Target Area Under The Curve Research Articles

#2047 Trough-level guided dosing is reliable for mycophenolate mofetil but not for enteric-coated mycophenolic sodium

Abstract Background and Aims While trough level (TL) guided dosing is usus for calcineurin inhibitors, mycophenolic acid (MPA) was marketed as a one-size-fits-all drug. TL has been reported to be a poor surrogate marker of MPA exposure by reason of complex pharmacokinetics. Measurement of area under the curve (AUC) remains the gold-standard for MPA dosing. Method We measured MPA TL and AUC in 299 KTRs at the University Hospital of Zurich. KTRs with agreement between TL and AUC target range of 40-60 mg/Lxh were compared to KTRs with missing agreement between TL and AUC for differences regarding baseline characteristics and co-medication. Results For mycophenolate mofetil (MMF, n = 218) a high correlation between TL and AUC was observed, p < 0.0001, r = 0.85, while correlation was only low for enteric-coated mycophenolate sodium (EC-MPS, n = 81), p = 0.002, r = 0.34, Fig. 1. However, a high correlation between MPA level 4 hours after EC-MPS intake (C4L) and AUC was found, p < 0.0001, r = 0.94. ROC analysis defined an MMF-TL range of >2.05 mg/l (sensitivity 68%, specificity 89%) and <3.05 mg/l (sensitivity 70%, specificity 81%) correlating with an AUC of 40-60 mg/Lxh. Lack of proton pump inhibitors (PPI) use was significantly associated with incorrect classification (n = 71/218). For EC-MPS C4L a range of >1.25 mg/l (sensitivity 98, specificity 100) and <4.4 mg/l (sensitivity 93, specificity 91) was defined for an AUC of 40-60 mg/Lxh. Here, non-tacrolimus-based immunosuppression was significantly associated with incorrect classification (n = 7/81). Conclusion MMF dosing according to TL highly correlates with AUC especially in KTRs treated with PPI. In contrast, EC-MPS dosing according to C4L is preferred especially in context of tacrolimus-based immunosuppression.

Impact of a 20 mg/kg vancomycin loading dose on early AUC target attainment

This retrospective chart review evaluated whether 20 mg/kg vancomycin loading doses increase early area under the curve (AUC) target attainment within 48 hours in comparison to non-loading dose regimens. There were no differences between groups for the primary outcome (46 % vs. 50 %; P = 0.58).

Comparison of vancomycin area under the curve calculated based on Bayesian approach versus equation-based approach.

Area under the curve (AUC)-based vancomycin dose adjustment is recommended to treat methicillin-resistant Staphylococcus aureus (MRSA) infections. AUC estimation methods include Bayesian software programs and simple analytical equations. This study compared the AUC obtained using the Bayesian approach with that obtained using an equation-based approach. Patients receiving intravenous vancomycin for MRSA infection were included. Peak and trough levels were measured for each patient on days 3, 7, and 10 post vancomycin dosing (day 1). AUC was calculated using software based on the Bayesian method (MwPharm Online) and an equation-based calculator, Stanford Health Care (SHC) calculator. The AUC estimated using MwPharm Online was similar to that estimated using the SHC calculator. The geometric mean ratio (GMR) and their 90% confidence intervals (90% CI) were 1.08 (1.05-1.11), 1.03 (0.99-1.07), and 0.99 (0.94-1.05) at days 3, 7, and 10, respectively. Furthermore, according to the software used, there were no significant differences in the proportions of patients in the categories "within" and "below or above" the AUC target range. Additionally, trough levels predicted by both software programs were lower than the observed ones. Still, there was no significant difference between the predicted and observed peak levels for both software programs on day 10. AUC calculated using the Bayesian software allows for calculation with samples at a non-steady state, can integrate covariates, and is interconvertible with that estimated using an equation-based calculator, which is simpler and relies on fewer assumptions. Therefore, either method can be used, considering each method's strengths and limitations.

Vancomycin AUC-Based Dosing Practices in a Non-Teaching Community Hospital and Associated Outcomes: A One-Year Survey of Uniform Targets for Infections with or without MRSA.

Intravenous (IV) vancomycin area under the curve (AUC)-based dosing is used uniformly for Gram-positive organisms in non-teaching community hospitals. However, evidence for using vancomycin AUC-based dosing for non-methicillin-resistant Staphylococcus aureus (non-MRSA) and less serious infections is limited in the literature. A gap in the literature also exists with respect to comparisons between the outcomes that can be derived using the regimens suggested by Bayesian programs and target doses of the AUC of 400-499 and 500-600. A retrospective review of all patients hospitalized in a non-teaching community hospital who used AUC-based vancomycin was performed over a 1-year period. Only 17.6% of the included patients had confirmed MRSA. The values for the overall early response rate, 30-day all-cause mortality, and rate of acute kidney injury (AKI) were 50.3%, 11.3%, and 3.8%, respectively, in this population. In regression analysis, compared to non-MRSA infections, a significantly higher rate of early response was seen in patients with MRSA (unadjusted OR = 2.68, 95% CI [1.06-6.76] p = 0.04). Patients in the AUC 400-499 group had a non-significant higher incidence of 30 d mortality and new AKI compared to patients in the AUC 500-600 group. In our Kaplan-Meier survival analysis, there was no statistically significant difference between the comparison groups. Early response was lower in patients with non-MRSA compared to patients with MRSA despite achieving the AUC target. There was no apparent difference in clinical outcomes between the higher and lower AUC groups. Further large-scale research is needed to confirm these findings.

