Cyclophosphamide disposition in an anephric child

Guidance to develop individual dose recommendations for patients on chronic hemodialysis

INTRODUCTION

In addition to tailored clinical trials in patients on chronic hemodialysis (HD) during drug development, clinician-initiated post-marketing studies and case reports on individual pharmacokinetic (PK) assessments provide an important source of information about drug dialysability and individualized dose recommendations in this vulnerable population. Areas covered: First, factors that may alter drug exposure in HD patients are explained. Second, available regulatory and methodological guidelines for PK assessments in this population are summarized. Third, a 4-step approach is proposed to develop individual dose recommendations for HD patients receiving drugs without data from a PK study: (1) literature search, (2) model-based dosage decisions, (3) validation and refinement through concentration monitoring, and (4) publication of relevant observations. Fourth, clinician-initiated PK assessments and case reports to evaluate and individualize use of drugs in HD patients are reviewed, and recommendations to enhance their quality are discussed. Expert commentary: Guidance on collecting and reporting PK information in individual HD patients is warranted to ensure completeness and consistency of such PK studies. A checklist and template for easy-to-implement PK calculations and pharmacometric modeling is provided to facilitate evaluation and individualization of dosing strategies in these patients.

Sequential renal and bone marrow transplants in a child with Fanconi anemia

FA is an autosomal recessive disorder characterized by small stature and renal abnormalities. FA can lead to progressive bone marrow failure, myelodysplastic syndrome, or acute leukemia. Using a multidisciplinary team approach, we managed a 3-yr-old boy with FA who simultaneously developed renal and hematopoietic failure. Because renal function was insufficient to support the conditioning regimen for HCT, we performed a deceased donor renal transplant in December 2012 prior to HCT with the known risk of graft-versus-graft rejection of the donor kidney. Seven months later he underwent allogeneic HCT. He obtained myeloid engraftment on day +11 and peripheral blood chimerism demonstrated all donor by day +21. He developed asymptomatic CMV reactivation and despite antirejection medications, mild skin graft-versus-host disease. He has maintained excellent renal function and remains transfusion independent with full hematopoietic recovery. He has not experienced any renal rejection episodes nor developed donor-specific antibodies toward his renal donor. Peripheral blood chimerism remains completely HCT donor. He is clinically well, now greater than two and a half yr after renal transplant and two yr after HCT. The continuing close collaboration between the Pediatric Nephrology and Bone Marrow Transplant teams is a major factor in this successful outcome.

Medulloblastoma treatment in a child on dialysis

SUMMARY Managing patients who suffer from both cancer and end-stage renal disease is challenging because there is a paucity of data, especially for children. There are no published reports of adjuvant chemotherapy for medulloblastoma being used in children on dialysis. In this article we describe the case of an Italian 5-year-old boy on hemodialysis for chronic renal failure who presented with a desmoplastic medulloblastoma with extensive nodularity and nuclear β-catenin expression. The patient was treated with craniospinal irradiation after complete surgical resection, followed by six cycles of cyclophosphamide and vincristine. Vincristine was administered at the usual dosage for children with normal kidney function, cyclophosphamide was delivered after dialysis and over the course of the following day, starting with 50% of the commonly used dosage. This is the first case report of chemotherapy given during hemodialysis in a child with medulloblastoma. This treatment proved easy to administer despite the child’s kidney disease and it maintained disease remission with no additional toxicity.

Role of pharmacogenetics in busulfan/cyclophosphamide conditioning therapy prior to hematopoietic stem cell transplantation

Hematopoietic stem cell transplantation (HSCT) is a curative treatment for several malignant and nonmalignant disorders. Busulfan (Bu) and cyclophosphamide (Cy) are the most commonly used alkylators in high-dose pretransplant conditioning for HSCT; a treatment that is correlated with drug-related toxicity and relapse. Pharmacogenetic investigations have shown that CYP450, as well as aldehyde dehydrogenase, are clearly involved with Cy metabolism and are associated with altered treatment response, Cy metabolism and the unique stem-cell sparing capacity. Moreover, glutathione-S-transferase isoenzymes have been associated with cellular outward transport of various alkylating agents, including Cy metabolites, melphalan, Bu and chlorambucil. A shift from genetic-based studies to whole-genome-based investigations of Cy- and Bu-associated markers may contribute to personalizing the conditioning therapy and enhancing the clinical outcome of HSCT.

