Gabriele I. Kirchner

Clinical Pharmacokinetics of Everolimus

Abstract Everolimus is an immunosuppressive macrolide bearing a stable 2-hydroxy-ethyl chain substitution at position 40 on the sirolimus (rapamycin) structure. Everolimus, which has greater polarity than sirolimus, was developed in an attempt to improve the pharmacokinetic characteristics of sirolimus, particularly to increase its oral bioavailability. Everolimus has a mechanism of action similar to that of sirolimus. It blocks growth-driven transduction signals in the T-cell response to alloantigen and thus acts at a later stage than the calcineurin inhibitors ciclosporin and tacrolimus. Everolimus and ciclosporin show synergism in immunosuppression both in vitro and in vivo and therefore the drugs are intended to be given in combination after solid organ transplantation. The synergistic effect allows a dosage reduction that decreases adverse effects.For the quantification of the pharmacokinetics of everolimus, nine different assays using high performance liquid chromatography coupled to an electrospray mass spectrometer, and one enzyme-linked immunosorbent assay, have been developed.Oral everolimus is absorbed rapidly, and reaches peak concentration after 1.3–1.8 hours. Steady state is reached within 7 days, and steady-state peak and trough concentrations, and area under the concentration-time curve (AUC), are proportional to dosage. In adults, everolimus pharmacokinetic characteristics do not differ according to age, weight or sex, but bodyweight-adjusted dosages are necessary in children.The interindividual pharmacokinetic variability of everolimus can be explained by different activities of the drug efflux pump P-glycoprotein and of metabolism by cytochrome P450 (CYP) 3A4, 3A5 and 2C8. The critical role of the CYP3A4 system for everolimus biotransformation leads to drug-drug interactions with other drugs metabolised by this cytochrome system. In patients with hepatic impairment, the apparent clearance of everolimus is significantly lower than in healthy volunteers, and therefore the dosage of everolimus should be reduced by half in these patients.The advantage of everolimus seems to be its lower nephrotoxicity in comparison with the standard immunosuppressants ciclosporin and tacrolimus. Observed adverse effects with everolimus include hypertriglyceridaemia, hypercholesterolaemia, opportunistic infections, thrombocytopenia and leucocytopenia.Because of the variable oral bioavailability and narrow therapeutic index of everolimus, blood concentration monitoring seems to be important. The excellent correlation between steady-state trough concentration and AUC makes the former a simple and reliable index for monitoring everolimus exposure. The target trough concentration of everolimus should range between 3 and 15 µg/L in combination therapy with ciclosporin (trough concentration 100–300 µg/L) and prednisone.

Automated, fast and sensitive quantification of drugs in blood by liquid chromatography–mass spectrometry with on-line extraction: immunosuppressants

We developed a universal LC-mass spectrometry assay with automated online extraction (LC/LC-MS) to quantify the immunosuppressants cyclosporine, tacrolimus, sirolimus and SDZ-RAD alone or in combination in whole blood. After protein precipitation, samples were loaded on a C18 extraction column, were washed and, after activation of the column-switching valve, were backflushed onto the C8 analytical column. [M+Na]+ ions were detected in the selected ion mode. For tacrolimus, sirolimus and SDZ-RAD, the assay was linear from 0.25 to 100 microg/l and for cyclosporine from 7.5 to 1250 microg/l (all r2>0.99). Analytical recovery was >85% and, in general, inter-day, intra-day variability for precision and accuracy were <10%.

