Focusing on Ischemic Reperfusion Injury in the New Era of Dynamic Machine Perfusion in Liver Transplantation.

Liver transplantation is the most effective treatment for end-stage liver disease. Transplant indications have been progressively increasing, with a huge discrepancy between the supply and demand of optimal organs. In this context, the use of extended criteria donor grafts has gained importance, even though these grafts are more susceptible to ischemic reperfusion injury (IRI). Hepatic IRI is an inherent and inevitable consequence of all liver transplants; it involves ischemia-mediated cellular damage exacerbated upon reperfusion and its severity directly affects graft function and post-transplant complications. Strategies for organ preservation have been constantly improving since they first emerged. The current gold standard for preservation is perfusion solutions and static cold storage. However, novel approaches that allow extended preservation times, organ evaluation, and their treatment, which could increase the number of viable organs for transplantation, are currently under investigation. This review discusses the mechanisms associated with IRI, describes existing strategies for liver preservation, and emphasizes novel developments and challenges for effective organ preservation and optimization.

Therapeutic Drug Monitoring and Dosage Adjustments of Immunosuppressive Drugs When Combined With Nirmatrelvir/Ritonavir in Patients With COVID-19.

ABSTRACT: Nirmatrelvir/ritonavir (Paxlovid) consists of a peptidomimetic inhibitor (nirmatrelvir) of the SARS-CoV-2 main protease and a pharmacokinetic enhancer (ritonavir). It is approved for the treatment of mild-to-moderate COVID-19. This combination of nirmatrelvir and ritonavir can mediate significant and complex drug-drug interactions (DDIs), primarily due to the ritonavir component. Indeed, ritonavir inhibits the metabolism of nirmatrelvir through cytochrome P450 3A (CYP3A) leading to higher plasma concentrations and a longer half-life of nirmatrelvir. Coadministration of nirmatrelvir/ritonavir with immunosuppressive drugs (ISDs) is particularly challenging given the major involvement of CYP3A in the metabolism of most of these drugs and their narrow therapeutic ranges. Exposure of ISDs will be drastically increased through the potent ritonavir-mediated inhibition of CYP3A, resulting in an increased risk of adverse drug reactions. Although a decrease in the dosage of ISDs can prevent toxicity, an inappropriate dosage regimen may also result in insufficient exposure and a risk of rejection. Here, we provide some general recommendations for therapeutic drug monitoring of ISDs and dosing recommendations when coadministered with nirmatrelvir/ritonavir. Particularly, tacrolimus should be discontinued, or patients should be given a microdose on day 1, whereas cyclosporine dosage should be reduced to 20% of the initial dosage during the antiviral treatment. Dosages of mammalian target of rapamycin inhibitors (m-TORis) should also be adjusted while dosages of mycophenolic acid and corticosteroids are expected to be less impacted.

Genotype and Phenotype Influence the Personal Response to Prostaglandin Analogues and Beta-Blockers in Spanish Glaucoma and Ocular Hypertension Patients.

Analysis of the genotype that predicts the phenotypic characteristics of a cohort of glaucoma and ocular hypertension patients, and the correlation with their personal pharmacological response to beta-blockers (BB) and prostaglandin analogues (PGA). Prospective study that included 139 eyes from 72 patients under BB and/or PGA treatment, and in some cases other types of ocular hypotensive treatments. Five single-nucleotide polymorphisms were genotyped by real-time PCR assays: prostaglandin-F2α receptor (rs3766355, rs3753380); cytochrome-P450 2D6 (rs16947, rs769258); and beta-2-adrenergic receptor (rs1042714). Other studied variables were mean deviation (MD) of visual field, previous ocular interventions, medical treatment, baseline (bIOP), and treated intraocular pressure (tIOP). From a total of 139 eyes, 71 (51.1%) were left eyes. The main diagnosis was primary open angle glaucoma (66.2%). A total of 57 (41%) eyes were under three or more medications (PGA + BB + other) and, additionally, 57 eyes (41%) had had some kind of glaucoma surgery. The mean bIOP and tIOP were 26.55 ± 8.19 and 21.01 ± 5.54 mmHg, respectively. Significant differences in tIOP were found between heterozygous (HT) (21.07 ± 0.607 mmHg) and homozygous (HM) (20.98 ± 0.639 mmHg) rs3766355 with respect to wildtype individuals (16 ± 1.08 mmHg) (p = 0.031). The MD values presented significant differences between wildtype rs3766355 (-2 ± 2.2 dB), HT (-3.87 ± 4 dB), and HM carriers (-9.37 ± 9.51 dB) (p = 0.009). Significant differences were also observed between the MD in wildtype rs3753380 (-6.1 ± 8.67 dB), HT (-9.02 ± 8.63 dB), and HM carriers (-9.51 ± 7.44 dB) (p = 0.017). Patients carrying the variant rs3766355 in HM or HT presented clinically-significantly higher tIOP than wildtype patients. Additionally, some differences in MD were found in rs3766355 and rs3753380 carriers, and the more alleles that were affected, the worse the MD value, meaning greater severity of the glaucoma. Poor response to treatment and more visual field damage may be associated with being a carrier of these mutated alleles.