Should the trough concentration of vancomycin be abandoned in therapeutic drug monitoring? A multicentre, retrospective study of critically ill patients without any form of dialysis

There are conflicts in guideline recommendations about the value and range of vancomycin trough concentration during therapeutic drug monitoring (TDM). This multicenter retrospective study was conducted to explore the usefulness of trough concentration in specific patients who were critically ill without any form of dialysis. Patient information from 5 centers was retrospectively collected, and the 24-hour area under the curve (AUC) was estimated by a Bayesian method. Patients were categorized into four groups according to trough concentration: <10, 10-15, 15-20, and >20 mg/L, and the corresponding AUC was analyzed. A multivariable logistic regression model was used to investigate the relationship between trough concentration and AUC. Overall, 645 trough concentrations available from 416 patients were included in this study. The results indicated that the AUC was always below 400 mg/L∙h or above 600 mg/L∙h in the <10 or >20 mg/L groups, whereas the ratio of vancomycin AUC target attainment (400-600 mg/L∙h) was 48.8% and 92.3% in the 10-15 mg/L and 15-20 mg/L groups, respectively. Augmented renal clearance, low daily dose and non-q12h administration were found to be independent risk factors associated with AUC target nonattainment for patients with trough concentrations of 10-15 mg/L. Vancomycin trough concentration is a good marker of AUC for critically ill adults without any form of dialysis. However, for patients with trough concentrations of 10-15 mg/L, AUC-guided TDM may be needed, especially for those with risk factors.

Drug monitoring detects under- and overdosing in patients receiving 5-fluorouracil-containing chemotherapy—results of a prospective, multicenter German observational study

Body surface area (BSA)-based dosing of 5-fluorouracil (5-FU) results in marked inter-individual variability in drug levels, whereas determination of plasma 5-FU concentration and area under the curve (AUC) is a more precise dosing method but has not been integrated into clinical routine. We conducted a multicenter, prospective study to study 5-FU AUC distributions and assess clinical factors predicting therapeutic dosing in patients receiving BSA-dosed 5-FU. Between June 2017 and January 2018, a total of 434 patients receiving continuous, infusional BSA-dosed 5-FU from 37 sites in Germany were included. Plasma 5-FU concentration and AUC were measured in venous blood samples at steady state. The primary objective was to determine 5-FU AUC distributions in relation to the target range, which is defined as 20-30 mg× h/l. The second objective was to explore clinical parameters that correlate with achievement of 5-FU AUC target range. The primary tumor was mainly located in the gastrointestinal tract (96.3%), with colorectal cancer being the most common (71.2%) tumor entity. 5-FU was administered as monotherapy (8.1%) or as part of FOLFOX (33.2%), FOLFIRI (26.3%), or other regimens (12.4%). Treatment setting was adjuvant (31.3%) or metastatic (64.5%). The median AUC was 16 mg× h/l. Only 20.3% of patients received 5-FU treatment within the target range, whereas the majority of patients (60.6%) were underdosed and 19.1% of patients were overdosed. In the univariate logistic regression, treatment setting was the only clinical parameter that significantly correlated with achievement of the target range. Patients treated in the metastatic setting had a 2.1 (95% confidence interval 1.186-3.776, P= 0.011) higher odds to reach the target range compared with patients treated in the adjuvant setting. The majority of patients received suboptimal doses of 5-FU using BSA dosing. Therapeutic drug monitoring of 5-FU is an option for optimized individualized cancer therapy and should be integrated into the clinical practice.

Phase 1 Trial of AUC-Targeted Melphalan in Myeloma Patients Undergoing Autologous Transplant (The MyMel Study)