Autoimmunity Resulting From Cytokine Treatment Predicts Long-Term Survival in Patients With Metastatic Renal Cell Cancer

PURPOSE In patients undergoing cytokine therapy, systemically applied interleukin-2 (IL-2) and/or interferon-alpha (IFN-alpha) have been reported to induce thyroid dysfunction as well as thyroid autoantibodies. We analyzed the correlation of thyroid autoimmunity with HLA phenotype, various other autoimmune parameters, and patient survival. PATIENTS AND METHODS For this purpose, antithyroglobulin autoantibodies, antimicrosomal thyroid autoantibodies, thyroglobulin receptor autoantibodies, thyroid dysfunction, and multiple clinical parameters were determined in 329 unselected patients with metastatic renal cell cancer before and after systemic IL-2 and IFN-alpha2 therapy. For statistical analysis, we used both univariate and multivariate Cox proportional hazards models and the two-tailed Fishers exact test. RESULTS Antithyroglobulin autoantibodies and antimicrosomal thyroid autoantibodies were detected in 60 patients (18%); positive autoantibody titers of various other autoimmune parameters were statistically unrelated. The presence of thyroid autoantibodies was correlated with prolonged survival (P<.0001). There was a statistically significant difference in frequencies of HLA-Cw7 expression between thyroid autoantibody-positive and -negative patients (P< or =.05), and the Cw7 expression was associated with prolonged overall survival (P = .009). CONCLUSION The evaluation of thyroid autoantibodies during cytokine therapy could be a useful prognostic marker for patients with renal cell carcinoma who benefit from cytokine treatment. IL-2- and IFN-alpha2-induced tumor control and prolonged survival may require breaking of immunologic tolerance against self-antigens.

Outcome and quality of life in patients with polycystic liver disease after liver or combined liver‐kidney transplantation

In advanced stages of polycystic liver disease, often associated with polycystic kidney disease, a curative therapy is liver or combined liver‐kidney transplantation. However, little is known about long‐term outcome and quality of life. Between 1990 and 2003, 36 patients (32 female, 4 male) with polycystic liver or combined liver‐kidney disease underwent liver (n = 21) or liver‐kidney (n = 15) transplantation at our center. Main indications for liver transplantation were cachexia, muscle atrophy, loss of weight, recurrent cyst infections, portal hypertension, and ascites. Apart from clinical parameters, 2 anonymous questionnaires (standard short form 36 and self‐designed) addressing quality of life and social status were evaluated. Five patients (14 %) died due to sepsis or myocardial infarction with pneumonia, all within 61 days after transplantation. The follow‐up time of the remaining 31 patients ranged from 5 to 156 months, with a mean of 62 months. Of the 23 (74%) answered the questionnaires, 91% of patients felt “much better” or “better,” only 9% felt “worse” than before, and 52% of patients participated in sports regularly. Fatigue, physical fitness, loss of appetite, and vomiting improved significantly after transplantation. Physical attractiveness and interest in sex increased as well. Professional occupation did not change for 71% of patients. Family situation before and after transplantation changed in 1 case only. Finally, 78% of patients said they would opt for transplantation again, while 17% were undecided; 1 patient would not repeat transplantation. In conclusion, patients with advanced polycystic liver or polycystic liver‐kidney disease have an excellent survival rate and an improved quality of life after liver or combined liver‐kidney transplantation. Liver Transpl 12:1268‐1277, 2006.

Simultaneous quantification of sirolimus, everolimus, tacrolimus and cyclosporine by liquid chromatography-mass spectrometry (LC-MS).

Abstract We developed a universal liquid chromatographymass spectrometry (LC-MS) assay with automated online extraction to quantify simultaneously the immunosuppressants sirolimus, everolimus, tacrolimus, and cyclosporine. Whole blood (300 μl) plus 6 μl 32-desmethoxyrapamycin (1 ng/μl) as internal standard was treated with 600 μl methanol/0.2 M ZnSO4 (80/20 v/v). After vortexing (30 s) and centrifugation (20000 g, 5 min) 50 μl of the supernatant were loaded on an extraction column, were washed by 0.35 ml/min water for 3 min and, after activation of a column-switching valve, were back-flushed by 0.25 ml/min methanol/ water (90/10 v/v) onto a C18 analytical column. After 22 min the extraction column was washed for 2 min with methanol and for 3 min with water before starting the next run. Column temperatures were kept at 33 °C. Sodium adduct ions [M+Na]+ ions were detected in the selected ion mode. For sirolimus, everolimus and tacrolimus the assay was linear from 0.3 to 200 μg/l and for cyclosporine from 5 to 1000 μg/l (all r2>0.999). Recovery of all immunosuppressants and the internal standard was >90% and in general, inter-day and intra-day precision was <10%. The simultaneous quantification of blood levels by LC-MS seems to be the method of choice in transplanted patients receiving multiple immunosuppressants.

