Background:the study aims to evaluate whether high plasma trough levels of the kinase inhibitors (K.I.s) crizotinib, alectinib, osimertinib, dabrafenib, and trametinib were associated with a higher... Show moreBackground:the study aims to evaluate whether high plasma trough levels of the kinase inhibitors (K.I.s) crizotinib, alectinib, osimertinib, dabrafenib, and trametinib were associated with a higher risk of toxicity in non-small-cell lung cancer patients.Methods:In this retrospective cohort study, patients with non-small-cell lung cancer treated with the selected K.I.s were included if at least one plasma trough level at steady state (Cmin,ss) was available. Data were extracted from electronic medical records and laboratory databases. The high group for each K.I. was defined as 10% of patients with the highest first Cmin,ss. The remaining patients were placed in the non-high group. The frequency of dose-limiting toxicities (DLTs), defined as adverse events leading to dose reduction, dose interruption, or permanent discontinuation, was compared between the 2 groups.Results:A total of 542 patients were included in the different K.I. groups. A high Cmin,ss of crizotinib (n = 96), alectinib (n = 105), osimertinib (n = 227), dabrafenib (n = 52), and trametinib (n = 62) correlated with a Cmin,ss >= 490, >= 870, >= 405, >= 150, and >= 25 ng/mL, respectively. DLTs were more common in the alectinib high group than in the alectinib non-high group (64% vs. 29%, P = 0.036). Liver toxicity was observed in 4 (36%) patients in the high group and 5 (5%) patients in the non-high group (P = 0.007). For other K.I.s, no significant differences were observed in the frequency of DLTs between the high and non-high groups.Conclusions:For alectinib, high Cmin,ss was correlated with a higher risk of DLT. No differences in the frequency of DLTs were observed between the high and non-high groups for crizotinib, osimertinib, dabrafenib, and trametinib. Show less
Background:The clinical outcomes of busulfan-based conditioning regimens for hematopoietic cell transplantation (HCT) have been improved by personalizing the doses to target narrow busulfan plasma... Show moreBackground:The clinical outcomes of busulfan-based conditioning regimens for hematopoietic cell transplantation (HCT) have been improved by personalizing the doses to target narrow busulfan plasma exposure. An interlaboratory proficiency test program for the quantitation, pharmacokinetic modeling, and busulfan dosing in plasma was developed. Previous proficiency rounds (ie, the first 2) found that 67%-85% and 71%-88% of the dose recommendations were inaccurate, respectively.Methods:A proficiency test scheme was developed by the Dutch Foundation for Quality Assessment in Medical Laboratories (SKML) and consisted of 2 rounds per year, with each round containing 2 busulfan samples. In this study, 5 subsequent proficiency tests were evaluated. In each round, the participating laboratories reported their results for 2 proficiency samples (ie, low and high busulfan concentrations) and a theoretical case assessing their pharmacokinetic modeling and dose recommendations. Descriptive statistics were performed, with +/- 15% for busulfan concentrations and +/- 10% for busulfan plasma exposure. The dose recommendations were deemed accurate.Results:Since January 2020, 41 laboratories have participated in at least 1 round of this proficiency test. Over the 5 rounds, an average of 78% of the busulfan concentrations were accurate. Area under the concentration-time curve calculations were accurate in 75%-80% of the cases, whereas only 60%-69% of the dose recommendations were accurate. Compared with the first 2 proficiency test rounds (PMID 33675302, October, 2021), the busulfan quantitation results were similar, but the dose recommendations worsened. Some laboratories repeatedly submit results that deviated by more than 15% from the reference values.Conclusions:The proficiency test showed persistent inaccuracies in busulfan quantitation, pharmacokinetic modeling, and dose recommendations. Additional educational efforts have yet to be implemented; regulatory efforts seem to be needed. The use of specialized busulfan pharmacokinetic laboratories or a sufficient performance in busulfan proficiency tests should be required for HCT centers that prescribe busulfan. Show less
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... Show moreNirmatrelvir/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. Show less
