immunoglobulins and is a preferred method for the identification of lower-affinity antibodies. The bioassay is needed to determine if the antibodies identified have the capacity to neutralize a biological effect of the drug in a cell-based system.

EPO or Not-EPO? An Evidence Based Informed Consent

Background

Informed consent is crucial in therapeutic choices; however, the forms presented to patients are often locally developed and information may not be homogeneous.

Objective

To prepare an evidence-based model for informed consent, applied in the case of erythropoietin therapy (EPO) as a teaching tool for medical students.

Methods

Methodological tools of Evidence-Based Medicine (EBM) were developed within the EBM Course in the Medical School of Torino, Italy, as problem solving and patient information tools (5th year students work in small groups under the supervision of statisticians, epidemiologists and experts of internal medicine - nephrology in this case).

Results

Methodological and ethical problems were identified: in the pre-dialysis field, evidence from randomized clinical trials (RCT) is scant; how to use evidence gathered in dialysis? How to deal with implementation? How with the mass media? Do we need to discuss the drug choice with the patients? How to deal with rare and severe side effects?). The “evidence” was searched for on Medline/Embase, by using key-words and free terms. About 680 papers were retrieved and screened. Forms available on the Internet were retrieved and a general scheme was drawn: it included 5 areas: title, aim and targets (patients and family physicians); search strategies and updating; pros and cons of therapy; alternative options; open questions.

Conclusions

EBM may offer valuable tools for systematically approaching patient information; the inclusion of this kind of exercise in the Medical School EBM courses may help enhance the awareness of future physicians of the correct communication with patients.

Assessment of pure red cell aplasia in US dialysis patients: the limits of the medicare data

BACKGROUND

A report of neutralizing antibodies to recombinant human erythropoietin (rHuEPO) in European dialysis patients raised concerns that US dialysis patients may be at similar risk. We investigated the frequency of diagnosis codes that include pure red cell aplasia (PRCA) in the Medicare end-stage renal disease data.

METHODS

Medicare claims data were used to identify incident dialysis patients from 1995 through 1999 aged 67 years or older who did not have a diagnosis code for aplastic anemia (AA; which includes PRCA) or were not administered rHuEPO before dialysis therapy initiation. Patients were assessed for complicating conditions, rHuEPO dose, hematocrit level, blood transfusion, bone marrow testing, and AA diagnosis (maximal follow-up, 13 months).

RESULTS

Of 101,782 patients eligible for study, 9,896 patients had diagnosis codes for AA after dialysis therapy initiation, 3,894 patients underwent bone marrow tests (required for PRCA diagnosis), 19 patients had diagnosis codes for AA based on bone marrow examination and no other complicating conditions, and 5 patients were administered blood transfusion in 1 or more months during follow-up, of whom only 1 patient had persistent low hematocrit levels while being administered rHuEPO and blood transfusion. This latter patient was identified from a total of 101,782 patients, or 70,706.75 person-years of rHuEPO exposure.

CONCLUSION

Diagnosis codes in the Medicare data are inadequate for the conclusive study of PRCA in US dialysis patients. Despite limitations of this study, it appears that few cases of rHuEPO-associated PRCA have occurred in US Medicare dialysis patients. Additional investigation is needed to determine whether apparent differences between US complication rates and those elsewhere result from differences in the manufacturing and/or use of erythropoietin products.

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 experience with darbepoietin alfa (NESP) in children undergoing hemodialysis

