High Treosulfan Exposure is Associated with Early Toxicity in Pediatric Hematopoietic Stem Cell Transplantation: A Prospective Multicenter Study

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Model-Informed Development of a Cost-Saving Dosing Regimen for Sacituzumab Govitecan

Background: The antibody–drug conjugate sacituzumab govitecan is approved for metastatic triple-negative breast cancer and has shown promising results in various other types of cancer. Its costs may limit patient access to this novel effective treatment modality. Objective: The purpose of this study was to develop an evidence-based rational dosing regimen that results in targeted drug exposure within the therapeutic range while minimizing financial toxicity, to improve treatment access. Patients and Methods: Exposure equivalent dosing strategies were developed based on pharmacokinetic modeling and simulation by using the published pharmacokinetic model developed by the license holder. The alternative dose was based on the principle of using complete vials to prevent spillage and on the established non-linear relationship between body weight and systemic exposure. Equivalent exposure compared to the approved dosing regimen of 10 mg/kg was aimed for. Equivalent exposure was conservatively defined as calculated geometric mean ratios within the 0.9–1.11 boundaries for area under the concentration–time curve (AUC), trough concentration (Ctrough) and maximum concentration (Cmax) of the alternative dosing regimen compared to the approved dosing regimen. Since different vial sizes are available for the European Union (EU) and United States (US) market, because body weight distributions differ between these populations, we performed our analysis for both scenarios. Results: Dosing regimens of sacituzumab govitecan for the EU (&lt; 50 kg: 400 mg, 50–80 kg: 600 mg, and &gt; 80 kg: 800 mg) and US population (&lt; 40 kg: 360 mg, 40–65 kg: 540 mg, 65–90 kg: 720 mg, and &gt; 90 kg: 900 mg) were developed, based on weight bands. The geometric mean ratios for all pharmacokinetic outcomes were within the predefined equivalence boundaries, while the quantity of drug used was 21.5% and 19.0% lower for the EU and US scenarios, respectively. Conclusions: With the alternative dosing proposal, an approximately 20% reduction in drug expenses for sacituzumab govitecan can be realized while maintaining an equivalent and more evenly distributed exposure throughout the body weight range, without notable increases in pharmacokinetic variability.</p

Application of Electronic Health Record Text Mining: Real-World Tolerability, Safety, and Efficacy of Adjuvant Melanoma Treatments

Introduction: Nivolumab (N), pembrolizumab (P), and dabrafenib plus trametinib (D + T) have been registered as adjuvant treatments for resected stage III and IV melanoma since 2018. Electronic health records (EHRs) are a real-world data source that can be used to review treatments in clinical practice. In this study, we applied EHR text-mining software to evaluate the real-world tolerability, safety, and efficacy of adjuvant melanoma treatments. Methods: Adult melanoma patients receiving adjuvant treatment between January 2019 and October 2021 at the Leiden University Medical Center, the Netherlands, were included. CTcue text-mining software (v3.1.0, CTcue B.V., Amsterdam, The Netherlands) was used to construct rule-based queries and perform context analysis for patient inclusion and data collection from structured and unstructured EHR data. Results: In total, 122 patients were included: 54 patients treated with nivolumab, 48 with pembrolizumab, and 20 with D + T. Significantly more patients discontinued treatment due to toxicity on D + T (N: 16%, P: 6%, D + T: 40%), and X2 (6, n = 122) = 14.6 and p = 0.024. Immune checkpoint inhibitors (ICIs) mainly showed immune-related treatment-limiting adverse events (AEs), and chronic thyroid-related AE occurred frequently (hyperthyroidism: N: 15%, P: 13%, hypothyroidism: N: 20%, P: 19%). Treatment-limiting toxicity from D + T was primarily a combination of reversible AEs, including pyrexia and fatigue. The 1-year recurrence-free survival was 70.3% after nivolumab, 72.4% after pembrolizumab, and 83.0% after D + T. Conclusions: Text-mining EHR is a valuable method to collect real-world data to evaluate adjuvant melanoma treatments. ICIs were better tolerated than D + T, in line with RCT results. For BRAF+ patients, physicians must weigh the higher risk of reversible treatment-limiting AEs of D + T against the risk of long-term immune-related AEs

Association between Busulfan Exposure and Outcome in Children Receiving Intravenous Busulfan before Hematologic Stem Cell Transplantation

