Higher Peak Tacrolimus Concentrations after Allogeneic Hematopoietic Stem Cell Transplantation Increase the Risk of Endothelial Cell Damage Complications

Bayesian optimization of tacrolimus exposure in stable kidney transplant patients

STUDY OBJECTIVE

The objective was to compare tacrolimus AUC0-12 determined by Non-Compartmental Analysis (NCA) using intensive sampling to Maximum a Posteriori-Bayesian (MAP-Bayesian) estimates from robust (n = 9 samples/subject) and sparse (n = 2 samples/subject) sampling in 67 stable KTRs and a validation group of similar patients.

DESIGN

This open-label, prospective, single center 12-h PK study included nine serial samples collected in KTRs to determine steady-state NCA tacrolimus AUC0-12 .

SETTING

This study was conducted at a single site within a large, urban hospital in the western New York area.

PATIENTS

This study described tacrolimus pharmacokinetics in stable kidney transplant recipients on maintenance tacrolimus therapy.

INTERVENTION

Robust and sparse AUC0-12 estimates by a MAP-Bayesian approach were obtained using the Advanced Dosing Solutions (AdDS) and ADAPT5 freeware. Limited sampling strategies were evaluated using the original population PK model (n = 67), which was also assessed using a validation group (n = 15). AUC0-12 agreement was tested by paired t-tests with intraclass correlation coefficient (ICC) and Bland Altman analysis.

MEASUREMENTS AND MAIN RESULTS

A total of 35 Black and 32 White stable KTRs (estimated glomerular filtration rate [eGFR] = 55.2 ± 15.7 mL/min/1.73m2 ) received the tacrolimus dose of 3.4 ± 1.7 mg/study with troughs of 6.8 ± 1.8 ng/mL. The NCA-AUC0-12 was 123.8 ± 33.6 μg·h/L compared to MAP-Bayesian estimates for Robust-AUC0-12 of 124.7 ± 33.3 μg·h/L and optimal 2-specimen Sparse-AUC0-12 of 119.7 ± 32.7 μg·h/L for the training group. Comparison of Robust-AUC0-12 to NCA-AUC0-12 had an ICC of 0.96 (p = 0.99) while comparison of Robust-AUC0-12 to Sparse-AUC0-12 using Pre-dose trough [C(t0h )] and 1 h [C(t1h )] resulted in an ICC of 0.93 (p = 0.014). In the validation group, 5 Black and 10 White KTRs (eGFR = 56.4 ± 16.8 mL/min/1.73m2 ) received a mean tacrolimus dose of 1.9 ± 1.2 mg/study with a trough of 6.0 ± 1.7 ng/mL. The validation group's NCA-AUC0-12 (88.4 ± 33.1 μg·h/L) was comparable to Robust-AUC0-12 (85.1 ± 33.8 μg·h/L, ICC = 0.93; p = 0.12) and Sparse-AUC0-12 determined from C(t0h ) and C(t4h ) (86.7 ± 33.9 μg·h/L, ICC = 0.91; p = 0.61).

CONCLUSION

MAP-Bayesian estimation for patient-specific AUC0-12 using sparse, two-specimen sampling is comparable to NCA and may enhance tacrolimus TDM in stable KTRs.

Early vascular endothelial complications after hematopoietic cell transplantation: Role of the endotheliopathy in biomarkers and target therapies development

