High tacrolimus intra-patient variability is associated with graft rejection, and de novo donor-specific antibodies occurrence after liver transplantation

Impact of Intrapatient Immunosuppression Variability in Liver Transplantation Outcomes: A Systematic Review and Meta-analysis

Background

To investigate the impact of intrapatient variability (IPV) in the levels of immunosuppressant drugs on health outcomes after liver transplantation.

Methods

A comprehensive systematic review and meta-analysis were conducted, examining literature from MEDLINE/PubMed, Embase, Web of Science, Cochrane Reviews, and Cochrane CENTRAL.

Results

The analysis focused on acute rejection, graft survival, acute kidney injury, and cancer risk as health outcomes. Of 2901 articles screened, 10 met the inclusion criteria. The results indicate a 19% reduction in the risk of acute rejection in patients with lower IPV (RR = 0.81; 95% confidence interval, 0.66-0.99), although 6 studies found no significant association between high IPV and acute rejection. Contrasting results were observed for graft survival, with 1 study indicating worse outcomes for high IPV, whereas another reported no significant difference. High IPV was consistently associated with acute kidney injury across 3 studies. One study suggested a link between high IPV and hepatocellular carcinoma, although a meta-analysis for these outcomes was not feasible.

Conclusions

These findings point to a marginal but statistically significant association between high IPV and an increased risk of acute rejection, highlighting the importance of precise management of immunosuppressive drugs in liver transplant recipients to enhance patient outcomes.

Machine-learning model to predict the tacrolimus concentration and suggest optimal dose in liver transplantation recipients: a multicenter retrospective cohort study

Titrating tacrolimus concentration in liver transplantation recipients remains a challenge in the early post-transplant period. This multicenter retrospective cohort study aimed to develop and validate a machine-learning algorithm to predict tacrolimus concentration. Data from 443 patients undergoing liver transplantation between 2017 and 2020 at an academic hospital in South Korea were collected to train machine-learning models. Long short-term memory (LSTM) and gradient-boosted regression tree (GBRT) models were developed using time-series doses and concentrations of tacrolimus with covariates of age, sex, weight, height, liver enzymes, total bilirubin, international normalized ratio, albumin, serum creatinine, and hematocrit. We conducted performance comparisons with linear regression and populational pharmacokinetic models, followed by external validation using the eICU Collaborative Research Database collected in the United States between 2014 and 2015. In the external validation, the LSTM outperformed the GBRT, linear regression, and populational pharmacokinetic models with median performance error (8.8%, 25.3%, 13.9%, and - 11.4%, respectively; P < 0.001) and median absolute performance error (22.3%, 33.1%, 26.8%, and 23.4%, respectively; P < 0.001). Dosing based on the LSTM model's suggestions achieved therapeutic concentrations more frequently on the chi-square test (P < 0.001). Patients who received doses outside the suggested range were associated with longer ICU stays by an average of 2.5 days (P = 0.042). In conclusion, machine learning models showed excellent performance in predicting tacrolimus concentration in liver transplantation recipients and can be useful for concentration titration in these patients.

Influence of Tacrolimus Intrapatient Variability on Allograft Rejection Frequency and Survival Following Liver Transplantation

BACKGROUND

Tacrolimus is the primary calcineurin inhibitor used in immunosuppressive regimens to prevent allograft rejection (AR) after organ transplantation. Recent studies have linked intrapatient variability (IPV) of tacrolimus with AR occurrence and reduced survival, especially in kidney transplant recipients. However, limited data are available on the impact of tacrolimus IPV on adverse outcomes after liver transplantation (LT).

AIMS

The aim of this study was to assess the association between tacrolimus IPV using various methodologies with acute AR and long-term patient survival after LT.

METHODS

All patients who underwent LT from January 2010 to July 2021 were retrospectively evaluated. Tacrolimus IPV was calculated for each patient using the mean and SD, mean absolute deviation (MAD), coefficient of variation (CV), and time in therapeutic range (TTR). These measures were then compared with AR within the first 24 months after LT and to long-term survival.

RESULTS

Out of 234 patients, 32 (13.7%) developed AR and 183 (78.2%) survived, with a mean follow-up of 101 ± 43 months. Tacrolimus IPV, assessed by mean, SD, MAD, and CV, was 8.3 ± 2.1, 2.7 ± 1.3, 32.0% ± 11.7%, and 39.4% ± 15.4%, respectively. There was no statistically significant correlation between Tacrolimus IPV and AR or survival post-LT.

CONCLUSIONS

In a large cohort of patients from diverse racial backgrounds, tacrolimus IPV was not associated with clinically relevant outcomes such as AR and survival after LT.

A Feasibility Open-Labeled Clinical Trial Using a Second-Generation Artificial-Intelligence-Based Therapeutic Regimen in Patients with Gaucher Disease Treated with Enzyme Replacement Therapy

Background/Objectives: Gaucher Disease type 1 (GD1) is a recessively inherited lysosomal storage disorder caused by a deficiency in the enzyme β-glucocerebrosidase. Enzyme replacement therapy (ERT) has become the standard of care for patients with GD. However, over 10% of patients experience an incomplete response or partial loss of response to ERT, necessitating the exploration of alternative approaches to enhance treatment outcomes. The present feasibility study aimed to determine the feasibility of using a second-generation artificial intelligence (AI) system that introduces variability into dosing regimens for ERT to improve the response to treatment and potentially overcome the partial loss of response to the enzyme. Methods: This was an open-label, prospective, single-center proof-of-concept study. Five patients with GD1 who received ERT were enrolled. The study used the Altus Care™ cellular-phone-based application, which incorporated an algorithm-based approach to offer random dosing regimens within a pre-defined range set by the physician. The app enabled personalized therapeutic regimens with variations in dosages and administration times. Results: The second-generation AI-based personalized regimen was associated with stable responses to ERT in patients with GD1. The SF-36 quality of life scores improved in one patient, and the sense of change in health improved in two; platelet levels increased in two patients, and hemoglobin remained stable. The system demonstrated a high engagement rate among patients and caregivers, showing compliance with the treatment regimen. Conclusions: This feasibility study highlights the potential of using variability-based regimens to enhance ERT effectiveness in GD and calls for further and longer trials to validate these findings.

Recurrent rejections after liver transplantation for hepatocellular carcinoma with stem cell features in an adult patient

Patients with hepatoblastoma featuring carcinoma characteristics have better outcomes after liver transplantation, than after chemotherapy and resection. Possibly this should be extrapolated to aggressive subtypes of hepatocellular carcinomas in non-cirrhotic livers, where early liver transplantation might also be indicated. However, the risks associated with liver transplantation and immunosuppressive treatment after liver transplantation are once again demonstrated by this case of a 32-year-old women with a negative personal and familial history of liver diseases. She underwent transplantation (DBD) for a hepatocellular carcinoma with stem cell features (HCC-HS; an aggressive 'hepatoblast subtype' of hepatocellular carcinoma) after chemotherapeutical downstaging techniques failed to sufficiently downstage the tumor. Despite being on conventional immunosuppressive regimens (tacrolimus and mycophenolate mofetil with initial corticosteroids tapered), this patient still developed two severe rejection episodes, one of which necessitated retransplantation (DCD). Both episodes were preceded by alterations in tacrolimus trough levels, either intentionally, when tacrolimus was reduced within a nephroprotective regimen, or unintentionally, when rifampicin, a CYP3A4 inducer, significantly lowered the trough levels. Together, these episodes stress the importance of therapeutic drug monitoring of tacrolimus. Furthermore, the patient experienced an everolimus-linked drug-induced thrombotic microangiopathy, underwent multiple ERCPs for an anastomotic stricture and only one and a half year after the first liver transplantation she already suffers from long-term immunosuppressive-related side effects such as impaired glucose tolerance, hypertension and a potential cardiomyopathy. At present, she is still alive and experienced no recurrence of her primary tumor. Her case underscores the significant challenges in post-liver transplantation care.

High intra-patient variability of tacrolimus within post-operative 1 month predicted worse 1-year outcomes in pediatric liver transplant recipients

BACKGROUND

The pharmacokinetics of tacrolimus (TAC) show high intra-patient variability (IPV), which is associated with poor long-term outcomes following adult liver transplantation (LT). However, this relationship remains to be confirmed in pediatric liver transplant (PLT) recipients. The present study aimed to investigate the association between TAC IPV and grafts or patient outcomes after pediatric liver transplantion.

METHODS

This retrospective study included 848 PLT recipients (including infants) between January, 2016, and June, 2021. The IPV of TAC concentrations was estimated by calculating the coefficient of variation (CV) of trough concentrations in whole blood within 1 month after transplantation. Patients were categorized into two groups, low IPV (CV < 45%) and high IPV (CV ≥ 45%), based on the third quartile of the CV distribution.

