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.     

Thiopurine S-methyltransferase pharmacogenetics: Functional characterization of a novel rapidly degraded variant allozyme

A novel human thiopurine S-methyltransferase (TPMT) variant allele, (319 T > G, 107Tyr > Asp, *27), was identified in a Thai renal transplantation recipient with reduced erythrocyte TPMT activity. The TPMT*27 variant allozyme showed a striking decrease in both immunoreactive protein level and enzyme activity after transient expression in a mammalian cell line. We set out to explore the mechanism(s) responsible for decreased expression of this novel variant of an important drug-metabolizing enzyme. We observed accelerated degradation of TPMT*27 protein in a rabbit reticulocyte lysate. TPMT*27 degradation was slowed by proteasome inhibition and involved chaperone proteins—similar to observations with regard to the degradation of the common TPMT*3A variant allozyme. TPMT*27 aggresome formation was also observed in transfected mammalian cells after proteasome inhibition. Inhibition of autophagy also decreased TPMT*27 degradation. Finally, structural analysis and molecular dynamics simulation indicated that TPMT*27 was less stable than was the wild type TPMT allozyme. In summary, TPMT*27 serves to illustrate the potential importance of protein degradation - both proteasome and autophagy-mediated degradation - for the pharmacogenetic effects of nonsynonymous SNPs.     

Outcome of microemulsion cyclosporine C2 concentration monitoring in kidney transplantation

Profiling of absorption of cyclosporine (CsA) microemulsion is a concept in therapeutic drug monitoring (TDM) designed to optimize the clinical benefits of the drug in transplant recipients. A single blood concentration at 2 h (C(2)) after CsA microemulsion administration in kidney transplant recipients accurately predicts graft outcome. An international guidelines has recommended the target C(2) over time-course post-transplantation. We determined whether this recommendation is appropriate for our patients who are Asian ethnic. The clinical data of these C(2) monitoring kidney transplant recipients were compared with the historical cohort of microemulsion CsA trough (C(0)) level monitoring during the first 24-month post-transplantation. The inclusion and exclusion criteria were applied for both C(2) and C(0) cohorts. The mean target C(2) concentrations at 1, 3, 6, and 12-month post-transplantation were achieved in the C(2) cohort as the international guildlines. At 3-month post-transplantation, patients who had C(2) concentrations over 1500 ng/mL had higher serum creatinine as compared with those who had C(2) levels <1300 ng/mL (2.23 +/- 0.8 vs. 1.44 +/- 0.38 mg/dL: p = 0.01). Also, at 6-month post-transplantation, patients who had C(2) concentrations over 1300 ng/mL had higher serum creatinine (1.96 +/- 0.29 vs. 1.37 +/- 0.34 mg/dL: p < 0.01) as compared with those who had C(2) levels <1100 ng/mL. There was no statistical difference of acute rejection episodes between the two cohorts. The international consensus for C(2) concentraion may be too high for Asian ethnic kidney transplant recipients. The data from this study indicated lower than recommended C(2) concentraion as an appropriate C(2) target concentraion.     

Prevalence and risk of residual viremia after ART in low- and middle-income countries: A cross-sectional study

In order to design effective strategies to eradicate the HIV, an understanding of persistent viral reservoirs is needed. Many studies have demonstrated HIV residual viremia prevalence in high income countries, data from low- and middle-income countries (LMIC) are limited. We assessed the prevalence, and factors associated with residual viremia in people with HIV (PWH), who were virally-suppressed on antiretroviral therapy (ART) in LMIC. We also compared residual viremia prevalence between the LMIC and US.This is a cross-sectional, retrospective study that utilized stored specimen samples from the AIDS clinical trials group (ACTG) studies A5175 and A5208. The last available sample among participants with plasma HIV RNA < 400 copies/mL for ≥3 years were tested by the HIV molecular and monitoring core gag (HMMCgag) single copy assay (SCA). Residual viremia was defined as detectable if ≥1 copy/mL. Spearman''s correlation and multivariable stepwise logistic regression were used to assess associations of various factors with SCA.A total of 320 participants, 246 (77%) from LMIC and 74 (23%) from US, were analyzed. Median (IQR) age was 33 (2840) years; baseline CD4 166 (88,230) cells/mm³; HIV RNA 5.0 (4.5, 5.3) log10 copies/mL; duration of viral suppression 3.4 (3.1, 4.0) years and 48% were male. In 85 participants with information available, 53% were subtype C, 42% subtype B and 5% other subtypes. Overall prevalence of residual viremia was 57% [95% CI, 52–63] with 51% [40–63] in US and 59% [53–65] in LMIC. Among participants with detectable SCA, the median (IQR) HIV RNA was 3.8 (2.2, 8.1) copies/mL. The multivariable model conducted in LMIC participants showed that higher baseline HIV RNA was associated with detectable residual RNA (OR 2.9, 95% CI 1.8, 4.6 for every log10 increase, P < .001). After including both US and LMIC in the final model, baseline HIV RNA remained significant. No difference in SCA detestability was found between US and LMIC sites (OR 1.1 [0.6, 2.0], P = .72) after adjusting for baseline RNA and parent study.The prevalence of residual viremia between both groups were not different and more than half of the participants had detectable viremia. Higher baseline HIV RNA was independently associated with residual viremia.     