This work aims to review the role of endothelial dysfunction underlying the main complications appearing early after autologous and allogeneic hematopoietic cell transplantation (HCT). The endothelial damage as the pathophysiological substrate of sinusoidal obstruction syndrome (SOS) is well established. However, there is growing evidence of the involvement of endothelial dysfunction in other complications, such as acute graft-versus-host disease (aGVHD) and transplant-associated thrombotic microangiopathy (TA-TMAs). Moreover, HCT-related endotheliopathy is not only limited to the HCT setting, as there is increasing evidence of its implication in complications derived from other cellular therapies. We also review the incidence and the risk factors of the main HCT complications and the biological evidence of the endothelial involvement and other linked pathways in their development. In addition, we cover the state of the art regarding the potential use of the biomarkers of endotheliopathy in the prediction, the early diagnosis, and the follow-up of the HCT complications and summarize current knowledge points to the endothelium and the other linked pathways described as potential targets for the prevention and treatment of HCT-complications. Lastly, the endothelium-focused therapeutic strategies that are emerging and might have a potential impact on the survival and quality of life of post-HCT-patients are additionally reviewed.

Putting function back in dysfunction: Endothelial diseases and current therapies in hematopoietic stem cell transplantation and cellular therapies

Endothelial dysfunction is characterized by altered vascular permeability and prothrombotic, pro-inflammatory phenotypes. Endothelial dysfunction results in end-organ damage and has been associated with diverse disease pathologies. Complications observed after hematopoietic stem cell transplantation (HCT) and chimeric antigen receptor-T cell (CAR-T) therapy for hematologic and neoplastic disorders share overlapping clinical manifestations and there is increasing evidence linking these complications to endothelial dysfunction. Despite advances in supportive care and treatments, end-organ toxicity remains the leading cause of mortality. A new strategy to mitigate endothelial dysfunction could lead to improvement of clinical outcomes for patients. Statins have demonstrated pleiotropic effects of immunomodulatory and endothelial protection by various molecular mechanisms. Recent applications in immune-mediated diseases such as autoimmune disorders, chronic inflammatory conditions, and graft-versus-host disease (GVHD) have shown promising results. In this review, we cover the mechanisms underlying endothelial dysfunction in GVHD and CAR-T cell-related toxicities. We summarize the current knowledge about statins and other agents used as endothelial protectants. We propose further studies using statins for prophylaxis and prevention of end-organ damage related to extensive endothelial dysfunction in HCT and CAR-T.

Intrapatient variability in concentration/dose ratio of tacrolimus predicts transplant-associated thrombotic microangiopathy

Tacrolimus (TAC) is essential for prophylaxis of acute graft-versus-host disease (aGVHD) after allogeneic hematopoietic cell transplantation (allo-HSCT). We have sometimes observed large fluctuations in TAC concentration. However, links between the variability in the concentration or the concentration/dose (C/D) ratio of TAC and clinical complications remain ambiguous. To clarify relationships between various parameters of TAC and early complications such as pre-engraftment immune reactions/engraftment syndrome, aGVHD, and transplant-associated thrombotic microangiopathy (TA-TMA), a total of 146 patients who underwent allo-HSCT were included. Intrapatient variabilities in the concentration and C/D ratio of TAC were estimated by intrapatient mean absolute deviation (iMAD). The mean concentration and C/D ratio of TAC were not significantly different between with and without complications. A strong association was observed between greater iMAD for TAC C/D ratio from days 15 to 21 and the development of TA-TMA. iMAD values for TAC C/D ratio of 11.4 or greater was a risk factor for TA-TMA and the cumulative incidence of nonrelapse mortality (NRM) was significantly higher in patients with iMAD values for TAC C/D ratio of 11.4 or greater. Intrapatient variability in the C/D ratio of TAC was associated with the incidence of TA-TMA and NRM and might be useful for predicting TA-TMA.

The stability of initial tacrolimus concentration following allogeneic hematopoietic stem cell transplantation reduces the risk of acute GVHD

BACKGROUND

Early tacrolimus (TAC) concentrations correlate with the risk of acute graft-versus-host disease (aGVHD); however, whether the variability of early TAC concentrations after allo-HSCT governs the occurrence of aGVHD remains unknown. Here, we evaluate the correlation between the intrapatient variability (IPV) of initial TAC concentrations and the development of aGVHD.

