Risk Factors for Subtherapeutic Tacrolimus Levels after Conversion from Continuous Intravenous Infusion to Oral in Children after Allogeneic Hematopoietic Cell Transplantation

Comparison of tacrolimus vs. cyclosporine in pediatric hematopoietic stem cell transplantation for thalassemia

OBJECTIVES

Graft-versus-host disease (GvHD) is one of the leading causes of morbidity and mortality in patients undergoing allogeneic HSCT, and effective prevention of GvHD is critical for the success of the HSCT procedure. Calcineurin inhibitors (CNI) have been used for decades as the backbone of GvHD prophylaxis. In this study, the efficacy and safety of Cyclosporine A (CsA) and tacrolimus (TCR) were compared in pediatric HSCT for thalassemia.

MATERIALS AND METHODS

This is a retrospective analysis of 129 pediatric patients who underwent HSCT with the diagnosis of thalassemia at Medicalpark Göztepe and Antalya Hospitals between January 2017 and December 2020.

RESULTS

Despite the GvHD prophylaxis, grade II-IV acute GvHD developed in 29 patients. Of these patients, 12 had only gut, 10 had only skin, 6 had combined gut and skin, and one had only liver GvHD. Fifteen of these 29 patients were in the CsA group, and 14 of them were in the TCR group. There was no significant difference between the groups in terms of acute GvHD occurrence, GvHD stage, or involvement sites. In terms of CNI-related toxicity, neurotoxicity in 15 (CsA n = 9, TCR n = 6) and nephrotoxicity in 18 (CsA n = 4, TCR n = 14) patients were observed. While there was no difference between the two groups in terms of neurotoxicity, more nephrotoxicity developed in patients using TCR (p = .013). There was no significant difference between the groups in terms of engraftment syndrome, veno-occlusive disease, CMV reactivation, PRES, or graft rejection.

CONCLUSION

Regarding GvHD, there was no difference in efficacy between TCR and CsA usage. Patients taking TCR experienced noticeably higher nephrotoxicity in terms of adverse effects. This difference should be considered according to the patient's clinical situation while choosing a CNI.

Highlights of Pharmacist Roles in Hematopoietic Cell Transplantation and Cellular Therapy

Patients with hematological malignancies receiving hematopoietic stem cell transplantation (HSCT) or chimeric antigen receptor (CAR) T-cell therapy are known to have complex pharmacotherapy. To ensure safe and effective care in preventing and managing drug-related problems, pharmacists trained in HSCT and CAR T-cell therapy fulfill various roles in providing care for these patients. With polypharmacy and complex medication regimens, drug interactions are one of the major aspects that pharmacists review regularly to ensure the efficacy of treatment while minimizing toxicity. Pharmacists anticipate various complex drug interactions, understanding the possible mechanisms of drug interactions, and manage these complex drug regimens in patients undergoing HSCT and CAR T-cell therapy. In addition, antimicrobial prophylaxis is also important supportive care for immunocompromised patients. Pharmacists are capable of evaluating the risk of opportunistic infections, anticipating the type of antimicrobial prophylaxis required, and setting a policy with a robust antimicrobial regime. This can promote consistency in patient care and improve patient outcomes in terms of morbidity and mortality associated with opportunistic infections. Lastly, pharmacists are equipped with a skillset to ensure a seamless transition of care, provide education for patients and healthcare providers, promote medication adherence, and contribute to research and quality improvement.