Standard 200 mg/m2 high dose melphalan (HDM) yields a 500% variation in plasma melphalan exposure, i.e. area under the curve (AUC), leading to unpredictable DNA damage and widely variable clinical responses. Strategies to predict melphalan AUC have been unsuccessful given population PK models (Nath, Br J Clin Pharmacol 2010 & Cho Clin Pharmacol Ther 2017) are ineffective on an individual patient level and only explain ~20% of the variability observed, and test dose predictions have failed to accurately represent melphalan AUC for doses >100 mg/m2. PK directed dose adjustment of HDM would require a 24-hour turnaround for sample collection, shipping, processing and data analysis. Previously we described methods for measuring melphalan PK after the Day -2 HDM dose, allowing for real-time dose adjustments (Sweiss, Br J Clin Pharmacol 2020). Here, we set out to perform the first phase 1 study of AUC-targeted HDM in ASCT (NCT04483206). This multicenter phase 1 trial (Fig 1) is designed to test 7 AUC ranges (13-21 mg*h/L) to determine the maximum tolerated systemic exposure (MTSE). The feasibility portion focuses on the first 2 AUCs (phase A, n=20) in patients with ≥2L therapy, where we measure accuracy of achieving target AUCs of 13.5 and 14.5 mg∗h/L, respectively. Patients receive HDM 100 mg/m2 on day -3 with PK measurement and subsequent dose-adjustment on day -1 to achieve the total target AUC. 7 blood samples are drawn, processed and shipped frozen for LC-MS/MS analysis. PK parameter estimations are determined from noncompartmental analysis (NCA) and per FDA guidance used to adjust doses. Nonlinear mixed effects modeling (NONMEM) is performed in parallel to compare PK estimations. Using observed first-dose HDM clearance (Clobs) from NCA and assuming that Cl is consistent between doses, linear dose-proportional adjustments are performed to achieve the target AUC0-inf. After a planned FDA review of these cohorts, we will begin to dose escalate to determine the MTSE with up to 5 AUC levels (15.5-19.5 mg∗h/L). Bone marrow (BM) MRD status will be assessed at Day 90 as part of the Phase B primary objective. Correlatives include measuring DNA damage in circulating PBMCs post-HDM to correlate with AUC, piloting a DNA fiber combing assay on primary MM cells from patient BM samples to quantify DNA replicative stress, and assessing PROs using NCI PRO-CTCAE v.1.0. We have enrolled 8 patients into the first AUC cohort with 110 blood samples collected. Median age was 69 (56-75) years, with 7 (87.5%) males, and 4 (50%) Blacks. The median day -3 HDM Clobs and AUC0-inf were 22.05 (16.3-38.2) L/hr and 9.53 (6.97-11.82) mg∗h/L, respectively. All shipped blood samples were received in suitable frozen condition, and in 7 (87.5%) of 8 patients, LC-MS/MS run with NCA estimation and dose reporting was done within 12 hours of receiving samples. One patient whose samples were delayed from shipping had the dose reported on day-1 resulting in 5 of 7 day-1 samples collected. Covariates of HDM PK (i.e., FFM, hematocrit) were entered into our developed PK model to further enrich our data prediction. All 8 day -1 doses were adjusted, with a resulting median total BSA-based HDM dose of 139.6 (110.93-192.6) mg/m2. After adjustment, median day -1 Clobs and AUC0-inf were 24.48 (19.3-35.8) L/hr and 3.84 (1.7-7) mg∗h/L, respectively. For accuracy of dose adjustment, 107 (97.3%) samples were evaluable for PK parameter estimation, with 3 concentrations excluded (n=3 patients). One subject whose last 2 day -1 samples were not collected was removed from analysis as it resulted in 19% AUC extrapolation and 33% variance between day -3 and -1 Cl values. Of 7 patients, 6 (85.7%) achieved the target AUC, with less than 10% variance in Cl between doses. (Fig 2). In the one patient, it was assessed that the day -1 Cl deviated by 24% as a result of prolonged time from drug admixture to completion of infusion leading to drug degradation. Estimated melphalan Cl generated from NCA and NONMEM correlated well (r=0.99). This is the first trial in MM implementing a novel personalized dosing approach using drug exposure as the target to define each cohort. We demonstrate feasibility of real-time PK sampling, shipping, processing, NCA PK parameter estimation, and dose adjustment of HDM. So far we report a high rate of accuracy in achieving the target AUC which we hypothesize will deliver reliable DNA damage to MM cells. Enrollment is active and mature data will be presented at the conference. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Body Mass Index of Elderly Patients with Normal Renal Function as a Determining Factor for Initial Vancomycin Regimen Designing

Introduction: Currently, the use of actual body weight is recommended for dosing in vancomycin regimen designs, and it is important to perform therapeutic drug monitoring for efficacy and safety. However, the method to determine the appropriate vancomycin regimen for underweight or obese patients remains controversial. The aim of this study was to evaluate the impact of body mass index (BMI) on the relationship among vancomycin doses, trough concentration, and area under the curve (AUC). In addition, we identified the group of patients who were potentially more affected by BMI and evaluated the optimal dosing regimen to achieve the target AUC. Methods: We retrospectively collected data from 462 patients who received vancomycin at the Osaka City University Hospital between January 2013 and September 2019. Patients were classified by their BMI group (underweight <18.5, normal weight 18.5–24.9, and obese ≥25.0 kg/m2). We assessed the association between vancomycin dose versus trough concentration or AUC as well as dose-adjusted trough concentration and AUC in each BMI subgroup to determine the doses for achieving the target AUC. Results: The dose-adjusted trough concentration and AUC in elderly patients with normal renal function appeared to increase significantly with an increase in BMI (p < 0.05). Vancomycin doses that enabled the achievement of AUC400 in elderly patients with normal renal function decreased with increasing BMI: 17.7, 15.8, and 12.9 mg/kg per time in the underweight, normal weight, and obesity groups, respectively (p < 0.05). Conclusion: Elderly patients with normal renal function were the most affected by BMI on vancomycin trough concentration and AUC. The vancomycin regimen design in these patients should be adjusted carefully, not only based on the patient’s renal function but also based on BMI.

Individualized Dosage Optimization for Myeloablative Conditioning before Unrelated Cord Blood Transplantation in a Diamond–Blackfan Anemia Patient with Germline RPL11 Mutation: A Case Study

Unrelated cord blood transplantation (CBT) for Diamond–Blackfan anemia (DBA), a systemic ribosomopathy affecting the disposition of conditioning agents, has resulted in outcomes inferior to those by transplantations from matched donors. We report the experience of the pharmacokinetics-guided myeloablative unrelated CBT in a DBA patient with a germline RPL11 mutation. The conditioning consisted of individualized dosing of fludarabine (based on weight and renal function with a target area under the curve (AUC) of 17.5 mg·h/L) and busulfan (based on therapeutic drug monitoring with a target AUC of 90 mg·h/L), as well as dosing and timing of thymoglobulin (based on body weight and pre-dose lymphocyte count to target pre-CBT AUC of 30.7 AU·day/mL and post-CBT AUC of 4.3 AU·day/mL, respectively). The pharmacokinetic measures resulted in a 27.5% reduction in busulfan and a 35% increase in fludarabine, as well as an over three-fold increase in thymoglobulin dosage with the start time changed to day-9 instead of day-2 compared to regular regimens. The transplantation resulted in rapid, complete, and sustained hematopoietic engraftment. The patient is now healthy over 3 years after CBT. A pharmacokinetics-guided individualized dosing strategy for conditioning might be a feasible option to improve the outcomes of DBA patients receiving unrelated myeloablative CBT.