Tigecycline population pharmacokinetics in critically ill patients with decompensated cirrhosis and severe infections.

OBJECTIVES: Physiopathological changes in advanced cirrhosis could alter tigecycline pharmacokinetics (PK), thus affecting serum drug concentrations and compromising target attainment. We aimed to describe tigecycline PK in patients with decompensated cirrhosis and severe bacterial infections, identify the sources of PK variability and assess the performance of different dosing regimens to optimize the PK/pharmacodynamic (PD) target. METHODS: Serum concentrations and covariates were obtained from patients with severe infections under tigecycline treatment. A population PK analysis was performed using non-linear mixed-effects modelling and the final model was used to simulate tigecycline exposure to assess the PTA. RESULTS: Twenty critically ill patients were enrolled in the study. Data were best described by a two-compartment linear model. Mean ± SD parameter estimates for clearance (CL), intercompartmental clearance (Q), central and peripheral volumes of distribution (V1 and V2) were 14.8 ± 11 L/h, 38.4 ± 24 L/h, 63.7 ± 14 L and 233 ± 30 L, respectively. MELD score significantly influenced tigecycline CL, and total serum proteins significantly affected V1. Monte Carlo simulations showed that tigecycline elimination is hampered as MELD score values increase, consequently requiring lower drug doses. Patients with hypoproteinaemia would have lower peak tigecycline concentrations but similar steady-state concentrations compared with patients with normoproteinaemia. CONCLUSIONS: Our study confirms that tigecycline dose adjustment is needed in severe hepatic dysfunction and suggests using the MELD score for dose optimization since it is identified as a covariate that significantly influences tigecycline CL. Dosing regimens are recommended to reach several PK/PD targets considering this clinical variable and any MIC within the susceptibility range.

Monitoring of Donor-Derived Cell-Free DNA by Short Tandem Repeats: Concentration of Total Cell-Free DNA and Fragment Size for Acute Rejection Risk Assessment in Liver Transplantation.

Monitoring of graft function is essential during the first months after liver transplantation (LT), but current liver function tests (LFTs) lack the specificity and sensitivity to ensure an efficient diagnosis of acute rejection (AR). Recently, donor-derived cell-free DNA (ddcfDNA) has emerged as a noninvasive biomarker to assess graft integrity. This study evaluated the feasibility of measuring the ddcfDNA through short tandem repeat (STR) analysis by quantitative fluorescent-polymerase chain reaction (QF-PCR) and to assess the role of the concentration and fragment size of total cfDNA as AR biomarkers. The total concentration and fragment size of cfDNA and the ddcfDNA percentage were monitored in plasma of 20 patients without rejection and 7 patients with T-cell-mediated AR during the first 3 months after LT. The median ddcfDNA percentage was 3-fold higher before AR diagnosis (34.8%; P < 0.001) and moderately higher at AR confirmatory diagnosis (23.8%; P = 0.049) compared with that of nonrejector patients (10.6%), showing a better performance (area under the curve = 84.6%) than conventional LFTs to predict the risk of rejection within the first 2 weeks following LT. The fraction of 100-250-bp cfDNA fragments was higher at AR diagnosis compared with that of nonrejector patients (68.0% versus 57.9%, P = 0.02). STR amplification by QF-PCR may be an alternative strategy for rapid ddcfDNA quantification, which is easily implementable in clinical laboratories. The results of this pilot study indicate that ddcfDNA increases very early, even 1-2 weeks before the diagnosis of AR, and so it could be useful as a prognostic biomarker in improving patient risk stratification.

Polyethylene Glycol Drug-Eluting Embolic Microspheres Loaded with Doxorubicin for the Treatment of Hepatocellular Carcinoma: Feasibility, Safety, and Pharmacokinetic Study.