Darbepoietin alfa (NESP) is a new long-acting erythropoietin, with a half-life 3 times longer than the old epoietins. In the present study, we evaluated the efficacy of NESP in a group of children on hemodialysis. Seven children, five male and two female, with a mean age of 11.5 +/- 3 years and a mean weight of 34.1 +/- 11 kg, were enrolled in the study. All had been treated for at least 6 months with epoietin alfa at a mean dose of 106 +/- 76 IU/kg 3 times/week i.v. They were then given NESP at a mean dose of 1.59 +/- 1.19 microg/kg once a week i.v., according to the suggested conversion index (weekly epoietin alfa dose/200=weekly NESP dose). Anemia was evaluated at the end of a dialysis session. This was especially important for children less compliant with water restriction. Serum ferritin and percentage transferrin saturation (TSAT) were also monitored, as were dialysis efficacy (Kt/V), blood pressure, and heparin requirements. Before starting the new treatment, all patients had an adequate mean hemoglobin (Hb) level (11.19 +/- 1.7 g/dl) and an adequate iron status (TSAT 24.2 +/- 11.5, serum ferritin 220 +/- 105 mg/dl). Five of the seven patients were also treated with intravenous ferric gluconate (10-20 mg/kg per week). Six children were on antihypertensive treatment. After the 1st month of treatment, we observed an excessive increase in Hb, 12.3 +/- 1.7 g/dl, (P<0.05), with severe hypertension in the youngest two patients (Hb>13 g/dl). A short discontinuation of the medication, followed by restarting at a decreased dosage, allowed us to continue with the treatment. At the 2nd month of follow-up, a mean plasma Hb level of 12.2 +/- 1.2 g/dl was observed, with a NESP mean dose of 0.79 +/- 0.4 microg/kg per week. Steady state was reached at 3 months, with a mean Hb of 11.8 +/- 1.4 g/dl and a mean NESP dose of 0.51 +/- 0.18 microg/kg per week (P<0.05). These results persisted at 6 months of follow-up; only one child had a persistent increase in platelet level (373,000 vs. 555,000). Dialysis efficiency and heparin requirements during dialysis did not change significantly. The high efficacy of NESP allowed a consistent reduction in dosage. The suggested conversion index does not appear to be correct for pediatric patients. Our experience suggests that in this population the correct dose could be 0.25-0.75 microg/kg per week. Hypertension was the only major side effect reported. The influence of NESP on platelet proliferation needs to be further investigated. The single weekly administration of NESP could be effective and beneficial for both patients and clinicians.

Neonatal transfusion practice

Many previously widely accepted neonatal transfusion practices are changing as neonatologists become more aware of the risks to their patients of multiple blood product transfusions. Recent literature and research on neonatal transfusion practice are here reviewed, and practical guidelines and trigger thresholds for blood products commonly used in neonatal medicine are proposed.

Haemopoietic growth factors for neonates: assessing risks and benefits

This review summarises the rationale, clinical trial evidence for benefit and potential toxicities of Erythropoietin, Thrombopoietin, Granulocyte Colony Stimulating Factor and Granulocyte-Macrophage Colony Stimulating Factor. Erythropoietin has failed to have a clinical impact on red cell transfusion requirement in very low birth weight infants; it is uncertain whether Thrombopoietin will find a significant clinical role in neonatal thrombocytopenia and there is, as yet, insufficient evidence for the routine use of Granulocyte- or Granulocyte-Macrophage Colony Stimulating Factor to prevent or treat bacterial infection. A number of theoretical risks of haemopoietic growth factor use in neonates have been suggested, but no toxicities have been observed during their clinical use. Exploring the potential for benefit in selected groups of infants should be encouraged.

Recovery from pure red cell aplasia caused by anti-erythropoietin antibodies after kidney transplantation

The use of recombinant human erythropoietin (rHuEPO) is a major advance in the treatment of patients with anemia caused by chronic renal failure (CRF). The development of antierythropoietin (anti-EPO) antibodies following treatment with rHuEPO has been observed in an increasing number of patients. This causes pure red cell aplasia (PRCA) and requires the definitive withdrawal of rHuEPO. Many patients require immunosuppressive therapy before anti-EPO antibodies disappear completely. We report a case of PRCA owing to anti-EPO in a 20-year-old hemodialyzed man who was receiving immunosuppressive therapy for a liver transplantation carried out in childhood. He required repeated red cell transfusions until a kidney transplantation was performed. He received an induction therapy with antithymocyte globulins and a maintenance regimen consisting of steroids, tacrolimus and mycophenolate mofetil. This new immunosuppressive treatment led to the complete disappearance of anti-EPO antibodies within a few weeks after the kidney transplantation. Erythropoiesis and endogenous erythropoietin synthesis were restored following transplantation, without leading to an increase in the titer of anti-EPO antibodies.

Minimizing the immunogenicity of protein therapeutics

As is cautioned in many package inserts, 'with all therapeutic proteins, there is a potential for immunogenicity'. Immunogenicity problems in humans, which currently can be detected only in clinical trials or after product launch, pose a significant barrier to the development and acceptance of protein drugs. Recent and ongoing research, presented in this review, seeks to address the challenge of protein therapeutic immunogenicity by elucidating the mechanisms underlying immune recognition of protein therapeutics, establishing preclinical methods for assessing immunogenicity and developing strategies for minimizing immune responses.