Background:Alemtuzumab is a humanized monoclonal antibody that targets the CD52 glycoprotein expressed on most lymphocytes, subsequently inducing complement-mediated and antibody-mediated... Show moreBackground:Alemtuzumab is a humanized monoclonal antibody that targets the CD52 glycoprotein expressed on most lymphocytes, subsequently inducing complement-mediated and antibody-mediated cytotoxicity. Owing to its ability to induce profound immune depletion, alemtuzumab is frequently used in patients before allogeneic hematopoietic stem cell transplantation to prevent graft rejection and acute graft-versus-host disease. In this clinical context, a stable immunoassay with high sensitivity and specificity to determine alemtuzumab levels is essential for performing pharmacokinetic and pharmacodynamic analyses; however, the available methods have several limitations. Here, we report the successful development and validation of an efficient and highly sensitive enzyme-linked immunosorbent assay technique based on commercially available reagents to quantify alemtuzumab in human serum or plasma.Methods:This enzyme-linked immunosorbent assay technique was developed and validated in accordance with the European Medicines Agency guidelines on bioanalytical method validation.Results:The assay sensitivity (lower limit of quantification) is 0.5 ng center dot mL(-1), and the dynamic range is 0.78-25 ng center dot mL(-1). To accommodate quantification of peak concentration and concentrations below the lympholytic level (<0.1 mcg center dot mL(-1)), patients' serum samples were prediluted 20-400 times according to the expected alemtuzumab concentration. The overall within-run accuracy was between 96% and 105%, whereas overall within-run precision (coefficient of variation) was between 3% and 9%. The between-run assessment provided an overall accuracy between 86% and 95% and an overall coefficient of variation between 5% and 14%.Conclusions:The developed assay provides accurate insight into alemtuzumab exposure and its effects on the clinical response to treatment, which is key to optimizing treatment strategies. Show less
Francke, M.I.; Hesselink, D.A.; Andrews, L.M.; Gelder, T. van; Keizer, R.J.; Winter, B.C.M. de 2022
Background: Initial algorithm-based dosing appears to be effective in predicting tacrolimus dose requirement. However, achieving and maintaining the target concentrations is challenging. Model... Show moreBackground: Initial algorithm-based dosing appears to be effective in predicting tacrolimus dose requirement. However, achieving and maintaining the target concentrations is challenging. Model-based follow-up dosing, which considers patient characteristics and pharmacological data, may further personalize treatment. This study investigated whether model-based follow-up dosing could lead to more accurate tacrolimus exposure than standard therapeutic drug monitoring (TDM) in kidney transplant recipients after an initial algorithm-based dose. Methods: This simulation trial included patients from a prospective trial that received an algorithm-based tacrolimus starting dose followed by TDM. For every measured tacrolimus predose concentration (C-0,C-obs), model-based dosing advice was simulated using the InsightRX software. Based on previous tacrolimus doses and C-0, age, body surface area, CYP3A4 and CYP3A5 genotypes, hematocrit, albumin, and creatinine, the optimal next dose, and corresponding tacrolimus concentration (C-0,C-pred) were predicted. Results: Of 190 tacrolimus C-0 values measured in 59 patients, 121 (63.7%; 95% CI 56.8-70.5) C-0,C-obs were within the therapeutic range (7.5-12.5 ng/mL) versus 126 (66.3%, 95% CI 59.6-73.0) for C-0,C-pred (P = 0.89). The median absolute difference between the tacrolimus C-0 and the target tacrolimus concentration (10.0 ng/mL) was 1.9 ng/mL for C-0,C-obs versus 1.6 ng/mL for C-0,C-pred. In a historical cohort of 114 kidney transplant recipients who received a body weight-based starting dose followed by TDM, 172 of 335 tacrolimus C-0 (51.3%) were within the therapeutic range (10.0-15.0 ng/mL). Conclusions: The combination of an algorithm-based tacrolimus starting dose with model-based follow-up dosing has the potential to minimize under- and overexposure to tacrolimus in the early posttransplant phase, although the additional effect of model-based follow-up dosing on initial algorithm-based dosing seems small. Show less
Rojas, A.M.; Hesselink, D.A.; Besouw, N.M. van; Dieterich, M.; Kuiper, R. de; Baan, C.C.; Gelder, T. van 2022
Background: Kidney transplant recipients with high intrapatient variability (IPV) in tacrolimus (Tac) exposure experience more rejection and reduced graft survival. To understand the underlying... Show moreBackground: Kidney transplant recipients with high intrapatient variability (IPV) in tacrolimus (Tac) exposure experience more rejection and reduced graft survival. To understand the underlying pathophysiology of this association, the authors investigated whether patients with high tacrolimus IPV have a more activated immune system than patients with low IPV. In addition, exposure to tacrolimus and mycophenolic acid (MPA) was studied in relation to rejection and graft survival. Methods: At the time of patient inclusion (5-7 years post-transplantation), the frequency of donor-reactive cells was determined by enzyme-linked immunosorbent assay, and the development of donor-specific anti-Human Leukocyte Antigen antibodies (DSA) was measured by Luminex Single Antigen assay. Tacrolimus IPV was retrospectively calculated between 6 and 12 months and the exposure to tacrolimus and MPA was determined between 1 and 5 years post-transplantation. Results: A total of 371 kidney transplant recipients were included in this study, of whom 56 developed a rejection episode after 12 months and 60 experienced graft failure after 5-7 