PURPOSE: Polyethylene glycol drug-eluting microspheres (PEG-DEMs) can be loaded to elute doxorubicin. The current study evaluated the pharmacokinetic profile and safety of PEG-DEMs in the treatment of patients with hepatocellular carcinoma (HCC). MATERIALS AND METHODS: The current prospective, multicenter, dose-escalation study enrolled 25 patients (68% men) with early or intermediate stage HCC and a performance status of 0. Patients in Cohort I were assigned to receive target doxorubicin doses of 75, 100, or 150 mg. Analyses were performed on the basis of the specific dose of doxorubicin that the patients received because some patients received less than the assigned dose. Patients in Cohort II received the maximum safe tested dose. Adverse events were classified according to the Common Terminology Criteria for Adverse Events version 4.03. The tumor response was evaluated every 3 months according to the European Association for the Study of the Liver criteria and modified Response Evaluation Criteria in Solid Tumors. RESULTS: The maximum tested safe dose of doxorubicin was 150 mg. For the groups that received ≤75, 75-100, and 101-150 mg of doxorubicin, the peak plasma concentrations were 286.7 ng/mL ± 220.1, 157.1 ng/mL ± 94.6, and 245.4 ng/mL ± 142.8, respectively; the areas under the curves calculated from 0 to 24 h were 421.7 (ng × h)/mL ± 221.2, 288.1 (ng × h)/mL ± 100.9, and 608.3 (ng × h)/mL ± 319.3, respectively, with almost complete clearance at 24 h. There was no death within 30 d. The best objective response rate was 81%, and the disease control rate was 91%. The median overall survival was 27.2 months (95% confidence interval [CI], 17.5 months to not evaluated [n.e.]); the median progression-free survival was 9.8 months (95% CI, 5.5 months to n.e.). CONCLUSIONS: PEG-DEMs demonstrated a favorable safety profile with low systemic concentration of doxorubicin, and promising efficacy.

Advantages of plasmatic CXCL-10 as a prognostic and diagnostic biomarker for the risk of rejection and subclinical rejection in kidney transplantation.

This study evaluate the potential of plasmatic CXCL-10 (pCXCL-10) as a pre&post transplantation prognostic and diagnostic biomarker of T-cell-mediated rejection (TCMR), antibody-mediated rejection (ABMR) and subclinical rejection (SCR) risk in adult kidney recipients considering BKV and CMV infections as possible clinical confounder factors. Twenty-eight of 100 patients included experienced rejection (TCMR:14; ABMR:14); 8 SCR; 13 and 16 were diagnosed with BKV and CMV infection, respectively. Pre-transplantation pCXCL-10 was significantly increased in TCMR and ABMR and post-transplantation in TCMR, ABMR and SCR compared with nonrejectors. All CMV+ patients showed pCXCL-10 levels above the cutoff values established for rejection whereas the 80% of BKV+ patients showed pCXCL-10 concentration < 100 pg/mL. pCXCL-10 could improve pre-transplantation patient stratification and immunosuppressive treatment selection according to rejection risk; and after kidney transplantation could be a potential early prognostic biomarker for rejection. Clinical confounding factor in BKV+ and particularly in CMV+ patients must be discarded.

Dysregulation of homocysteine homeostasis in acute intermittent porphyria patients receiving heme arginate or givosiran.

Acute intermittent porphyria (AIP) is a rare metabolic disease caused by mutations within the hydroxymethylbilane synthase gene. Previous studies have reported increased levels of plasma total homocysteine (tHcy) in symptomatic AIP patients. In this study, we present long-term data for tHcy and related parameters for an AIP patient cohort (n = 37) in different clinical disease-states. In total, 25 patients (68%) presented with hyperhomocysteinemia (HHcy; tHcy > 15 µmol/L) during the observation period. HHcy was more frequent in AIP patients with recurrent disease receiving heme arginate, than in nonrecurrent (median tHcy: 21.6 µmol/L; range: 10-129 vs median tHcy: 14.5 µmol/L; range 6-77). Long-term serial analyses showed a high within-person tHcy variation, especially among the recurrent patients (coefficient of variation: 16.4%-78.8%). HHcy was frequently associated with low blood concentrations of pyridoxal-5'-phosphate and folate, while cobalamin concentration and the allele distribution of the methylene-tetrahydrofolate-reductase gene were normal. Strikingly, 6 out of the 9 recurrent patients who were later included in a regime of givosiran, a small-interfering RNA that effectively reduced recurrent attacks, showed further increased tHcy (median tHcy in 9 patients: 105 µmol/L; range 16-212). Screening of amino acids in plasma by liquid-chromatography showed co-increased levels of methionine (median 71 µmol/L; range 23-616; normal <40), suggestive of acquired deficiency of cystathionine-ß-synthase. The kynunerine/tryptophan ratio in plasma was, however, normal, indicating a regular metabolism of tryptophan by heme-dependent enzymes. In conclusion, even if HHcy was observed in AIP patients receiving heme arginate, givosiran induced an aggravation of the dysregulation, causing a co-increase of tHcy and methionine resembling classic homocystinuria.