Development and Validation of an Insulin Resistance Predicting Model Using a Machine-Learning Approach in a Population-Based Cohort in Korea.

Background: Insulin resistance is a common etiology of metabolic syndrome, but receiver operating characteristic (ROC) curve analysis shows a weak association in Koreans. Using a machine learning (ML) approach, we aimed to generate the best model for predicting insulin resistance in Korean adults aged > 40 of the Ansan/Ansung cohort using a machine learning (ML) approach. Methods: The demographic, anthropometric, biochemical, genetic, nutrient, and lifestyle variables of 8842 participants were included. The polygenetic risk scores (PRS) generated by a genome-wide association study were added to represent the genetic impact of insulin resistance. They were divided randomly into the training (n = 7037) and test (n = 1769) sets. Potentially important features were selected in the highest area under the curve (AUC) of the ROC curve from 99 features using seven different ML algorithms. The AUC target was ≥0.85 for the best prediction of insulin resistance with the lowest number of features. Results: The cutoff of insulin resistance defined with HOMA-IR was 2.31 using logistic regression before conducting ML. XGBoost and logistic regression algorithms generated the highest AUC (0.86) of the prediction models using 99 features, while the random forest algorithm generated a model with 0.82 AUC. These models showed high accuracy and k-fold values (>0.85). The prediction model containing 15 features had the highest AUC of the ROC curve in XGBoost and random forest algorithms. PRS was one of 15 features. The final prediction models for insulin resistance were generated with the same nine features in the XGBoost (AUC = 0.86), random forest (AUC = 0.84), and artificial neural network (AUC = 0.86) algorithms. The model included the fasting serum glucose, ALT, total bilirubin, HDL concentrations, waist circumference, body fat, pulse, season to enroll in the study, and gender. Conclusion: The liver function, regular pulse checking, and seasonal variation in addition to metabolic syndrome components should be considered to predict insulin resistance in Koreans aged over 40 years.

Iron Chelation With Deferasirox Increases Busulfan AUC During Conditioning Chemotherapy Prior to Allogeneic Stem Cell Transplantation

The negative effects of iron overload caused by repetitive blood transfusions and iron release during cytotoxic chemotherapy might be ameliorated by early treatment with an iron chelator. However, in the setting of allogeneic hematopoietic stem cell transplantation (HSCT), chelation therapy is often postponed until the late post-transplantation period because of potential drug interactions. Therefore we systematically investigated the influence of iron chelation with deferasirox on the pharmacokinetics of intravenous busulfan in adult patients in the context of routine therapeutic drug monitoring (TDM) before HSCT. We conducted a single-center, prospective, observational study in 25 adult patients with planned allogeneic HSCT after myeloablative, busulfan-based, TDM-guided conditioning chemotherapy. Busulfan was administered intravenously over 3 hours with an initial dose of 3.2 mg/kg once daily (based on adjusted ideal body weight [AIBW] in overweight patients). Four consecutive dosages were planned to achieve a cumulative area under the curve (AUC) of 80 mg · h/L. Patients received deferasirox for transfusional iron overload as per approval from the start of conditioning until day 3 after transplantation. Model-based calculation of the busulfan AUC was carried out by means of Bayesian prediction based on a population pharmacokinetic model after the first or second dose of busulfan, and dose adjustments were performed accordingly. Calculated median cumulative AUC before dose adjustment was 93.7 mg · h/L (65.1-151.4 mg · h/L), which was considerably above the target AUC of 80 mg · h/L ± 10%. Median dose adjustment was -17.1% (-50.0% to 18.2%), and patients ultimately received busulfan with a median cumulative dose of 10.60 mg/kg (6.38 - 15.62) mg/kg. A busulfan dose reduction was necessary in 19 patients (76%) whereas a dose increase was only needed in 1 patient. After dose adjustment the median AUC was 79.7 mg/L · h (62.5 - 84.2 mg/L · h). Median busulfan clearance was 0.134 L/h/kg (0.084 - 0.203 L/h/kg), which is significantly lower than the average clearance of 0.2 L/h/kg reported in the literature, whereas volume of distribution was not altered. We were able to demonstrate, that TDM is the key point to facilitate a safe co-administration of both medications, because the intake of deferasirox leads to a considerable increase in the busulfan AUC of about 35% to 40%. The reason for the increase in busulfan AUC is a reduction in busulfan clearance by about one third; therefore a lower initial dose of busulfan followed by TDM could be considered in patients with comedication with deferasirox.

Population Pharmacokinetic Analysis of Pazopanib in Patients and Determination of Target AUC.