Pure red cell aplasia with anti-erythropoietin antibodies occurs more commonly with one formulation of epoetin alfa than another

OBJECTIVE

To compare rates of pure red cell aplasia (PRCA) over time in patients with chronic renal failure treated with subcutaneous injections of two brands of epoetin alfa (either Eprex or Epogen) or epoetin beta (NeoRecormon).

METHODS

Cases of antibody-mediated PRCA associated with epoetin alfa-treated patients were obtained from public databases and company websites and limited to time periods when exposure data also were available The subcutaneous exposure rates per 100 000 patient-years were calculated for the periods 1989-1998 and 1999-2002.

RESULTS

The event rate for antibody-mediated PRCA for Epogen and Eprex were similar from 1989 to 1998, but the number of cases of Eprex-associated PRCA has increased markedly since 1999, even after accounting for subcutaneous exposure. In contrast, rates have remained low for Epogen and NeoRecormon.

CONCLUSIONS

The recent increase in PRCA appears to be product specific and cannot be explained solely as a consequence of increased use of the subcutaneous route of administration.

Erythropoietin: a candidate compound for neuroprotection in schizophrenia

Erythropoietin (EPO) is a candidate compound for neuroprotection in human brain disease capable of combating a spectrum of pathophysiological processes operational during the progression of schizophrenic psychosis. The purpose of the present study was to prepare the ground for its application in a first neuroprotective add-on strategy in schizophrenia, aiming at improvement of cognitive brain function as well as prevention/slowing of degenerative processes. Using rodent studies, primary hippocampal neurons in culture, immunohistochemical analysis of human post-mortem brain tissue and nuclear imaging technology in man, we demonstrate that: (1) peripherally applied recombinant human (rh) EPO penetrates into the brain efficiently both in rat and humans, (2) rhEPO is enriched intracranially in healthy men and more distinctly in schizophrenic patients, (3) EPO receptors are densely expressed in hippocampus and cortex of schizophrenic subjects but distinctly less in controls, (4) rhEPO attenuates the haloperidol-induced neuronal death in vitro, and (4) peripherally administered rhEPO enhances cognitive functioning in mice in the context of an aversion task involving cortical and subcortical pathways presumably affected in schizophrenia. These observations, together with the known safety of rhEPO, render it an interesting compound for neuroprotective add-on strategies in schizophrenia and other human diseases characterized by a progressive decline in cognitive performance.

A Study of the Response of Elderly Patients with End-Stage Renal Disease to Epoetin Alfa or Beta

BACKGROUND

Anaemia correction in patients with end-stage renal disease has been enhanced following the use of epoetin alfa or beta and there are a number of studies detailing its application. Dialysis centres are dealing with greater numbers of elderly patients and anaemia correction in these individuals may differ by virtue of co-existing comorbidity and their age.

OBJECTIVE

The aim of this study was to examine the response of the elderly patients to anaemia correction using a locally devised anaemia correction protocol while receiving dialysis.

METHODS

An incident, non-randomised, cohort observational study in a single centre was used to compare the correction of anaemia in a population of elderly (> or =65 years of age) and young dialysis patients. All incident patients starting peritoneal dialysis and haemodialysis (HD) between January 1998 and December 2000 were selected and treated using a locally devised anaemia correction protocol and observed for at least 1 year. Anaemia correction following adjustments for factors such as age, comorbidity, dialysis type, dialysis access type and predialysis nephrological care was assessed.

RESULTS

198 patients commenced dialysis with 86 elderly patients (mean age +/- SD 73.7 +/- 4.9 years). The elderly patients had similar periods of predialysis nephrological care as the younger patients. Most patients received HD and required a tunnelled dialysis catheter (TC) as vascular access. Equivalent numbers of elderly patients received peritoneal dialysis. Comorbid scores were greater in the elderly and patient survival was dependent upon these comorbid factors. Following the strict use of TCs, patient survival was similar to those patients commencing HD with arterio-venous fistulae. Anaemia correction in the elderly was similar to the younger patients, with a median haemoglobin of 11.3 g/dL. By 6 months of dialysis, most patients achieved the UK Renal Association anaemia correction standard (haemoglobin above 10 g/dL). The elderly patients maintained significantly higher serum ferritin levels throughout (median 209 microg/L) and required less epoetin alfa or beta (median 91.6 units/kg/wk), indicating that functional iron deficiency in the elderly dialysis patients is less. Intravenous iron sucrose doses were similar in both age groups and iron overload (serum ferritin above 800 microg/L) had been avoided following the use of the intravenous iron protocol.

