Personalized dosing of cyclophosphamide in the total body irradiation-cyclophosphamide conditioning regimen: a phase II trial in patients with hematologic malignancy

Immunosuppressant adherence in adult outpatient hematopoietic cell transplant recipients

INTRODUCTION

Medication nonadherence continues to be challenging for allogeneic hematopoietic cell transplant (HCT) recipients. The risk and severity of chronic graft-versus-host disease (GVHD) are associated with low immunosuppressant concentrations (which can be improved with model-informed precision dosing (MIPD)) and with immunosuppressant nonadherence (which can be improved with acceptable interventions).

METHODS

With the goals of improving adherence and achieving therapeutic concentrations of immunosuppressants to eliminate GVHD, we characterized the feasibility of using the Medication Event Monitoring (MEMS®) Cap in adult HCT recipients.

RESULTS

Of the 27 participants offered the MEMS® Cap at the time of hospital discharge, 7 (25.9%) used it, which is below our a priori threshold of 70%. These data suggest the MEMS® Cap is not feasible for HCT recipients. The MEMS® Cap data were available for a median of 35 days per participant per medication (range: 7-109 days). The average daily adherence per participant ranged from 0 to 100%; four participants had an average daily adherence of over 80%.

CONCLUSIONS

MIPD may be supported by MEMS® technology to provide the precise time of immunosuppressant self-administration. The MEMS® Cap was used by only a small percentage (25.9%) of HCT recipients in this pilot study. In accordance with larger studies using less accurate tools to evaluate adherence, immunosuppressant adherence varied from 0% to 100%. Future studies should establish the feasibility and clinical benefit of combining MIPD with newer technology, specifically the MEMS® Button, which can inform the oncology pharmacist of the time of immunosuppressant self-administration.

The estimation of glomerular filtration in acute and critical illness: Challenges and opportunities

Recent events have made it apparent that the creatinine based estimating equations for glomerular filtration have their flaws. Some flaws have been known for some time; others have prompted radical modification of the equations themselves. These issues persist in part owing to the behaviour of the creatinine molecule itself, particularly in acute and critical illness. There are significant implications for patient treatment decisions, including drug and fluid therapies and choice of imaging modality (contrast vs. non-contrast CT scan for example). An alternative biomarker, Cystatin C, has been used with some success both alone and in combination with creatinine to help improve the accuracy of particular estimating equations. Problems remain in certain circumstances and costs may limit the more widespread use of the alternative assay. This review will explore both the historical and more recent evidence for glomerular filtration estimation, including options to directly measure glomerular filtration (rather than estimate), perhaps the holy grail for both Biochemistry and Nephrology.

Influence of Renal Function on Phosphoramide Mustard Exposure: A Nonlinear Mixed-Effects Analysis

Phosphoramide mustard (PM) is the final cytotoxic metabolite formed from the parent compound cyclophosphamide through a complex metabolic pathway, primarily through hepatic metabolism. Little is known about the effect of renal elimination on the disposition of PM. We evaluated the effect of renal function on PM exposure after single doses of cyclophosphamide in 85 patients undergoing allogeneic hematopoietic cell transplantation using nonlinear mixed-effects modeling. Mixed linear and nonlinear elimination pathways were required to adequately describe the disposition of PM. Creatinine clearance (CrCL) was incorporated as a covariate associated with first-order elimination, representing renal clearance (Cl_R ) of PM. For a 70-kg patient, Cl_R was 14.9 L/h, Volume of distribution was 525 L, maximum rate was 81.2 mg/h, and the concentration to achieve 50% of maximum rate was 0.51 mg/L. We conducted simulations to explore the impact of CrCL as a measure of renal function and observed that when CrCL decreases from 120 to 40 mL/min, PM area under the plasma concentration-time curve (AUC) from time 0 to 8 hours and AUC increases by 9.2% and 80.9% on average after a single dose, respectively. Our data suggest that renal function has limited influence on PM exposure during the first 8 hours after dosing but has a large impact on the total exposure. Dose adjustment of cyclophosphamide may not be necessary in hematopoietic cell transplant recipients with moderate to severe kidney dysfunction to attain targeted exposures based on AUC from time 0 to 8 hours. However, dose reduction may be necessary if demonstrated at some future time that total AUC is a better surrogate for safety or toxicity.

Lipidomics of cyclophosphamide 4-hydroxylation in patients receiving post-transplant cyclophosphamide

Biomarker-guided dosing may improve the efficacy and toxicity of cyclophosphamide (CY); however, clinical studies evaluating their association with the area under the plasma concentration-time curve (AUC) of CY and its metabolites are time- and resource-intensive. Therefore, we sought to identify lipidomic biomarkers associated with the time-varying differences in CY formation clearance to 4-hydroxycyclophosphamide (4HCY), the principal precursor to CY's cytotoxic metabolite. Hematopoietic cell transplant (HCT) patients receiving post-transplant CY (PT-CY) were enrolled, cohort 1 (n = 25) and cohort 2 (n = 26) donating longitudinal blood samples before they started HCT (pre-HCT), before infusion of the donor allograft (pre-graft), before the first dose of PT-CY (pre-CY) and 24 h after the first dose of PT-CY (24-h post-CY) which is also immediately before the second dose of CY. A total of 409 and 387 lipids were quantitated in the two cohorts, respectively. Associations between lipids, individually and at a class level, and the ratio of 4HCY/CY AUC (i.e., 4HCY formation clearance) were evaluated using linear regression with a false discovery rate <0.05. There were no individual lipids that passed control for false discovery at any time point. These results demonstrate the feasibility of lipidomics, but future studies in larger samples with multiple omic tools are warranted to optimize CY dosing in HCT.

The Nitrogen Mustards

The nitrogen mustards are powerful cytotoxic and lymphoablative agents and have been used for more than 60 years. They are employed in the treatment of cancers, sarcomas, and hematologic malignancies. Cyclophosphamide, the most versatile of the nitrogen mustards, also has a place in stem cell transplantation and the therapy of autoimmune diseases. Adverse effects caused by the nitrogen mustards on the central nervous system, kidney, heart, bladder, and gonads remain important issues. Advances in analytical techniques have facilitated the investigation of the pharmacokinetics of the nitrogen mustards, especially the oxazaphosphorines, which are prodrugs requiring metabolic activation. Enzymes involved in the metabolism of cyclophosphamide and ifosfamide are very polymorphic, but a greater understanding of the pharmacogenomic influences on their activity has not yet translated into a personalized medicine approach. In addition to damaging DNA, the nitrogen mustards can act through other mechanisms, such as antiangiogenesis and immunomodulation. The immunomodulatory properties of cyclophosphamide are an area of current exploration. In particular, cyclophosphamide decreases the number and activity of regulatory T cells, and the interaction between cyclophosphamide and the intestinal microbiome is now recognized as an important factor. New derivatives of the nitrogen mustards continue to be assessed. Oxazaphosphorine analogs have been synthesized in attempts to both improve efficacy and reduce toxicity, with varying degrees of success. Combinations of the nitrogen mustards with monoclonal antibodies and small-molecule targeted agents are being evaluated. SIGNIFICANCE STATEMENT: The nitrogen mustards are important, well-established therapeutic agents that are used to treat a variety of diseases. Their role is continuing to evolve.

Evaluation of a Meropenem and Piperacillin Monitoring Program in Intensive Care Unit Patients Calls for the Regular Assessment of Empirical Targets and Easy-to-Use Dosing Decision Tools

The drug concentrations targeted in meropenem and piperacillin/tazobactam therapy also depend on the susceptibility of the pathogen. Yet, the pathogen is often unknown, and antibiotic therapy is guided by empirical targets. To reliably achieve the targeted concentrations, dosing needs to be adjusted for renal function. We aimed to evaluate a meropenem and piperacillin/tazobactam monitoring program in intensive care unit (ICU) patients by assessing (i) the adequacy of locally selected empirical targets, (ii) if dosing is adequately adjusted for renal function and individual target, and (iii) if dosing is adjusted in target attainment (TA) failure. In a prospective, observational clinical trial of drug concentrations, relevant patient characteristics and microbiological data (pathogen, minimum inhibitory concentration (MIC)) for patients receiving meropenem or piperacillin/tazobactam treatment were collected. If the MIC value was available, a target range of 1–5 × MIC was selected for minimum drug concentrations of both drugs. If the MIC value was not available, 8–40 mg/L and 16–80 mg/L were selected as empirical target ranges for meropenem and piperacillin, respectively. A total of 356 meropenem and 216 piperacillin samples were collected from 108 and 96 ICU patients, respectively. The vast majority of observed MIC values was lower than the empirical target (meropenem: 90.0%, piperacillin: 93.9%), suggesting empirical target value reductions. TA was found to be low (meropenem: 35.7%, piperacillin 50.5%) with the lowest TA for severely impaired renal function (meropenem: 13.9%, piperacillin: 29.2%), and observed drug concentrations did not significantly differ between patients with different targets, indicating dosing was not adequately adjusted for renal function or target. Dosing adjustments were rare for both drugs (meropenem: 6.13%, piperacillin: 4.78%) and for meropenem irrespective of TA, revealing that concentration monitoring alone was insufficient to guide dosing adjustment. Empirical targets should regularly be assessed and adjusted based on local susceptibility data. To improve TA, scientific knowledge should be translated into easy-to-use dosing strategies guiding antibiotic dosing.