RESULTS

A total of 848 patients were included in our study. The low CV group included 614 patients, with a mean TAC trough concentration of 8.59 ± 1.65 ng/ml and a median CV of 32.37%. In contrast, the high CV group included 214 patients, the mean TAC trough concentration and median CV were 8.81 ± 2.00 ng/ml and 54.88%, respectively. The median hospital duration was significantly higher in the high CV group (22 days vs. 20 days, P = 0.01). Univariate analysis was performed to evaluate the significant differences in 1-year recipient survival (P = 0.041) and 1-year graft survival (P = 0.005) between the high- and low-CV groups. Moreover, high CV (HR 2.316, 95%CI 1.026-5.231, P = 0.043) and persistent EBV viremia (HR 13.165, 95%CI 3.090-56.081, P < 0.001) were identified as independent risk factors for 1- year mortality after PLT.

CONCLUSIONS

PLT recipients with high TAC trough concentration of CV in the first month were associated with poor 1-year outcomes. This CV calculation provides a valuable strategy to monitor TAC exposure.

Association of the Stanford Integrated Psychosocial Assessment for Transplant and 1-Year Outcome of Living Kidney Transplantation in Japan

BACKGROUND

Because most kidney transplantations in Japan are performed on the basis of living donors, after-transplant outcomes should achieve optimum results, overcoming participants' possible reduced adherence.

OBJECTIVE

To investigate the association between the Japanese version of the Stanford Integrated Psychosocial Assessment for Transplantation (SIPAT-J) and outcomes, 1 year after the patient's living kidney transplant (LKT).

METHODS

The prospective cohort study was undertaken at Tokyo Women's Medical University Hospital from January 2020 to July 2021, with a 1-year follow-up period. The SIPAT-J assesses 18 psychosocial risk factors: (1) Patient's Readiness Level and Illness Management (SIPAT A), (2) Social Support System Level of Readiness (SIPAT B), (3) Psychological Stability and Psychopathology (SIPAT C), and (4) Lifestyle and Effect of Substance Use (SIPAT D). The evaluators, a psychiatrist and 3 clinical psychologists, conducted an independent, blinded application of the SIPAT-J using participants' medical records. The study focused on physical composite outcomes, psychiatric outcomes, and nonadherent behaviors.

RESULTS

The participants were 173 LKT recipients (median age [interquartile range], 51 [38-59]); 67.1% were male and 67.1% were employed. The median (interquartile range) SIPAT scores were SIPAT A [7 (5-9)], SIPAT B [7 (5-9)], SIPAT C [2 (0-4)], SIPAT D [3 (3-4)], and SIPAT total [20 (16-23)]. The physical composite outcome was 25 (14.5%), psychiatric outcome 9 (5.2%), and nonadherent behavior 17 (9.8%). SIPAT C (odds ratio = 1.34, 95% confidence interval = 1.06-1.72, P = 0.02) was significantly associated with the psychiatric outcome. SIPAT B (odds ratio = 1.49, 95% confidence interval = 1.12-1.98, P = 0.01) and SIPAT total (odds ratio = 1.13, 95% confidence interval = 1.03-1.24, P = 0.01) were significantly associated with nonadherent behaviors. There was no significant association between the SIPAT and physical composite outcomes.

CONCLUSION

This study is the first to examine the association between SIPAT and physical and psychiatric outcomes 1 year after LKT, controlling for follow-up periods and factors other than SIPAT. Comprehensive psychosocial assessment before LKT and early identification of factors that may negatively affect transplant success can allow targeted interventions to be implemented and increase the likelihood of favorable recipient outcomes.

Cognitive function, self-management, and outcomes among liver transplant recipients: LivCog, a multicenter, prospective study

Liver transplantation is a life-saving option for decompensated cirrhosis. Liver transplant recipients require advanced self-management skills, intact cognitive skills, and care partner support to improve long-term outcomes. Gaps remain in understanding post-liver transplant cognitive and health trajectories, and patient factors such as self-management skills, care partner support, and sleep. Our aims are to (1) assess pre-liver transplant to post-liver transplant cognitive trajectories and identify risk factors for persistent cognitive impairment; (2) evaluate associations between cognitive function and self-management skills, health behaviors, functional health status, and post-transplant outcomes; and (3) investigate potential mediators and moderators of associations between cognitive function and post-liver transplant outcomes. LivCog is a longitudinal, prospective observational study that will enroll 450 adult liver transplant recipients and their caregivers/care partners. The duration of the study is 5 years with 24 additional months of patient follow-up. Data will be collected from participants at 1, 3, 12, and 24 months post-transplant. Limited pre-liver transplant data will also be collected from waitlisted candidates. Data collection methods include interviews, surveys, cognitive assessments, and actigraphy/sleep diary measures. Patient measurements include sociodemographic characteristics, pretransplant health status, cognitive function, physical function, perioperative measures, medical history, transplant history, self-management skills, patient-reported outcomes, health behaviors, and clinical outcomes. Caregiver measures assess sociodemographic variables, health literacy, health care navigation skills, self-efficacy, care partner preparedness, nature and intensity of care, care partner burden, and community participation. By elucidating various health trajectories from pre-liver transplant to 2 years post-liver transplant, LivCog will be able to better characterize recipients at higher risk of cognitive impairment and compromised self-management. Findings will inform interventions targeting health behaviors, self-management, and caregiver supports to optimize outcomes.

Safety and Efficacy of Conversion to Once-Daily Tacrolimus from Twice-Daily Tacrolimus in Pediatric Liver Transplant Recipients

BACKGROUND

Nonadherence to immunosuppression is the most common cause of late acute rejection in pediatric liver transplant (LT) recipients. A prolonged-release once-daily tacrolimus formulation was developed to improve adherence and long-term allograft survival.

METHODS

We screened 179 pediatric LT recipients who converted from twice-daily tacrolimus (TD-TAC) to once-daily tacrolimus (OD-TAC) between February 2011 and September 2019.

RESULTS

One hundred seventy-nine recipients converted to OD-TAC and were followed for 18 months. 152 OD-TAC-converted recipients (84.9%) experienced uneventful follow-up, while 21 recipients showed LFT elevation. Four recipients had biopsy-proven acute rejection within six months of conversion, all of which were successfully treated with steroid pulse. 166 recipients (92.7%) remain on OD-TAC and 13 (7.3%) were switched back to TD-TAC. The mean tacrolimus trough level significantly decreased three months following conversion (3.14 ± 1.9 ng/mL) compared with pre-conversion levels (3.69 ± 1.98 ng/mL). Mean tacrolimus trough levels remained unchanged from 3 months to 12 months following conversion. Percent coefficient of variation of tacrolimus trough levels decreased significantly from 32.5 ± 16.4 ng/mL to 27.5 ± 15.6 ng/mL after conversion to OD-TAC, reflecting a decrease in variation of tacrolimus trough levels following conversion.

CONCLUSIONS

Conversion to OD-TAC in pediatric LT recipients with stable graft function is safe and effective.

LEVEL OF EVIDENCE

Level IV.

Patient randomised controlled trial of technology enabled strategies to promote treatment adherence in liver transplantation: rationale and design of the TEST trial

BACKGROUND AND AIMS

Liver transplantation is a life-saving procedure for end-stage liver disease. However, post-transplant medication regimens are complex and non-adherence is common. Post-transplant medication non-adherence is associated with graft rejection, which can have long-term adverse consequences. Transplant centres are equipped with clinical staff that monitor patients post-transplant; however, digital health tools and proactive immunosuppression adherence monitoring has potential to improve outcomes.

METHODS AND ANALYSIS

This is a patient-randomised prospective clinical trial at three transplant centres in the Northeast, Midwest and South to investigate the effects of a remotely administered adherence programme compared with usual care. The programme monitors potential non-adherence largely levering text message prompts and phenotypes the nature of the non-adhere as cognitive, psychological, medical, social or economic. Additional reminders for medications, clinical appointments and routine self-management support are incorporated to promote adherence to the entire medical regimen. The primary study outcome is medication adherence via 24-hour recall; secondary outcomes include additional medication adherence (ASK-12 self-reported scale, regimen knowledge scales, tacrolimus values), quality of life, functional health status and clinical outcomes (eg, days hospitalised). Study implementation, acceptability, feasibility, costs and potential cost-effectiveness will also be evaluated.

ETHICS AND DISSEMINATION

The University of Pennsylvania Review Board has approved the study as the single IRB of record (protocol # 849575, V.1.4). Results will be published in peer-reviewed journals and summaries will be provided to study funders.

TRIAL REGISTRATION NUMBER

NCT05260268.

Impact of tacrolimus intra-patient variability in adverse outcomes after organ transplantation

Tacrolimus (Tac) is currently the most common calcineurin-inhibitor employed in solid organ transplantation. High intra-patient variability (IPV) of Tac (Tac IPV) has been associated with an increased risk of immune-mediated rejection and poor outcomes after kidney transplantation. Few data are available concerning the impact of high Tac IPV in non-kidney transplants. However, even in kidney transplantation, there is still a controversy whether high Tac IPV is indeed detrimental in respect to graft and/or patient survival. This may be due to different methods employed to evaluate IPV and distinct time frames adopted to assess graft and patient survival in those reports published up to now in the literature. Little is also known about the influence of high Tac IPV in the development of other untoward adverse events, update of the current knowledge regarding the impact of Tac IPV in different outcomes following kidney, liver, heart, lung, and pancreas tran splantation to better evaluate its use in clinical practice.