METHODS

We retrospectively assessed 202 patients who underwent allo-HSCT and received standard GVHD prophylaxis by continuous intravenous (iv) infusion of TAC and iv methotrexate. IPV was calculated by using the % coefficient of variation in the initial 4 weeks.

RESULTS

With median follow-up duration of 20.7 months, 24 patients were diagnosed with grades II-IV aGVHD. Overall survival (OS) and relapse at 12 months after allo-HSCT were 70.6% (95% confidence interval [CI], 63.7%-76.4%) and 18.9% (95% CI, 13.0%-24.4%), respectively. When IPV was categorized into two groups (high: ≥9.5%; low: <9.5%), the cumulative incidence of grades II-IV aGVHD was greater in the IPV-high group at week 3 (odds ratio: 4.15; 95% CI, 1.37%-12.6%, P = .01). No significant differences were observed in OS and relapse between the two groups.

CONCLUSION

We concluded that adjusting early TAC concentration stable may reduce aGVHD after allo-HSCT without affecting the relapse rate.

Effect of Sirolimus levels between days 11 and 20 after allogeneic stem cell transplantation on the risk of hepatic sinusoidal obstruction syndrome

Sinusoidal obstruction syndrome (SOS) is a serious complication of hematopoietic stem cell transplantation (HSCT). Sirolimus plus tacrolimus is an accepted regimen for graft-versus-host disease (GVHD) prophylaxis, with both agents implicated as risk factors for SOS. We analyzed 260 consecutive patients who underwent allogeneic HSCT following myeloablative conditioning using total body irradiation (TBI)-based (n = 151) or chemotherapy only (n = 109) regimens, with sirolimus plus tacrolimus for GVHD prophylaxis. SOS occurred in 28 patients at a median of 22 (range, 12-58) days. Mean sirolimus trough levels were higher between days 11 and 20 following transplant in patients who developed SOS (10.3 vs. 8.5 ng/ml, P = 0.008), with no significant difference in mean trough levels between days 0 and 10 (P = 0.67) and days 21-30 (P = 0.37). No differences in mean tacrolimus trough levels during the same time intervals were observed between those developing SOS and others. On multivariable analysis, a mean sirolimus trough level ≥ 9 ng/ml between days 11 and 20 increased the risk of SOS (hazard ratio 3.68, 95% CI: 1.57-8.67, P = 0.003), together with a longer time from diagnosis to transplant (P = 0.004) and use of TBI (P = 0.006). Our results suggest that mean trough sirolimus levels ≥ 9 ng/mL between days 11 and 20 post transplant may increase the risk of SOS and should be avoided.

Endothelial cell function and endothelial-related disorders following haematopoietic cell transplantation

Use of haematopoietic cell transplantation (HCT) in the treatment of haematologic and neoplastic diseases may lead to life-threatening complications that cause substantial morbidity and mortality if untreated. In addition to patient- and disease-related factors, toxicity associated with HCT puts patients at risk for complications that share a similar pathophysiology involving endothelial cells (ECs). Normally, the endothelium plays a role in maintaining homeostasis, including regulation of coagulation, vascular tone, permeability and inflammatory processes. When activated, ECs acquire cellular features that may lead to phenotypic changes that induce procoagulant, pro-inflammatory and pro-apoptotic mediators leading to EC dysfunction and damage. Elevated levels of coagulation factors, cytokines and adhesion molecules are indicative of endothelial dysfunction, and endothelial damage may lead to clinical signs and symptoms of pathological post-HCT conditions, including veno-occlusive disease/sinusoidal obstruction syndrome, graft-versus-host disease, transplant-associated thrombotic microangiopathy and idiopathic pneumonia syndrome/diffuse alveolar haemorrhage. The endothelium represents a rational target for preventing and treating HCT complications arising from EC dysfunction and damage. Additionally, markers of endothelial damage may be useful in improving diagnosis of HCT-related complications and monitoring treatment effect. Continued research to effectively manage EC activation, injury and dysfunction may be important in improving patient outcomes after HCT.