Pharmacometabonomic Association of Cyclophosphamide 4-hydroxylation in Hematopoietic Cell Transplant Recipients

The widely used alkylating agent cyclophosphamide (CY) has substantive interpatient variability in the area under the curve (AUC) of it and its metabolites. Numerous factors may influence the drug‐metabolizing enzymes that metabolize CY to 4‐hydroxycyclophosphamide (4HCY), the principal precursor to CY’s cytotoxic metabolite. We sought to identify endogenous metabolomics compounds (EMCs) associated with 4HCY formation clearance (ratio of 4HCY/CY AUC) using global metabolomics. Patients who undergo hematopoietic cell transplantation receiving post‐transplant CY (PT‐CY) were enrolled, cohort 1 (n = 26) and cohort 2 (n = 25) donating longitudinal blood samples before they started HCT (pre‐HCT), before infusion of the donor allograft (pre‐graft), before the first dose of PT‐CY (pre‐CY), and 24 h after the first dose of PT‐CY (24‐h post‐CY), which is also immediately before the second dose of CY. A total of 512 and 498 EMCs were quantitated in two cohorts, respectively. Both univariate linear regression with false discovery rate (FDR), and pathway enrichment analyses using a global association test were performed. At the pre‐CY time point, no EMCs were associated at FDR less than 0.1. At pre‐HCT, cohort 1 had one EMC (levoglucosan) survive the FDR threshold. At pre‐graft, cohort 1 and cohort 2 had 20 and 13 EMCs, respectively, exhibiting unadjusted p values less than 0.05, with the only EMCs having an FDR less than 0.1 being two unknown EMCs. At 24‐h post‐CY, there were three EMCs, two ketones, and threitol, at FDR less than 0.1 in cohort 2. These results demonstrate the potential of pharmacometabonomics, but future studies in larger samples are needed to optimize CY.

Higher Fludarabine and Cyclophosphamide Exposures Lead to Worse Outcomes in Reduced-Intensity Conditioning Hematopoietic Cell Transplantation for Adult Hematologic Malignancy

Reduced-intensity conditioning regimens using fludarabine (Flu) and cyclophosphamide (Cy) have been widely used in hematopoietic cell transplantation (HCT) recipients. The optimal exposure of these agents remains to be determined. We aimed to delineate the exposure-outcome associations of Flu and Cy separately and then both combined on HCT outcomes. This is a single-center, observational, pharmacokinetic (PK)-pharmacodynamic (PD) study of Flu and Cy in HCT recipients age ≥18 years who received Cy (50 mg/kg in a single dose), Flu (150 to 200 mg/m² given as 5 daily doses), and total body irradiation (TBI; 200 cGy). We measured trough concentrations of 9-β-D-arabinosyl-2-fluoradenine (F-ara-A), an active metabolite of Flu, on days -5 and -4 (F-ara-A_Day-5 and F-ara-A_Day-4, respectively), and measured phosphoramide mustard (PM), the final active metabolite of Cy, and estimated the area under the curve (AUC). The 89 enrolled patients had a nonrelapse mortality (NRM) of 9% (95% confidence interval [CI], 3% to 15%) at day +100 and 15% (95% CI, 7% to 22%) at day +180, and an overall survival (OS) of 73% (95% CI, 63% to 81%) at day +180. In multivariate analysis, higher PM area under the curve (AUC) for 0 to 8 hours (PM AUC_{0-8 hr}) was an independent predictor of worse NRM (P < .01 at both day +100 and day +180) and worse day +180 OS (P < .01), but no associations were identified for F-ara-A trough levels. We observed lower day +100 NRM in those with both high F-ara-A_Day-4 trough levels (≥40 ng/mL; >25th percentile) and low PM AUC_{0-8 hr} (<34,235 hr ng/mL; <75th percentile), compared with high exposures to both agents (hazard ratio, 0.06; 95% CI, 0.01 to 0.48). No patients with low F-ara-A_Day-4 (<40 ng/mL; <25th percentile) had NRM by day +100, regardless of PM AUC. The interpatient PK variability was large in F-ara-A_Day-4 trough and PM AUC_{0-8 hr} (29-fold and 5.0-fold, respectively). Flu exposure alone was not strongly associated with NRM or OS in this reduced Flu dose regimen; however, high exposure to both Flu and Cy was associated with a >16-fold higher NRM. These results warrant further investigation to optimize reduced-intensity regimens based on better PK-PD understanding and possible adaptation to predictable factors influencing drug clearance.

Fused Deposition Modeling (FDM), the new asset for the production of tailored medicines

Over the last few years, conventional medicine has been increasingly moving towards precision medicine. Today, the production of oral pharmaceutical forms tailored to patients is not achievable by traditional industrial means. A promising solution to customize oral drug delivery has been found in the utilization of 3D Printing and in particular Fused Deposition Modeling (FDM). Thus, the aim of this systematic literature review is to provide a synthesis on the production of pharmaceutical solid oral forms using FDM technology. In total, 72 relevant articles have been identified via two well-known scientific databases (PubMed and ScienceDirect). Overall, three different FDM methods have been reported: "Impregnation-FDM", "Hot Melt Extrusion coupled with FDM" and "Print-fill", which yielded to the formulation of thermoplastic polymers used as main component, five families of other excipients playing different functional roles and 47 active ingredients. Solutions are underway to overcome the high printing temperatures, which was the initial brake on to use thermosensitive ingredients with this technology. Also, the moisture sensitivity shown by a large number of prints in preliminary storage studies is highlighted. FDM seems to be especially fitted for the treatment of rare diseases, and particular populations requiring tailored doses or release kinetics. For future use of FDM in clinical trials, an implication of health regulatory agencies would be necessary. Hence, further efforts would likely be oriented to the use of a quality approach such as "Quality by Design" which could facilitate its approval by the authorities, and also be an aid to the development of this technology for manufacturers.

GFR Measurement and Chemotherapy Dosing in Patients with Kidney Disease and Cancer

Chemotherapeutic agents require precise dosing to ensure optimal efficacy and minimize complications. For those agents that are removed from the body by the kidney, accurate knowledge of GFR is critical. In addition, GFR needs to be determined rapidly, easily, and, if possible, with little additional cost. The ability to easily measure GFR also allows for rapid detection of nephrotoxicity. Current methodologies include direct clearance measurement of an indicator substance or estimation of creatinine clearance or GFR through regression equations that use a serum marker, such as creatinine or cystatin C. These methodologies all have shortfalls and limitations, some of which are specific to the patient with cancer. Newer methodologies that directly measure GFR are in clinical trials and offer the ability to rapidly and noninvasively provide accurate estimates of drug clearance as well as detection of nephrotoxicity. These methods offer the opportunity to refine drug dosing and improve outcomes.