Incidence and predictors of alcohol relapse following living donor liver transplantation for alcohol related liver disease

BACKGROUND

Alcohol relapse after liver transplantation has a negative impact on outcomes. There is limited data on its burden, the predictors, and impact following live donor liver transplantation (LDLT).

METHODS

A single-center observational study was carried out between July 2011 and March 2021 for patients undergoing LDLT for alcohol associated liver disease (ALD). The incidence, predictors of alcohol relapse, and post-transplant outcomes were assessed.

RESULTS

Altogether 720 LDLT were performed during the study period, 203 (28.19%) for ALD. The overall relapse rate was 9.85% (n = 20) with a median follow-up of 52 months (range, 12-140 months). Sustained harmful alcohol use was seen in 4 (1.97%). On multivariate analysis, pre-LT relapse (P = .001), duration of abstinence period (P = .007), daily intake of alcohol (P = .001), absence of life partner (P = .021), concurrent tobacco abuse before transplant (P = .001), the donation from second-degree relative (P = .003) and poor compliance with medications (P = .001) were identified as predictors for relapse. Alcohol relapse was associated with the risk of graft rejection (HR 4.54, 95% CI: 1.751-11.80, P = .002).

CONCLUSION

Our results show that the overall incidence of relapse and rate of harmful drinking following LDLT is low. Donation from spouse and first degree relative was protective. History of daily intake, prior relapse, shorter pretransplant abstinence duration and lack of family support significantly predicted relapse.

Gut microbiome modulates tacrolimus pharmacokinetics through the transcriptional regulation of ABCB1

BACKGROUND

Following solid organ transplantation, tacrolimus (TAC) is an essential drug in the immunosuppressive strategy. Its use constitutes a challenge due to its narrow therapeutic index and its high inter- and intra-pharmacokinetic (PK) variability. As the contribution of the gut microbiota to drug metabolism is now emerging, it might be explored as one of the factors explaining TAC PK variability. Herein, we explored the consequences of TAC administration on the gut microbiota composition. Reciprocally, we studied the contribution of the gut microbiota to TAC PK, using a combination of in vivo and in vitro models.

RESULTS

TAC oral administration in mice resulted in compositional alterations of the gut microbiota, namely lower evenness and disturbance in the relative abundance of specific bacterial taxa. Compared to controls, mice with a lower intestinal microbial load due to antibiotics administration exhibit a 33% reduction in TAC whole blood exposure and a lower inter-individual variability. This reduction in TAC levels was strongly correlated with higher expression of the efflux transporter ABCB1 (also known as the p-glycoprotein (P-gp) or the multidrug resistance protein 1 (MDR1)) in the small intestine. Conventionalization of germ-free mice confirmed the ability of the gut microbiota to downregulate ABCB1 expression in a site-specific fashion. The functional inhibition of ABCB1 in vivo by zosuquidar formally established the implication of this efflux transporter in the modulation of TAC PK by the gut microbiota. Furthermore, we showed that polar bacterial metabolites could recapitulate the transcriptional regulation of ABCB1 by the gut microbiota, without affecting its functionality. Finally, whole transcriptome analyses pinpointed, among others, the Constitutive Androstane Receptor (CAR) as a transcription factor likely to mediate the impact of the gut microbiota on ABCB1 transcriptional regulation.

CONCLUSIONS

We highlight for the first time how the modulation of ABCB1 expression by bacterial metabolites results in changes in TAC PK, affecting not only blood levels but also the inter-individual variability. More broadly, considering the high number of drugs with unexplained PK variability transported by ABCB1, our work is of clinical importance and paves the way for incorporating the gut microbiota in prediction algorithms for dosage of such drugs. Video Abstract.

Personalized Tacrolimus Dosing After Liver Transplantation: A Randomized Clinical Trial

Background

Inter- and intra-individual variability in tacrolimus dose requirements mandates empirical clinician-titrated dosing that frequently results in deviation from a narrow target range. Improved methods to individually dose tacrolimus are needed. Our objective was to determine whether a quantitative, dynamically-customized, phenotypic-outcome-guided dosing method termed Phenotypic Personalized Medicine (PPM) would improve target drug trough maintenance.

Methods

In a single-center, randomized, pragmatic clinical trial ( NCT03527238 ), 62 adults were screened, enrolled, and randomized prior to liver transplantation 1:1 to standard-of-care (SOC) clinician-determined or PPM-guided dosing of tacrolimus. The primary outcome measure was percent days with large (>2 ng/mL) deviation from target range from transplant to discharge. Secondary outcomes included percent days outside-of-target-range and mean area-under-the-curve (AUC) outside-of-target-range per day. Safety measures included rejection, graft failure, death, infection, nephrotoxicity, or neurotoxicity.

Results

56 (29 SOC, 27 PPM) patients completed the study. The primary outcome measure was found to be significantly different between the two groups. Patients in the SOC group had a mean of 38.4% of post-transplant days with large deviations from target range; the PPM group had 24.3% of post-transplant days with large deviations; (difference -14.1%, 95% CI: -26.7 to -1.5 %, P=0.029). No significant differences were found in the secondary outcomes. In post-hoc analysis, the SOC group had a 50% longer median length-of-stay than the PPM group [15 days (Q1-Q3: 11-20) versus 10 days (Q1-Q3: 8.5-12); difference 5 days, 95% CI: 2-8 days, P=0.0026].

Conclusions

PPM guided tacrolimus dosing leads to better drug level maintenance than SOC. The PPM approach leads to actionable dosing recommendations on a day-to-day basis.

Lay Summary

In a study on 62 adults who underwent liver transplantation, researchers investigated whether a new dosing method called Phenotypic Personalized Medicine (PPM) would improve daily dosing of the immunosuppression drug tacrolimus. They found that PPM guided tacrolimus dosing leads to better drug level maintenance than the standard-of-care clinician-determined dosing. This means that the PPM approach leads to actionable dosing recommendations on a day-to-day basis and can help improve patient outcomes.

Impact of Early Intrapatient Variability of Tacrolimus Concentrations on the Risk of Graft-Versus-Host Disease after Allogeneic Stem Cell Transplantation Using High-Dose Post-Transplant Cyclophosphamide

Tacrolimus (Tac) is a pivotal immunosuppressant agent used to prevent graft-versus-host disease (GVHD) after allogeneic stem cell transplantation (alloHSCT). Tac is characterized by a narrow therapeutic window and a high inter-patient and intra-patient pharmacokinetic variability (IPV). Although high IPV of Tac concentrations has been associated with adverse post-transplant outcomes following solid organ transplantation, the effects of Tac IPV on alloHSCT recipients have not been determined. Tac IPV was therefore retrospectively evaluated in 128 alloHSCT recipients receiving high-dose post-transplant cyclophosphamide (PTCy) and the effects of Tac IPV on the occurrence of acute GVHD (aGVHD) were analyzed. Tac IPV was calculated from pre-dose concentrations (C0) measured during the first month after Tac initiation. The cumulative rates of grades II-IV and grades III-IV aGVHD at day +100 were 22.7% and 7%, respectively. Higher Tac IPV was associated with a greater risk of developing GVHD, with patients having IPV > 50th percentile having significantly higher rates of grades II-IV (34.9% vs. 10.8%; hazard ratio [HR] 3.858, p < 0.001) and grades III-IV (12.7% vs. 1.5%; HR 9.69, p = 0.033) aGVHD than patients having IPV ≤ 50th percentile. Similarly, patients with IPV > 75th percentile had higher rates of grades II-IV (41.9% vs. 16.5%; HR 3.30, p < 0.001) and grades III-IV (16.1% vs. 4.1%; HR 4.99, p = 0.012) aGVHD than patients with IPV ≤ 75th percentile. Multivariate analyses showed that high Tac IPV (>50th percentile) was an independent risk factor for grades II-IV (HR 2.99, p = 0.018) and grades III-IV (HR 9.12, p = 0.047) aGVHD. Determination of Tac IPV soon after alloHSCT could be useful in identifying patients at greater risk of aGVHD.

