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Dialysis |



* Clinic of Nephrology Collegium Medicum, Jagiellonian University, Cracow, Poland;
Department of Nephrology and Dialysis, "A Manzoni" Hospital, Lecco, Italy;
Service de Néphrologie, CHU Clemenceau Centre, Caen, France;
Department of Nephrology, University of Debrecen, Debrecen, and || Fresenius Dialysis Center, University of Pecs, Pecs, Hungary; ¶ Renal Services and Urology, Leicester General Hospital, Leicester, United Kingdom; and ** Pharma Development, F. Hoffmann-La Roche Ltd., Basel, Switzerland
Address correspondence to: Prof. Wladyslaw Sulowicz, Collegium Medicum, Jagiellonian University Department of Nephrology, 15c Kopernika, 31-501, Cracow, Poland. Phone: +48-12-4247892; Fax: +48-12-4247149; E-mail: wladsul{at}mp.pl
| Abstract |
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or ß one to three times weekly.
Design, setting, participants, and measurements: In this three-arm, comparator-controlled, open-label, randomized, parallel-group, Phase III study, 572 dialysis patients (
18 yr) who were receiving stable subcutaneous epoetin one to three times weekly were randomly assigned (1:1:1) to continue epoetin or to receive subcutaneous C.E.R.A. once monthly or twice monthly for 52 wk. Dosage was adjusted to maintain Hb ±1.0 g/dl of baseline level. Primary end point was mean change in Hb level between baseline and the evaluation period (weeks 29 to 36).
Results: Mean Hb levels during the evaluation period were similar between groups (once-monthly C.E.R.A. 11.5 g/dl; twice-monthly C.E.R.A. 11.7 g/dl; epoetin 11.5 g/dl). The difference between C.E.R.A. and epoetin in mean change (97.5% confidence interval) in Hb concentration between baseline and evaluation was 0.022 g/dl (0.262 to 0.217) for once monthly and 0.141 g/dl (0.098 to 0.380) for twice monthly. Analysis demonstrated that C.E.R.A. was as effective as epoetin in maintaining Hb and was well tolerated.
Conclusions: Subcutaneous C.E.R.A. once or twice monthly successfully maintained tight and stable Hb levels in patients who were on dialysis and randomly converted directly from epoetin one to three times weekly.
| Introduction |
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11 g/dl (13,14,18). In addition, European and Australian guidelines specify an upper limit of 12.0 g/dl for patients with cardiovascular disease or diabetes (13,14), whereas US guidelines do not support routine maintenance of Hb >13 g/dl (18). Despite these guidelines, many patients still fail to achieve minimum Hb targets (17,19,20). For example, the Dialysis Outcomes and Practice Patterns Study demonstrated that more than one quarter of US patients on dialysis had an Hb level <11 g/dl, and the incidence was often higher (up to 77%) in other countries (17,20). Moreover, Hb levels fluctuate over short periods of time, such that many patients who have CKD and achieve Hb targets do not maintain their Hb level within target range for extended periods of time (2124). It has been estimated that only 5% of patients who are on hemodialysis and have an Hb between 11 and 12 g/dl persistently remain within that range for 6 mo (22).
Maintaining Hb levels within target ranges requires close monitoring of Hb and, with current agents, often requires frequent dosage adjustments (23). Hence, maintenance of stable Hb levels can be time-consuming and may burden renal units, which already have to cope with the growing incidence and prevalence of CKD (15,25,26). Consequently, we need agents that will provide predictable and stable Hb responses with minimal intervention from health care professionals.
The use of current ESAs at extended administration intervals has been examined in several studies in patients who already had stable Hb levels at administration intervals of at least once weekly (2731). However, only one study involved patients who were on dialysis (29), in which a stepwise introduction of longer intervals was required. Even so, a proportion of the enrolled patients did not maintain Hb levels. As a result, these studies do not provide strong evidence that such regimens can be applied to the spectrum of patients with CKD encountered in day-to-day clinical practice.
C.E.R.A., a continuous erythropoietin receptor activator, is a novel agent that provides correction of anemia and stable control of Hb levels at extended administration intervals (32). Preclinical and Phase I and II studies demonstrate that C.E.R.A. has unique pharmacologic properties, acting differently than epoetin at the erythropoietin receptor level (33), with a long serum half-life (mean 134 h after intravenous and 139 h after subcutaneous administration in patients who are on peritoneal dialysis) and low clearance (32,34,35).These half-life values are considerably longer than those reported in healthy volunteers for epoetin
(6.8 h [intravenous] and 19.4 h [subcutaneous]) and epoetin ß (8.8 h [intravenous] and 24.2 h [subcutaneous]) (36) and up to five times longer that those reported for darbepoetin
in patients who are on peritoneal dialysis (25.3 h [intravenous] and 48.8 h [subcutaneous]) (37).