Incidence of Anicteric Veno-Occlusive Disease/Sinusoidal Obstruction Syndrome and Outcomes with Defibrotide following Hematopoietic Cell Transplantation in Adult and Pediatric Patients

Veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) is a potentially life-threatening complication of hematopoietic cell transplantation (HCT) that is traditionally diagnosed using Baltimore or modified Seattle criteria. Whereas the Baltimore criteria require the presence of hyperbilirubinemia (bilirubin ≥2 mg/dL) for a diagnosis of VOD/SOS, the modified Seattle criteria do not. Before approval by the US Food and Drug Administration, defibrotide was available in the United States through an expanded-access study (T-IND). The T-IND protocol initially required post-HCT diagnosis of VOD/SOS by the Baltimore criteria or biopsy but was later amended to include patients diagnosed using the modified Seattle criteria. This post hoc analysis examined the incidence of VOD/SOS with a bilirubin level <2 mg/dL before and after Day 21 post-HCT in T-IND patients enrolled following the amendment allowing for diagnosis by the modified Seattle criteria. Survival of adult and pediatric patients with or without hyperbilirubinemia and with or without multiorgan dysfunction (MOD) was also evaluated. Of 803 post-HCT patients with VOD/SOS enrolled following the protocol amendment, 181 (23%) had a bilirubin level <2 mg/dL and would not have been diagnosed if hyperbilirubinemia was required. The bilirubin level at diagnosis was <2 mg/dL in 165 of 331 patients (50%) diagnosed by the modified Seattle criteria and in 16 of 23 patients (70%) diagnosed by biopsy. VOD/SOS with a bilirubin level <2 mg/dL was more common in pediatric patients (29%), although it also occurred in adult patients (15%). Patients with hyperbilirubinemia had lower Day 100 survival (54% versus 87% in patients with bilirubin <2 mg/dL) and a higher incidence of MOD (41% versus 26% in patients with bilirubin <2 mg/dL). The incidence of treatment-emergent adverse events and serious adverse events was lower in patients with a bilirubin level <2 mg/dL. These results indicate that anicteric VOD/SOS occurs in both adult and pediatric patients post-HCT and can be diagnosed before and after Day 21 in both groups. The worse survival in patients with bilirubin ≥2 mg/dL suggests that requiring hyperbilirubinemia may result in a progressed disease stage associated with worse outcomes. Taken together, these results highlight the importance of awareness and the possibility of VOD/SOS in the absence of elevated bilirubin level.

Impact of blood pressure early after allogeneic hematopoietic cell transplantation on clinical outcomes

Allogeneic hematopoietic transplantation (allo-HCT) is still associated with significant morbidity and mortality, and risk stratification is critical. In this study, we analyzed the relationship between blood pressure control early after allo-HCT and survival outcomes. All patients who survived longer than 28 days after allo-HCT at our center between June 2007 and June 2018 (n = 353) were included, and the average systolic blood pressure (asBP) from 1 to 28 days after allo-HCT was calculated. According to the results of a ROC curve analysis, an asBP of 131 mmHg was defined as a cut-off value between high and low asBP groups. Non-relapse mortality (NRM) and OS were significantly inferior in the high asBP group (2-year-NRM 28.0% vs 11.1%, P < 0.001; 2-year-OS 46.7% vs 65.7%, P = 0.001). In addition, baseline asBP before commencement of the conditioning regimen and elevation of asBP (asBP - baseline asBP) were both associated with inferior NRM. While these results were also observed in the younger patients (≤ 50 years), no relationship was observed in the older patients (> 50 years). High blood pressure within 28 days after allo-HCT was associated with inferior survival outcomes, especially in patients younger than 50 years.