Intrapatient Variability (IPV) and the Blood Concentration Normalized by the Dose (C/D Ratio) of Tacrolimus-Their Correlations and Effects on Long-Term Renal Allograft Function

Tacrolimus, in combination with mycophenolate mofetil and glucocorticoids, is the basis of immunosuppressive therapy after renal transplantation. Tacrolimus intrapatient variability (IPV) and the blood concentration normalized by the dose (concentration/dose ratio, C/D ratio) both have an effect on the function of the transplanted kidney. In this study, we examined whether the metabolism rate affected IPV, whether the C/D ratio value was stable in the long-term follow-up, and whether it could be used for IPV measurements. In addition, our study population was examined for the effect of the C/D ratio and IPV on long-term renal function. The C/D ratio and IPV were examined in 170 patients at appointments held at 3, 6, 12 and 24 months after RTx. The average time post renal transplantation was 70 months. Renal function defined as creatinine concentration at the last appointment was examined. Results: the mean C/D ratio in the study group was 1.63. A negative correlation between the C/D ratio and creatinine concentration at the end of the follow-up was observed. Between the C/D ratio < and ≥1.63 groups, significant differences in creatinine concentration at the last appointment were found. No relationship was identified between the mean C/D ratio and IPV. The C/D ratio values increased significantly over a longer post-transplant period (12, 24, 60 and 120 m). We did not find a correlation between the mean IPV and the creatinine concentration from the last appointment. Our study group was divided into terciles according to IPV, while no renal graft function differences were found at the same appointment. Conclusion: the C/D ratio is useful for assessing the effects of the metabolism rate of tacrolimus on the long-term renal graft function. The C/D ratio does not affect the IPV value. IPV calculated from variability of the C/D ratio does not influence transplanted kidney function. The C/D changes over time.

Plasma metabolomic profiling reveals factors associated with dose-adjusted trough concentration of tacrolimus in liver transplant recipients

Inter- and intrapatient variability of tacrolimus exposure is a vital prognostic risk factor for the clinical outcome of liver transplantation. New factors or biomarkers characterizing tacrolimus disposition is essential for optimal dose prediction in recipients of liver transplant. The aim of the study was to identify potential plasma metabolites associated with the dose-adjusted trough concentration of tacrolimus in liver transplant recipients by using a global metabolomic approach. A total of 693 plasma samples were collected from 137 liver transplant recipients receiving tacrolimus and regular therapeutic drug monitoring. Untargeted metabolomic analysis was performed by ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry. Univariate and multivariate analyses with a mixed linear model were conducted, and the results showed that the dose-adjusted tacrolimus trough concentration was associated with 31 endogenous metabolites, including medium- and long-chain acylcarnitines such as stearoylcarnitine (β = 0.222, p = 0.001), microbiota-derived uremic retention solutes such as indolelactic acid (β = 0.194, p = 0.007), bile acids such as taurohyodeoxycholic acid (β = -0.056, p = 0.002), and steroid hormones such as testosterone (β = 0.099, p = 0.001). A multiple linear mixed model including 11 metabolites and clinical information was established with a suitable predictive performance (correlation coefficient based on fixed effects = 0.64 and correlation coefficient based on fixed and random effects = 0.78). These data demonstrated that microbiota-derived uremic retention solutes, bile acids, steroid hormones, and medium- and long-chain acylcarnitines were the main metabolites associated with the dose-adjusted trough concentration of tacrolimus in liver transplant recipients.

Clinical association between tacrolimus intra-patient variability and liver transplantation outcomes in patients with and without hepatocellular carcinoma

Tacrolimus is the mainstay of immunosuppression in liver transplantation to prevent rejection. However, the clinical use of tacrolimus is complicated by its narrow therapeutic window and significant intra-patient variability (IPV). High tacrolimus IPV is associated with overexposure and adverse effects, including malignancy. The effects of tacrolimus IPV in liver transplant recipients with and without hepatocellular carcinoma (HCC) are unknown. We investigated the association between tacrolimus IPV and transplant outcomes in 636 liver transplant patients. Tacrolimus IPV was determined by calculating the coefficient of variance (CV) of outpatient tacrolimus trough levels from 3 to 12 months after transplantation. High tacrolimus IPV was defined as CV > 30%. Patients were grouped according to tacrolimus IPV and HCC status. Among 636 liver transplant patients, 349 had HCC and 287 had no HCC. Overall survival in HCC patients was significantly reduced with high tacrolimus IPV (P < 0.001), whereas survival of non-HCC patients was not associated with tacrolimus IPV. Multivariable analysis confirmed the independent association between high tacrolimus IPV and overall mortality in HCC patients (HR, 3.010; 95% CI, 1.084–4.918). HCC recurred in 59 patients (16.9%) post-transplantation. After adjusting for donor/recipient factors, immunosuppression, and tumor characteristics, high tacrolimus IPV was independently associated with an increased risk of HCC recurrence (HR, 2.196; 95% CI, 1.272–3.791). High tacrolimus IPV was associated with significantly increased risks of overall mortality and HCC recurrence in liver transplant recipients with HCC.

Impact of Tacrolimus Trough Variability on Acute Rejection Following Lung Transplantation

BACKGROUND

Acute rejection is a risk factor for the development of chronic lung allograft dysfunction, the leading cause of morbidity and mortality in lung transplant recipients. Calcineurin inhibitors are the cornerstone of immunosuppression regimens after lung transplantation.

METHODS

We retrospectively evaluated the association of tacrolimus level variability with total acute rejection score at 12 months post-transplant. Secondary outcomes included the development of chronic lung allograft dysfunction and antibody-mediated rejection at 24months post-transplant. There were 229 lung transplant recipients included.

RESULTS

The mean (standard deviation) total rejection score of the cohort was 1.6 (1.7). Patients with high tacrolimus variability at 0 to 3, 3 to 6, and 6 to 12 months on average scored 0.18 (mean 1.6 vs 1.5; 95% CI): -0.3 to 0.66, P =.46), 0.14 (mean 1.7 vs 1.5; 95% CI: -0.32 to 0.6, P = .55), and 0.12 (mean 1.6 vs 1.5; 95% CI: -0.34 to 0.58, P = .62) point higher in 12-month total acute rejection scores, respectively; however, these differences were not statistically significant. The incidences of chronic lung allograft dysfunction and antibody-mediated rejection were numerically greater in the high variability group throughout certain periods; however, this was not consistent throughout all study timeframes and statistical significance was not evaluated.

CONCLUSIONS

High tacrolimus variability was not associated with increased 12-month total acute rejection score. Further studies are needed to assess long-term outcomes with tacrolimus level variability.

Insights into the Pharmacogenetics of Tacrolimus Pharmacokinetics and Pharmacodynamics

The influence of pharmacogenetics in tacrolimus pharmacokinetics and pharmacodynamics needs further investigation, considering its potential in assisting clinicians to predict the optimal starting dosage and the need for a personalized adjustment of the dose, as well as to identify patients at a high risk of rejection, drug-related adverse effects, or poor outcomes. In the past decade, new pharmacokinetic strategies have been developed to improve personalized tacrolimus treatment. Several studies have shown that patients with tacrolimus doses C0/D < 1 ng/mL/mg may demonstrate a greater incidence of drug-related adverse events and infections. In addition, C0 tacrolimus intrapatient variability (IPV) has been identified as a potential biomarker to predict poor outcomes related to drug over- and under-exposure. With regard to tacrolimus pharmacodynamics, inconsistent genotype-phenotype relationships have been identified. The aim of this review is to provide a concise summary of currently available data regarding the influence of pharmacogenetics on the clinical outcome of patients with high intrapatient variability and/or a fast metabolizer phenotype. Moreover, the role of membrane transporters in the interindividual variability of responses to tacrolimus is critically discussed from a transporter scientist’s perspective. Indeed, the relationship between transporter polymorphisms and intracellular tacrolimus concentrations will help to elucidate the interplay between the biological mechanisms underlying genetic variations impacting drug concentrations and clinical effects.

Next-Generation Personalized Medicine: Implementation of Variability Patterns for Overcoming Drug Resistance in Chronic Diseases

Chronic diseases are a significant healthcare problem. Partial or complete non-responsiveness to chronic therapies is a significant obstacle to maintaining the long-term effect of drugs in these patients. A high degree of intra- and inter-patient variability defines pharmacodynamics, drug metabolism, and medication response. This variability is associated with partial or complete loss of drug effectiveness. Regular drug dosing schedules do not comply with physiological variability and contribute to resistance to chronic therapies. In this review, we describe a three-phase platform for overcoming drug resistance: introducing irregularity for improving drug response; establishing a deep learning, closed-loop algorithm for generating a personalized pattern of irregularity for overcoming drug resistance; and upscaling the algorithm by implementing quantified personal variability patterns along with other individualized genetic and proteomic-based ways. The closed-loop, dynamic, subject-tailored variability-based machinery can improve the efficacy of existing therapies in patients with chronic diseases.

Development of De Novo Donor-specific HLA Antibodies and AMR in Renal Transplant Patients Depends on CYP3A5 Genotype

BACKGROUND

The single-nucleotide polymorphism CYP3A5 rs776746 is related to a reduction in the metabolizing activity of the CYP3A5 enzyme. People carrying at least one copy of the wild-type allele, defined as CYP3A5 expressers, exhibit higher clearance and lower trough concentrations of tacrolimus than homozygous nonexpressers, and this difference may affect alloimmunization and allograft function.