Bile duct damage after cold storage of deceased donor livers predicts biliary complications after liver transplantation

BACKGROUND & AIMS The aim of this study was to examine the development of biliary epithelial damage between organ retrieval and transplantation and its clinical relevance for patients. METHODS Common bile duct samples during donor hepatectomy, after cold storage, and after reperfusion were compared to healthy controls by hematoxylin and eosin (H&E) staining and immunofluorescence for tight junction protein 1 and Claudin-1. A bile duct damage score to quantify biliary epithelial injury was developed and correlated with recipient and donor data and patient outcome. RESULTS Control (N=16) and donor hepatectomy bile ducts (N=10) showed regular epithelial morphology and tight junction architecture. After cold storage (N=37; p=0.0119), and even more after reperfusion (N=62; p=0.0002), epithelial damage, as quantified by the bile duct damage score, was markedly increased, and both tight junction proteins were detected with inappropriate morphology. Patients with major bile duct damage after cold storage had a significantly increased risk of biliary complications (relative risk 18.75; p<0.0001) and graft loss (p=0.0004). CONCLUSIONS In many cases, the common bile duct epithelium shows considerable damage after cold ischemia with further damage occurring after reperfusion. The extent of epithelial damage can be quantified by our newly developed bile duct damage score and is a prognostic parameter for biliary complications and graft loss. Possibly, in an intraoperative histological examination, this bile duct damage score may influence decision-making in transplantation surgery.

Simultaneous on-line extraction and analysis of sirolimus (rapamycin) and ciclosporin in blood by liquid chromatography–electrospray mass spectrometry

We developed a sensitive and specific semi-automated liquid chromatography-electrospray mass spectrometric (HPLC-ESI-MS) assay for the simultaneous quantification of sirolimus and ciclosporin in blood. Following a simple protein precipitation step, the supernatants were injected into the HPLC system and extracted on-line. After column switching, the analytes were backflushed from the extraction column onto the analytical narrow-bore column and eluted into the ESI-MS system. The assay was linear from 0.4 to 100 microg/l sirolimus and from 2 to 1500 microg/l ciclosporin. The mean recoveries of sirolimus and ciclosporin were 98 and 96%, respectively. The mean interday precision/accuracy was 8.6%/-4.8% for sirolimus and 9.3%/-2.9% for ciclosporin.

Biliary Strictures and Recurrence After Liver Transplantation for Primary Sclerosing Cholangitis: A Retrospective Multicenter Analysis

Liver transplantation (LT) is the only definitive treatment for patients with end‐stage liver disease due to primary sclerosing cholangitis (PSC), but a high rate of biliary strictures (BSs) and of recurrent primary sclerosing cholangitis (recPSC) has been reported. In this multicenter study, we analyzed a large patient cohort with a long follow‐up in order to evaluate the incidence of BS and recPSC, to assess the impact on survival after LT, and to identify risk factors. We collected clinical, surgical, and laboratory data and records on inflammatory bowel disease (IBD), immunosuppression, recipient and graft outcome, and biliary complications (based on cholangiography and histology) of all patients who underwent LT for PSC in 10 German transplant centers between January 1990 and December 2006; 335 patients (68.4% men; mean age, 38.9 years; 73.5% with IBD) underwent transplantation 8.8 years after PSC diagnosis with follow‐up for 98.8 months. The 1‐, 5‐, and 10‐year recipient and graft survival was 90.7%, 84.8%, 79.4% and 79.1%, 69.0%, 62.4%, respectively. BS was diagnosed in 36.1% after a mean time of 3.9 years, and recPSC was diagnosed in 20.3% after 4.6 years. Both entities had a significant impact on longterm graft and recipient survival. Independent risk factors for BS were donor age, ulcerative colitis, chronic ductopenic rejection, bilirubin, and international normalized ratio (INR) at LT. Independent risk factors for recPSC were donor age, IBD, and INR at LT. These variables were able to categorize patients into risk groups for BS and recPSC. In conclusion, BS and recPSC affect longterm graft and patient survival after LT for PSC. Donor age, IBD, and INR at LT are independent risk factors for BS and recPSC and allow for risk estimation depending on the recipient‐donor constellation. Liver Transpl 22:42‐52, 2016.