Impact of Pharmacogenetics on Intravenous Tacrolimus Exposure and Conversions to Oral Therapy

CYP3A5 and CYP3A4 are the predominant enzymes responsible for tacrolimus metabolism; however only a proportion of the population expresses CYP3A5 secondary to genetic variation. CYP3A5 is expressed in both the intestine and the liver and has been shown to impact both the bioavailability and metabolism of orally administered tacrolimus. Increasing the initial tacrolimus dose by 50% to 100% is recommended in patients who are known CYP3A5 expressers; however, whether this dose adjustment is appropriate for i.v. tacrolimus administration is unclear. The objective of this study was to evaluate the impact of CYP3A5 genotype as well as other pharmacogenes on i.v. tacrolimus exposure to determine whether the current genotype-guided dosing recommendations are appropriate for this formulation. In addition, this study aimed to investigate dose conversion requirements among CYP3A5 genotypes when converting from i.v. to p.o. tacrolimus. This study is a retrospective chart review of all patients who underwent allogeneic stem cell transplantation at Michigan Medicine between June 1, 2014, and March 1, 2018, who received i.v. tacrolimus at the time of their transplantation. Secondary use samples were obtained for genotyping CYP3A5, CYP3A4, and ABCB1. Patient demographic information, tacrolimus dosing and trough levels, and concomitant medications received at the time of tacrolimus trough were collected retrospectively from the patients' medical records. The i.v. dose-controlled concentration (C/D) and the i.v.:p.o. exposure ratio was calculated for all tacrolimus doses and patients, respectively. The impact of CYP3A5, CYP3A4, and ABCB1 genotypes on the i.v. C/D were evaluated with linear mixed modeling. The impact of CYP3A5 genotype on the i.v.:p.o. ratio was evaluated while controlling for age and concomitant use of an azole inhibitor. CYP3A5 and CYP3A4 genotypes were significantly associated with the i.v. C/D, with CYP3A5 expressers and CYP3A4 rapid metabolizers having 20% lower tacrolimus exposure. Neither genotype remained significant in the multivariable model, although age, hematocrit, and concomitant use of strong azole inhibitors were associated with increased i.v. C/D. When controlling for patient age and sex, CYP3A5 expressers had significantly higher i.v.:p.o. ratios than CYP3A5 nonexpressers (3.42 versus 2.78; P = .04). Post hoc analysis showed that the i.v.:p.o. ratio may differ among different CYP3A5 genotypes and azole inhibitor combinations. This study demonstrates that the current genotype-guided tacrolimus dose adjustment recommendations are inappropriate for CYP3A5 expressers receiving i.v. tacrolimus. Although CYP3A5 genotype is likely a minor contributor to i.v. tacrolimus exposure, genotype, in addition to capturing concomitant CYP3A inhibitors, would likely improve i.v.:p.o. dose conversion selection. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Cost-effectiveness of once-daily vs twice-daily tacrolimus among Hispanic and Black kidney transplant recipients