METHODS

We retrospectively studied 400 kidney transplant recipients treated with a tacrolimus-based immunosuppression regimen to detect CYP3A5 genotype, de novo formation of HLA antibodies and donor-specific antibodies (DSAs), and clinical outcome up to 5 y after transplant.

RESULTS

We found that 69 (17%) of the 400 patients were CYP3A5 expressers. During the first 3 y after transplant, CYP3A5 expressers tended to have lower tacrolimus trough levels than nonexpressers, although their tacrolimus dosage was as much as 80% higher. De novo DSAs were found more frequently in CYP3A5 expressers than in nonexpressers (13/69 [19%] versus 33/331 [10%], P = 0.02). De novo DSA-free survival rates (P = 0.02) were significantly lower for expressers than for nonexpressers. CYP3A5 genotype had no effect on allograft failure, but CYP3A5 expressers exhibited a significantly higher frequency of antibody-mediated rejection. CYP3A5 expresser status was an independent risk factor for the development of de novo DSAs (relative risk, 2.34, P = 0.01).

CONCLUSIONS

Early detection of CYP3A5 expressers, enabling genotype-based dose adjustment of tacrolimus immediately after renal transplant, may be a useful strategy for reducing the risk of de novo DSA production and antibody-mediated rejection.

High intrapatient variability of tacrolimus exposure associated with poorer outcomes in liver transplantation

Tacrolimus (TAC) is a dose‐dependent immunosuppressor with considerable intrapatient variability (IPV) in its pharmacokinetics. The aim of this work is to ascertain the association between TAC IPV at 6 months after liver transplantation (LT) and patient outcome. This single‐center cohort study retrospectively analyzed adult patients who underwent transplantation from 2015 to 2019 who survived the first 6 months with a functioning graft. The primary end point was the patient’s probability of death and the secondary outcome was the loss of renal function between month 6 and the last follow‐up. TAC IPV was estimated by calculating the coefficient of variation (CV) of the dose‐corrected concentration (C₀/D) between the third and sixth months post‐LT. Of the 140 patients who underwent LT included in the study, the low‐variability group (C₀/D CV < 27%) comprised 105 patients and the high‐variability group (C₀/D CV ≥ 27%) 35 patients. One‐, 3‐, and 5‐year patient survival rates were 100%, 82%, and 72% in the high‐variability group versus 100%, 97%, and 93% in the low‐variability group, respectively (p = 0.005). Moreover, significant impaired renal function was observed in the high‐variability group at 1 year (69 ± 16 ml/min/1.73 m² vs. 78 ± 16 ml/min/1.73 m², p = 0.004) and at 2 years post‐LT (69 ± 17 ml/min/1.73 m² vs. 77 ± 15 ml/min/1.73 m², p = 0.03). High C₀/D CV 3–6 months remained independently associated with worse survival (hazard ratio = 3.57, 95% CI = 1.32–9.67, p = 0.012) and loss of renal function (odds ratio = 3.47, 95% CI = 1.30–9.20, p = 0.01). Therefore, high IPV between the third and sixth months appears to be an early and independent predictor of patients with poorer liver transplant outcomes.

The Role of Intra-Patient Variability of Tacrolimus Drug Concentrations in Solid Organ Transplantation: A Focus on Liver, Heart, Lung and Pancreas

Tacrolimus, the keystone immunosuppressive drug administered after solid organ transplantation, presents a narrow therapeutic index and wide inter- and intra-patient pharmacokinetic variability (IPV). The latter has been fairly studied in kidney transplantation, where it could impact outcomes. However, literature about other transplanted organ recipients remains inconclusive. This review aimed at summarizing the evidence about the IPV of tacrolimus concentrations outside of the scope of kidney transplantation. First, factors influencing IPV will be presented. Then, the potential of IPV as a biomarker predictive of graft outcomes will be discussed in liver, heart, lung and pancreas transplantation. Lastly, strategies to reduce IPV will be reviewed, with the ultimate objective being ready-to-implement solutions in clinical practice by transplantation professionals.

A Subject-Tailored Variability-Based Platform for Overcoming the Plateau Effect in Sports Training: A Narrative Review

The plateau effect in training is a significant obstacle for professional athletes and average subjects. It evolves from both the muscle-nerve-axis-associated performance and various cardiorespiratory parameters. Compensatory adaptation mechanisms contribute to a lack of continuous improvement with most exercise regimens. Attempts to overcome this plateau in exercise have been only partially successful, and it remains a significant unmet need in both healthy subjects and those suffering from chronic neuromuscular, cardiopulmonary, and metabolic diseases. Variability patterns characterize many biological processes, from cellular to organ levels. The present review discusses the significant obstacles in overcoming the plateau in training and establishes a platform to implement subject-tailored variability patterns to prevent and overcome this plateau in muscle and cardiorespiratory performance.

Non-invasive diagnosis and follow-up in liver transplantation

The field of liver transplantation directly or indirectly embodies all liver diseases, in addition to specific ones related to organ rejection (cellular and humoral). The recommended non-invasive methods for determining the indication for liver transplantation are the Model for End-stage Liver Disease score, and the alpha-foetoprotein score in case of hepatocellular carcinoma. Radiological methods are the cornerstones for the diagnosis of vascular and biliary complications after liver transplantation. The possible diseases of the liver graft after transplantation are multiple and often intertwined. Non-invasive diagnostic methods have been poorly evaluated in this context, apart from the recurrence of hepatitis C. Liver biopsy remains the gold standard for evaluating graft lesions in the majority of cases, especially graft rejection.

Monitoring Tacrolimus Concentrations in Whole Blood and Peripheral Blood Mononuclear Cells: Inter- and Intra-Patient Variability in a Cohort of Pediatric Patients

Tacrolimus (TAC) is a first-choice immunosuppressant for solid organ transplantation, characterized by high potential for drug-drug interactions, significant inter- and intra-patient variability, and narrow therapeutic index. Therapeutic drug monitoring (TDM) of TAC concentrations in whole blood (WB) is capable of reducing the incidence of adverse events. Since TAC acts within lymphocytes, its monitoring in peripheral blood mononuclear cells (PBMC) may represent a valid future alternative for TDM. Nevertheless, TAC intracellular concentrations and their variability are poorly described, particularly in the pediatric context. Therefore, our aim was describing TAC concentrations in WB and PBMC and their variability in a cohort of pediatric patients undergoing constant immunosuppressive maintenance therapy, after liver transplantation. TAC intra-PBMCs quantification was performed through a validated UHPLC–MS/MS assay over a period of 2–3 months. There were 27 patients included in this study. No significant TAC changes in intracellular concentrations were observed (p = 0.710), with a median percent change of −0.1% (IQR −22.4%–+46.9%) between timings: this intra-individual variability was similar to the one in WB, −2.9% (IQR −29.4–+42.1; p = 0.902). Among different patients, TAC weight-adjusted dose and age appeared to be significant predictors of TAC concentrations in WB and PBMC. Intra-individual seasonal variation of TAC concentrations in WB, but not in PBMC, have been observed. These data show that the intra-individual variability in TAC intracellular exposure is comparable to the one observed in WB. This opens the way for further studies aiming at the identification of therapeutic ranges for TAC intra-PBMC concentrations.

A digital health platform for assisting the diagnosis and monitoring of COVID-19 progression: An adjuvant approach for augmenting the antiviral response and mitigating the immune-mediated target organ damage

Coronavirus disease 2019 (COVID-19), which is a respiratory illness associated with high mortality, has been classified as a pandemic. The major obstacles for the clinicians to contain the disease are limited information availability, difficulty in disease diagnosis, predicting disease prognosis, and lack of disease monitoring tools. Additionally, the lack of valid therapies has further contributed to the difficulties in containing the pandemic. Recent studies have reported that the dysregulation of the immune system leads to an ineffective antiviral response and promotes pathological immune response, which manifests as ARDS, myocarditis, and hepatitis. In this study, a novel platform has been described for disseminating information to physicians for the diagnosis and monitoring of patients with COVID-19. An adjuvant approach using compounds that can potentiate antiviral immune response and mitigate COVID-19-induced immune-mediated target organ damage has been presented. A prolonged beneficial effect is achieved by implementing algorithm-based individualized variability measures in the treatment regimen.

