Khajohn Tiranathanagul

Biosimilar recombinant human erythropoietin induces the production of neutralizing antibodies

Recombinant human erythropoietin (r-HuEpo) has been used for the treatment of renal anemia. With the loss of its patent protection, there has been an upsurge of more affordable biosimilar agents, increasing patient access to treatment for these conditions. The complexity of the manufacturing process for these recombinant proteins, however, can result in altered properties that may significantly affect patient safety. As it is not known whether various r-HuEpo products can be safely interchanged, we studied 30 patients with chronic kidney disease treated by subcutaneous injection with biosimilar r-HuEpo and who developed a sudden loss of efficacy. Sera from 23 of these patients were positive for r-HuEpo-neutralizing antibodies, and their bone marrow biopsies indicated pure red-cell aplasia, indicating the loss of erythroblasts. Sera and bone marrow biopsies from the remaining seven patients were negative for anti-r-HuEpo antibodies and red-cell aplasia, respectively. The cause for r-HuEpo hyporesponsiveness was occult gastrointestinal bleeding. Thus, subcutaneous injection of biosimilar r-HuEpo can cause adverse immunological effects. A large, long-term, pharmacovigilance study is necessary to monitor and ensure patient safety for these agents.

The need for robust validation for MDRD-based glomerular filtration rate estimation in various CKD populations

BACKGROUND Currently, estimated glomerular filtration rate (eGFR) equations have been validated only in Caucasians and African-Americans and is not applicable to people of other races/ethnicities as shown in studies conducted in two Asian populations: Chinese and Japanese. Because of this, it is important that eGFR equations are validated in its prospective population before applying it in the clinical setting and in epidemiologic studies. Therefore, we examined all eGFR equations available: reexpressed isotope dilution mass spectroscopy (IDMS)-traceable Modification of Diet in Renal Disease (MDRD) equation, Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, Chinese equation and Japanese equation. METHODS A total of 350 adult Thai CKD patients were studied. The (99m)Tc-DTPA plasma clearance was used as a reference for glomerular filtration rate (GFR). The serum creatinine was determined by IDMS reference enzymatic methods (Cr(Enz)) and Jaffes kinetic assay (Cr(Jaffe)) as indicated in each equation. RESULTS The disagreement between the reference GFR and eGFR (reference GFR minus eGFR) was 9.6 mL/min/1.73 m(2) for the reexpressed IDMS-traceable MDRD equation, 8.0 mL/min/1.73 m(2) for CKD-EPI equation, 1.9 mL/min/1.73 m(2) for eGFR equation from the Chinese study and 20.9 mL/min/1.73 m(2) for the eGFR equation from the Japanese study. The Thai coefficient for the reexpressed MDRD was 1.129. The reexpressed MDRD equation for Thais is as follows: 175 × Cr(Enz) ((-1.154)) × Age ((-0.203)) × 0.742 (if female) × 1.129 (if Thai). When stepwise multiple regression analysis was used, the Thai eGFR formula is: 375.5 × Cr(Enz) ((-0.848)) × Age ((-0.364)) × 0.712 (if female). CONCLUSIONS Differences in race/ethnicity can significantly affect the results obtained from MDRD-based eGFR equation. It is highly recommended that each population should validate eGFR equations before applying the equation in epidemiologic studies or clinical use.

Regional Citrate Anticoagulation Reduces Polymorphonuclear Cell Degranulation in Critically Ill Patients Treated With Continuous Venovenous Hemofiltration

Citrate which chelates ionized calcium can be used as regional anticoagulation in continuous venovenous hemofiltration (CVVH). This is the first study conducted to examine the potentially additive benefit effect of regional citrate anticoagulation (RCA) on polymorphonuclear (PMN) cell degranulation of myeloperoxidase (MPO) and cytokines production in patients with critically acute kidney injury (AKI) undergoing CVVH treatment. This prospective randomized controlled trial was conducted in 20 critically ill patients with AKI who underwent CVVH. The patients were randomized into regional citrate group (n = 10) and heparin group (n = 10). The pre‐dilution CVVH with polyethersulfone dialyzers were utilized in both groups. The levels of pre‐filter and post‐filter MPO as well as inflammatory and anti‐inflammatory cytokines were measured at baseline, 6 h, and 24 h after initiating CVVH. In the heparin group, the post‐filter serum MPO levels were significantly higher than the pre‐filter (median 49.0 vs. 60.5 ng/mL, P < 0.05) at 6 h. There were no significant differences between pre‐ and post‐dialyzer MPO levels in the citrate group. Citrate could significantly decrease systemic pre‐filter serum MPO levels from baseline at 6 h (median 43.5 vs. 17.3 ng/mL, P < 0.01) as well as IL‐8 levels (P < 0.05) whereas heparin provided only significant TNF‐α reduction (P < 0.05). The CVVH circuit survival in the citrate group was longer than the heparin group. In conclusion, citrate, utilized as a regional anticoagulant in CVVH, can reduce both membrane bioincompatibility‐induced and systemic oxidative stress and inflammation, and can prolong CVVH circuit survival time.