years. No correlations were found between tacrolimus IPV or immunosuppression exposure and the number of donor-reactive cells after 5 years of transplantation. DSA were detected more often in patients with low exposure to both tacrolimus and MMF [4/21 (19%) versus 17/350 (4.9%), P = 0.04]. In this cohort, neither tacrolimus IPV nor low overall immunosuppression exposure was associated with a higher incidence of rejection. However, regression analysis showed that a higher tacrolimus IPV was associated with an increased incidence of graft failure (odds ratio = 1.03, P = 0.02). Conclusions: This study verifies the relationship between high tacrolimus IPV and impaired kidney allograft survival in long-term follow-up. DSA was also found to be more prevalent in patients with subtherapeutic concentrations of tacrolimus and MPA. An increased prevalence of donor-specific alloreactivity is yet to be demonstrated in patients with high IPV. Show less
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... Show moreWhen 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. Show less
Gokoel, S.R.M.; Zwart, T.C.; Moes, D.J.A.R.; Boog, P.J.M. van der; Fijter, J.W. de 2020
Background: High intrapatient variability (IPV) in tacrolimus exposure has been associated with an increased risk of graft rejection and graft loss. It has been suggested that medication... Show moreBackground: High intrapatient variability (IPV) in tacrolimus exposure has been associated with an increased risk of graft rejection and graft loss. It has been suggested that medication nonadherence has high impact on IPV. The objective of this study is to assess the relationship between tacrolimus IPV and medication nonadherence in stable kidney transplant recipients. Methods: This study was conducted within the Reducing Renal Function Deterioration trial (Netherlands Trial Register: NTR7256), which included stable kidney transplant recipients. Nonadherence was assessed quantitatively by electronic monitoring (EM) and qualitatively using the composite adherence score (CAS) consisting of patient self-reporting (Immunosuppressant Therapy Adherence Scale), a physician report, and the tacrolimus trough concentrations (C-0). IPV in tacrolimus C(0)and area under the concentration-time curves (AUCs) was evaluated at 5 and 3 sampling instances, respectively. Results: Data of 64 kidney transplant recipients (43 males, 21 females; mean age 53.6 years), mean time post-transplantation 5.4 years, were collected. Mean missed tacrolimus intake was 7% (0.3%-13.4%) based on EM, missing one intake every 2 weeks. Based on the CAS, 68.9% of the patients were categorized as nonadherent. The mean IPV was 17.9% (4.4%-65.3%) and 20.2% (2.5%-51.6%) for tacrolimus C(0)and AUCs, respectively. The nonadherence data displayed a nonparametric distribution, with nonadherence scores mostly in the lower ranges. There was no significant difference in the mean IPV between adherent and nonadherent patients. There were no differences in EM, CAS, physician report, or time-in-therapeutic range, but patients with a low AUC IPV showed a slightly higher Immunosuppressant Therapy Adherence Scale score than those with a high AUC IPV (P= 0.035). Conclusions: There was no apparent relationship between IPV and nonadherence in this motivated kidney transplant recipient population, with one missed tacrolimus dose every 2 weeks. Show less
Background: Conception, pregnancy, and lactation following solid organ transplantation require appropriate management. The most frequently used immunosuppressive drug combination after solid organ... Show moreBackground: Conception, pregnancy, and lactation following solid organ transplantation require appropriate management. The most frequently used immunosuppressive drug combination after solid organ transplantation consists of tacrolimus (Tac) plus mycophenolic acid (MPA). Here, the effects of Tac and MPA on fertility, pregnancy, and lactation are systematically reviewed, and their implications for therapeutic drug monitoring (TDM) are discussed. Methods: A systematic literature search was performed (August 19, 2019) using Ovid MEDLINE, EMBASE, the Cochrane Central Register of controlled trials, Google Scholar, and Web of Science, and 102 studies were included. Another 60 were included from the reference list of the published articles. Results: As MPA is teratogenic, women who are trying to conceive are strongly recommended to switch from MPA to azathioprine. MPA treatment in men during conception seems to have no adverse effect on pregnancy outcomes. Nevertheless, in 2015, the drug label was updated with additional risk minimization measures in a pregnancy prevention program. Data on MPA pharmacokinetics during pregnancy and lactation are limited. Tac treatment during conception, pregnancy, and lactation seems to be safe in terms of the health of the mother, (unborn) child, and allograft. However, Tac may increase the risk of hypertension, preeclampsia, preterm birth, and low birth weight. Infants will ingest very small amounts of Tac via breast milk from mothers treated with Tac. However, no adverse outcomes have been reported in children exposed to Tac during