Tacrolimus Intrapatient Variability After Switching From Immediate or Prolonged-Release to Extended-Release Formulation, After an Organ Transplantation

Background and Purpose: Several formulations of tacrolimus are available, but evidence of the benefit of changing to the most recent formulations is lacking. Tacrolimus intra-patient variability (tacrolimus IPV) is an emerging risk factor associated with poor graft outcomes after solid organ transplantations. Here, we examined the modifications of tacrolimus IPV after switching to a different formulation of tacrolimus. Experimental Approach: We identified 353 solid organ transplant recipients that were switched in our center from immediate-release (IR-tacrolimus) or prolonged-release tacrolimus (PR-tacrolimus) to extended-release, LCP-tacrolimus (LCP-tacrolimus). Among them, 54 patients underwent at least 3 available tacrolimus blood concentrations before and after the switch, allowing us to investigate tacrolimus IPV. Key Results: The switch was considered as a safe procedure since only four of the 353 patients presented a graft rejection after the switch, and no patient was hospitalized for tacrolimus overdose. The tacrolimus IPV estimated by the coefficient of variation (CV-IPV) was stable before and after the switch to LCP-tacrolimus (CV-IPV: 29.0% (IQR 25-75 (15.5; 38.5) before and 24.0% (15.8; 36.5) after the switch, p = 0.65). Conclusion and Implications: Switching from IR- or PR-tacrolimus to LCP-tacrolimus is a safe procedure. However, the CV-tacrolimus IPV was not impacted by the change of formulation.

High Intrapatient Variability in Tacrolimus Exposure Calculated Over a Long Period Is Associated With De Novo Donor-Specific Antibody Development and/or Late Rejection in Thai Kidney Transplant Patients Receiving Concomitant CYP3A4/5 Inhibitors

BACKGROUND

High intrapatient variability in tacrolimus trough levels (Tac IPV) is associated with poor allograft outcomes. Tac IPV was previously calculated using trough levels 6-12 months after kidney transplantation (KT). Data on the accuracy of Tac IPV calculation over a longer period, the association between high Tac IPV and donor-specific antibody (DSA) development after KT in Asian patients, and the role of IPV in patients receiving concomitant cytochrome P450 (CYP)3A4/5 inhibitors (CYPinh) are limited.

METHODS

A retrospective review of patients who underwent KT at our center in 2005-2015, and who received Tac with mycophenolate during the first 2 years after KT was performed. IPV was calculated using Tac levels adjusted by dosage. DSA was monitored annually after KT using a Luminex microbead assay.

RESULTS

In total, 236 patients were enrolled. CYPinh were prescribed to 189 patients (80.1%): 145 (61.4%), 31 (13.1%), and 13 (5.5%) received diltiazem, fluconazole, and ketoconazole, respectively. Mean IPV calculated from adjusted Tac levels for 6-12 months (IPV6-12) and 6-24 months (IPV6-24) after KT were 20.64% ± 11.68% and 23.53% ± 10.39%, respectively. Twenty-six patients (11%) showed late rejection and/or DSA occurrence, and had significantly higher IPV6-24 (29.42% ± 13.78%) than others (22.77% ± 9.64%; P = 0.02). There was no difference in IPV6-12 (24.31% ± 14.98% versus 20.17% ± 10.90%; P = 0.18). IPV6-12 and IPV6-24 were comparable in patients who did and did not receive CYPinh. When using mean IPV6-24 as a cutoff, patients with higher IPV6-24 had a higher probability of developing DSA and/or late rejection (P = 0.048).

CONCLUSIONS

Tac IPV6-24 was higher and more significantly associated with DSA development and/or late rejection than Tac IPV6-12, independent of Tac trough level. This is the first study to demonstrate the impact of high IPV on DSA development in Asian patients, and that Tac IPV is comparable between patients with and without CYPinh.

Effect of glecaprevir/pibrentasvir on weight-adjusted tacrolimus trough/dose ratios in heart and kidney transplant recipients

OBJECTIVE

The pharmacokinetic implications of direct-acting antiviral (DAA) use on tacrolimus posttransplant are unknown. This study sought to investigate the effects of glecaprevir/pibrentasvir (G/P), a CYP3A4 substrate and inhibitor, on weight-adjusted tacrolimus (FK) trough/dose ratio (T/D) following heart or kidney transplantation.

MATERIAL AND METHODS

This was a single-center, retrospective analysis of hepatitis C virus (HCV) viremic donors to HCV negative heart or kidney transplant recipients who received 12 weeks of G/P therapy. Weight-adjusted T/D was assessed while patients were at steady-state before, during, and after G/P treatment. Forty-one HCV negative recipients (three heart, 38 kidney) were evaluated.

RESULTS

The weight-adjusted T/D significantly increased during G/P treatment (119.31, IQR 88-173.8) compared to before G/P treatment (67.4, IQR 53.4-115.9) (p < 0.01), but decreased after completion of treatment (90.1, IQR 52.9-122.7) (p < 0.01). There was no difference in weight-adjusted T/D before and after G/P treatment (p = 0.42). Four patients experienced acute rejection.

CONCLUSION

Initiation of G/P in heart or kidney transplant recipients induces a reversible change in tacrolimus metabolism. A 33%-50% tacrolimus dose reduction may be considered at the time of G/P initiation. Regardless of tacrolimus dose adjustment, tacrolimus trough levels should be monitored 3 days after initiation of G/P. No clear relationship between HCV viremic organ transplantation and rejection risk was found. Larger studies are warranted to validate these findings.

Improving Diuretic Response in Heart Failure by Implementing a Patient-Tailored Variability and Chronotherapy-Guided Algorithm

Heart failure is a major public health problem, which is associated with significant mortality, morbidity, and healthcare expenditures. A substantial amount of the morbidity is attributed to volume overload, for which loop diuretics are a mandatory treatment. However, the variability in response to diuretics and development of diuretic resistance adversely affect the clinical outcomes. Morevoer, there exists a marked intra- and inter-patient variability in response to diuretics that affects the clinical course and related adverse outcomes. In the present article, we review the mechanisms underlying the development of diuretic resistance. The role of the autonomic nervous system and chronobiology in the pathogenesis of congestive heart failure and response to therapy are also discussed. Establishing a novel model for overcoming diuretic resistance is presented based on a patient-tailored variability and chronotherapy-guided machine learning algorithm that comprises clinical, laboratory, and sensor-derived inputs, including inputs from pulmonary artery measurements. Inter- and intra-patient signatures of variabilities, alterations of biological clock, and autonomic nervous system responses are embedded into the algorithm; thus, it may enable a tailored dose regimen in a continuous manner that accommodates the highly dynamic complex system.

Evaluating the conversion to extended-release tacrolimus from immediate-release tacrolimus in liver transplant recipients

BACKGROUND

A new formulation of once daily extended-release tacrolimus (LCP-tac, Envarsus XR) was approved for use in the USA for kidney transplant recipients in 2015. There are limited data regarding real-world observations with conversion to LCP-tac in liver transplant recipients.

METHODS

We performed a retrospective analysis of liver transplant recipients treated with LCP-tac. Data collection included (1) reasons for switching to LCP-tac; (2) conversion ratio used; (3) kidney function at time of conversion and 3 months after; (4) outcomes of conversion [acute cellular rejection rates and cytomegalovirus (CMV) viremia] within 3 months of conversion.

RESULTS

Average conversion ratio used to achieve therapeutic drug level without further dose adjustment was 1:0.73 (SD 0.11). Median time after transplant was 508 days (IQR 736). Common reasons patients were switched to LCP-tac were from fluctuations in tacrolimus levels (44%) and adverse effect of tremor (32%). Among patients who were switched due to tremors 88% noted significant improvement. There was no difference in serum creatinine (P = 0.55) or glomerular filtration rate (P = 0.64) from baseline to 3 months postconversion. There were no episodes of acute cellular rejections or CMV viremia postconversion.

CONCLUSION

This observational study demonstrated that conversion of immediate-release tacrolimus to LCP-tac in liver transplant recipients was well tolerated and effective.

Therapeutic drug monitoring of immunosuppressive drugs in hepatology and gastroenterology

Immunosuppressive drugs have been key to the success of liver transplantation and are essential components of the treatment of inflammatory bowel disease (IBD) and autoimmune hepatitis (AIH). For many but not all immunosuppressants, therapeutic drug monitoring (TDM) is recommended to guide therapy. In this article, the rationale and evidence for TDM of tacrolimus, mycophenolic acid, the mammalian target of rapamycin inhibitors, and azathioprine in liver transplantation, IBD, and AIH is reviewed. New developments, including algorithm-based/computer-assisted immunosuppressant dosing, measurement of immunosuppressants in alternative matrices for whole blood, and pharmacodynamic monitoring of these agents is discussed. It is expected that these novel techniques will be incorporate into the standard TDM in the next few years.

Retrospective Analysis of Tacrolimus Intrapatient Variability as a Measure of Medication Adherence

Background:

Increased intrapatient variability (IPV) in tacrolimus levels is associated with graft rejection, de novo donor-specific antibodies, and graft loss. Medication nonadherence may be a significant contributor to high IPV.

Objective:

The objective of this study is to determine the utility of tacrolimus IPV in detecting nonadherence by examining the relationship between self-reported adherence and tacrolimus coefficient of variability (COV), a measure of IPV.

Design:

Retrospective cohort study.

Setting:

St. Michael’s Hospital, Toronto, Ontario.