Bioartificial kidney in the treatment of acute renal failure associated with sepsis

SUMMARY:  Acute renal failure (ARF) associated with sepsis has a high rate of mortality. It is not merely a surrogate marker for severity of disease but also an independent predictor of mortality and a separate pathogenic entity, even when nearly physiological doses of fluid and small‐molecule clearance are maintained with currently available renal replacement therapies (RRT). The techniques to remove cytokines, including high‐volume haemofiltration, haemodialysis using high‐cut‐off haemofilters, and absorptive techniques, lead to some improvement in outcome but are still insufficient to reverse the complicated biological dysregulation resulting from ARF associated with sepsis. The novel and exciting technique of cell therapy, which is based on the principle of using functional cells to replace a greater range of renal functions, may add significant benefit to current RRT in dealing with this disease process. Because renal tubule cells appear to play critical roles in immunoregulation, renal tubule cell therapy during ARF associated with sepsis should alter the detrimental multiple‐organ consequences of sepsis. The development of a bioartificial kidney consisting of a conventional haemofiltration cartridge in series with a renal tubule assist device containing renal proximal tubule cells represents a new therapeutic approach to this clinical disorder. The results to date of large animal studies and recent Phase I/II and Phase II clinical trials show that such a device replaces multiple kidney functions and modifies the sepsis condition to improve survival in ARF.

Effective bilirubin reduction by single-pass albumin dialysis in liver failure.

Albumin dialysis is widely accepted as a liver-support technique for patients with liver failure. The Molecular Adsorbent Recirculating System, the widely accepted albumin dialysis technique, has limited use in developing countries because of its technical difficulties and high cost. Therefore, we assessed the efficacy of the more practical modality, the single-pass albumin dialysis (SPAD), in terms of bilirubin reduction, as a marker of albumin-bound toxins removal, as well as the patient outcomes. Twelve acute or acute-on-chronic patients with liver failure who had hyperbilirubinemia (total bilirubin > 20 mg/dL) were treated with SPAD by using 2% human serum albumin dialysate for 6 h. SPAD treatment significantly improved the levels of total bilirubin, conjugated bilirubin, urea, and creatinine (P < 0.001 for all parameters). The reduction ratios of these four parameters were 22.9 +/- 3.8%, 20.9 +/- 5%, 19.0 +/- 4.1%, and 27.7 +/- 3.2%, respectively. No significant difference was observed between serum ammonia before and after treatment. No significant changes in mean arterial pressures were noted during the maneuver, representing cardiovascular tolerability. No treatment-related complications were found. The 15-day in-hospital survival was 16.7%. However, a subgroup of the patients who had moderate severity showed 100% 15-day-survival rate (2 of 2 patients). In conclusion, SPAD is salutarily effective in reducing bilirubin in patients with liver failure. The procedure is safe and simply set up.

Tissue engineering of an implantable bioartificial hemofilter

The first step in the tissue engineering of an implantable bioartificial kidney is the development of an implant that produces ultrafiltrate to replace glomerular function. A fabricated device containing synthetic hollow hemofiltration fibers was placed around the femoral vascular pedicle in rats, which initiated new tissue formation with a mature and durable neocapillary bed. The transudate fluid produced by this newly formed capillary bed accumulated through the hollow fibers into a subcutaneous port to allow evaluation of the fluid. In its first phase, this study evaluated various hollow fibers and tissue induction processes by the measurement of fluid volume, urea nitrogen, and total protein continuously for 6 weeks. New tissues formed within the implants surrounding the fibers, and the vascular density, vessel sizes, and percent cross-sectional vascular area were assessed by means of histomorphometric analysis after 6 weeks. The volume of fluid formation correlated with both vascular density and fiber membrane surface area. The implant fluid-to-serum ratios demonstrated a permselective filtrate. In a second phase, platelet-derived growth factor and vascular endothelial growth factor versus carrier alone were infused directly into the implants for the first 4 weeks in vivo through osmotic pumps and followed up to 9 weeks. Cumulative implant fluid volumes were significantly greater in the growth factor–treated group than in control animals and were associated with greater numbers of small-caliber blood vessels. These results provide the initial proof of concept in developing a tissue-engineered hemofilter prototype on a small scale in a rodent model.

Comparison of middle-molecule clearance between convective control double high-flux hemodiafiltration and on-line hemodiafiltration.