Pazopanib is a potent multi-targeted kinase inhibitor approved for the treatment of advanced renal cell carcinoma and soft tissue sarcoma. The pharmacokinetics of pazopanib is characterized by a significant inter- and intra-patient variability and a target through plasma concentration of 20.5 mg·L−1. However, routine monitoring of trough plasma concentrations at fixed hours is difficult in daily practice. Herein, we aimed to characterize the pharmacokinetic (PK) profile of pazopanib and to identify a target area under the curve (AUC) more easily extrapolated from blood samples obtained at various timings after drug intake. A population pharmacokinetic (popPK) model was constructed to analyze pazopanib PK and to estimate the pazopanib clearance of a patient regardless of the time of sampling. Data from the therapeutic drug monitoring (TDM) of patients with cancer at Institute Gustave Roussy and a clinical study (phase I/II) that evaluates the tolerance to pazopanib were used. From the individual clearance, it is then possible to obtain the patient’s AUC. A target AUC for maximum efficacy and minimum side effects of 750 mg·h·L−1 was determined. The comparison of the estimated AUC with the target AUC would enable us to determine whether plasma exposure is adequate or whether it would be necessary to propose therapeutic adjustments.

Feasibility, Tolerability, and Patient-Reported Outcomes with Pharmacokinetic (PK)-Directed Dosing of Evomela® (propylene glycol free melphalan) for Multiple Myeloma and AL Amyloidosis Patients Undergoing Autologous Hematopoietic Stem Cell Transplant (AHCT)

Background: For multiple myeloma (MM) and AL amyloidosis (AL) patients undergoing autologous hematopoietic stem cell transplant (AHCT), high-dose melphalan is given at a fixed dose based on body surface area with five-fold inter-patient variability in exposure, as measured by area under the curve (AUC). Patients with higher than the median AUC (12.85mg/L*h) have prolonged survival, but increased toxicity (Shaw et al., BBMT 2012). Pharmacokinetically (PK)-directed dosing has the potential to achieve an optimal concentration in each patient. We prospectively evaluated the feasibility of PK-directed dosing of propylene glycol free melphalan (Evomela®, PGF-MEL), a more stable and possibly less toxic intravenous formulation of melphalan, to personalize therapy for maximum efficacy and tolerability.Methods: MM and AL patients age 18-75 received a 10mg/m2 test dose of PGF-MEL within 14 days of AHCT. Serum samples were drawn at 5, 15, 30, 40, 75, and 150 min after PGF-MEL administration. Liquid chromatography tandem mass spectrometry was used to measure MEL concentrations. AUC PK modeling with Phoenix WinNonlin v6.4 was used to determine a target dose to achieve an AUC of 13.5mg/L*h (+/-1), which was given on day -2 prior to AHCT. PK samples were collected after the target dose at the same time points as after the test dose. AHCT with 3-10 x10^6 CD34+ cells/kg was conducted per institutional guidelines. Patient-reported symptom burden was collected prospectively using the MD Anderson Symptom Inventory - MM (MDASI-MM) on day +1, 6, 11, 30, 60, and 90. Toxicities were collected by chart review through day +100 after AHCT and compared using either a T-test or Fisher's exact test between patients above and below AUC 14.5 mg/L*h.Results: Ten patients (7 MM, 3 AL) with 50% male, median age 67yr (range 53-74), and median body surface area 1.95 (range 1.56-2.35) had a median of 4.5 days (range 1-24) between the test and target doses of PGF-MEL. Target doses were calculated for 90% of patients and 70% received the calculated dose. The reasons for not administering the calculated dose were inability to calculate a test dose AUC (N=1), toxicity after the test dose (N=1), and target dose outside study safety parameters (N=1). Median test and target dose AUCs were 0.655 (range 0.447-0.869) and 15.65mg/L*h (range 10.1-17.2, Figure 1), respectively. No patients receiving the calculated target dose had an AUC within the goal range. MDASI-MM AUCs were calculated for fatigue, pain, sleep, appetite, drowsiness, and the average of these 5 symptoms. Overall, higher scores were seen in patients with MEL AUCs above 14.5mg/L*h compared with below (Figure 2). More patients with higher AUCs had fevers (83 vs 50%), ≥500ml of diarrhea per day (83 vs 75%), grade ≥3 mucositis (50 vs 25%), and need for patient-controlled analgesia (33 vs 25%), but these were not statistically significantly different between the groups (Table 1). Neutrophil engraftment occurred at a median of 10 (range 9-11) days post AHCT in both groups; patients with AUCs above 14.5mg/L*h required more pRBC and platelet transfusions. With a median follow-up of 217 days (range 179-250) in surviving patients, no patients progressed, and one AL patient died of failure to thrive at 134 days post AHCT.Conclusion: Collection of PK levels and calculation of a target dose was feasible. However, using a 10mg/m2 test dose we did not achieve the target AUC in our patients. This could be due to the small test dose which may have been insufficient to saturate the two-compartment model, rendering the PK analysis inaccurate. Patients with higher AUCs required more transfusions, had more toxicities, and had prolonged patient-reported symptom burden. Due to the small number of patients, these differences were not statistically significant, but suggest there may be an ideal concentration to minimize toxicity and maximize efficacy. Disease response and outcome data continue to be collected. Further study is needed to determine the optimum test dose and schedule, and modifications to the schema are ongoing. [Display omitted] DisclosuresKoehne:Atara: Consultancy, Patents & Royalties. Landau:Janssen: Honoraria; Takeda: Research Funding; Spectrum Pharmaceuticals: Other: Advisory Board, Research Funding; Celgene: Other: Advisory Board; Pfizer: Honoraria; Karyopharm: Consultancy; Amgen: Research Funding.