BACKGROUND: Tacrolimus is a first-line immunosuppressive therapy to prevent rejection and graft failure in kidney transplant recipients. Once-daily extended-release tacrolimus tablets (LCPT) have been shown to be efficacious, particularly for Hispanic and Black patient subpopulations who are rapid metabolizers, but is more costly than twice-daily immediate-release tacrolimus (IR-Tac). OBJECTIVE: To evaluate the cost-effectiveness of LCPT during the first year of treatment vs IR-Tac in kidney transplant recipients who are Hispanic or Black. METHODS: A decision analytic model from a US payer perspective was developed using (1) subgroup outcomes data pooled from two phase 3 clinical trials that compared LCPT and IR-Tac, and (2) direct costs from real-world data sources (ie, costs of LCPT and IR-Tac treatments, biopsy-proven acute rejection, treatment-related serious adverse events [SAEs], graft failure, and consequent dialysis). The primary outcome was cost per successfully treated patient, defined as having a functioning graft after 1 year and without treatment-related SAEs. Probabilistic sensitivity analyses established distributions for cost and outcomes estimates, and a series of one-way sensitivity analyses identified parameters that had the most effect on results. RESULTS: Total overall cost for the Hispanic group was $14,765 for LCPT and $12,416 for IR-Tac, and total cost in the Black group was $16,626 for LCPT and $9,871 for IR-Tac. Total overall effectiveness of LCPT and IR-Tac was 88.32% and 84.75% in the Hispanic group and 93.24% and 85.78% in the Black group, respectively. The incremental cost-effectiveness ratio (ICER) for using LCPT over IR-Tac during the first year of treatment in the Hispanic group was $65,643 per additional successfully treated patient. The ICER for the Black group was $90,458. The single parameter having the most impact on results in both groups was the probability of a treatment-related SAE in IR-Tac, which accounted for 49% of variation in results in the Hispanic group and 46% in the Black group. CONCLUSIONS: Overall results for both groups show that LCPT is incrementally more costly and more effective compared with IR-Tac, indicating a trade-off scenario. LCPT is a cost-effective strategy if a decision makers' willingness to pay for 1 additional successfully treated patient exceeds the ICER and must be weighed against the costs of graft loss, continuing dialysis, and potential retransplant. This study provides a foundation for further research to update and expand inputs as more data become available to improve real-world relevance and decision making. DISCLOSURES: This study was funded by Veloxis Pharmaceuticals, Inc., which provided clinical trial file data and nonbinding feedback on the model structure, data interpretation, clinical expertise, manuscript review, and areas of publication interest (ie, managed care). Hurwitz, Grizzle, Villa Zapata, and Malone received grant funding from Veloxis Pharmaceuticals, Inc., through University of Arizona to conduct research and analysis for this study. Tyler is employed by Veloxis Pharmaceuticals, Inc. Some of the data reported and used in this research were available from the US Renal Data System, the US Bureau of Labor Statistics, and the Agency for Healthcare Research and Quality's Healthcare Cost and Utility Project. The interpretation and reporting of these data are the responsibility of the authors and in no way should be seen as an official policy or interpretation of the US government.

Analyzing the clinical outcomes of switching from cyclosporine to tacrolimus in pediatric hematopoietic stem cell transplantation

OBJECTIVE

The selection of graft-vs. -host disease (GvHD) prophylaxis is vital for the success of hematopoetic stem cell transplantation (HSCT), and calcineurin inhibitors (CNI) have been used for decades as the backbone of GvHD prophylaxis. The aim of this study is to analyze the results of switching cyclosporine (CSA) to tacrolimus because of acute GvHD, engraftment syndrome (ES), persistent low level of CSA, or various CSA-associated adverse events in the first 100 days of pediatric HSCT.

MATERIALS AND METHODS

This is a retrospective analysis of 192 patients who underwent allogeneic hematopoietic stem cell transplantation at Medicalpark Göztepe and Antalya Hospitals between April 2014 and May 2019 had therapy switched from CSA to tacrolimus-based immunosuppression within 100 days of transplant.

RESULTS

The reasons for conversion to tacrolimus were low level of CSA (n = 70), aGvHD (n = 63), CSA-associated neurotoxicity (n = 15), CSA-associated nephrotoxicity (n = 10), hypertension (n = 10), allergic reactions (n = 9), ES (n = 7), CSA-associated hepatotoxicity (n = 5), and vomiting (n = 3). The median day after transplant for conversion to tacrolimus for all patients was day 20 (range 0-100 days). Response rates to conversion were 38% for GvHD, 86% for neurotoxicity, 50% for nephrotoxicity, 60% for hepatotoxicity, 80% for hypertension, 66% for vomiting, and 57% for ES. Twenty-nine patients (15%) experienced tacrolimus-associated toxicities after therapy conversion to tacrolimus. Neurotoxicity emerged as posterior reversible encephalopathy syndrome (PRES), which was the most common toxicity observed after conversion (18/29 patients).

CONCLUSION

Our data support the quick conversion to tacrolimus in the condition of persistent low CSA levels with acceptable efficacy and safety. Although both drugs are CNI and share a very similar mechanism of action, the conversion could be preferred especially in specific organ toxicities with special attention for neurotoxicity after conversion.