Efficacy of enteric-coated mycophenolate sodium in patients with resistant-type lupus nephritis: a prospective study

The role of mycophenolate mofetil (MMF) is still controversial in the treatment of cyclophosphamide-resistant proliferative lupus nephritis (PLN). Enteric-coated mycophenolate sodium (EC-MPS) has less gastrointestinal adverse effects than MMF and is, therefore, increasingly utilised in organ transplantation. The aim of this study was to compare the efficacy and safety of EC-MPS versus an extended-course of intravenous cyclophosphamide (ED-IVCY) in resistant-type PLN. Thirty-one, biopsy-proven PLN, patients who failed to respond to an induction of IVCY were enrolled in a prospective, open-labelled, historically controlled study. Patients received 6 month of EC-MPS (720 mg b.i.d.) treatment. The patients in the ED-IVCY group, collected from a database, received a repeated 6-month course of monthly IVCY 0.5-1 g/m(2) of body surface area. Both groups received 0.5-1 mg/kg/day of prednisolone. Primary outcomes were partial or complete responses. A repeated kidney biopsy was performed to evaluate the histological response. No serious adverse events or patient deaths were observed during the study. Both groups had comparable baseline characteristics. At 6 months, the EC-MPS group had a comparable response rate with the ED-IVCY group. There were significantly less adverse events in the EC-MPS group. Repeated biopsies showed significant improvement in the EC-MPS group. EC-MPS provides salutary efficacy and safety in the treatment of resistant-type PLN and can be a suitably alternative treatment to ED-IVCY.     

High Prevalence of Obesity in Thai Renal Transplant Recipients: A Multicenter Study

Background

Obesity is a risk factor for cardiovascular disease and cardiovascular mortality in renal transplant recipients (RTRs). There are limited studies of prevalence and associated factors of obesity in Asian RTRs.

Methods

A cross-sectional study was conducted from July to December 2012 in 4 kidney transplant centers in Bangkok, Thailand. Obesity was diagnosed based on the International Obesity Taskforce-proposed classification. At risk of obesity, obese I, and obese II were defined as having a body mass index (BMI) of 23–24.9 kg/m², 25–29.9 kg/m², and ≥30 kg/m², respectively.

Results

Of 263 recipients studied, 50 (19.0%), 70 (26.6%), and 17 (6.5%) were at risk of obesity, obese I, and obese II, respectively. The prevalence of obesity was 12.6% in the 1st year, was 28.6% in the first 3 years, and rose to 39.7% after 3 years after transplantation. Age (odds ratio [OR], 1.04; 95% CI, 1.01–1.07), systolic blood pressure ≥130/85 mm Hg (OR, 2.82; 95% CI, 1.51–5.26), number of antihypertensive medications (OR, 1.99; 95% CI, 1.42–2.79), fasting plasma glucose (OR, 1.03; 95% CI, 1.01–1.04,) and high-density lipoprotein (HDL) cholesterol (OR, 0.96; 95% CI, 0.94–0.98) were associated with obesity. Compared with 100 RTRs with normal BMI, obese patients tended to have higher prevalence of chronic kidney disease (OR, 1.59; 95% CI, 0.89–2.83).

Conclusions

The study demonstrates the high prevalence of obesity in Thai RTRs especially after 3 years after transplantation. Obesity is more prevalent with advanced age and variable components of metabolic syndrome in the RTR population. Obese RTRs had significantly higher blood pressure and required more antihypertensive medication when compared with RTRs with normal BMI.     

Influence of ABCC2 and ABCC4 Polymorphisms on Tenofovir Plasma Concentrations in Thai HIV-Infected Patients

Tenofovir (TFV) is eliminated by renal excretion, which is mediated through multidrug-resistant protein 2 (MRP2) and MRP4, encoded by ABCC2 and ABCC4, respectively. Genetic polymorphisms of these transporters may affect the plasma concentrations of tenofovir. Therefore, the aim of this study was to investigate the influence of genetic and nongenetic factors on tenofovir plasma concentrations. A cross-sectional study was performed in Thai HIV-infected patients aged ≥18 years who had been receiving tenofovir disoproxil fumarate at 300 mg once daily for at least 6 months. A middose tenofovir plasma concentration was obtained. Multivariate analysis was performed to investigate whether there was an association between tenofovir plasma concentrations and demographic data, including age, sex, body weight, estimated glomerular filtration rate (eGFR), hepatitis B virus coinfection, hepatitis C virus coinfection, duration of tenofovir treatment, concomitant use of ritonavir-boosted protease inhibitors, and polymorphisms of ABCC2 and ABCC4. A total of 150 Thai HIV-infected patients were included. The mean age of the patients was 43.9 ± 7.2 years. The mean tenofovir plasma concentration was 100.3 ± 52.7 ng/ml. In multivariate analysis, a low body weight, a low eGFR, the concomitant use of ritonavir-boosted protease inhibitors, and the ABCC4 4131T → G variation (genotype TG or GG) were independently associated with higher tenofovir plasma concentrations. After adjusting for weight, eGFR, and the concomitant use of ritonavir-boosted protease inhibitors, a 30% increase in the mean tenofovir plasma concentration was observed in patients having the ABCC4 4131 TG or GG genotype. Both genetic and nongenetic factors affect tenofovir plasma concentrations. These factors should be considered when adjusting tenofovir dosage regimens to ensure the efficacy and safety of a drug. (This study has been registered at ClinicalTrials.gov under registration no. {"type":"clinical-trial","attrs":{"text":"NCT01138241","term_id":"NCT01138241"}}NCT01138241.)