Acute Kidney Injury and CKD Associated with Hematopoietic Stem Cell Transplantation

Hematopoietic stem cell transplantation is a life-saving therapy for many patients with cancer, as well as patients with some nonmalignant hematologic disorders, such as aplastic anemia, sickle cell disease, and certain congenital immune deficiencies. Kidney injury directly associated with stem cell transplantation includes a wide range of structural and functional abnormalities, which may be vascular (hypertension, thrombotic microangiopathy), glomerular (albuminuria, nephrotic glomerulopathies), and/or tubulointerstitial. AKI occurs commonly after stem cell transplant, affecting 10%-73% of patients. The cause is often multifactorial and can include sepsis, nephrotoxic medications, marrow infusion syndrome, hepatic sinusoidal obstruction syndrome, thrombotic microangiopathy, infections, and graft versus host disease. The risk of post-transplant kidney injury varies depending on patient characteristics, type of transplant (allogeneic versus autologous), and choice of chemotherapeutic conditioning regimen (myeloablative versus nonmyeloablative). Importantly, AKI is associated with substantial morbidity, including the need for KRT in approximately 5% of patients and the development of CKD in up to 60% of transplant recipients. AKI has been associated universally with higher all-cause and nonrelapse mortality regardless of transplant type, and studies have consistently shown extremely high (>80%) mortality rates in those patients requiring acute dialysis. Accordingly, prevention, early recognition, and prompt treatment of kidney injury are essential to improving kidney and patient outcomes after hematopoietic stem cell transplantation, and for realizing the full potential of this therapy.

Association of Antiepileptic Medications with Outcomes after Allogeneic Hematopoietic Cell Transplantation with Busulfan/Cyclophosphamide Conditioning

High-dose busulfan (BU) followed by high-dose cyclophosphamide (CY) before allogeneic hematopoietic cell transplantation (HCT) has long been used as treatment for hematologic malignancies. Administration of phenytoin or newer alternative antiepileptic medications (AEMs) prevents seizures caused by BU. Phenytoin induces enzymes that increase exposure to active CY metabolites in vivo, whereas alternative AEMs do not have this effect. Lower exposure to active CY metabolites with the use of alternative AEMs could decrease the risk of toxicity but might increase the risk of recurrent malignancy after HCT. Previous studies have not determined whether outcomes with alternative AEMs differ from those with phenytoin in patients treated with BU/CY before allogeneic HCT. We studied a cohort of 2155 patients, including 1460 treated with phenytoin and 695 treated with alternative AEMs, who received BU/CY before allogeneic HCT between 2004 and 2014. We found no differences suggesting decreased overall survival or relapse-free survival or increased risks of relapse, nonrelapse mortality, acute or chronic graft-versus-host disease, or regimen-related toxicity associated with the use of alternative AEMs compared with phenytoin. The risk of dialysis was lower in the alternative AEM group than in the phenytoin group. Alternative AEMs are safe for prevention of seizures after BU administration and can avoid the undesirable toxicities and drug interactions caused by phenytoin.

Rapid Advances in Immunotherapy to Treat Cancer

Immunotherapy is now the fourth pillar of cancer therapy, with surgery, radiation, and traditional chemotherapy being the remaining pillars. Over the past decade, enthusiasm for immunotherapy has increased because of, in part, data showing that it consistently improves overall survival in select patients with historically refractory cancers. This issue covers various aspects of immunotherapy ranging from use of 1) chimeric antigen receptor (CAR) T cells to treat patients with B-cell acute lymphoblastic leukemia; 2) population pharmacokinetic/dynamic modeling to develop new immune checkpoint inhibitors; and 3) simulations of existing population pharmacokinetic models of immunotherapy to minimize waste without compromising exposure and efficacy.

Early and late adverse renal effects after potentially nephrotoxic treatment for childhood cancer

BACKGROUND

Improvements in diagnostics and treatment for paediatric malignancies resulted in a major increase in survival. However, childhood cancer survivors (CCS) are at risk of developing adverse effects caused by multimodal treatment for their malignancy. Nephrotoxicity is a known side effect of several treatments, including cisplatin, carboplatin, ifosfamide, radiotherapy and nephrectomy, and can cause glomerular filtration rate (GFR) impairment, proteinuria, tubulopathy, and hypertension. Evidence about the long-term effects of these treatments on renal function remains inconclusive. It is important to know the risk of, and risk factors for, early and late adverse renal effects, so that ultimately treatment and screening protocols can be adjusted. This review is an update of a previously published Cochrane Review.

OBJECTIVES

To evaluate existing evidence on the effects of potentially nephrotoxic treatment modalities on the prevalence of renal dysfunction in survivors treated for childhood cancer with a median or mean survival of at least one year after cessation of treatment, where possible in comparison with the general population or CCS treated without potentially nephrotoxic treatment. In addition, to evaluate evidence on associated risk factors, such as follow-up duration, age at time of diagnosis and treatment combinations, as well as the effect of doses.

SEARCH METHODS

On 31 March 2017 we searched the following electronic databases: CENTRAL, MEDLINE and Embase. In addition, we screened reference lists of relevant studies and we searched the congress proceedings of the International Society of Pediatric Oncology (SIOP) and The American Society of Pediatric Hematology/Oncology (ASPHO) from 2010 to 2016/2017.

SELECTION CRITERIA

Except for case reports, case series and studies including fewer than 20 participants, we included studies with all study designs that reported on renal function (one year or longer after cessation of treatment), in CCS treated before the age of 21 years with cisplatin, carboplatin, ifosfamide, radiation involving the kidney region, a nephrectomy, or a combination of two or more of these treatments. When not all treatment modalities were described or the study group of interest was unclear, a study was not eligible for the evaluation of prevalence. We still included it for the assessment of risk factors if it had performed a multivariable analysis.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed study selection, 'Risk of bias' assessment and data extraction using standardised data collection forms. We performed analyses according to the guidelines of the Cochrane Handbook for Systematic Reviews of Interventions.

MAIN RESULTS

Apart from the remaining 37 studies included from the original review, the search resulted in the inclusion of 24 new studies. In total, we included 61 studies; 46 for prevalence, six for both prevalence and risk factors, and nine not meeting the inclusion criteria, but assessing risk factors. The 52 studies evaluating the prevalence of renal dysfunction included 13,327 participants of interest, of whom at least 4499 underwent renal function testing. The prevalence of adverse renal effects ranged from 0% to 84%. This variation may be due to diversity of included malignancies, received treatments, reported outcome measures, follow-up duration and the methodological quality of available evidence.Seven out of 52 studies, including 244 participants, reported the prevalence of chronic kidney disease, which ranged from 2.4% to 32%.Of these 52 studies, 36 studied a decreased (estimated) GFR, including at least 432 CCS, and found it was present in 0% to 73.7% of participants. One eligible study reported an increased risk of glomerular dysfunction after concomitant treatment with aminoglycosides and vancomycin in CCS receiving total body irradiation (TBI). Four non-eligible studies assessing a total cohort of CCS, found nephrectomy and (high-dose (HD)) ifosfamide as risk factors for decreased GFR. The majority also reported cisplatin as a risk factor. In addition, two non-eligible studies showed an association of a longer follow-up period with glomerular dysfunction.Twenty-two out of 52 studies, including 851 participants, studied proteinuria, which was present in 3.5% to 84% of participants. Risk factors, analysed by three non-eligible studies, included HD cisplatin, (HD) ifosfamide, TBI, and a combination of nephrectomy and abdominal radiotherapy. However, studies were contradictory and incomparable.Eleven out of 52 studies assessed hypophosphataemia or tubular phosphate reabsorption (TPR), or both. Prevalence ranged between 0% and 36.8% for hypophosphataemia in 287 participants, and from 0% to 62.5% for impaired TPR in 246 participants. One non-eligible study investigated risk factors for hypophosphataemia, but could not find any association.Four out of 52 studies, including 128 CCS, assessed the prevalence of hypomagnesaemia, which ranged between 13.2% and 28.6%. Both non-eligible studies investigating risk factors identified cisplatin as a risk factor. Carboplatin, nephrectomy and follow-up time were other reported risk factors.The prevalence of hypertension ranged from 0% to 50% in 2464 participants (30/52 studies). Risk factors reported by one eligible study were older age at screening and abdominal radiotherapy. A non-eligible study also found long follow-up time as risk factor. Three non-eligible studies showed that a higher body mass index increased the risk of hypertension. Treatment-related risk factors were abdominal radiotherapy and TBI, but studies were inconsistent.Because of the profound heterogeneity of the studies, it was not possible to perform meta-analyses. Risk of bias was present in all studies.

AUTHORS' CONCLUSIONS

The prevalence of adverse renal effects after treatment with cisplatin, carboplatin, ifosfamide, radiation therapy involving the kidney region, nephrectomy, or any combination of these, ranged from 0% to 84% depending on the study population, received treatment combination, reported outcome measure, follow-up duration and methodological quality. With currently available evidence, it was not possible to draw solid conclusions regarding the prevalence of, and treatment-related risk factors for, specific adverse renal effects. Future studies should focus on adequate study designs and reporting, including large prospective cohort studies with adequate control groups when possible. In addition, these studies should deploy multivariable risk factor analyses to correct for possible confounding. Next to research concerning known nephrotoxic therapies, exploring nephrotoxicity after new therapeutic agents is advised for future studies. Until more evidence becomes available, CCS should preferably be enrolled into long-term follow-up programmes to monitor their renal function and blood pressure.