Anaphylaxis Induced by Intravenous Tacrolimus Administration During Kidney Transplant Surgery: A Case Report

A 35-year-old male patient with end-stage renal disease due to vesicoureteral reflux preemptively received a renal graft from his father. The patient had a history of allergy to contrast-enhancing media. He received oral tacrolimus (TAC) and mycophenolate mofetil without any problems for 2 days before kidney transplantation. During the induction period of the surgery, his systolic blood pressure (sBP) decreased to 60 mmHg approximately 1 hour after initiating intravenous tacrolimus (TAC-IV) and intravenous piperacillin (PIPC), and the anesthesiologist suspected drug-induced anaphylaxis and stopped administration of the medications. Because TAC had been administered preoperatively without any adverse events, PIPC was suspected as the causative agent of the anaphylaxis. After the patient's hemodynamics returned to baseline, TAC-IV was restarted. However, his sBP rapidly decreased to 40 mmHg and the patient developed wheezing. He was diagnosed with drug-induced anaphylaxis due to castor oil derivatives in the TAC-IV formulation. The patient's sBP was restored with the administration of some vasopressors, and kidney transplantation was then performed without difficulty. Two days after kidney transplantation, oral TAC was administered without anaphylaxis. Clinicians should consider that not only the drug itself but also its additives or metabolites could induce anaphylaxis.

Use of sublingual tacrolimus in adults undergoing hematopoietic cell transplant: A pilot study

INTRODUCTION

Orally administered tacrolimus is widely used in hematopoietic cell transplant patients, but multiple clinical situations may arise rendering oral administration infeasible. The undesirable sequelae of intravenous administration, including toxicity, challenges with administration and cost call for innovative solutions to conserve existing supply and optimize safety and efficacy of medication delivery. We sought to demonstrate feasibility of sublingual tacrolimus use and estimate a sublingual-to-oral (SL:PO) conversion ratio in the hematopoietic cell transplant setting.

METHODS

Ten adults undergoing allogeneic hematopoietic cell transplant received tacrolimus 0.04 mg/kg/dose twice daily. Initial doses were given via sublingual route and a steady state trough level was collected after 4 consecutive doses. Participants were then switched to oral tacrolimus, the dose adjusted for a goal trough 8-12ng/mL, and another steady state trough was drawn. Total daily dose was divided by trough concentration for each route to determine the dosing ratio of SL:PO.

RESULTS

Median trough level following sublingual administration was 11.3 ng/mL. Three of these were within goal, 3 were low (4.7-6.4 ng/mL) and 4 were elevated (15.9-18.6 ng/mL). Median SL:PO ratio was 1.02. In 5 participants the SL:PO ratio was <1 (range 0.57-0.94) and in 5 the ratio was ≥1 (range 1.10-1.92). No significant barriers or intolerance to sublingual tacrolimus use were noted.

CONCLUSIONS

Results demonstrate reliable absorption with sublingual tacrolimus use in patients undergoing hematopoietic cell transplant. Sublingual administration may allow for avoidance of the undesirable complications of IV tacrolimus, such as increased toxicities, required hospitalization for continuous infusion, risk of dose conversion and dilution errors and increased cost.Trial Registry name: Use of Sublingual Tacrolimus in Adult Blood and Marrow Transplant Patients, NCT04041219https://clinicaltrials.gov/ct2/show/NCT04041219?term=NCT04041219&draw=2&rank=1.