Phase II studies in patients who have CKD indicate that C.E.R.A. corrects anemia and maintains Hb levels within guideline targets when administered up to once monthly in patients who are on dialysis and in those not yet dialyzed (3840). We report the results of PROTOS (Patients Receiving C.E.R.A. Once a month for the mainTenance Of Stable hemoglobin), a Phase III study of C.E.R.A. that was given subcutaneously at administration intervals of once monthly or twice monthly for the maintenance of Hb levels in patients who had CKD and were on dialysis and randomly converted directly from epoetin
or ß.
| Materials and Methods |
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18 yr of age, had chronic renal anemia, and were receiving hemodialysis or peritoneal dialysis for
12 wk before screening. They were required to have received treatment with subcutaneous epoetin one to three times weekly with the same administration interval for
8 wk before screening and to have a stable Hb concentration within the range 10.5 to 13.0 g/dl during the baseline period.
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Study Design
PROTOS was a three-arm, controlled, open-label, randomized, multicenter, parallel-group, Phase III study designed to compare the efficacy and tolerability of two dosing intervals of subcutaneous C.E.R.A. with that of continued epoetin therapy for the maintenance treatment of anemia in patients who had CKD and were receiving dialysis and had previously been maintained on subcutaneous epoetin
and ß (one to three times a week). After a 4-wk baseline period, when patients continued to receive epoetin, those who were eligible were randomly assigned (1:1:1) to receive subcutaneous C.E.R.A. once a month, to receive subcutaneous C.E.R.A. twice a month, or to continue receiving subcutaneous epoetin at their current dosage and administration interval (Figure 1). Patients were randomly assigned to study treatment via a central randomization center with stratification by geographic region.
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14 g/dl, and increased by 25% for Hb decreases >1 g/dl versus baseline or for Hb
9 and <10 g/dl. C.E.R.A. dosage decreases of 50% were made for Hb increases >2 g/dl versus baseline and increases of 50% for Hb decreases >2 g/dl versus baseline or Hb <9 g/dl. During the long-term safety period, C.E.R.A. dosage was increased or decreased by 25% for Hb
9 and <11 g/dl and Hb >13 and
14 g/dl, respectively, and increased by 50% for Hb <9 g/dl. Treatment was temporarily interrupted if Hb exceeded 14 g/dl. Dosage adjustments for epoetin
and ß were performed according to their respective labeling. For example, dosage increases for epoetin
were not performed more frequently than once a month, unless clinically indicated, and dosages for epoetin ß could be adjusted at intervals of 1 to 2 wk individually for the patient. For all treatment groups, Hb <9 or >14 g/dl and Hb changes >2 g/dl versus baseline were to be avoided for safety reasons. Iron supplementation was performed according to individual center practice and adjusted to maintain adequate iron status: serum ferritin
100 ng/ml and transferrin saturation
20% (or hypochromic red blood cells [RBC] <10%).
Study Drug
C.E.R.A. (F. Hoffmann-La Roche Ltd., Basel, Switzerland) was supplied as a solution in vials that contained 1 ml of 50, 100, 200, 400, or 1000 µg/ml. Epoetin ß was supplied in multidose vials by F. Hoffmann-La Roche Ltd. for participating study centers located outside the United States. Epoetin
was obtained from commercial sources by participating sites located in the United States.
Assessments
Patients were assessed weekly during the screening/baseline, titration, and evaluation periods and once every 2 wk during the long-term safety observation period. Hb, BP, and heart rate were measured at each visit. Iron and other laboratory parameters were measured at screening/baseline, then every 8 wk from week 5 (iron parameters were assessed every 4 wk during the evaluation period), and at the final visit. Physical examination and electrocardiograms were performed at screening/baseline, at weeks 29 and 37 (electrocardiogram only), and at the final visit. Immunogenicity testing to the study medications was carried out at weeks 1, 13, 29, and 41 and at the final visit using ELISA performed by a central laboratory.
Statistical Analyses
The primary efficacy analysis compared, separately, the mean change in Hb level between the baseline and evaluation period for patients who received C.E.R.A. once monthly or twice monthly with that for epoetin. For demonstration of noninferiority, the lower limit of the two-sided 97.5% adjusted confidence interval (CI) for the difference between epoetin and C.E.R.A. in mean change in Hb level had to be above 0.75 g/dl. The 97.5% CI was calculated with adjustment for covariates that might influence Hb response (baseline Hb and geographic region). A sample size of 465 patients (155 patients per treatment arm) was determined to provide 90% power to show that C.E.R.A. administered at a lower frequency is as effective as epoetin.