Multicentric phase II trial of TI‐CE high‐dose chemotherapy with therapeutic drug monitoring of carboplatin in patients with relapsed advanced germ cell tumors

ABSTRACTBackgroundHigh‐dose chemotherapy (HDCT) with TI‐CE regimen is a valid option for the treatment of relapsed advanced germ cell tumors (GCT). We report a phase II trial with therapeutic drug monitoring of carboplatin for optimizing area under the curve (AUC) of this drug.MethodsPatients with unfavorable relapsed GCT were treated according to TI‐CE regimen: two cycles combining paclitaxel and ifosfamide followed by three cycles of HD carboplatin plus etoposide administered on 3 days. Carboplatin dose was adapted on day 3 based on carboplatin clearance (CL) at day 1 in order to reach a target AUC of 24 mg.min/mL per cycle. The primary endpoint was the complete response (CR) rate.ResultsEighty‐nine patients who received HDCT were included in the modified intent‐to‐treat (mITT) analysis. Measured mean AUC was 24.4 mg.min/mL per cycle (22.4 and 26.8 mg.min/mL for 10th and 90th percentiles). Thirty‐five (44.3%) patients achieved a CR with or without surgery of residual masses and 20 patients achieved a partial response with negative tumor markers. With a median follow‐up of 44 months (m), median PFS was 12.3 m (95% CI: 7.5–25.9) and OS was 46.3 m (95% CI: 18.6–not reached). For high‐ and very high‐risk patients, according to the International Prognostic Score at first relapse or treated after at least one salvage treatment (n = 51), 2‐year PFS rate was 41.1%.ConclusionThe rates of complete and favorable responses were clinically relevant in this very poor risk population. Individual monitoring of carboplatin plasma concentration permitted to control more accurately the target AUC and avoided both underexposure and overexposure to the drug.

Real-World Infliximab Pharmacokinetic Study Informs an Electronic Health Record-Embedded Dashboard to Guide Precision Dosing in Children with Crohn's Disease.

Standard-of-care infliximab dosing regimens were developed prior to the routine use of therapeutic drug monitoring and identification of target concentrations. Not surprisingly, subtherapeutic infliximab concentrations in pediatric Crohn's disease (CD) are common. The primary aim was to conduct a real-world pharmacokinetic (PK) evaluation to discover blood biomarkers of rapid clearance, identify exposure targets, and a secondary aim to translate PK modeling to the clinic. In a multicenter observational study, 671 peak and trough infliximab concentrations from 78 patients with CD were analyzed with a drug-tolerant assay (Esoterix; LabCorp, Calabasas, CA). Individual area under the curve (AUC) estimates were generated as a measure of drug exposure over time. Population PK modeling (nonlinear mixed-effect modeling) identified serum albumin, antibody to infliximab, erythrocyte sedimentation rate (ESR), and neutrophil CD64 as biomarkers for drug clearance. Week 14 and week 52 biochemical remitters (fecal calprotectin<250µg/g) had higher infliximab exposure (AUC) throughout induction. The optimal infliximab AUC target during induction for week 14 biochemical remission was 79,348µg*h/mL (area under the receiver operating characteristic curve (AUROC) 0.77, [0.63-0.90], 85.7% sensitive, and 64.3% specific) with those exceeding the AUC target more likely to achieve a surgery-free week 52 biochemical remission (OR 4.3, [1.2-14.6]). Pretreatment predictors for subtherapeutic week 14 AUC included neutrophil CD64>6 (OR 4.5, [1.4-17.8]), ESR>30mm/h (OR 3.8, [1.4-11]), age<10years old (OR 4.2, [1.2-20]), and weight<30kg (OR 6.6, [2.1-25]). We created a decision-support PK dashboard with an iterative process and embedded the modeling program within the electronic health record. Model-informed precision dosing guided by real-world PKs is now available at the bedside in real-time.

First-Dose Vancomycin Pharmacokinetics Versus Empiric Dosing on Area-Under-the-Curve Target Attainment in Critically Ill Patients.

Early attainment of target area under the curve (AUC) to minimum inhibitory concentration (MIC) ratios have been associated with clinical success, as well as lower incidence of acute kidney injury (AKI), in patients receiving vancomycin for methicillin-resistant Staphylococcus aureus (MRSA). Critically ill patients are particularly vulnerable to poor outcomes from infection and face multiple risk factors for AKI, thus early precision dosing of vancomycin is vital in this population. We hypothesized that a personalized dosing approach, using vancomycin levels obtained after the first dose to guide further dosing, would be superior to empiric dosing in terms of AUC target attainment assessed at steady state (SS). A retrospective cohort study of 66 critically ill adult patients admitted to the medical intensive care unit without AKI and receiving vancomycin with at least two SS concentrations obtained for AUC calculation was performed. Patients were separated into cohorts based on whether they had two concentrations assessed after the first dose of vancomycin and were subsequently dosed based on personalized pharmacokinetic calculations (first-dose kinetics) or whether they were empirically dosed using population estimates. The primary outcome was AUC target attainment (400-600mghour/L) at SS. Compared with patients receiving empiric dosing by population estimates, using first-dose kinetics to guide subsequent dosing resulted in significantly greater AUC target attainment at SS (58.6% first-dose vs 32.4% empiric; p=0.033). Patients dosed empirically yielded more variable AUC values across a wide range compared with the first-dose kinetics group (coefficient of variation 40.7% empiric vs 26.1% first-dose). There was no difference in AKI up to 48 hours after SS concentrations between the two dosing schemes. A dosing strategy using two vancomycin serum concentrations after the first dose and calculating personalized pharmacokinetic parameters to guide subsequent dosing is associated with greater AUC target attainment at SS compared with empiric dosing of vancomycin in critically ill adults with relatively stable renal function.

