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PHARMACOKINETICS AND PHARMACODYNAMICS |
From ZLB Behring, Marburg, Germany (Dr Bosse, Dr Kiessling); Covidence, Marburg, Germany (Ms Praus, Mr Schindel); Quintiles, Uppsala, Sweden (Dr Nyman); Alza Corporation, Mountain View, California (Dr Andresen); and Delta Biotechnology Ltd., Nottingham, United Kingdom (Ms Waters).
Address for reprints: Peter Kiessling, PhD, ZLB Behring, Marburg, Germany.
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ABSTRACT |
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 TOP ABSTRACT METHODSRESULTSDISCUSSIONREFERENCES |
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Key Words: Recombinant human albumin • human serum albumin • drug safety • pharmacokinetics • pharmacodynamics
HSA is commonly produced by fractionation of plasma obtained from donors and is currently used in greater volumes than any other biopharmaceutical solution, with worldwide manufacturing on the order of hundreds of tonnes annually.4 The safety profile of HSA with respect to viral transmission has been excellent over the past 50 years.7 Nevertheless, the theoretical potential for the transmission of new and reemerging infectious agents (eg, hepatitis, human immunodeficiency virus, West Nile virus, variant Creutzfeldt-Jacob disease) with blood- and plasma-derived products is unlikely to be eliminated,2,8-11 and development of substitutes is recommended by regulatory authorities.12 In view of increasing viral safety demands in the past 10 years, recombinant human albumin (rHA) has become an interesting and appropriate alternative to the use of HSA, especially for use as a component in widespread medications (eg, childhood vaccines). As well as the absence of pathogenic blood-derived infectious agents,8,9 the likely advantages of using rHA over HSA include increased batch-to-batch consistency.13
The investigated recombinant human albumin is a highly purified 20% rHA, which is structurally equivalent to HSA. It has been produced using a yeast expression system (Saccharomyces cerevisiae) further developed from that described by Goodey,3 without any human- or animal-derived materials and is therefore considered free of viruses or other infectious agents. Considering the intended uses of rHA as a replacement for animal- or human-derived agents such as gelatins or HSA, extensive studies have been performed to evaluate rHA's structure, function, and biochemical properties in direct comparison to the well-established HSA product.2 Moreover, the recombinant human albumin was already successfully studied as culture media for oocytes of 85 women undergoing in vitro fertilization and may replace HSA in this setting to reduce the risk of prion contamination and transmission of plasma-derived impurities.14
The recombinant human albumin was developed specifically for use as an ingredient in pharmaceutical products—in the majority of cases, to replace the human-derived serum albumin.13,15 Many of the potential applications may involve repeated intramuscular, intravenous, or subcutaneous administrations.5 A clinical program was therefore developed to investigate the safety of this rHA using HSA as a direct comparator, following both intramuscular (IM) and intravenous (IV) administration. Central to the program was investigation of the potential antigenicity of the rHA product and its possible impurities (eg, host cell proteins and mannosylated rHA) versus HSA under what was considered a worse-case scenario. The product's pharmacokinetic/pharmacodynamic properties were also characterized and compared with HSA.
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METHODS |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONREFERENCES |
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Study Participants
The participants were selected from a pool of healthy male and female volunteers in Uppsala, Sweden. Volunteers were eligible for inclusion in the study, provided that they were 18 years of age or older, had a body mass index of 19 to 29, and were willing to comply with the study requirements. In addition, female subjects took adequate precautions against pregnancy.
Exclusion criteria were pregnancy; indication of active hepatitis; history of chronic hepatic, renal, autoimmune, cardiac, or pulmonary disease; history of allergic reaction to S. cerevisiae or yeast products; or history of alcohol, narcotic, or drug abuse. Volunteers with a history of anaphylactic or severe systemic response to human plasma proteins or who had received systemic treatment with corticosteroids or human plasma derivatives during the month prior to the study were also excluded.
The IgE status of all subjects included in the trials was evaluated using commercially available radio-allergosorbent test (RAST) methods (Phadiatope, Pharmacia) to give an indication of the atopic status of the study population, particularly any hypersensitivity to yeast. Subjects were tested against a pool of common environmental allergens (eg, mite, horse, dog and cat epithelium, mold, mugwort, timothy, and birch) and tested specifically against the yeasts S. cerevisiae and Candida albicans. No subjects, including those RAST positive to yeast, were excluded from the study on the basis of their RAST results.
Study Design
Two double-blind, randomized, phase I trials (one using IM and one using IV administration) were performed, each with 3 dose levels of rHA (Recombumin 20%, Delta Biotechnology Ltd, Nottingham, UK) and HSA (Human-Albumin N 20%, Bayer, Germany).