Patients:

All patients who were at least 1-year post-kidney transplant as of March 31, 2019, prescribed tacrolimus as an immunosuppressant and had a self-reported adherence status. Patients were excluded from the primary analysis of examining the correlation between COV and self-reported adherence if they lacked a calculatable COV.

Measurements:

Self-reported adherence, COV, demographic data, transplant, and medication history.

Methods:

A modified Basel Assessment of Adherence to Immunosuppressive Medications Scale (BAASIS) administered by healthcare professionals to assess self-reported adherence was used. The COV of tacrolimus trough levels was calculated and its correlation to BAASIS response was noted. The median COV was used as a cutoff to examine the characteristics of patients deemed “high COV” and “low COV.”

Results:

A total of 591 patients fit the initial criteria; however, only 525 had a recent calculatable COV. Overall, 92.38% of the population were adherent by self-report. Primary analysis identified a COV of 25.2% and 29.6% in self-reported adherent and nonadherent patients, respectively, though the result was not significant (P = .2). Secondary analyses showed a significant correlation between younger age at transplant and at the time of adherence self-reporting with nonadherence (P = .01). In addition, there was a strong correlation between those nonadherent with routine post-transplant blood work and younger age (P < .01).

Limitations:

The limitations included modified nonvalidated BAASIS questionnaire, social desirability bias, BAASIS only administered in English, and patients with graft failure not active in clinic not being captured.

Conclusions:

The COV should not be used as the sole method for determining medication adherence. However, COV may have some utility in capturing individuals who are not adherent to their blood work or patients who are having a poor response to tacrolimus and should be switched to another medication.

The Stanford Integrated Psychosocial Assessment for Transplant Is Associated With Outcomes Before and After Liver Transplantation

The Stanford Integrated Psychosocial Assessment for Transplant (SIPAT) is a standardized psychosocial evaluation tool used in liver transplantation (LT) evaluation. We assessed the impact of the SIPAT score and subdomains on transplant waitlisting decisions and post-LT outcomes including immunosuppression (IS) nonadherence, biopsy-proven rejection, andmortality/graft failure. We conducted a single-center observational cohort study of 1430 patients evaluated for LT. Patients were divided in 2 groups based on a SIPAT cutoff score of <21 or ≥21 (higher SIPAT scores indicate higher psychosocial risk). Regression models assessed relationships between total SIPAT score and domain scores and waitlisting decisions, IS nonadherence, allograft rejection, and death/graft failure. Elevated total SIPAT and SIPAT domain scores were associated not being added to the waitlist (total SIPAT core ≥21 adjusted odds ratio [aOR], 1.78 [95% confidence interval, CI, 1.36-2.33]; readiness score ≥5 aOR, 2.01 [95% CI, 1.36-2.76]; social support score ≥4aOR, 1.50 [95% CI, 1.15-1.94]; psychopathology score ≥7 aOR, 1.45 [95% CI, 1.07-1.94]; lifestyle/substance abuse score ≥12 aOR, 1.72 [95%CI, 1.23-2.39]) and were more likely to experience IS nonadherence as measured by the tacrolimus coefficient of variation (CoV) (total SIPAT score ≥21 aOR, 2.92 [95% CI, 1.69-5.03]; readiness score ≥5 aOR, 3.26 [95% CI, 1.63-6.52]; psychopathology score ≥7 aOR, 1.88 [95% CI, 1.00-3.50]; lifestyle substance abuse score ≥12 aOR, 3.03 [95% CI, 1.56-5.86]). SIPAT readinessscore ≥5 was associated with biopsy-proven allograft rejection (aOR, 2.66; 95% CI, 1.20-5.91). The SIPAT score was independently associated with LT listing decisions and IS nonadherence, and the readiness domain was associated with the risk of allograft rejection. These findings offer insights into higher risk recipients who require additional support before and aftertransplantation.

Development and validation of routine clinical laboratory data derived marker-based nomograms for the prediction of 5-year graft survival in kidney transplant recipients

Background: To develop and validate predictive nomograms for 5-year graft survival in kidney transplant recipients (KTRs) with easily-available laboratory data derived markers and clinical variables within the first year post-transplant.

Methods: The clinical and routine laboratory data from within the first year post-transplant of 1289 KTRs was collected to generate candidate predictors. Univariate and multivariate Cox analyses and LASSO were conducted to select final predictors. X-tile analysis was applied to identify optimal cutoff values to transform potential continuous factors into category variables and stratify patients. C-index, calibration curve, dynamic time-dependent AUC, decision curve analysis, and Kaplan-Meier curves were used to evaluate models’ predictive accuracy and clinical utility.

Results: Two predictive nomograms were constructed by using 0–6- and 0–12- month laboratory data, and showed good predictive performance with C-indexes of 0.78 and 0.85, respectively, in the training cohort. Calibration curves showed that the prediction probabilities of 5-year graft survival were in concordance with actual observations. Additionally, KTRs could be successfully stratified into three risk groups by nomograms.

Conclusions: These predictive nomograms combining demographic and 0–6- or 0–12- month markers derived from post-transplant laboratory data could serve as useful tools for early identification of 5-year graft survival probability in individual KTRs.

Association between medication adherence and intrapatient variability in tacrolimus concentration among stable kidney transplant recipients

This study analyzed the association between medication adherence and the intrapatient variability (IPV) of tacrolimus concentrations among kidney transplant recipients through a post hoc analysis of the dataset from a recently conducted randomized controlled trial. Among 138 patients enrolled in the original trial, 92 patients with ≥ 5 months of medication event monitoring system (MEMS) use and ≥ 4 tacrolimus trough values were included in this post hoc analysis. The variability of tacrolimus trough levels was calculated using coefficient variation (CV) and mean absolute deviation. Adherence was assessed using MEMS and self-report via the Basal Assessment of Adherence to Immunosuppressive Medication Scale. There were no statistically significant differences in the CV [median 16.5% [interquartile range 11.6–25.5%] and 16.0% [11.5–23.5%], respectively, P = .602] between the nonadherent (n = 59) and adherent groups (n = 33). There was also no significant correlation between the CV and adherence detected by MEMS (taking adherence, ρ = − 0.067, P = .527; dosing adherence, ρ = − 0.098, P = .352; timing adherence, ρ = − 0.113, P = .284). Similarly, adherence measured by self-report did not significantly affect the IPV (P = .452). In this post hoc analysis, nonadherent behavior, measured through electronic monitoring or self-report, did not affect the IPV.

Tacrolimus intrapatient variability in solid organ transplantation: A multiorgan perspective

BACKGROUND

Tacrolimus therapy in solid organ transplant (SOT) recipients is challenging due to its narrow therapeutic window and pharmacokinetic variability both between patients and within a single patient. Intrapatient variability (IPV) of tacrolimus trough concentrations has become a novel marker of interest for predicting transplant outcomes. The purpose of this review is to evaluate the association of tacrolimus IPV with graft and patient outcomes and identify interventions to improve IPV in SOT recipients.

METHODS

A systematic review of the literature was performed using PubMed and Embase from database inception to September 20, 2020. Studies were eligible only if they evaluated an association between tacrolimus IPV and transplant outcomes. Both pediatric and adult studies were included. Measures of variability were limited to standard deviation, coefficient of variation, and time in therapeutic range.

RESULTS

Forty-four studies met the inclusion criteria. Studies were published between 2008 and 2020 and were observational in nature. Majority of data were published in adult kidney transplant recipients and identified an association with rejection, de novo donor specific antibody (dnDSA) formation, graft loss, and patient survival. Evaluation of IPV-directed interventions was limited to small preliminary studies.

CONCLUSIONS

High tacrolimus IPV has been associated with poor outcomes including acute rejection, dnDSA formation, graft loss, and patient mortality in SOT recipients. Future research should prospectively explore IPV-directed interventions to improve transplant outcomes.

Second-Generation Digital Health Platforms: Placing the Patient at the Center and Focusing on Clinical Outcomes

Artificial intelligence (AI) digital health systems have drawn much attention over the last decade. However, their implementation into medical practice occurs at a much slower pace than expected. This paper reviews some of the achievements of first-generation AI systems, and the barriers facing their implementation into medical practice. The development of second-generation AI systems is discussed with a focus on overcoming some of these obstacles. Second-generation systems are aimed at focusing on a single subject and on improving patients' clinical outcomes. A personalized closed-loop system designed to improve end-organ function and the patient's response to chronic therapies is presented. The system introduces a platform which implements a personalized therapeutic regimen and introduces quantifiable individualized-variability patterns into its algorithm. The platform is designed to achieve a clinically meaningful endpoint by ensuring that chronic therapies will have sustainable effect while overcoming compensatory mechanisms associated with disease progression and drug resistance. Second-generation systems are expected to assist patients and providers in adopting and implementing of these systems into everyday care.