Monitoring of gene expression in tacrolimus-treated de novo renal allograft recipients facilitates individualized immunosuppression: Results of the IMAGEN study.

AIMS: Calcineurin inhibitors (CNI) have a small therapeutic window, and drug monitoring is required. Pharmacokinetic monitoring does not correlate sufficiently with clinical outcome. Therefore, the expression of nuclear factor of activated T cells (NFAT)-regulated genes in the peripheral blood has been suggested as a potentially useful immune monitoring tool to optimize CNI therapy. NFAT-regulated gene expression (RGE) was evaluated in renal allograft recipients as predictive biomarker to detect patients at risk of acute rejection or infections. METHODS: NFAT-RGE (interleukin-2, interferon-γ, granular-macrophage colony-stimulating factor) was evaluated by quantitative real-time polymerase chain reaction in whole blood samples at day 7, day 14, month 1, 3, and 6 after transplantation in 64 de novo renal allograft recipients from 3 European centres. Immunosuppression consisted of tacrolimus (Tac), mycophenolic acid, and corticosteroids. RESULTS: Tac concentrations (C0 and C1.5) correlated inversely with NFAT-RGE (P < .01). NFAT-RGE showed a high interindividual variability (1-61%). Patients with high residual gene expression (NFAT-RGE ≥30%) were at the increased risk of acute rejection in the following months (35 vs. 5%, P = .02), whereas patients with low residual gene expression (NFAT-RGE <30%) showed a higher incidence of viral complications, especially cytomegalovirus and BK virus replication (52.5 vs. 10%, P = .01). CONCLUSIONS: NFAT-RGE was confirmed as a potential noninvasive early predictive biomarker in the immediate post-transplant period to detect patients at risk of acute rejection and infectious complications in Tac-treated renal allograft recipients. Monitoring of NFAT-RGE may provide additional useful information for physicians to achieve individualized Tac treatment.

Personalized Therapy for Mycophenolate: Consensus Report by the International Association of Therapeutic Drug Monitoring and Clinical Toxicology.

ABSTRACT: When mycophenolic acid (MPA) was originally marketed for immunosuppressive therapy, fixed doses were recommended by the manufacturer. Awareness of the potential for a more personalized dosing has led to development of methods to estimate MPA area under the curve based on the measurement of drug concentrations in only a few samples. This approach is feasible in the clinical routine and has proven successful in terms of correlation with outcome. However, the search for superior correlates has continued, and numerous studies in search of biomarkers that could better predict the perfect dosage for the individual patient have been published. As it was considered timely for an updated and comprehensive presentation of consensus on the status for personalized treatment with MPA, this report was prepared following an initiative from members of the International Association of Therapeutic Drug Monitoring and Clinical Toxicology (IATDMCT). Topics included are the criteria for analytics, methods to estimate exposure including pharmacometrics, the potential influence of pharmacogenetics, development of biomarkers, and the practical aspects of implementation of target concentration intervention. For selected topics with sufficient evidence, such as the application of limited sampling strategies for MPA area under the curve, graded recommendations on target ranges are presented. To provide a comprehensive review, this report also includes updates on the status of potential biomarkers including those which may be promising but with a low level of evidence. In view of the fact that there are very few new immunosuppressive drugs under development for the transplant field, it is likely that MPA will continue to be prescribed on a large scale in the upcoming years. Discontinuation of therapy due to adverse effects is relatively common, increasing the risk for late rejections, which may contribute to graft loss. Therefore, the continued search for innovative methods to better personalize MPA dosage is warranted.

Meropenem population pharmacokinetics in patients with decompensated cirrhosis and severe infections.