The IM administration regime was designed to simulate chronic exposure to rHA if used as an excipient, as well as being similar to an aggressive accelerated vaccination schedule (eg, emergency rabies vaccination), in the potentially most immunogenic route. The IV study was designed with the aim of simulating conventional intravenous applications of HSA at therapeutic doses.
Five hundred volunteers were enrolled for the IM trial (which was conducted under a Food and Drug Administration investigational new drug process) and randomized (1:1) to receive either rHA or HSA. The study was performed in 3 separate phases for the investigation of the 3 dose levels: 5 mg (100 subjects), 15 mg (100 subjects), and 65 mg (100 subjects). An additional 200 subjects received the highest tolerated dose (65 mg). With an expected incidence of 5% potentially allergic events for the HSA treatment group, the power to detect a 3-fold increase of such events under rHA treatment was 80% for the 65-mg dose group and 95% for all doses combined.
Following each dosing step, safety data were reported to an independent data safety monitoring board for review, which then made a recommendation to proceed with the next higher dose level. Recipients at each dose level were injected 5 times at 1-week intervals (ie, on days 1, 8, 15, 22, and 29). Final assessments were performed 7 days after the final dose, and therefore the study duration was 36 days.
For the IV trial, a total of 30 healthy volunteers were enrolled and randomized (1:1) to receive either rHA or HSA. The duration of the study was 50 days, with each participant receiving 3 consecutive doses at 3-week intervals of 10 g on day 1, 20 g on day 22, and 50 g on day 43 (total 80 g). Following application of the 50-g dose on day 43, subjects were monitored for 24 hours, mainly for assessment of pharmacodynamic parameters over time following the infusion. Final assessments were performed 7 days after the final dose, on day 50.
With no prior data on colloid osmotic pressure (COP, the main pharmacodynamic endpoint), the sample size for the IV trial was chosen arbitrarily; a post hoc examination of COP results showed, however, that the conventional 2 standard error intervals for the mean COP values (±2 SEM) following the highest applied dose were within 10% of the mean.
Measurement of the frequency and severity of adverse events (AEs) was performed from the time of the first administration of the study drug (baseline) until the subject underwent a final examination. An additional category, potentially allergic events, was used—this was predefined in the study protocol as symptoms of allergy during the study period (ie, reddening [erythema] at the injection site or other parts of the body, exanthemas, urticaria, dyspnea, symptomatic decrease in blood pressure [within 24 hours], arthritis, nephritis, or neurologic symptoms). Nausea, vomiting, and abdominal pain were also defined as potentially allergic events, if considered study drug related. As with all adverse events, a potentially allergic event could be classed as mild, moderate, or serious.
For each investigated dose in both trials, P values for between-group differences in potentially allergic events and serious adverse events were derived from a 1-sided Fisher test.
Blood samples were taken at baseline (prior to administration) and 1 week following the final administration in both trials to investigate for the presence of IgG or IgE antibodies raised against the test products (rHA and HSA) and potential impurities (mannosylated rHA and yeast-derived antigens). Additional blood samples were taken 1 week after each dose for antibody analysis in the event of potentially allergic events. Measurement of IgG antibody was by antibody capture enzyme-linked immunosorbent assay (ELISA); IgE measurements were by antigen capture ELISA. The limits of quantitation (LOQ) for the IgG assays were established individually for each plate but ranged from 0.16 to 0.63 µg/mL. For all IgE assays, the LOQ was 0.56 µg/mL. For the pharmacodynamic assessments in the IV trial, measurements of COP and the hematocrit ratio were performed. COP was measured using an Osmomat 050 (Gentech, Berlin, Germany) device. The hematocrit ratio was calculated by the ratio of pre- and postinfusion values (Hct1/Hct2). In addition, albumin concentration in serum was measured by ELISA. Assessments were performed 5 minutes and 2 hours after infusion of study drugs on days 1 (baseline) and 22. In addition, 24-hour assessment was performed on days 43 to 44, and final measurements were performed 7 days after administration of the last dose (day 50).
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RESULTS |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONREFERENCES |
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Adverse Events
Within the IM trial, AEs were reported in 99 (39.6%) recipients of rHA compared with 106 (42.4%) in the HSA groups (Table II). All but 2 of these events were of mild or moderate intensity, and most were headache or rhinitis (Table III). AEs that were considered possibly related to study treatment by the investigators affected 6 recipients (2.4%) of both rHA and HSA. Potentially allergic events were reported in 15 subjects (8 rHA, 7 HSA); these were considered related to study treatment in 9 cases (4 rHA, 5 HSA). All but 2 of these events were skin related (Table III). There were no significant between-group differences in the incidence of potentially allergic events for any given dose, and there was no apparent association between dose and the incidence of these events. One serious adverse event was reported in 1 recipient of the 65-mg dose of HSA. This consisted of a ruptured ovarian cyst and was deemed unrelated to study treatment.