Liver Complications Following Treatment of Hematologic Malignancy With Anti-CD22-Calicheamicin (Inotuzumab Ozogamicin)

Treatment of hematological malignancy with antibody-drug conjugates (ADCs) may cause liver injury. ADCs deliver a toxic moiety into antigen-expressing tumor cells, but may also injure hepatic sinusoids (sinusoidal obstruction syndrome; SOS). We studied patients who received an anti-CD22/calicheamicin conjugate (inotuzumab ozogamicin; InO) to gain insight into mechanisms of sinusoidal injury, given that there are no CD22⁺ cells in the normal liver, but nonspecific uptake of ADCs by liver sinusoidal endothelial cells (LSECs). Six hundred thirty-eight patients (307 with acute lymphocytic leukemia [ALL], 311 with non-Hodgkin's lymphoma [NHL]) were randomized to either InO or standard chemotherapy (controls). While blinded to treatment assignment, we reviewed all cases with hepatobiliary complications to adjudicate the causes. Frequency of SOS among patients who received InO was 5 of 328 (1.5%), compared to no cases among 310 control patients. Drug-induced liver injury (DILI) developed in 26 (7.9%) InO recipients and 3 (1%) controls. Intrahepatic cholestasis (IHC) was observed in 4.9% of InO recipients and in 5.5% of controls. Subsequent to the randomization study, 113 patients with ALL underwent allogeneic hematopoietic cell transplantation (HCT); frequency of SOS in those previously exposed to InO was 21 of 79 (27%) versus 3 of 34 (9%) in controls. An exploratory multivariate model identified a past history of liver disease and thrombocytopenia before conditioning therapy as dominant risk factors for SOS after transplant. Conclusion: Frequencies of SOS and DILI after inotuzumab ozogamicin treatment were 1.5% and 7.9%, respectively, compared to none and 1% among controls who received standard chemotherapy. These data suggest that ADCs that do not target antigens present in the normal liver have a relatively low frequency of SOS, but a relatively high frequency of DILI.

Transplant-Associated Thrombotic Microangiopathy in Pediatric Hematopoietic Cell Transplant Recipients: A Practical Approach to Diagnosis and Management

Transplant-associated thrombotic microangiopathy (TA-TMA) is an endothelial damage syndrome that is increasingly identified as a complication of both autologous and allogeneic hematopoietic cell transplantation (HCT) in children. If not promptly diagnosed and treated, TA-TMA can lead to significant morbidity (e.g., permanent renal injury) or mortality. However, as the recognition of the early stages of TA-TMA may be difficult, we propose a TA-TMA "triad" of hypertension, thrombocytopenia (or platelet transfusion refractoriness), and elevated lactate dehydrogenase (LDH). While not diagnostic, this triad should prompt further evaluation for TA-TMA. There is increased understanding of the risk factors for the development of TA-TMA, including those which are inherent (e.g., race, genetics), transplant approach-related (e.g., second HCT, use of HLA-mismatched donors), and related to post-transplant events (e.g., receipt of calcineurin inhibitors, development of graft-vs. -host-disease, or certain infections). This understanding should lead to enhanced screening for TA-TMA signs and symptoms in high-risk patients. The pathophysiology of TA-TMA is complex, resulting from a cycle of activation of endothelial cells to produce a pro-coagulant state, along with activation of antigen-presenting cells and lymphocytes, as well as activation of the complement cascade and microthrombi formation. This has led to the formulation of a "Three-Hit Hypothesis" in which patients with either an underlying predisposition to complement activation or pre-existing endothelial injury (Hit 1) undergo a toxic conditioning regimen causing endothelial injury (Hit 2), and then additional insults are triggered by medications, alloreactivity, infections, and/or antibodies (Hit 3). Understanding this cycle of injury permits the development of a specific TA-TMA treatment algorithm designed to treat both the triggers and the drivers of the endothelial injury. Finally, several intriguing approaches to TA-TMA prophylaxis have been identified. Future work on the development of a single diagnostic test with high specificity and sensitivity, and the development of a robust risk-scoring system, will further improve the management of this serious post-transplant complication.

Kidney dysfunction after hematopoietic cell transplantation-Etiology, management, and perspectives

Kidney dysfunction is a common complication of hematopoietic cell transplantation (HCT) with proven negative impact on early and long-term mortality. Causes of this complication are diverse, usually overlapping, and poorly understood. Therefore, management implicates multidirectional investigations and simultaneous treatment of suspected causes. The etiology is frequently unconfirmed due to a lack of specific markers and prevalence of contraindications to renal biopsy among HCT recipients. Herein, we provide a summary of etiology and propose an algorithm for evaluation of kidney injury after HCT. We also map out the most urgent areas for research that aim to identify patients at risk of severe renal injury and develop nephroprotective strategies.

Enantioselectivity in the Metabolism of Cyclophosphamide in Patients With Multiple or Systemic Sclerosis

The aim of this study was to evaluate the enantioselective pharmacokinetics of cyclophosphamide and its metabolites 4-hydroxycyclophosphamide and carboxyethylphosphoramide mustard in patients with systemic or multiple sclerosis. Patients with systemic sclerosis (n = 10) or multiple sclerosis (n = 10), genotyped for the allelic variants of CYP2C9*2 and CYP2C9*3 and of the CYP2B6 G516T polymorphism, were treated with 50 mg cyclophosphamide/kg daily for 4 days. Serial blood samples were collected up to 24 hours after administration of the last cyclophosphamide dose. Cyclophosphamide, 4-hydroxycyclophosphamide, and carboxyethylphosphoramide enantiomers were analyzed in plasma samples using liquid chromatography-tandem mass spectrometry coupled to chiral column Chiralcel OD-R or Chiralpak AD-RH. Cytokines IL-2, IL-4, IL-6, IL-8, IL-10, IL- 12p70, IL-17, TNF-α, and INT-δ in the plasma samples collected before cyclophosphamide infusion were analyzed by Milliplex MAP human cytokine/chemokine. Pharmacokinetic parameters showed higher plasma concentrations of (S)-(-)-cyclophosphamide (AUC 215.0 vs 186.2 μg·h/mL for multiple sclerosis patients and 219.1 vs 179.2 μg·h/mL for systemic sclerosis patients) and (R)-4-hydroxycyclophosphamide (AUC 5.6 vs 3.7 μg·h/mL for multiple sclerosis patients and 6.3 vs 5.6 μg·h/mL for systemic sclerosis patients) when compared to their enantiomers in both groups of patients, whereas the pharmacokinetics of the carboxyethylphosphoramide metabolite was not enantioselective. Cytokines' plasma concentrations were similar between multiple and systemic sclerosis groups. The pharmacokinetics of cyclophosphamide is enantioselective in patients with systemic sclerosis and multiple sclerosis, with higher plasma concentrations of the (S)-(-)-cyclophosphamide enantiomer due to the preferential formation of the (R)-4-hydroxycyclophosphamide metabolite.

Pharmacokinetics, Pharmacodynamics, and Pharmacogenomics of Immunosuppressants in Allogeneic Hematopoietic Cell Transplantation: Part II

Part I of this article included a pertinent review of allogeneic hematopoietic cell transplantation (alloHCT), the role of postgraft immunosuppression in alloHCT, and the pharmacokinetics, pharmacodynamics, and pharmacogenomics of the calcineurin inhibitors and methotrexate. In this article (Part II), we review the pharmacokinetics, pharmacodynamics, and pharmacogenomics of mycophenolic acid (MPA), sirolimus, and the antithymocyte globulins (ATG). We then discuss target concentration intervention (TCI) of these postgraft immunosuppressants in alloHCT patients, with a focus on current evidence for TCI and on how TCI may improve clinical management in these patients. Currently, TCI using trough concentrations is conducted for sirolimus in alloHCT patients. Several studies demonstrate that MPA plasma exposure is associated with clinical outcomes, with an increasing number of alloHCT patients needing TCI of MPA. Compared with MPA, there are fewer pharmacokinetic/dynamic studies of rabbit ATG and horse ATG in alloHCT patients. Future pharmacokinetic/dynamic research of postgraft immunosuppressants should include '-omics'-based tools: pharmacogenomics may be used to gain an improved understanding of the covariates influencing pharmacokinetics as well as proteomics and metabolomics as novel methods to elucidate pharmacodynamic responses.