OBJECTIVES: Meropenem pharmacokinetics (PK) may be altered in patients with cirrhosis, hampering target attainment. We aimed to describe meropenem PK in patients with decompensated cirrhosis and severe bacterial infections, identify the sources of PK variability and assess the performance of different dosing regimens to optimize the PK/pharmacodynamic (PD) target. METHODS: Serum concentrations and covariates were obtained from patients with severe infections under meropenem treatment. A population PK analysis was performed using non-linear mixed-effects modelling and the final model was used to simulate meropenem exposure to assess the PTA. RESULTS: Fifty-four patients were enrolled in the study. Data were best described by a one-compartment linear model. The estimated typical mean value for clearance (CL) was 8.35 L/h and the estimated volume of distribution (V) was 28.2 L. Creatinine clearance (CLCR) and MELD score significantly influenced meropenem CL, and acute-on-chronic liver failure (ACLF) significantly affected V. Monte Carlo simulations showed that a lower meropenem dose would be needed as CLCR decreases and as the MELD score increases. Patients with ACLF would have lower peak meropenem concentrations but similar steady-state concentrations compared with patients with no ACLF. CONCLUSIONS: Our study identified two new covariates that influence meropenem PK in patients with decompensated cirrhosis in addition to CLCR: MELD score and ACLF. Dosing regimens are recommended to reach several PK/PD targets considering these clinical variables and any MIC within the susceptibility range.

MicroRNAs 155-5p, 122-5p, and 181a-5p Identify Patients With Graft Dysfunction Due to T Cell-Mediated Rejection After Liver Transplantation.

MicroRNAs (miRNAs) are small noncoding RNAs that can be detected in plasma and whose expression is associated with pathological processes. The role of miRNAs in the noninvasive diagnosis of T cell-mediated rejection (TCMR) after liver transplantation (LT) is unclear. Thus, we aimed to assess the effectiveness of a panel of 4 miRNAs (155-5p, 122-5p, 181a-5p, and 148-3p) in diagnosing TCMR in LT recipients with graft dysfunction (GD), and we compared its accuracy with previously published tests for diagnosing TCMR based on routine laboratory parameters. From a prospective cohort of 145 patients followed during the first year after transplant, 49 developed GD and underwent a liver biopsy and plasma collection for miRNA analysis using quantitative real-time polymerase chain reaction. Patients with GD due to TCMR (n = 21) exhibited significantly higher (P < 0.001) expression of miRNA 155-5p (2.05 versus 0.07), 122-5p (19.36 versus 1.66), and 181a-5p (1.33 versus 0.37) compared with those with GD from other causes (n = 28). The area under the receiver operating characteristic curve of miRNAs 155-5p, 122-5p, and 181a-5p for the diagnosis of TCMR was 0.87, 0.91, and 0.89, respectively, significantly higher than those of the other noninvasive tests (P < 0.001). Furthermore, miRNA 155-5p identified all patients who presented TCMR during the first 2 weeks after transplant. miRNA plasmatic expression differentiates TCMR from other causes of GD in patients who have undergone LT and may be a useful tool in clinical practice.

Nuclear factor of activated T cells as potential pharmacodynamic biomarker for the risk of acute and subclinical rejection in de novo liver recipients.

BACKGROUND & AIMS: Nuclear factor of activated T cell-regulated gene expression (NFAT-RGE) has been proposed as a pharmacodynamic biomarker for tacrolimus (Tac) and cyclosporine (CsA). Our aim was to evaluate the role of NFAT-RGE in modulating intralymphocytary IL-2 and IFN-γ expression and its clinical utility as an early non-invasive predictive biomarker for the risk of acute rejection (AR) and infection in de novo liver transplant (LT) recipients. METHODS: Fifty-six LT recipients treated with Tac or CsA [with and without mycophenolate mofetil (MMF)] were included: 30 free of rejection or infection, 11 rejectors (T cell-mediated acute rejection), 5 with subclinical rejection (SCR) and 10 with cytomegalovirus (CMV) infection. Within the first 3 months after transplantation, NFAT-RGE of IL-2, IFN-γ and GM-CSF and intralymphocytary synthesis of IL-2 and IFN-γ were evaluated by real-time PCR and flow cytometry respectively. RESULTS: A significant increase in NFAT-RGE was observed in patients who experienced TCMAR (75% [42-100%]) or SCR (41% [18-78%]) compared with patients without rejection or infection (14% [2-23%]). Positive correlations between the %NFAT-RGE-IFN and both the %CD8CD69IFN-γ and %CD4CD69IFN-γ and between the %NFAT-RGE-IL2 and the %CD8CD69IL2 were observed. NFAT-RGE was significantly lower in CMV+ patients than in non-infected patients. Finally, an inverse correlation between the Tac or CsA concentration and inhibition of NFAT-RGE were observed. CONCLUSIONS: Sequential post-transplantation NFAT-RGE monitoring combined with intralymphocytary IL-2 and IFN-γ before transplantation and at the first and third month post-transplantation may be key predictive and diagnostic biomarkers for the risk of TCMAR and SCR and better guide CNi therapy in LT patients.