LC/ESI-MS allows simultaneous and specific quantification of SDZ RAD and cyclosporine, including groups of their metabolites in human blood.

An analytic technique using liquid chromatography (LC) coupled with electrospray-mass spectrometry (ESI-MS) has been developed for the simultaneous determination of the new immunosuppressant SDZ RAD (40-O-[2-hydroxy)ethylrapamycin) and cyclosporine (Cs), including their metabolites in blood. With the time-sparing, automated on-line extraction technique, the recovery of SDZ RAD averaged 95% and that of Cs, 94%. The calibration lines were linear from 0.5 to 100 microg/L (r2 = 0.99) for SDZ RAD and from 10 to 1,000 microg/L (r2 = 0.99) for Cs. The method has been tested on blood samples from renal transplant recipients taken between 1 and 5 hours after oral SDZ RAD and Cs administration. In blood, we found the following metabolites: Hydroxy-SDZ RAD, dihydroxy-SDZ RAD, demethyl-SDZ RAD, and the ring-opened form of SDZ RAD. The main metabolite of SDZ RAD in blood was hydroxy-SDZ RAD. This novel LC/ESI-MS technique provided an excellent method for simultaneous quantitative monitoring of SDZ RAD and Cs, including their relevant groups of metabolites in patients treated simultaneously with these immunosuppressants.

Serum ferritin concentration and transferrin saturation before liver transplantation predict decreased long-term recipient survival†‡

Serum ferritin (SF) concentration is a widely available parameter used to assess iron homeostasis. It has been described as a marker to identify high‐risk patients awaiting liver transplantation (LT) but is also elevated in systemic immune‐mediated diseases, metabolic syndrome, and in hemodialysis where it is associated with an inferior prognosis. This study analyzed whether SF is not only a predictor of liver‐related mortality prior to LT but also an independent marker of survival following LT. In a dual‐center, retrospective study, a cohort of 328 consecutive first‐LT patients from Hannover Medical School, Germany (2003‐2008, follow‐up 1260 days), and 82 consecutive LT patients from Regensburg University Hospital, Germany (2003‐2007, follow‐up 1355 days) as validation cohort were analyzed. In patients exhibiting SF ≥365 μg/L versus <365 μg/L prior to LT, 1‐, 3‐, and 5‐year post‐LT survival was 73.3% versus 81.1%, 64.4% versus 77.3%, and 61.1% versus 74.4%, respectively (overall survival P = 0.0097), which was confirmed in the validation cohort (overall survival of 55% versus 83.3%, P = 0.005). Multivariate analyses identified SF ≥365 μg/L combined with transferrin saturation (TFS) <55%, hepatocellular carcinoma, and the survival after LT (SALT) score as independent risk factors for death. In patients with SF concentrations ≥365 μg/L and TFS <55%, overall survival was 54% versus 74.8% in the remaining group (P = 0.003). In the validation cohort, it was 28.6% versus 72% (P = 0.017), respectively. Conclusion: SF concentration ≥365 μg/L in combination with TFS <55% before LT is an independent risk factor for mortality following LT. Lower TFS combined with elevated SF concentrations indicate that acute phase mechanisms beyond iron overload may play a prognostic role. SF concentration therefore not only predicts pre‐LT mortality but also death following LT. (HEPATOLOGY 2011;)