The effect of cyclophosphamide on the immune system: implications for clinical cancer therapy

Cyclophosphamide is an alkylating agent belonging to the group of oxazaphosporines. As cyclophosphamide is in clinical use for more than 40 years, there is a lot of experience using this drug for the treatment of cancer and as an immunosuppressive agent for the treatment of autoimmune and immune-mediated diseases. Besides antimitotic and antireplicative effects, cyclophosphamide has immunosuppressive as well as immunomodulatory properties. Cyclophosphamide shows selectivity for T cells and is therefore now frequently used in tumour vaccination protocols and to control post-transplant allo-reactivity in haplo-identical unmanipulated bone marrow after transplantation. The schedule of administration is of special importance for the immunological effect: while cyclophosphamide can be used in high-dose therapy for the complete eradication of haematopoietic cells, lower doses of cyclophosphamide are relatively selective for T cells. Of special interest is the fact that a single administration of low-dose cyclophosphamide is able to selectively suppress regulatory T cells (Tregs). This effect can be used to counteract immunosuppression in cancer. However, cyclophosphamide can also increase the number of myeloid-derived suppressor cells. Combination of cyclophosphamide with other immunomodulatory agents could be a promising approach to treat different forms of advanced cancer.

How I treat hepatitis C virus infection in patients with hematologic malignancies

Hepatitis C virus (HCV) infection is not uncommon in cancer patients. Over the past 5 years, treatment of chronic HCV infection in patients with hematologic malignancies has evolved rapidly as safe and effective direct-acting antivirals (DAAs) have become the standard-of-care treatment. Today, chronic HCV infection should not prevent a patient from receiving cancer therapy or participating in clinical trials of chemotherapy because most infected patients can achieve virologic cure. Elimination of HCV from infected cancer patients confers virologic, hepatic, and oncologic advantages. Similar to the optimal therapy for HCV-infected patients without cancer, the optimal therapy for HCV-infected patients with cancer is evolving rapidly. The choice of regimens with DAAs should be individualized after thorough assessment for potential hematologic toxic effects and drug-drug interactions. This study presents clinical scenarios of HCV-infected patients with hematologic malignancies, focusing on diagnosis, clinical and laboratory presentations, complications, and DAA therapy. An up-to-date treatment algorithm is presented.

Cyclophosphamide pharmacokinetics and pharmacogenetics in children with B-cell non-Hodgkin's lymphoma

Introduction

Variation in cyclophosphamide pharmacokinetics and metabolism has been highlighted as a factor that may impact on clinical outcome in various tumour types. The current study in children with B-cell non-Hodgkin's lymphoma (NHL) was designed to corroborate previous findings in a large prospective study incorporating genotype for common polymorphisms known to influence cyclophosphamide pharmacology.

Methods

A total of 644 plasma samples collected over a 5 year period, from 49 B-cell NHL patients ≤18 years receiving cyclophosphamide (250 mg/m²), were used to characterise a population pharmacokinetic model. Polymorphisms in genes including CYP2B6 and CYP2C19 were analysed.

Results

A two-compartment model provided the best fit of the population analysis. The mean cyclophosphamide clearance value following dose 1 was significantly lower than following dose 5 (1.83 ± 1.07 versus 3.68 ± 1.43 L/h/m², respectively; mean ± standard deviation from empirical Bayes estimates; P < 0.001). The presence of at least one CYP2B6*6 variant allele was associated with a lower cyclophosphamide clearance following both dose 1 (1.54 ± 0.11 L/h/m² versus 2.20 ± 0.31 L/h/m², P = 0.033) and dose 5 (3.12 ± 0.17 L/h/m² versus 4.35 ± 0.37 L/h/m², P = 0.0028), as compared to homozygous wild-type patients. No pharmacokinetic parameters investigated were shown to have a significant influence on progression free survival.

Conclusion

The results do not support previous findings of a link between cyclophosphamide pharmacokinetics or metabolism and disease recurrence in childhood B-cell NHL. While CYP2B6 genotype was shown to influence pharmacokinetics, there was no clear impact on clinical outcome.

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The influence of cyclophosphamide clinical pharmacology on childhood cancer outcome has been investigated

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The presence of at least one CYP2B6*6 variant allele was associated with a lower rate of cyclophosphamide clearance

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Pharmacokinetic parameters investigated were not shown to have a marked influence on clinical outcome

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Findings do not support a link between cyclophosphamide metabolism and disease recurrence in B-cell non-Hodgkin's lymphoma

The Sequence of Cyclophosphamide and Myeloablative Total Body Irradiation in Hematopoietic Cell Transplantation for Patients with Acute Leukemia

Limited clinical data are available to assess whether the sequencing of cyclophosphamide (Cy) and total body irradiation (TBI) changes outcomes. We evaluated the sequence in 1769 (CyTBI, n = 948; TBICy, n = 821) recipients of related or unrelated hematopoietic cell transplantation who received TBI (1200 to 1500 cGY) for acute leukemia from 2003 to 2010. The 2 cohorts were comparable for median age, performance score, type of leukemia, first complete remission, Philadelphia chromosome-positive acute lymphoblastic leukemia, HLA-matched siblings, stem cell source, antithymocyte globulin use, TBI dose, and type of graft-versus-host disease (GVHD) prophylaxis. The sequence of TBI did not significantly affect transplantation-related mortality (24% versus 23% at 3 years, P = .67; relative risk, 1.01; P = .91), leukemia relapse (27% versus 29% at 3 years, P = .34; relative risk, .89, P = .18), leukemia-free survival (49% versus 48% at 3 years, P = .27; relative risk, .93; P = .29), chronic GVHD (45% versus 47% at 1 year, P = .39; relative risk, .9; P = .11), or overall survival (53% versus 52% at 3 years, P = .62; relative risk, .96; P = .57) for CyTBI and TBICy, respectively. Corresponding cumulative incidences of sinusoidal obstruction syndrome were 4% and 6% at 100 days (P = .08), respectively. This study demonstrates that the sequence of Cy and TBI does not impact transplantation outcomes and complications in patients with acute leukemia undergoing hematopoietic cell transplantation with myeloablative conditioning.

Population pharmacokinetic/dynamic model of lymphosuppression after fludarabine administration

PURPOSE

Quantitative relationships between 9-β-D-arabinofuranosyl-2-fluoroadenine (F-ara-A) concentrations and lymphosuppression have not been reported, but would be useful for regimen design. A population pharmacokinetic/pharmacodynamic model was constructed in this study using data from 41 hematopoietic cell transplant (HCT) recipients conditioned with busulfan in combination with fludarabine (total dose 120 mg/m², Protocol 1519) or with fludarabine (total dose 250 mg/m²) with rabbit antithymocyte globulin (rATG, Protocol 2041).

METHODS

Individual pharmacokinetic parameters were fixed to post hoc Bayesian estimates, and circulating absolute lymphocyte counts (ALC) were obtained during the 3 weeks prior to graft infusion. A semi-physiological cell-kill model with three lymphocyte transit compartments was applied and aptly characterized the time course of suppression of circulating ALC by fludarabine administration. Drug- and system-specific parameters were estimated using a maximum likelihood expectation maximization algorithm, and the final model was qualified using an internal visual predictive check.

RESULTS

The final model successfully characterized the time course and variability in ALC. Pharmacodynamic parameters exhibited considerable between subject variability (38.9-211 %). The HCT protocol was the only covariate associated with the pharmacodynamic parameters, specifically the lymphocyte kill rate, the transit rate between lymphocyte compartments, and the baseline ALC.

CONCLUSIONS

This model can be used to simulate the degree of lymphosuppression for design of future fludarabine-based conditioning regimens.

Liver disease after hematopoietic cell transplantation in adults

Liver-related complications constitute a large component of the overall morbidity and mortality associated with hematopoietic cell transplantation. Affecting up to 80% of allogeneic HCT recipients, prompt recognition and treatment are essential. The differential diagnosis is broad and is best categorized by time of onset after transplantation. Early complications include drug-induced liver injury, sinusoidal obstruction syndrome, and graft-versus-host disease. Late complications include infectious sequelae, cirrhosis, and hepatic malignancies. Patients being considered for hematopoietic cell transplantation should be screened and evaluated for liver-related complications to help improve outcomes.