Evaluating risk factors for acute graft versus host disease in pediatric hematopoietic stem cell transplant patients receiving tacrolimus

To identify the clinical and pharmacological risk factors associated with tacrolimus pharmacodynamics for acute graft‐versus‐host disease (aGVHD) in pediatric patients receiving allogeneic hematopoietic stem cell transplantation (HSCT) from a matched related donor. A retrospective cohort single center chart review study was conducted with pediatric patients who received tacrolimus prophylaxis after allogeneic HSCT between January 1, 2017, and December 31, 2019. Potential risk factors were tested separately between aGVHD and non‐aGVHD cohorts and were further analyzed in a logistic regression model with backward elimination and a partial least squares discriminant analysis. Thirty‐three patient cases were included in our study and 52% (17/33) developed aGVHD while on tacrolimus prophylaxis. When tested independently, donor age and sibling versus parent donor/recipient relation were shown to be statistically significant between aGVHD and non‐aGVHD patients (p < 0.005). Pharmacological factors associated with tacrolimus treatment failed to demonstrate a significant impact on patient’s risk of aGVHD. Using a best fit logistic regression model that tested all the variables together, donor age was the only significant variable predicting patient’s risk of aGVHD (p < 0.01). Donor relationship and donor age were unable to be evaluated separately and are therefore confounding variables. Among pediatric patients receiving allogeneic HSCT, aGVHD risk is significantly decreased by either sibling donor and/or younger donors. Although no conclusions were drawn on the effect of tacrolimus therapy (p = 0.08), results warrant additional research with a larger sample size to evaluate the accuracy of monitoring tacrolimus serum trough levels.

Clinical Factors Affecting the Dose Conversion Ratio from Intravenous to Oral Tacrolimus Formulation among Pediatric Hematopoietic Stem Cell Transplantation Recipients

BACKGROUND

Tacrolimus is converted from intravenous to oral formulation for the prophylaxis of graft-versus-host disease when patients can tolerate oral intake and graft-versus-host disease is under control. Oral tacrolimus formulation presents poor bioavailability with intraindividual and interindividual variations; however, some factors affecting its blood concentration among pediatric hematopoietic stem cell transplantation (HCT) recipients are still unclear. This study aimed to identify the clinical factors affecting tacrolimus blood concentrations after switching its formulation.

METHODS

Changes in the blood concentration/dose ratio (C/D) of tacrolimus in pediatric HCT recipients were analyzed after the switching of tacrolimus from intravenous to oral formulation. Clinical records of 57 pediatric patients who underwent allogenic HCT from January 2006 to April 2019 in our institute were retrospectively reviewed. The C/D of tacrolimus before discontinuation of intravenous infusion (C/Div) was compared with the tacrolimus trough level within 10 days after the initiation of oral administration (C/Dpo). Multiple linear regression analysis was performed to identify factors affecting (C/Dpo)/(C/Div).

RESULTS

The constant coefficient of (C/Dpo)/(C/Div) was 0.1692 [95% confidence interval (CI), 0.137-0.2011]. The concomitant use of voriconazole or itraconazole and female sex were significant variables with a beta coefficient of 0.0974 (95% CI, 0.062-0.133) and -0.0373 (95% CI, -0.072 to -0.002), respectively.

CONCLUSIONS

After switching of tacrolimus formulation, pediatric HCT recipients might need oral tacrolimus dose that is 5-6 and 3.5-4.5 times the intravenous dose to maintain tacrolimus blood concentrations and area under the concentration-time curve, respectively. With the concomitant use of voriconazole or itraconazole, an oral tacrolimus dose of 4-5 times the intravenous dose seemed appropriate to maintain blood tacrolimus concentration.

The Impact of Donor Type on Outcomes and Cost of Allogeneic Hematopoietic Cell Transplantation for Pediatric Leukemia: A Merged Center for International Blood and Marrow Transplant Research and Pediatric Health Information System Analysis