The primary end point analysis was conducted in the per-protocol (PP) population because this approach to noninferiority analysis is more stringent than using the intent-to-treat (ITT) population. Patients were excluded from the PP population on the basis of the following criteria: fewer that five Hb measurements during evaluation, missing doses of study medication in weeks 26 to 35, nonstable baseline Hb, inadequate iron status at baseline or evaluation, RBC transfusion at baseline or blood loss within weeks 21 to 33, hemoglobinopathies, or hemolysis. Secondary end points consisted of the number of patients who maintained average Hb concentration within ±1.0 g/dl of their average baseline Hb concentration during the evaluation period and the incidence of RBC transfusions during the titration and evaluation periods. Confirmatory analysis of the primary end point was performed on the ITT population (all patients who were randomly assigned to treatment). Secondary end points were compared among treatment groups in the ITT population using descriptive methods.
| Results |
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Patient disposition is shown in Figure 2. In total, 499 patients completed the evaluation phase and 461 patients completed the safety follow-up phase of the study. Reasons for premature withdrawal of 111 patients were death (n = 41), kidney transplantation (n = 39), refusal of treatment (n = 13), adverse events (AE; n = 2), insufficient therapeutic response (n = 2), failure to return (n = 1), and other (n = 13). One patient in the once-monthly C.E.R.A. group did not receive study medication and was excluded from the safety population (n = 571).
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16,000 IU/wk epoetin. Mean Hb levels at baseline were similar between treatment groups (Table 3). A similar percentage of patients were receiving supplementary iron at baseline in each treatment group (once-monthly C.E.R.A. 84%; twice-monthly C.E.R.A. 82%; epoetin 81%).
Efficacy Evaluation
Mean Hb levels during the baseline, evaluation, and follow-up periods were similar in the three study groups (Table 5, Figure 3). For the primary efficacy analysis (PP population), after adjustment for covariates, the mean change in Hb from baseline to the evaluation period was 0.131 g/dl for once-monthly C.E.R.A., 0.032 g/dl for twice-monthly C.E.R.A., and 0.109 g/dl for epoetin. The difference in the mean change (97.5% CI) in Hb between the C.E.R.A. groups and the epoetin group was 0.022 g/dl (0.262 to 0.217) for once-monthly C.E.R.A. and 0.141 g/dl (0.098 to 0.380) for twice-monthly C.E.R.A. The lower limit of the 97.5% CI was therefore well above the prespecified margin of 0.75 g/dl in both groups, demonstrating that once-monthly or twice-monthly C.E.R.A. (both P < 0.0001; Figure 4) is as effective as epoetin in maintaining anemia control among these patients who randomly converted directly from epoetin (one to three times a week). Similar data were obtained for the ITT population (Figure 4).
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In a post hoc analysis of intrapatient Hb variability, the mean within-patient SD for Hb during the titration period (ITT population) in the once-monthly C.E.R.A., twice-monthly C.E.R.A., and epoetin groups was 0.85, 0.84, and 0.78 g/dl, respectively (NS for each C.E.R.A. group versus the epoetin group). Within-patient SD for Hb during the evaluation period were also similar across treatment groups (ITT population): 0.57, 0.52, and 0.57 g/dl for once-monthly C.E.R.A., twice-monthly C.E.R.A., and epoetin, respectively (NS for each C.E.R.A. group versus the epoetin group).
The percentage of patients who required RBC transfusion was low in the once-monthly C.E.R.A. and twice-monthly C.E.R.A. groups (10.5 and 6.3%, respectively) and the epoetin group (9.9%; safety population), confirming the safety of direct conversion of patients who were stable on epoetin.
An exploration of dosages of trial medication in the safety population revealed that baseline median dosages were 120 µg/4 wk (interquartile range [IQR] 120 to 200) and 60 µg/2 wk (IQR 60 to 100) for C.E.R.A. and 6000 IU/wk (IQR 4000 to 10,000) for epoetin. During the evaluation period, the median dosages of C.E.R.A. were 150 µg/4 wk (IQR 91 to 250) and 56 µg/2 wk (IQR 27 to 84), and these remained the same during the rest of the study. The median dosage of epoetin was 5500 IU/wk (IQR 3000 to 9000) during the evaluation period and 6000 IU/wk (IQR 3000 to 10,000) during the remainder of the study. The median (IQR) number of dosage changes per patient throughout the entire study period was 6 (3 to 9) for twice-monthly C.E.R.A., 4 (2 to 7) for once-monthly C.E.R.A., and 5 (3 to 8) for epoetin; these occurred most frequently during the titration and long-term follow-up periods. For the epoetin group, this did not include dosage changes that were the result of differences in the split of doses from 1 wk to another, provided that the total weekly dosage remained the same.