CONCLUSION

The study has noted that elderly patients responded to anaemia corrective therapies as well as the younger patients, despite greater levels of comorbidity while requiring less epoetin alfa or beta.

Drug-induced and antibody-mediated pure red cell aplasia: a review of literature and current knowledge

Anti-erythropoietin (EPO)-induced pure red cell aplasia (PRCA) is an uncommon, potentially life-threatening condition in which the bone marrow stops manufacturing red blood cells. In the past few years, reports of drug-induced, anti-EPO antibody-mediated PRCA have increased substantially, with most cases attributed to the use of one erythropoiesis-stimulating protein, Eprex. A literature review was undertaken to document the reports of drug-induced PRCA, with all drugs and drug regimens. The sudden increase in reports of antibody-mediated PRCA is discussed.

Clinical and economic impact of epoetins in cancer care

Anaemia develops in most patients undergoing cancer therapy and invariably induces fatigue, which is a major determinant of QOL. Blood transfusions are reserved for patients with severe anaemia, since blood is a scarce resource and provides a short-lived benefit. Epoetins are recombinant proteins capable of alleviating therapy-related anaemia in 40-60% of cancer patients. The number of patients needed to be treated with epoetins to avoid the transfusion of one unit of blood ranges from 2.6 to 5.2; however, the absolute risk reduction depends on patients' characteristics and dose-escalation. The ratio between acquisition costs of epoetins and blood transfusion requirement is very high; thus, many thousands of dollars needs to be spent on epoetins to save 1 blood unit. Despite this, epoetins have been widely adopted by industrialised countries, where cancer patients are about 2% of the total population. The resulting budget impact of epoetins can be calculated at about 10% of the overall direct cost for cancer care, and it is expected to continue growing by about 20% each year, due to the expanding cancer population and the intensification of cancer therapies. The economic burden of epoetins needs to be weighed against the improvement of patients' QOL and society's willingness to pay for a non-life-saving therapy. All published economic evaluations of epoetins invariably report that this supportive therapy is not cost effective. Society should be made aware of the opportunity cost of treatments and should be allowed to elicit preferences for healthcare interventions and prioritisation criteria. In the near future we expect that a wider range of epoetins, drug patent expiry, a more appropriate patient selection criteria and an improved dosage schedule may help increase the efficiency of cancer-related anaemia management.

Erythropoietin gene therapy leads to autoimmune anemia in macaques

Gene therapy is being considered for the delivery of therapeutic proteins. We evaluated the delivery of the hormone erythropoietin (EPO) into cynomolgus macaques through intramuscularly administered adeno-associated virus (AAV) vectors. As expected, the animals developed supraphysiologic levels of EPO and polycythemia. However, severe anemia ensued in some animals because of an autoimmune response to endogenous and transgene derived EPO. This is the first example of gene therapy leading to inadvertent auto-immunity in primates.

Rights of chronic renal failure patients undergoing chronic dialysis therapy

The Patient Advocacy Committee of the International Federation of Kidney Foundations (IFKF) has developed a document proposing a set of rights for individuals with end stage renal failure (ESRF). These rights have been approved by the Board of Directors of the IFKF. Twenty rights have been developed and are organized into the following categories: (i) need of treatment and choice of patients; (ii) treatment of ESRF by haemodialysis; (iii) treatment of ESRF by peritoneal dialysis; and (iv) renal transplantation. It is the hope of this Committee and the IFKF that this document will provide a stimulus to more scientific inquiry and discussion as to what rights do patients possess with regard to treatment of chronic kidney disease, regardless of where they live or what may be their economic, social, ethnic or political status.