Preparative regimen dosing for hematopoietic stem cell transplantation in patients with chronic hepatic impairment: analysis of the literature and recommendations

Hematopoietic stem cell transplantation (HSCT) is a potentially life-saving therapy for patients with malignant and nonmalignant disease states. Transplant has been associated with high treatment-related morbidity and mortality, therefore limiting its usefulness in patients with baseline liver dysfunction. In the event that a patient with hepatic insufficiency is selected for HSCT, dosage adjustments may be considered; however, no reliable endogenous biomarkers can serve as a guide for adjustments. There is no clear standard or guideline for how to approach these patients, and most adjustments are made empirically on the basis of expert opinion. This article offers practical advice and outlines our personal approaches to provide dosing recommendations for commonly-used preparative agents in the setting of hepatic impairment with the aim to optimize dosing for this patient population.

Busulfan in infant to adult hematopoietic cell transplant recipients: a population pharmacokinetic model for initial and Bayesian dose personalization

PURPOSE

Personalizing intravenous busulfan doses to a target plasma concentration at steady state (Css) is an essential component of hematopoietic cell transplantation (HCT). We sought to develop a population pharmacokinetic model to predict i.v. busulfan doses over a wide age spectrum (0.1-66 years) that accounts for differences in age and body size.

EXPERIMENTAL DESIGN

A population pharmacokinetic model based on normal fat mass and maturation based on postmenstrual age was built from 12,380 busulfan concentration time points obtained after i.v. busulfan administration in 1,610 HCT recipients. Subsequently, simulation results of the initial dose necessary to achieve a target Css with this model were compared with pediatric-only models.

RESULTS

A two-compartment model with first-order elimination best fit the data. The population busulfan clearance was 12.4 L/h for an adult male with 62 kg normal fat mass (equivalent to 70 kg total body weight). Busulfan clearance, scaled to body size-specifically normal fat mass, is predicted to be 95% of the adult clearance at 2.5 years postnatal age. With a target Css of 770 ng/mL, a higher proportion of initial doses achieved the therapeutic window with this age- and size--dependent model (72%) compared with dosing recommended by the U.S. Food and Drug Administration (57%) or the European Medicines Agency (70%).

CONCLUSION

This is the first population pharmacokinetic model developed to predict initial i.v. busulfan doses and personalize to a target Css over a wide age spectrum, ranging from infants to adults.

Early and late renal adverse effects after potentially nephrotoxic treatment for childhood cancer

BACKGROUND

Great improvements in diagnostics and treatment for malignant disease in childhood have led to a major increase in survival. However, childhood cancer survivors (CCS) are at great risk for developing adverse effects caused by multimodal treatment for their malignancy. Nephrotoxicity is one of these known (acute) side effects of several treatments, including cisplatin, carboplatin, ifosfamide, radiotherapy and nephrectomy, and can cause glomerular filtration rate impairment, proteinuria, tubulopathy and hypertension. However, evidence about the long-term effects of these treatments on renal function remains inconclusive. To reduce the number of (long-term) nephrotoxic events in CCS, it is important to know the risk of, and risk factors for, early and late renal adverse effects, so that ultimately treatment and screening protocols can be adjusted.

OBJECTIVES

To evaluate existing evidence on the effects of potentially nephrotoxic treatment modalities on the prevalence of and associated risk factors for renal dysfunction in survivors treated for childhood cancer with a median or mean survival of at least one year after cessation of treatment, where possible in comparison with healthy controls or CCS treated without potentially nephrotoxic treatment.

SEARCH METHODS

We searched the following electronic databases: the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 4, 2011), MEDLINE/PubMed (from 1945 to December 2011) and EMBASE/Ovid (from 1980 to December 2011).

SELECTION CRITERIA

With the exception of case reports, case series and studies including fewer than 20 participants, we included studies with all study designs that reported on renal function (one year or longer after cessation of treatment) in children and adults who were treated for a paediatric malignancy (aged 18 years or younger at diagnosis) with cisplatin, carboplatin, ifosfamide, radiation including the kidney region and/or a nephrectomy.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed study selection, risk of bias assessment and data extraction using standardised data collection forms. Analyses were performed according to the guidelines of the Cochrane Handbook for Systematic Reviews of Interventions.

MAIN RESULTS

The search strategy identified 5504 studies, of which 5138 were excluded on the basis of title and/or abstract. The full-text screening of the remaining 366 articles resulted in the inclusion of 57 studies investigating the prevalence of and sometimes also risk factors for early and late renal adverse effects of treatment for childhood cancer. The 57 studies included at least 13,338 participants of interest for this study, of whom at least 6516 underwent renal function testing. The prevalence of renal adverse effects ranged from 0% to 84%. This variation may be due to diversity in included malignancies, prescribed treatments, reported outcome measurements and the methodological quality of available evidence.Chronic kidney disease/renal insufficiency (as defined by the authors of the original studies) was reported in 10 of 57 studies. The prevalence of chronic kidney disease ranged between 0.5% and 70.4% in the 10 studies and between 0.5% and 18.8% in the six studies that specifically investigated Wilms' tumour survivors treated with a unilateral nephrectomy.A decreased (estimated) glomerular filtration rate was present in 0% to 50% of all assessed survivors (32/57 studies). Total body irradiation; concomitant treatment with aminoglycosides, vancomycin, amphotericin B or cyclosporin A; older age at treatment and longer interval from therapy to follow-up were significant risk factors reported in multivariate analyses. Proteinuria was present in 0% to 84% of all survivors (17/57 studies). No study performed multivariate analysis to assess risk factors for proteinuria.Hypophosphataemia was assessed in seven studies. Reported prevalences ranged between 0% and 47.6%, but four of seven studies found a prevalence of 0%. No studies assessed risk factors for hypophosphataemia using multivariate analysis. The prevalence of impairment of tubular phosphate reabsorption was mostly higher (range 0% to 62.5%; 11/57 studies). Higher cumulative ifosfamide dose, concomitant cisplatin treatment, nephrectomy and longer follow-up duration were significant risk factors for impaired tubular phosphate reabsorption in multivariate analyses.Treatment with cisplatin and carboplatin was associated with a significantly lower serum magnesium level in multivariate analysis, and the prevalence of hypomagnesaemia ranged between 0% and 37.5% in the eight studies investigating serum magnesium.Hypertension was investigated in 24 of the 57 studies. Reported prevalences ranged from 0% to 18.2%. A higher body mass index was the only significant risk factor noted in more than one multivariate analysis. Other reported factors that significantly increased the risk of hypertension were use of total body irradiation, abdominal irradiation, acute kidney injury, unrelated or autologous stem cell donor type, growth hormone therapy and older age at screening. Previous infection with hepatitis C significantly decreased the risk of hypertension.Because of the profound heterogeneity of the studies, it was not possible to perform any meta-analysis.

AUTHORS' CONCLUSIONS

The prevalence of renal adverse events after treatment with cisplatin, carboplatin, ifosfamide, radiation therapy involving the kidney region and/or nephrectomy ranged from 0% to 84%. With currently available evidence, it was not possible to draw any conclusions with regard to prevalence of and risk factors for renal adverse effects. Future studies should focus on adequate study design and reporting and should deploy multivariate risk factor analysis to correct for possible confounding. Until more evidence becomes available, CCS should be enrolled into long-term follow-up programmes to monitor their renal function and blood pressure.

Comparison of an assumption-free Bayesian approach with Optimal Sampling Schedule to a maximum a posteriori Approach for Personalizing Cyclophosphamide Dosing

STUDY OBJECTIVE

Variable metabolism, dose-dependent efficacy, and a narrow therapeutic target of cyclophosphamide (CY) suggest that dosing based on individual pharmacokinetics (PK) will improve efficacy and minimize toxicity. Real-time individualized CY dose adjustment was previously explored using a maximum a posteriori (MAP) approach based on a five serum-PK sampling in patients with hematologic malignancy undergoing stem cell transplantation. The MAP approach resulted in an improved toxicity profile without sacrificing efficacy. However, extensive PK sampling is costly and not generally applicable in the clinic. We hypothesize that the assumption-free Bayesian approach (AFBA) can reduce sampling requirements, while improving the accuracy of results.