A Phase 1/2 Study of Lentiviral-Mediated Ex-Vivo Gene Therapy for Pediatric Patients with Severe Leukocyte Adhesion Deficiency-I (LAD-I): Results from Phase 1

Introduction: LAD-I is a rare inherited disorder of leukocyte (primarily neutrophil) adhesion to endothelial cell surfaces, migration, and chemotaxis resulting from ITGB2 gene mutations encoding for the β2-integrin component, CD18. Severe LAD-I (i.e., CD18 expression on &amp;lt;2% of PMNs) is characterized by recurrent severe infections, impaired wound healing, and childhood mortality. Although allogeneic hematopoietic stem cell transplant (alloHSCT) is potentially curative, its utilization and efficacy are limited by HLA-matched donor availability and risk of graft-versus-host disease (GVHD). RP-L201-0318 (clinical trials.gov # NCT03812263) is a phase 1/2 open-label clinical trial evaluating the safety and efficacy of autologous CD34+ cells transduced with a lentiviral vector (LV) carrying the ITGB2 gene encoding for CD18 (Chim-CD18-WPRE) in severe LAD-I. Methods: Pediatric patients ≥ 3 months old with severe LAD-I (demonstrated by CD18 expression on &amp;lt;2% PMNs and at least 1 prior significant bacterial or fungal infection) are eligible. Peripheral blood (PB) HSCs are collected via apheresis after mobilization with granulocyte-colony stimulating factor (G-CSF) and Plerixafor. CD34+ cells are selected, transduced with Chim-CD18-WPRE LV, and cryopreserved. Myeloablative conditioning with busulfan (with therapeutic drug monitoring (TDM) to adjust dosing to enable target area under the curve (AUC)) is administered, followed by infusion of the investigational drug product (RP-L201). Patients are followed for safety assessments (i.e., replication competent lentivirus (RCL) and insertion site analysis (ISA)), and efficacy -- survival to age 2 and at least 1-year post-infusion without alloHSCT, increase in neutrophil CD18 expression to at least 10%, PB vector copy number (VCN), decrease in infections and/or hospitalizations, and resolution of skin or periodontal abnormalities. Results: Two patients (ages 9 and 3) were treated in Phase 1. Both have a history of recurrent severe infections, documented ITGB2 mutations, and baseline CD18, CD11a, and CD11b expression &amp;lt; 1%. Mobilization and apheresis procedures were performed successfully and busulfan was administered at the target AUC. Investigational product comprised of 4.2x106 CD34+ cells/kg with VCN of 3.8 copies/cell (liquid culture) for Patient 1 and 2.8x106 CD34+ cells/kg with VCN of 2.5 for Patient 2 and were infused without complications. No serious treatment-emergent adverse events were reported. Neutrophil engraftment was observed in &amp;lt; 3 weeks in both patients. For Patient 1, PB PMN CD18 expression 6 months post-treatment was 47% (sustained from 45% at 3-months, vs. &amp;lt; 1% at baseline), with PB VCN of 1.3. Skin lesions present at baseline were resolving with no new lesions. Replication competent lentiviral (RCL) testing at 3 months and 6 months post-infusion were negative. Safety and efficacy data 12-months post-treatment for Patient 1 and 6-months post-treatment for Patient 2 will be available at the time of presentation. Conclusion: Initial results from Phase 1 demonstrate preliminary safety and efficacy of RP-L201 for reversal of severe LAD-I. Enrollment of patients in the Phase 2 study is underway. Disclosures Kohn: Allogene Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees; Orchard Therapeutics: Consultancy, Patents &amp; Royalties, Research Funding. Rao:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Almarza:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Nicoletti:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Law:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Beard:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company. Sevilla:Novartis: Other: Advisory Board; Sobi: Other: Advisory Board; Rocket Pharma: Consultancy; Amgen: Other: Advisory Board. Bueren:Rocket Pharmaceuticals, Inc.: Consultancy, Current equity holder in publicly-traded company, Other: Consultant for Rocket Pharmaceuticals, Inc. and has licensed medicinal products and receives research funding and equity from this company., Patents &amp; Royalties, Research Funding. Schwartz:Rocket Pharmaceuticals, Inc.: Current Employment, Current equity holder in publicly-traded company.

New dosing nomogram and population pharmacokinetic model for young and very young children receiving busulfan for hematopoietic stem cell transplantation conditioning.