Endothelial Activation and Stress Index (EASIX) at Admission Predicts Fluid Overload in Recipients of Allogeneic Stem Cell Transplantation

Fluid overload (FO) grade ≥2 (more than 10% weight gain from baseline) has recently been recognized as an important toxicity associated with a high rate of nonrelapse mortality in recipients of allogeneic hematopoietic cell transplantation (AHCT). The causes for FO remain unclear. We hypothesized that endothelial damage, possibly due to treatments received prior to AHCT, may be associated with this toxicity and sought to determine whether the Endothelial Activation and Stress Index (EASIX) (defined as lactate dehydrogenase [U/L] × creatinine [mg/dL]/platelets [10⁹ cells/L]) correlates with grade ≥2 FO in 2 cohorts of recipients of AHCT at our institution. We tested our hypothesis in a cohort of 145 consecutive recipients (study cohort) of AHCT transplant from HLA-haploidentical donors and validated the findings in a cohort of 449 (validation cohort) recipients of AHCT from HLA-matched donors who underwent transplantation between 2010 and 2015. Predictors of grade ≥2 FO were evaluated using competing risks regression in univariate analysis and classification and regression tree (CART) analysis in multivariate analysis. The cumulative incidence of grade ≥2 FO was estimated considering death as a competing risk. EASIX scores were evaluated based on log₂-transformed values. Optimal predictive EASIX cutoff values were determined based on receiver operating characteristics curve analysis. Grade ≥2 FO occurred in 21% and 6% of the study and validation cohorts, respectively, with the majority of these cases being diagnosed before the day of AHCT. Median log₂ EASIX score at admission was 2.4 (interquartile range [IQR], 1.3, 3.7) and 2.5 (IQR, 1.4, 3.9) in the 2 respective cohorts. In univariate analysis, high EASIX at admission was a significant predictor of grade ≥2 FO in the study (cutoff: 4.4, hazard ratio [HR] = 4.8, P < .001) and in the validation (cutoff: 4.3, HR = 4.8, P < .001) cohorts. The significant effect of EASIX persisted in multivariate CART analysis in the study (HR = 6.3, P < .001) and the validation (HR = 28, P = .002) cohorts. Additional predictors in multivariate analysis included body weight below 80 kg in recipients older than 55 years (HR = 4.5, P < .001) in the study cohort and diabetes (HR = 34, P = .001) and age >60 years (HR = 9.6, P = .04) in the validation cohort. At admission, the prevalence of EASIX score of >4.3 (18% versus 17%, P = .9) was not different between the diabetics and nondiabetics. EASIX score at admission is a significant predictor of grade ≥2 FO in recipients of AHCT from HLA-haploidentical or HLA-matched donors. Independently of EASIX, older patients with low weight were associated with increased risk of grade ≥2 FO for recipients of HLA-haploidentical transplants. For the HLA-matched cohort, diabetes and older age were associated with increased FO risk. These findings require validation in external cohorts.

Tacrolimus in adult hematopoietic stem cell transplantation

Introduction: Graft-versus-host disease (GVHD) is the most common complication of hematopoietic stem cell transplantation (HSCT); therefore, the prevention of GVHD is important for a successful treatment. Tacrolimus (Tac), a calcineurin inhibitor, has been widely used for the prophylaxis of GVHD in HSCT recipients. Areas covered: This review introduces phase II/III of clinical trials related with Tac's roles in the prevention of GVHD in HSCT. Furthermore, we discuss the normal ranges of Tac concentrations, pharmacogenetics, and drug interactions of Tac, as well as its side effects in adult HSCT recipients. Expert opinion: A series of studies has established the efficacy and safety of Tac alone or in combination with other agents in HSCT. However, successful administration of Tac is complicated by its narrow therapeutic window, inter-patient pharmacokinetic variability, and a spectrum of undesirable side effects. It is necessary to maintain concentrations of Tac within the desired ranges for GVHD prophylaxis. Moreover, various factors contribute to significant variability in Tac pharmacokinetics, including drug interactions and genomic variation.