DESIGN

Retrospective analysis of previously published CY PK data from 20 patients undergoing stem cell transplantation. In that study, Bayesian estimation based on the MAP approach of individual PK parameters was accomplished to predict individualized day-2 doses of CY. Based on these data, we used the AFBA to select the optimal sampling schedule and compare the projected probability of achieving the therapeutic end points.

MEASUREMENTS AND MAIN RESULTS

By optimizing the sampling schedule with the AFBA, an effective individualized PK characterization can be obtained with only two blood draws at 4 and 16 hours after administration on day 1. The second-day doses selected with the AFBA were significantly different than the MAP approach and averaged 37% higher probability of attaining the therapeutic targets.

CONCLUSIONS

The AFBA, based on cutting-edge statistical and mathematical tools, allows an accurate individualized dosing of CY, with simplified PK sampling. This highly accessible approach holds great promise for improving efficacy, reducing toxicities, and lowering treatment costs.

Nonrelapse mortality and mycophenolic acid exposure in nonmyeloablative hematopoietic cell transplantation

We evaluated the pharmacodynamic relationships between mycophenolic acid (MPA), the active metabolite of mycophenolate mofetil (MMF), and outcomes in 308 patients after nonmyeloablative hematopoietic cell transplantation. Patients were conditioned with total body irradiation ± fludarabine, received grafts from HLA-matched related (n = 132) or unrelated (n = 176) donors, and received postgrafting immunosuppression with MMF and a calcineurin inhibitor. Total and unbound MPA pharmacokinetics were determined to day 25; maximum a posteriori Bayesian estimators were used to estimate total MPA concentration at steady state (Css). Rejection occurred in 9 patients, 8 of whom had a total MPA Css less than 3 μg/mL. In patients receiving a related donor graft, MPA Css was not associated with clinical outcomes. In patients receiving an unrelated donor graft, low total MPA Css was associated with increased grades III to IV acute graft-versus-host disease and increased nonrelapse mortality but not with day 28 T cell chimerism, disease relapse, cytomegalovirus reactivation, or overall survival. We conclude that higher initial oral MMF doses and subsequent targeting of total MPA Css to greater than 2.96 μg/mL could lower grades III to IV acute graft-versus-host disease and nonrelapse mortality in patients receiving an unrelated donor graft.

Hepatic sinusoidal obstruction syndrome after allogeneic hematopoietic stem cell transplantation in adult patients with idiopathic aplastic anemia

We retrospectively investigated the incidence, risk factors, and outcomes of SOS (sinusoidal obstruction syndrome; previously veno-occlusive disease [VOD]) after allogeneic hematopoietic stem cell transplantation (alloHSCT) in aplastic anemia. Two hundred and sixty patients were included in the analysis. SOS developed in 7.3% (n=19/260) of patients. Classical Cy (200 mg/m(2))-ATG was the most common conditioning regimen (84.2%) in the SOS group. The SOS mortality rate was 4/19 (21.1%). Univariate analyses revealed that Cy 200 mg/m(2) conditioning (p=0.035), classical Cy-ATG conditioning (p=0.007), and horse ATG conditioning (p<0.001) were significant risk factors for developing SOS. Multivariate analysis revealed that only horse ATG conditioning was a poor prognostic factor (HR=3.484; 95% CI 1.226-9.904; p=0.002). Rabbit ATG (HR 12.719; 95% CI 2.332-69.373; p=0.003) and weight gain>10% (HR 35.655; 95% CI 2.208-575.805; p=0.012) were risk factors in the overall SOS group. Both rabbit ATG conditioning and weight gain of more than 10% were associated with poor overall survival with a median of 1.2 months (5Y survival rate, any risk factor vs. none: 74.6% vs. 0.0%; p<0.001; Fig. 2) in the SOS group. In conclusion, SOS is a relatively rare (7.3%) but highly fatal (21.1%) acute complication of alloHSCT in AA, and the horse ATG conditioning regimen was a significant risk factor for developing SOS.

Cyclophosphamide followed by intravenous targeted busulfan for allogeneic hematopoietic cell transplantation: pharmacokinetics and clinical outcomes

Targeted busulfan ((T)BU) and cyclophosphamide (CY) for allogeneic hematopoietic cell transplantation carries a high risk of sinusoidal obstruction syndrome (SOS) in patients undergoing transplantation for myelofibrosis. We tested the hypothesis that reversing the sequence of administration (from (T)BU/CY to CY/(T)BU) would reduce SOS and day +100 nonrelapse mortality. We enrolled 51 patients with myelofibrosis (n = 20), acute myelogenous leukemia (n = 20), or myelodysplastic syndrome (n = 11) in a prospective trial of CY/(T)BU conditioning for allogeneic hematopoietic cell transplantation. CY 60 mg/kg/day i.v. for 2 days was followed by daily i.v. BU for 4 days, targeted to a concentration at steady state (Css) of 800-900 ng/mL. Compared with (T)BU/CY-conditioned patients, CY/(T)BU-conditioned patients had greater exposure to CY (P < .0001) and less exposure to 4-hydroxycyclophosphamide (P < .0001). Clinical outcomes were compared between cases and controls (n = 271) conditioned with (T)BU/CY for the same indications. In patients with myelofibrosis, CY/(T)BU conditioning was associated with a significantly reduced incidence of SOS (0% versus 30% after (T)BU/CY; P = .006), whereas the incidence of SOS was low in both cohorts with acute myelogenous leukemia/myelodysplastic syndrome. Day +100 mortality was significantly lower in the CY/(T)BU cohort (2% versus 13%; P = .01). CY/(T)BU conditioning had a marked affect on the pharmacokinetics of CY and was associated with significantly lower incidence of SOS and day +100 mortality, suggesting that CY/(T)BU is superior to (T)BU/CY as conditioning for patients with myelofibrosis.

Variation in prescribing patterns and therapeutic drug monitoring of intravenous busulfan in pediatric hematopoietic cell transplant recipients

Personalizing intravenous (IV) busulfan doses in children using therapeutic drug monitoring (TDM) is an integral component of hematopoietic cell transplant. The authors sought to characterize initial dosing and TDM of IV busulfan, along with factors associated with busulfan clearance, in 729 children who underwent busulfan TDM from December 2005 to December 2008. The initial IV busulfan dose in children weighing ≤12 kg ranged 4.8-fold, with only 19% prescribed the package insert dose of 1.1 mg/kg. In those children weighing >12 kg, the initial dose ranged 5.4-fold, and 79% were prescribed the package insert dose. The initial busulfan dose achieved the target exposure in only 24.3% of children. A wide range of busulfan exposures were targeted for children with the same disease (eg, 39 target busulfan exposures for the 264 children diagnosed with acute myeloid leukemia). Considerable heterogeneity exists regarding when TDM is conducted and the number of pharmacokinetic samples obtained. Busulfan clearance varied by age and dosing frequency but not by underlying disease. The authors- group is currently evaluating how using population pharmacokinetics to optimize initial busulfan dose and TDM (eg, limited sampling schedule in conjunction with maximum a posteriori Bayesian estimation) may affect clinical outcomes in children.

Topotecan and cyclophosphamide in adults with relapsed sarcoma

Background. The combination of topotecan and cyclophosphamide (TC) has activity in pediatric patients with recurrent sarcoma, especially Ewing's sarcoma (EWS). We sought to determine the toxicity of and response to TC in adults with recurrent sarcoma. Patients and Methods. Adults treated with TC from 2005 to 2010 were reviewed who received T = topotecan at 0.75 mg/m(2)/day (days 1-5) and C = cyclophosphamide at 250 mg/m(2)/day (days 1-5) every 21 days. Results. Fifteen patients, median age 31 years (range 17.5-56) had nonpleomorphic rhabdomyosarcoma (RMS, n = 6), EWS, n = 5, synovial sarcoma (SS, n = 2) leiomyosarcoma (LMS, n = 1), and desmoplastic small round cell tumour (DSRCT, n = 1). Median time to progression was 2.5 months (range 1.6-13.0). Partial responses were seen in 2/6 RMS and 1/2 SS. Stable disease was seen in 2/5 EWS, 1/2 SS and 1 DSRCT. The most common reason for stopping treatment was progressive disease 12/15, (80%). Hematologic toxicity was common; 7 (47%) patients required blood product transfusion, 5 (33%) patients had fever/neutropenia. At median follow-up time of 7.7 months, all but 1 patient had died of disease.

CONCLUSION

TC combination is tolerable but has only modest activity in adults with recurrent sarcoma. Other regimens deserve exploration for this high-risk group of patients.