Allogeneic hematopoietic stem cell transplantation (alloHCT) may be associated with significant morbidity and mortality, resulting in increased healthcare utilization (HCU). To date, no multicenter comparative cost analyses have specifically evaluated alloHCT in children with acute leukemia. In this retrospective cohort study, we examined the relationship between survival and HCU while investigating the hypothesis that matched sibling donor (MSD) alloHCT has significantly lower inpatient HCU with unrelated donor (URD) alloHCT, and that among URDs, umbilical cord blood (UCB) alloHCT will have higher initial utilization but lower long-term utilization. Clinical and transplantation outcomes data from the Center for International Blood and Marrow Transplant Research (CIBMTR) were merged with inpatient cost data from the Pediatric Health Information System (PHIS) database using a probabilistic merge methodology. The merged dataset comprised US patients age 1 to 21 years who underwent alloHCT for acute leukemia between 2004 and 2011 with comprehensive CIBMTR data at a PHIS hospital. AlloHCT was analyzed by donor type, with specific analysis of utilization and costs using PHIS claims data. The primary outcomes of overall survival (OS), leukemia-free survival (LFS), and inpatient costs were evaluated using Kaplan-Meier curves and Cox and Poisson models. A total of 632 patients were identified in both the CIBMTR and PHIS data. The 5-year LFS was 60% for MSD alloHCT, 47% for well-matched matched unrelated donor bone marrow (MUD) alloHCT, 48% for mismatched unrelated donor alloHCT, and 45% for UCB alloHCT (P = .09). Total adjusted costs were significantly lower for MSD alloHCT versus MUD alloHCT by day 100 (adjusted cost ratio [ACR], .73; 95% confidence interval [CI], .62 to .86; P < .001), and higher for UCB alloHCT versus MUD alloHCT (ACR, 1.27; 95% CI, 1.11 to 1.45; P < .001). By 2 years, total adjusted costs remained significantly lower for MSD alloHCT compared with MUD alloHCT (ACR, .67; 95% CI, .56 to .81; P < .001) and higher for UCB alloHCT compared with MUD alloHCT (ACR, 1.25; 95% CI, 1.02 to 1.52; P = .0280). Our data show that UCB and MUD alloHCT provide similar survival outcomes; however, MUD alloHCT has a significant advantage in cost by day 100 and 2 years. More research is needed to determine whether the cost difference among URD alloHCT approaches remains significant with a larger sample size and/or beyond 2 years post-alloHCT.

Tacrolimus Levels in the Prophylaxis of Acute Graft-Versus-Host Disease in the Chinese Early After Hematopoietic Stem Cell Transplantation

BACKGROUND

Tacrolimus has been widely accepted as the backbone of acute graft-versus-host disease (aGVHD) prophylaxis in allogeneic hematopoietic stem cell transplantation (alloHSCT). The present work evaluated whether tacrolimus concentrations early after transplant correlate with the incidence of aGVHD in Chinese alloHSCT recipients.

METHODS

One hundred four Chinese alloHSCT recipients were included in this retrospective study. All patients received standard prophylaxis with tacrolimus and short-term methotrexate. Blood samples were taken at steady-state for those on i.v. tacrolimus (Cv) or predose (C0) and 2 hours after the last oral dose (C2).

RESULTS

In the first 8 weeks after alloHSCT, significant variability in Cv, C0, and C2 of Chinese patients was observed. It was found that higher tacrolimus C0 and C2 values tended to be associated with a reduced risk of aGVHD, although this was a nonsignificant trend due to the small sample size involved. Receiver operating characteristic curve analysis indicated that Cv levels of ≥16.52 ng/mL, C0 levels of ≥5.56 ng/mL, and C2 levels of ≥7.83 ng/mL minimized the incidence of treatment failure during weeks 3-4 with intravenous administration and weeks 5-6 with oral administration. There was no statistically significant association of the patient liver and kidney function with the blood concentration of tacrolimus in the desired range of 5-20 ng/mL.

CONCLUSIONS

Tacrolimus therapeutic drug monitoring improved treatment outcomes of Chinese alloHSCT recipients. Cv measurements during weeks 3-4 and C0 or C2 measurements during weeks 5-6 better predicted aGVHD (I-IV) than the concentrations measured at other time points during the first 6 weeks after alloHSCT.