Pharmacokinetics and pharmacogenetics of sorafenib in patients with hepatocellular carcinoma: Implications for combination trials.

BACKGROUND & AIMS: Sorafenib and lenvatinib are the first-line treatments approved in hepatocellular carcinoma (HCC), but information is lacking about the relationships between their pharmacokinetics, patients pharmacogenetic profiles, adverse events (AE) and overall survival. We aimed to elucidate these relationships of tyrosine Kinase Inhibitors, such as sorafenib, in order to improve the design of trials testing it in combination with checkpoint inhibitors. METHODS: We assessed the pharmacokinetics of sorafenib and its N-oxide metabolite at day-0, day-7, day-30, day-60, day-90, day-120, day-150 and day-180 and nine single-nucleotide polymorphisms (SNP) in five genes related to sorafenib metabolism/transport to identify the best point for starting the combination between tyrosine kinases and checkpoint inhibitors. RESULTS: We prospectively included 49 patients (96% cirrhotic, 37% hepatitis-C, 82% Child-Pugh-A and 59% BCLC-C). Pharmacokinetic values peaked at day-7 and progressively declined until day-60. In the 16 patients without further dose modifications after day-60, pharmacokinetic values remained stable through day-180 (sorafenib P = .90; N-oxide P = .93). Pharmacokinetic values were higher in patients with early dermatological adverse events and lower in patients with early diarrhoea. Sorafenib and N-oxide pharmacokinetic values varied linearly with different alleles of MRP2*3972. CONCLUSIONS: Sorafenib's pharmacokinetics is heterogeneous across HCC patients. This heterogeneity affects adverse events development and must be taken into account in setting the dose and timing of its combination with checkpoint inhibitors.

Measuring Intracellular Concentrations of Calcineurin Inhibitors: Expert Consensus from the International Association of Therapeutic Drug Monitoring and Clinical Toxicology Expert Panel.

BACKGROUND: Therapeutic drug monitoring (TDM) of the 2 calcineurin inhibitors (CNIs), tacrolimus (TAC) and cyclosporin A, has resulted in improvements in the management of patients who have undergone solid organ transplantation. As a result of TDM, acute rejection (AR) rates and treatment-related toxicities have been reduced. Irrespective, AR and toxicity still occur in patients who have undergone transplantation, showing blood CNI concentrations within the therapeutic range. Moreover, the AR rate is no longer decreasing. Hence, smarter TDM approaches are necessary. Because CNIs exert their action inside T lymphocytes, intracellular CNIs may be a promising candidate for improving therapeutic outcomes. The intracellular CNI concentration may be more directly related to the drug effect and has been favorably compared with the standard, whole-blood TDM for TAC in liver transplant recipients. However, measuring intracellular CNIs concentrations is not without pitfalls at both the preanalytical and analytical stages, and standardization seems essential in this area. To date, there are no guidelines for the TDM of intracellular CNI concentrations. METHODS: Under the auspices of the International Association of TDM and Clinical Toxicology and its Immunosuppressive Drug committees, a group of leading investigators in this field have shared experiences and have presented preanalytical and analytical recommendations for measuring intracellular CNI concentrations.

Portal pressure and liver stiffness measurements in the prediction of fibrosis regression after sustained virological response in recurrent hepatitis C.

Sustained virological response (SVR) improves survival in post-liver transplant (LT) recurrent hepatitis C. However, the impact of SVR on fibrosis regression is not well defined. In addition, the performance of noninvasive methods to evaluate the presence of fibrosis and portal hypertension (PH) post-SVR has been scarcely evaluated. We aimed to investigate the degree of fibrosis regression (decrease ≥1 METAVIR stage) after-SVR and its associated factors in recurrent hepatitis C, as well as the diagnostic capacity of noninvasive methods in the assessment of liver fibrosis and PH after viral clearance. We evaluated 112 hepatitis C virus-infected LT recipients who achieved SVR between 2001 and 2015. A liver biopsy was performed before treatment and 12 months post-SVR. Hepatic venous pressure gradient (HVPG), liver stiffness measurement (LSM), and Enhanced Liver Fibrosis (ELF) score were also determined at the same time points. Sixty-seven percent of the cohort presented fibrosis regression: 43% in recipients with cirrhosis and 72%-85% in the remaining stages (P = 0.002). HVPG, LSM, and ELF significantly decreased post-SVR. Liver function significantly improved, and survival was significantly better in patients achieving fibrosis regression. Baseline HVPG and LSM as well as decompensations before therapy were independent predictors of fibrosis regression. One year post-SVR, LSM had a high diagnostic accuracy to discard the presence of advanced fibrosis (AF) and clinically significant PH (AUROC, 0.902 and 0.888). CONCLUSION: In conclusion, SVR post-LT induces fibrosis regression in most patients, leading to significant clinical benefits. Pretreatment HVPG and LSM are significant determinants of the likelihood of fibrosis regression. Finally, LSM accurately predicts the presence of AF and PH 1 year after SVR and thus can be used to determine monitoring strategies. (Hepatology 2018;67:1683-1694).