Busulfan, combined with therapeutic drug monitoring-guided dosing, is associated with higher event-free survival (EFS) rates due to fewer graft failures/relapses and lower toxicity. The optimal target area under the curve (AUC) and dosing schedule of intravenous busulfan in children undergoing hematopoietic stem cell transplantation (HSCT) remain unclear, however. We conducted a retrospective analysis of the association between busulfan exposure and clinical outcome in 102 children age 0.2 to 21 years who received busulfan 1 or 4 times daily before undergoing HSCT (46 malignant and 56 nonmalignant indications). EFS and overall survival after a median of 2 years of follow-up were 68% and 72%, respectively. EFS was optimal when the exposure of busulfan (AUC) was 78 mg*h/L (95% confidence interval = 74 to 82 mg*h/L). Acute graft-versus-host disease (aGVHD) grade II-IV occurred more frequently with greater busulfan exposure. The addition of melphalan was an independent risk factor; melphalan use combined with high busulfan exposure (AUC > 74 mg*h/L) was associated with high incidences of aGVHD (58%), veno-occlusive disease (66%), and mucositis grade III-IV (26%). Dosing frequency (1 or 4 times daily) was not related to any outcome. In conclusion, dose targeting of busulfan to a narrow therapeutic range was found to increase EFS in children. Adding melphalan to optimal busulfan exposure is associated with a high incidence of toxicity

Body weight-dependent pharmacokinetics of busulfan in paediatric haematopoietic stem cell transplantation patients: Towards individualized dosing

Background and Objectives: The wide variability in pharmacokinetics of busulfan in children is one factor influencing outcomes such as toxicity and event-free survival.Ameta-analysis was conducted to describe the pharmacokinetics of busulfan in patients from 0.1 to 26 years of age, elucidate patient characteristics that explain the variability in exposure between patients and optimize dosing accordingly. Patients and Methods: Data were collected from 245 consecutive patients (from 3 to 100 kg) who underwent haematopoietic stem cell transplantation (HSCT) in four participating centres. The inter-patient, interoccasion and residual variability in the pharmacokinetics of busulfan were estimated with a population analysis using the nonlinear mixed-effects modelling software NONMEM VI. Covariates were selected on the basis of their known or theoretical relationships with busulfan pharmacokinetics and were plotted independently against the individual pharmacokinetic parameters and the weighted residuals of the model without covariates to visualize relations. Potential covariates were formally tested in the model. Results: In a two-compartment model, body weight was the most predictive covariate for clearance, volume of distribution and inter-compartmental clearance and explained 65%, 75% and 40% of the observed variability, respectively. The relationship between body weight and clearance was characterized best using an allometric equation with a scaling exponent that changed with body weight from 1.2 in neonates to 0.55 in young adults. This implies that an increase in body weight in neonates results in a larger increase in busulfan clearance than an increase in body weight in older children or adults. Clearance on the first day was 12% higher than that of subsequent days (p < 0.001). Inter-occasion variability on clearance was 15%between the 4 days. Based on the final pharmacokinetic-model, an individualized dosing nomogram was developed. Conclusions: The model-based individual dosing nomogram is expected to result in predictive busulfan exposures in patients ranging between 3 and 65 kg and thereby to a safer and more effective conditioning regimen for HSCT in children

Effect of Busulfan and Treosulfan on Gonadal Function after Allogeneic Stem Cell Transplantation in Children and Adolescents with Nonmalignant Diseases Is Not Exposure-Dependent

With an increasing number of young patients surviving into adulthood after hematopoietic stem cell transplantation (HSCT), gonadal dysfunction becomes an important late effect with significant impact on quality of life. In this retrospective study, we evaluated the exposure of busulfan (Bu) and treosulfan (Treo) in relation to gonadal function in pediatric patients who underwent HSCT for a nonmalignant disease between 1997 and 2018. In the Bu group, 56 patients could be evaluated, and gonadal dysfunction was found in 35 (63%). Lower Bu exposure (ie, cumulative area under the curve [AUC] <70 mg*h/L) was not associated with a reduced risk of gonadal dysfunction (odds ratio [OR], .92; 95% confidence interval [CI], .25 to 3.49; P = .90). In the Treo cohort, 32 patients were evaluable and gonadal insufficiency occurred in 9 patients (28%). Lower Treo exposure (AUC <1750 mg*h/L on day 1) was not associated with a reduced risk of gonadal dysfunction (OR, 1.6; 95% CI, .16 to 36.6; P = .71). Our data do not support the premise that reduced-intensity Bu-based conditioning reduces the risk for gonadal toxicity, and it is unlikely that therapeutic drug monitoring-based reduced treosulfan exposure will further limit the risk of gonadal dysfunction