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Within the IV trial, AEs were reported by 6 (40%) subjects in the rHA group and 8 (53%) in the HSA group (Table II). These were mostly headache and rhinitis (Table III). All AEs were mild or moderate in severity, and only 1 (affecting a subject in the rHA group) was considered related to study treatment. No serious or potentially allergic events were reported in either study group. There was no apparent increase in AEs with increasing dose.
Antibody Analysis
There were no clinically relevant changes in IgG or IgE for any of the 4 antigens (HSA, rHA, mannosylated rHA, and yeast-derived proteins) during either trial. This finding applied to all of the treatment groups, including subjects reporting potential allergic events.
In both trials, IgG against the yeast production strain (>95% subjects) and mannosylated rHA (>50% of subjects) were observed at baseline for both the rHA and HSA recipients, but no relevant increases in these levels were detected after administration (Figures 1 and 2). These predose positive antibody concentrations are not unexpected and are due to cross-reactivity between the production strain antigen preparation and antibodies produced as part of the normal humoral response to environmental yeasts (eg, species of Candida and Saccharomyces).16,17 In the case of the mannosylated rHA, the cross-reactivity would be due to antibodies produced to naturally occurring yeast glycoproteins and the mannose moiety on rHA that is introduced by the yeast production strain.16,18 For the majority of subjects, the levels of rHA- and HSA-specific IgG were below the limit of quantification at baseline; again, there were no relevant increases after administration (Figures 1 and 2).
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Only 4 subjects (3 rHA, 1 HSA; all from the IM trial) had detectable levels of IgE prior to treatment on day 1. In each case, the IgE specificity was for yeast protein (most likely due to exposure to naturally occurring yeast antigens in the environment). However, no significant postdose increase was observed in any of these subjects. None of the subjects showed detectable IgE to HSA, rHA, or mannosylated rHA on day 1 prior to treatment with rHA or HSA. After treatment, the follow-up investigation revealed only 1 subject with an increased IgE value against mannosylated rHA. This participant of the IM trial received HSA and did not experience any potentially allergic events. Shift graphs are not provided for the IgE analysis because almost all values were below the limit of quantification.
Pharmacokinetics and Pharmacodynamics
Serum albumin concentrations in the IV trial increased in both treatment groups (Figure 3), with highest values after the 50-g dose; rHA and HSA treatment showed a very similar course of serum albumin concentrations, with increased values persisting until day 50.
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The observed pharmacodynamic effects of rHA and HSA in the IV trial were in close agreement. Both rHA and HSA infusions were well tolerated at the administered doses of 10, 20, and 50 g. As expected, COP values increased moderately and remained highest 7 days after the third dose (day 50), which reflected the course of the albumin levels (Figure 4). The extent of hemodilution (hematocrit ratio) was moderate, even with the highest administered dose of 50 g (Figure 5). Hematocrit ratios reached peak mean values of 1.08 after the highest dose under either treatment.
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The observed increase in albumin levels, combined with the maximum extent of hemodilution after the 50-g dose, suggested a moderate volume expansion. Distribution of the infused albumin beyond the central plasma compartment was likely because the observed increase of serum albumin concentrations after the 50-g dose (approximately 7 g/L) was clearly less than expected from distribution to plasma alone.
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DISCUSSION |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONREFERENCES |
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The present studies provide valuable information on the safety profile of rHA compared to HSA, which has been used as an excipient for many biological and biotechnologically derived pharmaceutical products over the past 15 years. The maximum amount of HSA excipient in an already marketed product is 16.5 mg (IM administration).19 By administering doses that were more than 3.5-fold (IM route) and 3000-fold (IV route) higher than this, the present clinical investigations demonstrate large safety margins for the use of the recombinant human albumin as an excipient.
A variety of analytical methods have previously demonstrated rHA to be structurally equivalent to HSA.2 Against this background, the results of the present rHA studies, demonstrating similarity with HSA, are not unexpected. However, as with all products of genetic engineering using S. cerevisiae cells, there is a potential for rHA to contain some level of yeast-derived impurities,16 which may have the capacity to elicit a possible allergic response. In addition, potential differences in glycosylation profiles (mannosylation) of rHA compared to HSA raise the possibility of neoantigens. This was the basis for investigating the potential for an immune response to rHA and its potential impurities. The lack of clinically relevant changes in IgG or IgE indicates no propensity for an immunologic reaction to the rHA product, even in subjects with RAST-positive results to yeast. Given the high doses administered, the demonstration of clinical tolerability is not trivial16 and reflects the fact that levels of yeast-derived impurities and mannosylated rHA in the test product are extremely low; this is attributable to the high degree of purification and the choice of yeast production strain. In addition, the studies support preclinical neoantigenicity studies, which showed no evidence of neoantigens in the recombinant human albumin compared to HSA (data not shown).