Pharmacodynamic Monitoring of mTOR Inhibitors.

Pharmacodynamic (PD) monitoring may complement routine pharmacokinetic monitoring of mTOR inhibitors (mTORis) in an attempt to better guide individualized sirolimus (SRL) or everolimus (EVR) treatment after organ transplantation. This review focuses on current knowledge about PD biomarkers for personalized mTORi therapies. Different strategies have already been used in the evaluation of the pharmacodynamics of SRL and EVR as a proxy for their effects on the immune response after transplantation. These include measuring p70S6K (70 kDa ribosomal protein S6 kinase) activity, p70S6K phosphorylation (P-p70S6K), or P-S6 protein expression. Compared with Western blot and ELISA, phosphoflow cytometry can detect phosphorylated proteins and differentiate activation-induced changes of signaling molecules inside the cell from unstimulated populations of identical cells in the same sample. Alternatively, in patients receiving a combined therapy, the other PD approach is to consider biomarkers such as NFAT residual expression for calcineurin inhibitors or to evaluate nonspecific effects of the drugs such as lymphocyte proliferation, interleukin synthesis, specific peripheral blood T regulatory subsets, or lymphocyte surface antigens, which have the advantage to reflect the overall immunosuppressive status achieved. Although limited, the available data on mTOR pathway biomarkers seem promising. Before clinical implementation, the analytical methodologies must be standardized and cross-validated, and the selected biomarkers will have to demonstrate their clinical utility for SRL or EVR dose individualization in multicenter clinical trials.

Therapeutic Drug Monitoring of Tacrolimus-Personalized Therapy: Second Consensus Report.

Ten years ago, a consensus report on the optimization of tacrolimus was published in this journal. In 2017, the Immunosuppressive Drugs Scientific Committee of the International Association of Therapeutic Drug Monitoring and Clinical Toxicity (IATDMCT) decided to issue an updated consensus report considering the most relevant advances in tacrolimus pharmacokinetics (PK), pharmacogenetics (PG), pharmacodynamics, and immunologic biomarkers, with the aim to provide analytical and drug-exposure recommendations to assist TDM professionals and clinicians to individualize tacrolimus TDM and treatment. The consensus is based on in-depth literature searches regarding each topic that is addressed in this document. Thirty-seven international experts in the field of TDM of tacrolimus as well as its PG and biomarkers contributed to the drafting of sections most relevant for their expertise. Whenever applicable, the quality of evidence and the strength of recommendations were graded according to a published grading guide. After iterated editing, the final version of the complete document was approved by all authors. For each category of solid organ and stem cell transplantation, the current state of PK monitoring is discussed and the specific targets of tacrolimus trough concentrations (predose sample C0) are presented for subgroups of patients along with the grading of these recommendations. In addition, tacrolimus area under the concentration-time curve determination is proposed as the best TDM option early after transplantation, at the time of immunosuppression minimization, for special populations, and specific clinical situations. For indications other than transplantation, the potentially effective tacrolimus concentrations in systemic treatment are discussed without formal grading. The importance of consistency, calibration, proficiency testing, and the requirement for standardization and need for traceability and reference materials is highlighted. The status for alternative approaches for tacrolimus TDM is presented including dried blood spots, volumetric absorptive microsampling, and the development of intracellular measurements of tacrolimus. The association between CYP3A5 genotype and tacrolimus dose requirement is consistent (Grading A I). So far, pharmacodynamic and immunologic biomarkers have not entered routine monitoring, but determination of residual nuclear factor of activated T cells-regulated gene expression supports the identification of renal transplant recipients at risk of rejection, infections, and malignancy (B II). In addition, monitoring intracellular T-cell IFN-g production can help to identify kidney and liver transplant recipients at high risk of acute rejection (B II) and select good candidates for immunosuppression minimization (B II). Although cell-free DNA seems a promising biomarker of acute donor injury and to assess the minimally effective C0 of tacrolimus, multicenter prospective interventional studies are required to better evaluate its clinical utility in solid organ transplantation. Population PK models including CYP3A5 and CYP3A4 genotypes will be considered to guide initial tacrolimus dosing. Future studies should investigate the clinical benefit of time-to-event models to better evaluate biomarkers as predictive of personal response, the risk of rejection, and graft outcome. The Expert Committee concludes that considerable advances in the different fields of tacrolimus monitoring have been achieved during this last decade. Continued efforts should focus on the opportunities to implement in clinical routine the combination of new standardized PK approaches with PG, and valid biomarkers to further personalize tacrolimus therapy and to improve long-term outcomes for treated patients.