Once-daily intravenous busulfan with therapeutic drug monitoring compared to conventional oral busulfan improves survival and engraftment in children undergoing allogeneic stem cell transplantation

AbstractBecause of intra- and interindividual variability, bioavailability, and pharmacokinetics of busulfan (Bu) in children, oral busulfan without therapeutic drug monitoring (TDM) is assumed to be associated with higher graft failure rates as well as higher toxicity (eg, veno-occlusive disease [VOD]). This study compares the outcome of hematopoietic stem cell transplantation (HSCT) of 2 groups: 1) 30 patients who received myeloablation with once-daily intravenous (i.v.) dose-targeted busulfan (BUdtIV) based on TDM and 2) 30 patients who received the current practice of untargeted oral busulfan (BUPO). Patients received a 3-hour infusion of Bu at a first dose of 120 mg/m2 (age ≥1 year) or 80 mg/m2 (<1 year), or BUPO 1 mg/kg 4 times daily. Both regimens were continued for 4 days. The target area under the curve (AUC) was defined as 17,500 μg∗h/l. BUdtIV resulted in higher event-free survival (EFS) and survival rates compared to BUPO (EFS: 30% versus 83%, P < .001, survival: 53% versus 83%, P = .016). BUdtIV was associated with more cases of VOD. TDM was feasible in routine clinical practice. The results show that i.v. Bu using TDM is preferable over oral Bu in children undergoing allogeneic stem cell transplantation, especially in those at high risk for graft failure/relapse

Association of busulfan exposure with survival and toxicity after haemopoietic cell transplantation in children and young adults: a multicentre, retrospective cohort analysis

BackgroundIntravenous busulfan combined with therapeutic drug monitoring to guide dosing improves outcomes after allogeneic haemopoietic cell transplantation (HCT). The best method to estimate busulfan exposure and optimum exposure in children or young adults remains unclear. We therefore assessed three approaches to estimate intravenous busulfan exposure (expressed as cumulative area under the curve [AUC]) and associated busulfan AUC with clinical outcomes in children or young adults undergoing allogeneic HCT.MethodsIn this retrospective analysis, patients from 15 centres in the Netherlands, USA, Canada, Switzerland, UK, Italy, Germany, and Australia who received a busulfan-based conditioning regimen between March 18, 2001, and Feb 12, 2015, were included. Cumulative AUC was calculated by numerical integration using non-linear mixed effect modelling (AUCNONMEM), non-compartmental analysis (AUC from 0 to infinity [AUC0-∞] and to the next dose [AUC0-τ]), and by individual centres using various approaches (AUCcentre). The main outcome of interest was event-free survival. Other outcomes of interest were graft failure or relapse, or both; transplantation-related mortality; acute toxicity (veno-occlusive disease or acute graft versus-host disease [GvHD]); chronic GvHD; overall survival; and chronic-GvHD-free event-free survival. We used propensity-score-adjusted Cox proportional hazard models, Weibull models, and Fine-Gray competing risk regressions for statistical analyses.Findings790 patients were enrolled, 674 of whom were included: 274 (41%) with malignant and 400 (59%) with non-malignant disease. Median age was 4·5 years (IQR 1·4-10·7). The median busulfan AUCNONMEM was 74·4 mg × h/L (95% CI 31·1-104·6), which correlated with the standardised method AUC0-∞ (r2=0·74), but the latter correlated poorly with AUCcentre (r2=0·35). Estimated 2-year event-free survival was 69·7% (95% CI 66·2-73·0). Event-free survival at 2 years was 77·0% (95% CI 72·1-82·9) in the 257 patients with an optimum intravenous busulfan AUC of 78-101 mg × h/L compared with 66·1% (60·9-71·4) in the 235 patients at the low historical target of 58-86 mg × h/L and 49·5% (29·2-66·0) in the 44 patients with a high (&gt;101 mg × h/L) busulfan AUC (p=0·011). Compared with the low AUC group, graft failure or relapse occurred less frequently in the optimum AUC group (hazard ratio [HR] 0·57, 95% CI 0·39-0·84; p=0·0041). Acute toxicity (HR 1·69, 1·12-2·57; p=0·013) and transplantation-related mortality (2·99, 1·82-4·92; p&lt;0·0001) were significantly higher in the high AUC group (&gt;101 mg × h/L) than in the low AUC group (&lt;78 mg × h/L), independent of indication; no difference was noted between AUC groups for chronic GvHD (&lt;78 mg × h/L vs ≥78 mg × h/L, HR 1·30, 95% CI 0·73-2·33; p=0·37).InterpretationImproved clinical outcomes are likely to be achieved by targeting the busulfan AUC to 78-101 mg × h/L using a new validated pharmacokinetic model for all indications.FundingResearch Allocation Program and the UCSF Helen Friller Family Comprehensive Cancer Center and the Mt Zion Health Fund of the University of California, San Francisco