lactation. During pregnancy, changes in Tac pharmacokinetics result in increased unbound to whole-blood Tac concentration ratio. To maintain Tac concentrations within the target range, increased Tac dose and intensified TDM may be required. However, it is unclear if dose adjustments during pregnancy are necessary, considering the higher concentration of (active) unbound Tac. Conclusions: Tac treatment during conception, pregnancy and lactation seems to be relatively safe. Due to pharmacokinetic changes during pregnancy, a higher Tac dose might be indicated to maintain target concentrations. However, more evidence is needed to make recommendations on both Tac dose adjustments and alternative matrices than whole-blood for TDM of Tac during pregnancy. MPA treatment in men during conception seems to have no adverse effect on pregnancy outcomes, whereas MPA use in women during conception and pregnancy is strongly discouraged. Show less
Elens, L.; Langman, L.J.; Hesselink, D.A.; Bergan, S.; Moes, D.J.A.R.; Molinaro, M.; ... ; Lemaitre, F. 2020
Background: COVID-19 is a novel infectious disease caused by the severe acute respiratory distress (SARS)-coronavirus-2 (SARS-CoV-2). Several therapeutic options are currently emerging but none... Show moreBackground: COVID-19 is a novel infectious disease caused by the severe acute respiratory distress (SARS)-coronavirus-2 (SARS-CoV-2). Several therapeutic options are currently emerging but none with universal consensus or proven efficacy. Solid organ transplant recipients are perceived to be at increased risk of severe COVID-19 because of their immunosuppressed conditions due to chronic use of immunosuppressive drugs (ISDs). It is therefore likely that solid organ transplant recipients will be treated with these experimental antivirals. Methods: This article is not intended to provide a systematic literature review on investigational treatments tested against COVID-19; rather, the authors aim to provide recommendations for therapeutic drug monitoring of ISDs in transplant recipients infected with SARS-CoV-2 based on a review of existing data in the literature. Results: Management of drug-drug interactions between investigational anti-SARS-CoV-2 drugs and immunosuppressants is a complex task for the clinician. Adequate immunosuppression is necessary to prevent graft rejection while, if critically ill, the patient may benefit from pharmacotherapeutic interventions directed at limiting SARS-CoV-2 viral replication. Maintaining ISD concentrations within the desired therapeutic range requires a highly individualized approach that is complicated by the pandemic context and lack of hindsight. Conclusions: With this article, the authors inform the clinician about the potential interactions of experimental COVID-19 treatments with ISDs used in transplantation. Recommendations regarding therapeutic drug monitoring and dose adjustments in the context of COVID-19 are provided. Show less
Background: Oral anticancer drugs show a high interpatient variability in pharmacokinetics (PK), leading to large differences in drug exposure. For many of these drugs, exposure has been linked to... Show moreBackground: Oral anticancer drugs show a high interpatient variability in pharmacokinetics (PK), leading to large differences in drug exposure. For many of these drugs, exposure has been linked to efficacy and toxicity. Despite this knowledge, these drugs are still administered in a one-size-fits-all approach. Consequently, individual patients have a high probability to be either underdosed, which can lead to decreased antitumor efficacy, or overdosed, which could potentially result in increased toxicity. Therapeutic drug monitoring (TDM), personalized dosing based on measured drug levels, could be used to circumvent underdosing and overdosing and thereby optimize treatment outcomes.Methods: In this prospective clinical study (www.trialregister.nl; NL6695), the feasibility, tolerability, and efficacy of TDM of oral anticancer drugs will be evaluated. In total, at least 600 patients will be included for (at least) 23 different compounds. Patients starting regular treatment with one of these compounds at the approved standard dose can be included. PK sampling will be performed at 4, 8, and 12 weeks after the start of treatment and every 12 weeks thereafter. Drug concentrations will be measured, and trough concentrations (C-min) will be calculated. In cases where C-min, falls below the predefined target and acceptable toxicity, a PK-guided intervention will be recommended. This could include emphasizing compliance, adapting concomitant medication (due to drug-drug interactions), instructing to take the drug concomitant with food, splitting intake moments, or recommending a dose increase.Discussion: Despite a strong rationale for the use of TDM for oral anticancer drugs, this is currently not yet widely adopted in routine patient care. This prospective study will be a valuable contribution to demonstrate the additional value of dose optimization on treatment outcome for these drugs. Show less
Brunet, M.; Gelder, T. van; Asberg, A.; Haufroid, V.; Hesselink, D.A.; Langman, L.; ... ; Bergan, S. 2019