Safety and Tolerability
The incidences of AEs and serious AEs are given in Table 6. In total, 90% of patients across all treatment groups experienced at least one AE. The most commonly reported AEs were hypertension, procedural hypotension (induced by dialysis), nasopharyngitis, headache, and diarrhea (Table 6). Most events were mild or moderate in intensity and distributed evenly across the three treatment groups.
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| Discussion |
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or ß one to three times weekly to C.E.R.A. at extended dosing intervals is effective for maintaining tight, sustained, and predictable control of Hb levels within target range in this patient population. Moreover, mean Hb values remained stable during the evaluation and long-term safety periods, demonstrating maintenance of Hb control over time. In addition, C.E.R.A. was generally well tolerated. Most AEs that were reported during the study were consistent with the morbidity that is associated with advanced CKD and not considered related to study medication. PROTOS thus confirms findings from Phase II studies that the unique pharmacologic properties of C.E.R.A. enable it to provide sustained maintenance of target Hb levels when administered up to once monthly (3840). Furthermore, data from this study are consistent with the results of a similarly designed Phase III study in which intravenous C.E.R.A. effectively maintained Hb levels in patients who had CKD and were on dialysis and converted directly from epoetin one to three times weekly to once- or twice-monthly C.E.R.A. (41). One previous, single-arm study examined the efficacy of once-monthly ESA administration in patients who had CKD and were on dialysis (29); the administration interval was sequentially extended contingent on patient response. In contrast, our study required patients to convert directly to receive C.E.R.A. only at the administration interval to which they were randomly assigned.
The demographic and baseline characteristics of patients were consistent with the general dialysis population and demonstrated a high prevalence of comorbid diseases. Hence, the study population was largely representative of patients who are on dialysis and treated for renal anemia in clinical practice.
The growing number of patients with CKD and the burden of managing this disease and its complications (15,42,43) highlight the expected benefits of C.E.R.A. We propose that the ability of C.E.R.A. to maintain tight Hb levels with once-monthly administration should improve anemia management in CKD by alleviating the increasing workload of health care professionals. Once-monthly administration will save up to 144 injections per patient per year compared with three times weekly dosing.
| Conclusion |
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| Disclosures |
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| Acknowledgments |
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Data from this study were previously published in abstract form ([Abstract SP424]. Nephrol Dial Transplant 21[Suppl 4]: iv156iv157, 2006).
PROTOS Study Investigators: H.J. Adrogue, F.W. Albert, A. Albertazzi, J.-C. Aldigier, M. Amato, H.-G. Asmus, A. Bajo Rubio, J. Balla, P. Barany, E. Barranco, G. Barril, P. Bataille, F. Berthoux, K. Bidas, T. Bochicchio, C. Breen, W. Buranachokpaisan, J. Burkart, P.-L. Caraman, N. Coplon, R. Correa-Rotter, M. Couttenye, B. Csiky, S. Dawood, A. Debure, H. Deodhar, H. Dieperink, S.A. Draibe, R. D'Souza, M. Feriani, J. Fort, L.E. Garrett, Jr., J. Gasco Company, M. Germain, C. Granolleras, K. Harris, I. Henderson, J.C. Kallmeyer, J. Kaufman, H. Keuleers, M. Klinger, P. Koskinen, E. Ladányi, N. Lameire, E. Le Guen, K. Lempert, F. Locatelli, K. Lynn, I.C. Macdougall, I. MacPhee, F. Malberti, P. Marchini, A.P. Maxwell, R. McCrary, F. Metivier, K. Metsarinne, I.P. Naicker, E.D. Neto, P. Nolen, S. Opatrna, J.-P. Ortiz, P. Peeters, J. Penfield, J. Pengloan, R. Perez, W. Phumratanaprapin, G. Pidgeon, L. Piera, J. Portoles, W.Y. Qunibi, M.C. Riella, C. Rikker, B. Rutkowski, J.-P. Ryckelynck, H. Saha, D. Sanchez-Guisande, R. Schmidt, R. Selgas, K.-H. Shu, D. Sobotova, T. Stompor, W. Sulowicz, V. Sumethkul, C. Sun, P. Thanakitcharu, P. Thon, K. Tungsanga, I. Valkovsky, D. Verbeelen, Z. Vezekenyi, L.G. Weiss, P. Williams, K.-D. Wu.
Medical writing support was provided by Margaret Duggan-Keen, Melanie Jones, and Christine Gardner at Prime Medica Ltd. during the preparation of this article, supported by F. Hoffmann-La Roche Ltd.
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Responsibility for opinions, conclusions, and interpretation of data lies with the authors.
Received October 31, 2006. Accepted April 16, 2007.
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