Association of busulfan exposure with survival and toxicity after haemopoietic cell transplantation in children and young adults: a multicentre, retrospective cohort analysis

BACKGROUND: Intravenous busulfan combined with therapeutic drug monitoring to guide dosing improves outcomes after allogeneic haemopoietic cell transplantation (HCT). The best method to estimate busulfan exposure and optimum exposure in children or young adults remains unclear. We therefore assessed three approaches to estimate intravenous busulfan exposure (expressed as cumulative area under the curve [AUC]) and associated busulfan AUC with clinical outcomes in children or young adults undergoing allogeneic HCT. METHODS: In this retrospective analysis, patients from 15 centres in the Netherlands, USA, Canada, Switzerland, UK, Italy, Germany, and Australia who received a busulfan-based conditioning regimen between March 18, 2001, and Feb 12, 2015, were included. Cumulative AUC was calculated by numerical integration using non-linear mixed effect modelling (AUCNONMEM), non-compartmental analysis (AUC from 0 to infinity [AUC0-∞] and to the next dose [AUC0-τ]), and by individual centres using various approaches (AUCcentre). The main outcome of interest was event-free survival. Other outcomes of interest were graft failure or relapse, or both; transplantation-related mortality; acute toxicity (veno-occlusive disease or acute graft versus-host disease [GvHD]); chronic GvHD; overall survival; and chronic-GvHD-free event-free survival. We used propensity-score-adjusted Cox proportional hazard models, Weibull models, and Fine-Gray competing risk regressions for statistical analyses. FINDINGS: 790 patients were enrolled, 674 of whom were included: 274 (41%) with malignant and 400 (59%) with non-malignant disease. Median age was 4·5 years (IQR 1·4-10·7). The median busulfan AUCNONMEM was 74·4 mg × h/L (95% CI 31·1-104·6), which correlated with the standardised method AUC0-∞ (r(2)=0·74), but the latter correlated poorly with AUCcentre (r(2)=0·35). Estimated 2-year event-free survival was 69·7% (95% CI 66·2-73·0). Event-free survival at 2 years was 77·0% (95% CI 72·1-82·9) in the 257 patients with an optimum intravenous busulfan AUC of 78-101 mg × h/L compared with 66·1% (60·9-71·4) in the 235 patients at the low historical target of 58-86 mg × h/L and 49·5% (29·2-66·0) in the 44 patients with a high (>101 mg × h/L) busulfan AUC (p=0·011). Compared with the low AUC group, graft failure or relapse occurred less frequently in the optimum AUC group (hazard ratio [HR] 0·57, 95% CI 0·39-0·84; p=0·0041). Acute toxicity (HR 1·69, 1·12-2·57; p=0·013) and transplantation-related mortality (2·99, 1·82-4·92; p101 mg × h/L) than in the low AUC group (<78 mg × h/L), independent of indication; no difference was noted between AUC groups for chronic GvHD (<78 mg × h/L vs ≥78 mg × h/L, HR 1·30, 95% CI 0·73-2·33; p=0·37). INTERPRETATION: Improved clinical outcomes are likely to be achieved by targeting the busulfan AUC to 78-101 mg × h/L using a new validated pharmacokinetic model for all indications. FUNDING: Research Allocation Program and the UCSF Helen Friller Family Comprehensive Cancer Center and the Mt Zion Health Fund of the University of California, San Francisco