Establishing patient-tailored variability-based paradigms for anti-cancer therapy: Using the inherent trajectories which underlie cancer for overcoming drug resistance

Drug resistance is a major obstacle for successful therapy of many malignancies and is affecting the loss of response to chemotherapy and immunotherapy. Tumor-related compensatory adaptation mechanisms contribute to the development of drug resistance. Variability is inherent to biological systems and altered patterns of variability are associated with disease conditions. The marked intra and inter patient tumor heterogeneity, and the diverse mechanism contributing to drug resistance in different subjects, which may change over time even in the same patient, necessitate the development of personalized dynamic approaches for overcoming drug resistance. Altered dosing regimens, the potential role of chronotherapy, and drug holidays are effective in cancer therapy and immunotherapy. In the present review we describe the difficulty of overcoming drug resistance in a dynamic system and present the use of the inherent trajectories which underlie cancer development for building therapeutic regimens which can overcome resistance. The establishment of a platform wherein patient-tailored variability signatures are used for overcoming resistance for ensuing long term sustainable improved responses is presented.

Donor-specific antibodies in liver transplantation: challenges in diagnosis and determining clinical impact

PURPOSE OF REVIEW

Our understanding of the clinical impact of donor-specific antibodies in liver transplant recipients has evolved in recent years as outcomes for liver allografts have improved and advances in diagnostic testing have made recognition of antibody mediated rejection in transplant patients more sensitive.

RECENT FINDINGS

Two main types of donor-specific antibodies - preformed and de novo - have been reported in the literature to have a negative impact on graft survival, and researchers have been able to further identify subclasses of class II donor-specific antibodies as being the most clinically impactful. Furthermore, there is evidence that donor-specific antibody formation can augment cellular rejection in liver grafts and lead to worsened clinical outcomes. Recent data have shown a higher prevalence of donor-specific antibody formation than previously reported.

SUMMARY

This review explores the most recent literature regarding the clinical impact of both preformed and de-novo donor-specific antibodies and potential management guidelines for patients undergoing liver transplantation. The best practice guidelines for undergoing monitoring for donor-specific antibody formation and protocol biopsies in sensitized patients will depend on further multiinstitutional studies.

Genomics and Liver Transplantation: Genomic Biomarkers for the Diagnosis of Acute Cellular Rejection

Acute cellular rejection (ACR) is a common complication in liver transplantation recipients (LTRs), especially within the first 12 months, and it is associated with increased morbidity and mortality. Although abnormalities in standard liver biochemistries may raise the clinical suspicion for ACR, it lacks specificity, and invasive liver biopsies, which are associated with numerous risks, are required for definitive diagnoses. Biomarker discovery for minimally invasive tools for diagnosis and prognostication of ACR after liver transplantation (LT) has become a rapidly evolving field of research with a recent shift in focus to omics-based biomarker discovery. Although none are yet ready to replace the standard of care, there are several promising minimally invasive, blood-derived biomarkers that are under intensive research for the diagnosis of ACR in LTRs. These omics-based biomarkers, encompassing DNA, RNA, proteins, and metabolites, hold tremendous potential. Some are likely to become integrated into ACR diagnostic algorithms to assist clinical decision making with a high degree of accuracy that is cost-effective and reduces or even obviates the need for an invasive liver biopsy.

Variation in Tacrolimus Trough Concentrations in Liver Transplant Patients Undergoing Endoscopic Retrograde Cholangiopancreatography: A Retrospective, Observational Study

Objective

High variabilities in tacrolimus (TAC) exposure are still problems that confuse physicians. TAC trough levels (TAC C_min) fluctuated considerably after endoscopic retrograde cholangiopancreatography (ERCP) treatment in several liver transplant (LT) patients. We aimed to investigate the variation regularity of TAC C_min post-ERCP and related factors.

Methods

This study was a retrospective, observational study conducted at the First Affiliated Hospital of Zhejiang University in China. From October 2017 to January 2019, 26 LT patients that received ERCP were included (73 TAC C_min measures). The absolute difference and the variation extent in TAC C_min pre- and post-ERCP were analyzed. Patients were divided into mild and obvious variation groups, and the differences were compared.

Results

The TAC C_min in LT patients significantly increased in the first three days post-ERCP (p<0.05) and increased by more than 20% in 18 out of 26 (69.2%) patients. The mean extent of variation in TAC C_min was 45.1% (95% confidence interval [CI]: 28.3–81.3%) and 31.4% (95% CI: 9.7–53.1%) on days 1 and 3 post-ERCP, respectively. The increasing TAC C_min gradually returned to baseline within a week (p>0.05). The daily TAC dose and total bile acid (TBA) level were significantly higher (p<0.05) in patients with obvious variation in TAC C_min. The differences in other demographics, clinical characteristics, variation in laboratory data, and serum amylase levels between the two groups were not significant.

Conclusion

The TAC C_min significantly increased in LT patients during the first three days after ERCP, and the level returned to baseline within a week. The daily TAC dose and TBA levels may be related to this increase. Frequent drug concentration monitoring should be executed in the early phase post-ERCP, especially in patients with related factors.

Maintenance Immunosuppression in Solid Organ Transplantation: Integrating Novel Pharmacodynamic Biomarkers to Inform Calcineurin Inhibitor Dose Selection

Calcineurin inhibitors, the primary immunosuppressive therapy used to prevent alloreactivity of transplanted organs, have a narrow therapeutic index. Currently, treatment is individualized based on clinical assessment of the risk of rejection or toxicity guided by trough concentration monitoring. Advances in immune monitoring have identified potential markers that may have value in understanding calcineurin inhibitor pharmacodynamics. Integration of these markers has the potential to complement therapeutic drug monitoring. Existing pharmacokinetic-pharmacodynamic (PK-PD) data is largely limited to correlation between the biomarker and trough concentrations at single time points. Immune related gene expression currently has the most evidence supporting PK-PD integration. Novel biomarker-based approaches to pharmacodynamic monitoring including development of enhanced PK-PD models are proposed to realize the full clinical benefit.

Impacts of High Intra- and Inter-Individual Variability in Tacrolimus Pharmacokinetics and Fast Tacrolimus Metabolism on Outcomes of Solid Organ Transplant Recipients

Tacrolimus is a first-line calcineurin inhibitor (CNI) and an integral part of the immunosuppressive strategy in solid organ transplantation. Being a dose-critical drug, tacrolimus has a narrow therapeutic index that necessitates periodic monitoring to maintain the drug’s efficacy and reduce the consequences of overexposure. Tacrolimus is characterized by substantial intra- and inter-individual pharmacokinetic variability. At steady state, the tacrolimus blood concentration to daily dose ratio (C/D ratio) has been described as a surrogate for the estimation of the individual metabolism rate, where a low C/D ratio reflects a higher rate of metabolism. Fast tacrolimus metabolism (low C/D ratio) is associated with the risk of poor outcomes after transplantation, including reduced allograft function and survival, higher allograft rejection, CNI nephrotoxicity, a faster decline in kidney function, reduced death-censored graft survival (DCGS), post-transplant lymphoproliferative disorders, dyslipidemia, hypertension, and cardiovascular events. In this article, we discuss the potential role of the C/D ratio in a noninvasive monitoring strategy for identifying patients at risk for potential adverse events post-transplant.

Prior Relapse, Ongoing Alcohol Consumption, and Failure to Engage in Treatment Predict Alcohol Relapse After Liver Transplantation

BACKGROUND

Alcohol-related liver disease (ALD) is the leading indication for liver transplantation (LT) in the USA. Alcohol relapse post-LT can negatively impact long-term outcomes, and prognostic scoring systems are available for further study.

AIMS

Our study aims were to: (1) evaluate the relationship between alcohol relapse and rejection and mortality, (2) investigate risk factors for relapse, and (3) assess predictive validity of the SIPAT (Stanford Integrated Psychosocial Assessment for Transplant) and SALT (Sustained Alcohol Use Post-Liver Transplant) scores on post-LT alcohol relapse.

METHODS

We conducted a retrospective chart review of 155 patients transplanted for chronic ALD at a single transplant center. Cox proportional hazard models assessed the relationship between alcohol relapse and allograft rejection and psychosocial risk factors for relapse.

RESULTS

20% of patients met criteria for alcohol relapse. Alcohol relapse was associated with allograft rejection (HR 2.33, 95% CI 1.11-4.91, p = .03). Three variables most strongly associated with alcohol relapse: prior relapse, failure to engage in recommended alcohol treatment, and continued drinking with liver disease, which were combined into a psychosocial model. SIPAT score≥ 21 and SALT score ≥ 7 were associated with alcohol relapse (HR 6.40, 95% CI 1.36-30.18, p = .019 and HR 2.30, 95% CI 1.12-4.75, p = .024). Receiver operator characteristic analysis compared predictive ability of our psychosocial model to SIPAT (C-statistic .83 compared to .71) and SALT (C-statistic = .77 compared to .62).

CONCLUSION

We identified important psychosocial predictors of post-LT alcohol relapse and validated SIPAT and SALT scores as pre-transplant risk factors for alcohol relapse.