Busulfan (Bu) is the cornerstone of conditioning regimens prior to hematopoietic stem cell transplantation, widely used in both adults and children for the treatment of malignant and nonmalignant diseases. Despite an intravenous formulation, interindividual variability (IIV) remains high and optimal exposure difficult to achieve, especially in neonates and infants. To ensure both efficacy and safety, we set up in 2005 an observational study designed for children not fully assessed during the drug registration procedure. From a large cohort of 540 patients, we developed a Bu population pharmacokinetic model based on body weight (BW) and maturation concepts to reduce IIV and optimize exposure. A new dosing nomogram was evaluated to better fit the population pharmacokinetic model. Bu clearance IIV was significantly decreased from 61.3% (covariate-free model) to 28.6% when combining BW and maturation function. Median Bu area under the curve (AUC) was 1179µmol/L×min compared to 1025 with the EMA dosing nomogram for children <9kg. The target AUC was reached for each BW strata, significantly increasing the percentages of patients achieving reaching the targeted AUC as compared to FDA schedule. This new model made it possible to propose a novel dosing nomogram that better considered children below 16kg of BW and allowed better initial exposure as compared to existing dosing schedules. This nomogram, which would be easy to use to determine an optimal dosing schedule in daily practice, will need to be validated in clinical routine. Therapeutic drug monitoring remains strongly advisable for small children and those with specific diseases.

Pharmacokinetically-guided preoperative FOLFOX chemotherapy for locally advanced colon cancer patients.

4104 Background: Preliminary results from ongoing randomised trials suggest that neoadjuvant chemotherapy (NAC) may be an alternative approach to conventional adjuvant therapy. We assessed the feasibility and activity of incorporating a pharmacokinetically (PK) guided dose adjustment of 5-FU within preoperative Folfox. Methods: Radiologically staged LACC pts, T4 or T3 with extramural depth &gt;5mm beyond the muscularis propia, were planned to receive 4-6 biweekly cycles of Oxalipatin (85mg/m²), Leucovorin (400 mg/m²), bolus 5-FU (400 mg/m2) and infusional 5-FU (initial dose of 2400mg/m² in 46h and subsequent cycles tailored according to PK monitoring in order to reach a target 5-FU area under the curve (AUC) between 20-30 mg∙h∙L-1). Dihidrouracil deshidrogenase was determined before the first cycle in order to detect pts with 5-Fu intolerance. Three serum samples were obtained during the 5-Fu infusion in the first two cycles. Pathological tumor regression was graded according to the MSKCC classification and toxicity to the NCI-CTCAE 4.0. Results: From June 2012 to August 2017, 45 pts (M/F: 35/10; median age 63) with LACC (T3: 66.7%; T4: 31.1%; T2: 2.2%; N+:66.6%) were evaluated. Median dose of 5-FU was 4500 mg. 48.9% of the pts required a 5-FU dose increase to reach the target AUC. Side effects profile included G3 neutropenia (3 pts), G2 diarrhea (2 pts) and G2 asthenia (9 pts). NAC was discontinued in 3 pts due to small bowell obstruction requiring surgery (no progressive disease during NAC). R0 resection rate was 100% (93.3% laparoscopy-assited). MSKCC score included grades 4, 3+ and 3 in 11.1%, 26.7% and 28.9% of pts, respectively. A complete pathological response was found in 5 pts (11.1%). Median number of harvested nodes was 16 (7-51), 80% ypN0. Those pts with AUC 25-30 had a 3-fold higher likelihood of achieving a MSKCC 3, 3+ and 4 responses. Median time to hospital discharge was 7 days (range 4-22). After a median follow-up of 60 months (44-66), 5-year actuarial PFS is 88.8%. Conclusions: Preoperative PK-adjusted FOLFOX in LACC pts is safe and well tolerated, achieving remarkable rates of major pathological responses and R0 resections.

Sorafenib administered using a high-dose, pulsatile regimen in patients with advanced solid malignancies: a phase I exposure escalation study

Background(Pre)clinical evidence is accumulating that intermittent exposure to increased doses of protein kinase inhibitors may improve their treatment benefit. In this phase I trial, the safety of high-dose, pulsatile sorafenib was studied.Patients and methodsHigh-dose sorafenib was administered once weekly in exposure escalation cohorts according to a 3 + 3 design. Drug monitoring was performed in weeks 1–3 and doses were adjusted to achieve a predefined target plasma area under the curve (AUC)(0–12 h). The effect of low gastric pH on improving sorafenib exposure was investigated by intake of the acidic beverage cola.ResultsSeventeen patients with advanced malignancies without standard treatment options were included. Once weekly, high-dose sorafenib exposure was escalated up to a target AUC(0–12 h) of 125–150 mg/L/h, achieving a twofold higher Cmax compared to standard continuous dosing. Dose-limiting toxicity was observed in three patients: grade 3 duodenal perforation (2800 mg sorafenib), grade 5 multiorgan failure (2800 mg sorafenib) and grade 5 biliary tract perforation (3600 mg sorafenib). The mean difference between observed and target AUC(0–12 h) was 45% (SD ± 56%) in week 1 using a fixed starting dose of sorafenib compared to 2% (SD ± 32%) in week 3 as a result of drug monitoring (P = 0.06). Dissolving sorafenib in cola, instead of water, did not improve sorafenib exposure. Clinical benefit with stable disease as the best response was observed in two patients.ConclusionTreatment with high-dose, once weekly sorafenib administration resulted in dose-limiting toxicity precluding dose escalation above the exposure cohort of 125–150 mg/L/h. Drug monitoring was a successful strategy to pursue a target exposure.