Human population-based identification of CD4(+) T-cell peptide epitope determinants

A human cell-based method to identify functional CD4(+) T-cell epitopes in any protein has been developed. Proteins are tested as synthetic 15-mer peptides offset by three amino acids. Percent responses within a large donor population are tabulated for each peptide in the set. Peptide epitope regions are designated by difference in response frequency from the overall background response rate for the compiled dataset. Epitope peptide responses are reproducible, with a median coefficient of variance of 21% when tested on multiple random-donor sets. The overall average response rate within the dataset increases with increasing putative human population antigenic exposure to a given protein. The background rate was high for HPV16 E6, and was low for human-derived cytokine proteins. The assay identified recall epitope regions within the donor population for the protein staphylokinase. For an industrial protease with minimal presumed population exposure, immunodominant epitope peptides were identified that were found to bind promiscuously to many HLA class II molecules in vitro. The peptide epitope regions identified in presumably unexposed donors represent a subset of the total recall epitopes. Finally, as a negative control, the assay found no peptide epitope regions in human beta2-microglobulin. This method identifies functional CD4(+) T-cell epitopes in any protein without pre-selection for HLA class II, suggests whether a donor population is pre-exposed to a protein of interest, and does not require sensitized donors for in vitro testing.

Drug-induced myelosuppression : diagnosis and management

Myelosuppression is a common and anticipated adverse effect of cytotoxic chemotherapy. It is a potential but rare idiosyncratic effect with any other drug, but there is a recognised association with a number of higher-risk agents which justify additional vigilance. Genetic risk factors are being identified which may predispose individuals to this reaction with particular drugs. As marker tests become available, dose adjustment or alternative treatment choices may help to avoid more severe reactions. Myelosuppression is potentially life threatening because of the infection and bleeding complications of neutropenia and thrombocytopenia. Strategies for monitoring, early detection, diagnostic confirmation and appropriate supportive care are well developed for cytotoxic therapy. Developments in antimicrobial chemotherapy, blood product transfusion support and growth factor therapy have improved outcomes. These advances are largely applicable to idiosyncratic drug-induced myelosuppression, reinforcing the importance of early recognition and referral to appropriate expertise. Many reactions will resolve on drug withdrawal with appropriate supportive care during the period of cytopenia. Prolonged marrow failure may require more specific treatment with intensive immunosuppression or consideration of bone marrow transplantation.

The detection of anti-erythropoietin antibodies in human serum and plasma

Rare cases of unexplained sudden severe anemia or red cell aplasia and resistance to recombinant human erythropoietin (rHuEPO) in patients with chronic renal failure (CRF) have been attributed to the development of anti-EPO antibodies. The development and validation of a radioimmunoprecipitation (RIP) assay to detect human anti-EPO antibodies in serum or plasma has been hampered by the lack of purified antibody to fully characterize and validate the assay. We have prepared an affinity-purified human antibody to EPO and used the antibody to characterize and validate a sensitive and reproducible RIP assay that can qualitatively measure anti-EPO antibody in serum or plasma samples. The lower limit of detection of the assay is 8 ng/ml of purified antibody. The threshold for detecting antibody is > or =0.9% cpm bound. The precision of the assay using purified antibody standards ranges from 5.8% to 15.3% and the precision of the assay using dilutions of the positive control ranges from 15.9% to 18.7%. EPO in the samples did not interfere with detection of the anti-EPO antibody except at high concentrations.

Successful treatment of refractory pure red cell aplasia associated with lymphoproliferative disorders with the anti-CD52 monoclonal antibody alemtuzumab (Campath-1H)

Acquired pure red cell aplasia (PRCA) is a rare, but significant, complication of lymphoproliferative disorders. It is characterized by anaemia, absence of red cell precursors in the bone marrow and normal granulopoiesis and megakaryopoiesis. We describe two patients with refractory pure red cell aplasia associated with chronic lymphocytic leukaemia (CLL) and a large granular CD8 T-lymphocytic leukaemia (LGL) respectively. Both patients had failed multiple treatment regimens for PRCA and were transfusion dependent. Both patients were subsequently treated with the anti-CD52 humanized monoclonal antibody, alemtuzumab, receiving total doses in excess of 300 mg. Response to treatment, as documented by a rapid increase in the reticulocyte count, occurred as early as the third infusion. At the time of this report, both patients remain in complete remission with normal haemoglobin levels. Alemtuzumab appears to be an effective and well-tolerated therapy for pure red blood cell aplasia associated with lymphoproliferative disorders.