Hemodiafiltration (HDF) is now a well-recognized treatment modality for end-stage renal disease (ESRD) patients. It provides superior characteristics over conventional hemodialysis in many respects. On-line HDF, however, which has been mainly used in clinical practice, requires a special machine. Interestingly, the recently innovated convective-control double high-flux hemodiafiltration (CC-DHF) machine can provide HDF treatment with an adjustable convection rate by using the conventional volume-controlled dialysate flow hemodialysis machine in a modified way. The present study was conducted to compare the efficacy of CC-DHF compared to on-line HDF in terms of middle and small solute clearances in 12 stable, chronic hemodialysis patients who underwent hemodialysis three times a week for at least 6 months. The results showed that the β2-microglobulin (β2M) removal represented by the β2M clearance in CC-DHF was comparable to that in on-line HDF (112.4±17.0 vs. 119.4±15.5 ml/min respectively, NS). Also, the β2M reduction ratio in the CC-DHF group did not differ from the on-line HDF group (85.5±4.2% vs. 86.1±6.7%, NS). With regard to small solute clearances, the values of single-pool Kt/V and phosphate clearance did not differ between CC-DHF and on-line HDF groups. In conclusion, CC-DHF provides removal of β2M and small molecule uremic toxins that is comparable to on-line HDF. An on-line HDF machine may not be available in all hemodialysis centers, whereas CC-DHF can be easily set up, with proper precautions regarding the fluid quality. Therefore, CC-DHF can provide the benefits of convective therapy to patients in situations where use of an on-line HDF machine is limited.

Oxidative stress from rapid versus slow intravenous iron replacement in haemodialysis patients.

Methods and Results:  Oxidative stress was examined in 19 erythropoietin‐treated haemodialysis patients who were receiving 100 mg of iron sucrose every 2 weeks by two intravenous methods, rapid injection and slow infusion. There were no significant differences in incidence of iron oversaturation state between the two methods. Regarding oxidative stress markers, the values of plasma and red blood cell thiobarbituric acid reactive substances (TBARS) expressed in terms of malonyldialdehyde (MDA) equivalents following the two methods did not increase, and the values of area under the curve (AUC) of both markers were not different between both regimens. Also, there were no significant differences in the values of plasma and AUC of anti‐oxidant markers including total anti‐oxidant status, reduced thiols, and vitamin E among both periods treated with two intravenous iron methods.

Efficacy Comparison Between Simple Mixed-Dilution and Simple Mid-Dilution On-Line Hemodiafiltration Techniques: A Crossover Study

Mid-dilution and mixed-dilution on-line hemodiafiltration (OL-HDF) techniques are innovated to overcome the limitations of two standard techniques including predilution and postdilution. Unfortunately, the head-to-head comparisons between these two novel techniques in the same study are still limited. Moreover, the original mid-dilution and mixed-dilution OL-HDF need special dialyzers and special machines. In the present study, simple mid-dilution and simple mixed-dilution OL-HDF were settled with the aim for clinical use in general hemodialysis (HD) centers. The efficacies of uremic toxins removal between both modalities were measured and compared. This prospective randomized crossover study was conducted on 12 stable HD patients undergoing simple mixed-dilution and simple mid-dilution OL-HDF techniques. HD prescriptions were similar in both techniques. The dialysis efficacies were determined by calculating small- (urea, creatinine, and phosphate) and middle-molecule (beta-2 microglobulin [β2M]) removal. Moreover, potential complications such as high transmembrane pressure (TMP) and protein loss were also observed. Simple mixed-dilution OL-HDF provided significantly greater clearances of urea, creatinine, and β2M when compared with the simple mid-dilution OL-HDF techniques. Phosphate clearances in both techniques were comparable. In addition, TMP and dialysate albumin loss were not different. There were no intradialytic complications in both techniques. Simple mixed-dilution OL-HDF could provide greater efficacy for small- and middle-molecule clearances and acceptable potential risks, while phosphate removal is comparable.

Enhanced vascular endothelial growth factor and inflammatory cytokine removal with online hemodiafiltration over high-flux hemodialysis in sepsis-related acute kidney injury patients.

Hypercytokinemia plays a central role in pathogenesis and is related to the high mortality in sepsis‐related acute kidney injury (AKI). Besides the established cytokines, vascular endothelial growth factor (VEGF) is demonstrated as an important factor in enhancing vascular leakage in sepsis. This prospective randomized trial was conducted to compare the efficacy of cytokine removal between online hemodiafiltration (HDF), which combines convective and diffusive solute removal, and high‐flux hemodialysis (HD). Twenty‐eight sepsis‐related AKI patients were included and randomized into online HDF and high‐flux HD. The percentages of the reduction ratio in plasma cytokines were measured as primary outcomes. Other clinical parameters were determined as secondary outcomes. When compared with high‐flux HD, online HDF provided significantly greater percentages of the reduction ratio in plasma cytokine levels, including VEGF (P < 0.001), IL‐6 (P = 0.001), IL‐8 (P = 0.021), IL‐10 (P = 0.011), and tumor necrosis factor‐α (P = 0.029). There were no significant differences in intradialytic blood pressures. Online HDF revealed better renal recovery and shorter length of hospitalization than high‐flux HD. In conclusion, online HDF in sepsis‐related AKI could provide significantly better removal of VEGF and other cytokines and these were associated with better renal outcome than high‐flux HD. Thus, online HDF would offer a potential role in hypercytokinemic state in sepsis‐related AKI.