The present clinical program provides the first direct evidence for the potential to use highly purified rHA in both IM and IV clinical settings, whereas previous data indicate the structural and physical similarity of the recombinant product with native HSA.2,16 Although the studies were designed to assess the safety and tolerability of rHA as an excipient for pharmaceutical and biological products, the data indicate that rHA could be developed for all medical applications in which HSA is currently used. In this context, the effective distribution of infused rHA beyond the central plasma compartment becomes particularly important (the maximum albumin increase of 7 g/L after the 50-g IV dose indicates that this is the case).
In summary, the clinical studies described in this article demonstrate that the investigated recombinant human albumin is a suitable non-human- or animal-derived alternative to HSA for excipient and therapeutic use. It is as safe and well tolerated as HSA for IM and IV administration at a range of doses. There was no evidence of antibody production against rHA or its impurities, and this is believed to be attributable to the high degree of purification of the rHA product and the choice of yeast production strain.
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FOOTNOTES |
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Submitted for publication April 5, 2004; Revised version accepted July 29, 2004.
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REFERENCES |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONREFERENCES |
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1. Peters TJ. The albumin molecule: its structure and chemical properties. In: Peters TJ, ed. All About Albumin: Biochemistry, Genetics and Medical Applications. New York: Academic Press, 1996: 9-75.
2. Dodsworth N, Harris R, Denton K, Woodrow J, Wood PC, Quirk A. Comparative studies of recombinant human albumin and human serum albumin derived by blood fractionation. Biotechnol Appl Biochem. 1996;24(Pt 2): 171-176.
3. Goodey AR. The production of heterologous plasma proteins. Trends Biotechnol. 1993;11: 430-433.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
4. Matejtschuk P, Dash CH, Gascoigne EW. Production of human albumin solution: a continually developing colloid. Br J Anaesth. 2000;85: 887-895.
5. Chuang VT, Kragh-Hansen U, Otagiri M. Pharmaceutical strategies utilizing recombinant human serum albumin. Pharm Res. 2002;19: 569-577.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
6. Emerson TE Jr. Unique features of albumin: a brief review. Crit Care Med. 1989;17: 690-694.[Web of Science][Medline] [Order article via Infotrieve]
7. Erstad BL. Viral infectivity of albumin and plasma protein fraction. Pharmacotherapy. 1996;16: 996-1001.[Web of Science][Medline] [Order article via Infotrieve]
8. Chamberland ME, Alter HJ, Busch MP, Nemo G, Ricketts M. Emerging infectious disease issues in blood safety. Emerg Infect Dis. 2001;7: 552-553.[Web of Science][Medline] [Order article via Infotrieve]
9. Chamberland M, Khabbaz RF. Emerging issues in blood safety. Infect Dis Clin North Am. 1998;12: 217-229.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
10. Llewelyn CA, Hewitt PE, Knight RS, et al. Possible transmission of variant Creutzfeldt-Jakob disease by blood transfusion. Lancet. 2004;363: 417-421.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
11. Bird SM. Recipients of blood or blood products "at vCJD risk." Br Med J. 2004;328: 118-119.
12. CPMP position statement on Creutzfeldt-Jakob disease and plasma-derived and urine-derived medical products, EMEA/CPMP/BWP/2879/02, February 20, 2003.
13. Tarelli E, Mire-Sluis A, Tivnann HA, et al. Recombinant human albumin as a stabilizer for biological materials and for the preparation of international reference reagents. Biologicals. 1998;26: 331-346.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
14. McClelland DB. Safety of human albumin as a constituent of biologic therapeutic products. Transfusion. 1998;38: 690-699.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
15. Bungum M, Humaidan P, Bungum L. Recombinant albumin as protein source in culture media used for IVF: a prospective randomised study. Reprod Biomed Online. 2002;4: 233-236.[Medline] [Order article via Infotrieve]
16. Savolainen J, Rantala A, Nermes M, Lehtonen L, Viander M. Enhanced IgE response to Candida albicans in postoperative invasive candidiasis. Clin Exp Allergy. 1996;26: 452-460.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
17. Nermes M, Falth-Magnusson K, Savolainen J, Viander M, Bjorksten B. A comparison of the development of antibody responses to the polysaccharide antigen (Candida albicans mannan) in atopic and healthy infants and children. Clin Exp Allergy. 1996;26: 164-170.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
18. Kobori T. Aiming to reduce costs by ¥10 billion. Pharma Japan. 2003;1849: 1-3.
19. Physicians' Desk Reference. 57th ed. Montvale, NJ: Medical Economics, 2003.
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