Influence of donor liver CYP3A4*20 loss-of-function genotype on tacrolimus pharmacokinetics in transplanted patients.

OBJECTIVE: Cytochrome P450 3A4 (CYP3A4) metabolizes about half of all drugs on the market; however, the impact of CYP3A4 loss-of-function variants on drug exposures remains poorly characterized. Here, we report the effect of the CYP3A4*20 frameshift allele in two Spanish liver transplant patients treated with tacrolimus. PATIENTS AND METHODS: A series of 90 transplanted patients (with DNA available for 89 of the recipients and 76 of the liver donors) treated with tacrolimus were included in the study. The genotypes of liver donors and of the recipients for CYP3A4*20 (rs67666821), CYP3A4*22 (rs35599367) and CYP3A5*3 (rs776746) were compared with weight-adjusted tacrolimus dose (D), tacrolimus trough concentration (C0), and dose-adjusted tacrolimus trough concentrations (C0/D) using the Mann-Whitney U-nonparametric test. RESULTS: The CYP3A4*20 allele was detected in two of the liver donors. This genotype yielded at all times higher C0/D (2.6-fold, average) than intermediate CYP3A metabolizers (CYP3A4*1/*1 and CYP3A5*3/*3) (P=0.045, 90 days after transplantation). CYP3A4*22 carriers showed a 1.9-fold average increase in C0/D (P=0.047, 0.025, and 0.053; at days 7, 14, and 30 after transplantation, respectively) compared with intermediate metabolizers. In terms of recipients' genotype, CYP3A5*1 had reduced (P=0.025) and CYP3A4*22 increased C0/D (P=0.056) 7 days after transplantation. The incidence of biopsy-proven acute rejection was 0, 12, and 20% for livers with poor, intermediate, and extensive CYP3A-metabolizing capacity, respectively (P=0.0995). CONCLUSION: This first description of CYP3A4*20 null genotype in liver-transplanted patients, supports the relevance of CYP3A genotyping in tacrolimus therapy.

Cyclosporine A in addition to standard ART during primary HIV-1 infection: pilot randomized clinical trial.

Background: Initiating ART during acute/recent HIV-1 infection reduces viral reservoir formation. It has been proposed that, during this phase, the size of the viral reservoir could be further reduced by the association of immunomodulatory therapy with ART. Contradictory results have emerged, however, from two trials evaluating the impact on immune recovery and the viral reservoir of adding cyclosporine A to ART during primary HIV-1 infection. Patients and methods: Twenty patients with acute/recent HIV-1 infection were randomized to receive ART alone (tenofovir, emtricitabine and lopinavir/ritonavir) or associated with 8 weeks of cyclosporine A (0.3-0.6 mg/kg twice daily). The impact on viral load, immune response and integrated and non-integrated DNA viral reservoir at 0, 8 and 36 weeks of treatment was evaluated. Results: The estimated median time from HIV-1 infection to ART onset was 63 days (IQR 53; 79.5) with 90% of patients at Fiebig V stage. No significant differences were observed in viral load decay, CD4 T cell recovery, immune response markers or the evolution of integrated DNA at week 8 (end of cyclosporine A) and week 36 between groups. However, non-integrated DNA significantly increased in the cyclosporine A arm between weeks 0 and 36. Cyclosporine A was well tolerated. Conclusions: Adding cyclosporine A to ART during acute/recent infection did not improve immune recovery. However, unintegrated DNA increased in the cyclosporine A group, suggesting an anti-integration effect, a point warranting further research (ClinicalTrials.gov Identifier: NCT00979706).