A pilot pharmacologic biomarker study of busulfan and fludarabine in hematopoietic cell transplant recipients

PURPOSE

Sixteen patients diagnosed with various hematologic malignancies participated in a phase II study evaluating the addition of rabbit antithymocyte globulin (rATG, Thymoglobulin(®)) to the hematopoietic cell transplant (HCT) conditioning regimen of IV fludarabine monophosphate (fludarabine) and targeted intravenous (IV) busulfan (fludarabine/(T)busulfan). Our goal was to evaluate pharmacologic biomarkers pertinent to both medications in these patients.

METHODS

We characterized the interpatient variability of pharmacologic biomarkers relevant to busulfan, specifically busulfan concentration at steady state, and fludarabine, specifically F-ara-A area under the curve (AUC) and fludarabine triphosphate (F-ara-ATP) intracellular accumulation and concentration in separate CD4(+) and CD8(+) T-lymphocyte populations.

RESULTS

Acute and chronic graft versus host disease (GvHD) occurred in 11 patients and one patient, respectively. Four patients died before day +100 of non-relapse causes, which met the protocol stopping guidelines. The cumulative incidence of relapse was 25% at 3 year post-HCT. Interpatient variability in the busulfan- and fludarabine-relevant pharmacologic biomarkers was 2.1- to 2.5-fold. F-ara-A AUC and accumulated F-ara-ATP in CD8(+) cells had the highest hazard ratio for non-relapse mortality and overall survival, respectively. However, neither achieved statistical significance.

CONCLUSIONS

The low rates of GvHD, particularly in its chronic form, were encouraging, and further biomarker studies are warranted to optimize the fludarabine/(T)busulfan/rATG conditioning regimen.

Patterns of chemotherapy-induced toxicities in younger children and adolescents with rhabdomyosarcoma: a report from the Children's Oncology Group Soft Tissue Sarcoma Committee

BACKGROUND

Patients aged >10 years with rhabdomyosarcoma have an inferior outcome compared with patients ages 1 to 9 years, which may be explained by toxicities (adverse events [AEs]) that result in chemotherapy dose reductions.

METHODS

AEs observed during 1 of 3 randomized chemotherapy regimens (vincristine, dactinomycin, and cyclophosphamide [VAC]; vincristine, dactinomycin, and ifosfamide [VAI]; or vincristine, ifosfamide, and etoposide [VIE]) in the Fourth Intergroup Rhabdomyosarcoma Study were recorded. The incidence of toxicities by age and treatment regimen was determined. The odds of developing AEs in a particular age group (ages 5-9 years, 10-14 years, and 15-20 years) were compared with the odds in the control group of patients ages 1 to 4 years.

RESULTS

In total, 657 patients were eligible for analysis. The estimated 5-year event-free survival rates were 78%, 83%, 67%, and 58% for the groups ages 1 to 4 years, 5 to 9 years, 10 to 14 years, and 15 to 20 years, respectively. Patients ages 15 to 20 years experienced less neutropenia (odds ratio [OR], 0.43; P < .0001), thrombocytopenia (OR, 0.41; P < .0001), anemia (OR, 0.34; P < .0001), and infection (OR, 0.41; P < .0001) compared with younger patients, although they received similar amounts of chemotherapy. In contrast, peripheral nervous system toxicity was higher in adolescents aged >10 years (OR, 4.18; P < .0001). Females experienced more neutropenia (OR, 1.28; P = .05) and thrombocytopenia (OR, 1.26; P = .06) compared with males.

CONCLUSIONS

Adolescents who received treatment for rhabdomyosarcoma experienced significantly less hematologic toxicity and more peripheral nervous system toxicity compared with younger children despite receiving similar amounts of chemotherapy. Although outcomes were inferior in adolescents, it was unclear whether the differences in toxicity observed in the current study had an impact on outcome. The authors concluded that future studies examining the age-related and sex-related differences in pharmacokinetics of chemotherapy are necessary.

Accurate targeting of daily intravenous busulfan with 8-hour blood sampling in hospitalized adult hematopoietic cell transplant recipients

Daily intravenous (i.v.) busulfan is increasingly being used in hematopoietic cell transplantation (HCT) conditioning regimens. Intravenous busulfan doses administered at the traditional frequency of every 6 hours can be targeted ((T)Bu) to a patient-specific concentration at steady state (C(ss)) using therapeutic drug monitoring (TDM). In this report, we describe our experiences with TDM of daily i.v. busulfan in an adult population, with the specific aims of (1) evaluating covariates associated with busulfan clearance, and (2) assessing the feasibility of TDM for outpatient administration of daily (T)Bu with pharmacokinetic sampling over 6 hours. A retrospective pharmacokinetic analysis was conducted in 87 adults receiving daily (T)Bu as part of cyclophosphamide followed by (T)BU (CY/(T)BU), fludarabine monophosphate (fludarabine) followed by (T)BU, or (T)BU concurrent with fludarabine conditioning. The desired C(ss) was achieved in 85% of patients receiving daily i.v. busulfan. Busulfan clearance was not associated with sex or age, but was associated with the day of dosing and conditioning regimen (P = .0016). In patients receiving CY/(T)BU, no differences in clearance were found between dosing days (P > .36); however, clearance decreased significantly in patients receiving fludarabine-based regimens (P = .0016). Busulfan clearance and C(ss) estimates from pharmacokinetic sampling over 8, 11, or 24 hours were comparable (P > .4). However, pharmacokinetic modeling of individual patient concentration-time data over 6 hours could not reliably estimate busulfan clearance or C(ss).

Immunotherapy for treating metastatic colorectal cancer

BACKGROUND

Colorectal cancer remains one of the leading causes of death in the world. Surgery still remains the mainstay of treatment for primary and metastatic colorectal cancer. Immunotherapy used as an adjunct to surgery can play an important role in controlling the spread of tumour.

METHODS

The online databases PubMed, Medline, Scirus and Medscape Oncology were used to identify articles of relevance. Keywords included; "Immunotherapy", "Cellular Immunotherapy", "Metastatic Colorectal Cancer", "Monoclonal Antibody" "Tumour Vaccines" and "Adoptive Cell Therapy". The databases search was from the period of June 1995 until May 2010 inclusive.

RESULTS

Our understanding of tumour immunology has allowed the development of some successful therapies. Immunotherapy through the use of monoclonal antibodies is an effective adjunct to chemotherapy for metastatic colorectal cancer. Other modalities that are in the stages of development are cellular and conjugated vaccines. However, these vaccines are being experimented in advanced stages of colorectal tumours.

CONCLUSION

Colorectal cancer vaccines are being developed for advanced stages of colorectal tumour. However, their use as an early adjunct could potentially limit the spread of tumour or even result in cure. Further trials are required to ensure the safety and efficacy of cellular vaccines against colorectal tumours to allow their use on patients early in their disease presentation.

Allogeneic hematopoietic cell transplantation with full-intensity conditioning for adult acute lymphoblastic leukemia: results from a single center, 1998-2006

A retrospective analysis identified 161 consecutive adults with acute lymphoblastic leukemia who underwent allogeneic hematopoietic cell transplantation (HCT) with full-intensity (myeloablative) conditioning between 1998 and 2006. Median patient age was 36.1 years. Seventy-six patients were in first complete remission (CR1), and 85 were in second or greater CR or in relapse. Fifty-nine patients had Philadelphia chromosome-positive acute lymphoblastic leukemia. A total of 159 patients received chemotherapy plus total body irradiation for conditioning. Graft-versus-host disease prophylaxis included a calcineurin inhibitor plus methotrexate or mycophenolate mofetil. Sixty of the donors were related, and 101 were unrelated. A total of 110 patients received granulocyte-colony stimulating factor-stimulated peripheral blood, 47 received bone marrow, and 4 received cord blood as the stem cell source. Fifty-five patients relapsed at a median of 231 days after transplantation. The estimated 5-year probabilities of relapse-free survival, relapse, and nonrelapse mortality were 47%, 30%, and 29%, respectively. By multivariate analyses, transplantation while in CR1 was the most important predictor of successful transplantation. Pretransplantation evidence of minimal residual disease, especially as detected by flow cytometric analysis, was associated with both lower overall survival and lower relapse-free survival. Compared with a similar cohort of patients undergoing transplantation between 1990 and 1997, overall survival was similar for patients undergoing transplantation in CR1, with lower nonrelapse mortality being offset by higher rates of relapse in patients who underwent transplantation more recently.