Population pharmacokinetics of cyclophosphamide and metabolites in children with neuroblastoma: a report from the Children's Oncology Group

Cyclophosphamide-based regimens are front-line treatment for numerous pediatric malignancies; however, current dosing methods result in considerable interpatient variability in tumor response and toxicity. In this pediatric population, the authors' objectives were (1) to quantify and explain the pharmacokinetic variability of cyclophosphamide and 2 of its metabolites, hydroxycyclophosphamide (HCY) and carboxyethylphosphoramide mustard (CEPM), and (2) to apply a population pharmacokinetic model to describe the disposition of cyclophosphamide and these metabolites. A total of 196 blood samples were obtained from 22 children with neuroblastoma receiving intravenous cyclophosphamide (400 mg/m2/d) and topotecan. Blood samples were quantitated for concentrations of cyclophosphamide, HCY, and CEPM using liquid chromatography-mass spectrometry and analyzed using nonlinear mixed-effects modeling with the NONMEM software system. After model building was complete, the area under the concentration-time curve (AUC) was computed using NONMEM. Cyclophosphamide elimination was described by noninducible and inducible routes, with the latter producing HCY. Glomerular filtration rate was a covariate for the fractional elimination of HCY and its conversion to CEPM. Considerable interpatient variability was observed in the AUC of cyclophosphamide, HCY, and CEPM. These results represent a critical first step in developing pharmacokinetic-linked pharmacodynamic studies in children receiving cyclophosphamide to determine the clinical relevance of the pharmacokinetic variability in cyclophosphamide and its metabolites.

Topotecan distribution in an anephric infant with therapy-resistant bilateral Wilms tumor with a novel germline WT1 gene mutation

The therapeutic strategy for bilateral Wilms tumor (WT) remains a challenge. Especially in cases with chemotherapy resistant disease, bilateral nephrectomy is sometimes inevitable. For optimal cure rates stage V WT patients benefit from adjuvant treatment; however, there are limited data available on chemotherapy pharmacokinetics in anephric children. In this report, we describe a 10-month old girl with bilateral Wilms tumor and a novel germline WT1 gene mutation. This patient hardly showed any response on preoperative chemotherapy, and ultimately, underwent sequential bilateral tumor-nephrectomy. Subsequently, during peritoneal dialysis, she received topotecan as adjuvant chemotherapy based on plasma levels, indicating that this is a reasonable option as adjuvant treatment in therapy-resistant Wilms tumor patients after bilateral nephrectomy. This case showed a novel germline WT1 gene mutation of which the correlation with resistant phenotype has to be confirmed in larger cohorts of WT patients.

Renal failure does not preclude cure in children receiving chemotherapy for Wilms tumor: a report from the National Wilms Tumor Study Group

BACKGROUND

Children with Wilms tumor can develop renal failure during treatment. Since there are few published data concerning the appropriate chemotherapy for this situation, we reviewed the experience of children who developed renal failure while being treated on National Wilms Tumor Study Group (NWTSG) studies 1-4 (1969-1994).

PATIENTS AND METHODS

Data files in the NWTSG Data Center for all patients with Wilms tumor were screened. Patient demographics and tumor and treatment data were abstracted from those who developed renal failure.

RESULTS

Twenty-eight of 5,910 (0.47%) children with Wilms tumor registered on NWTSG studies I through IV (1971-1994) were treated with chemotherapy after developing renal failure. Among these patients vincristine at full dose (0.05 mg/kg dose) did not increase the risk of severe toxicity. Dactinomycin (full dose: 15 mcg/kg day x 5) increased the risk for severe neutropenia when given at 75-100% of full dose. There was no compelling evidence for increased toxicity of doxorubicin when given at 100% versus 50% dosing (full dose: 20 mg/m(2) day x 3), but the number of patients analyzed was small. The overall survival percentage was 39%, but 64% for those patients who were in their initial treatment phase at the time of renal failure.

CONCLUSION

The data suggest that, in the setting of renal failure, reduction of dosing is not necessary for the three main agents used for treatment of newly diagnosed Wilms tumor, and cure is not precluded. Accurate pharmacologic and pharmacokinetic studies are needed for any patient being treated while in renal failure.

Systemic anticancer therapy in gynecological cancer patients with renal dysfunction

Chronic kidney disease is a common occurrence in patients with gynecological cancer. Systemic anticancer treatment in such patients is a challenge for clinicians because of altered drug pharmacokinetics. For those drugs that are excreted mainly by the kidneys, decreased renal function may lead to increased systemic exposure and increased toxicity. Dose adjustment based on pharmacokinetic changes is required in this situation to avoid life-threatening toxicity. In this review, we summarize the nephrotoxicity and pharmacokinetic data of agents commonly used in systemic anticancer treatment of gynecological cancers and dose adjustment guidelines in the presence of impaired renal function. We review 17 medications that need dose adjustment (cisplatin, carboplatin, doxorubicin, epirubicin, cyclophosphamide, ifosfamide, topotecan, irinotecan, etoposide, capecitabine, bleomycin, methotrexate, actinomycin D, granulocyte-macrophage colony-stimulating factor, metoclopramide, cimetidine, and diphenhydramine) as well as 27 drugs that do not (paclitaxel, docetaxel, pegylated liposomal doxorubicin, gemcitabine, oxaliplatin, fluorouracil, vincristine, letrozole, anastrozole, tamoxifen, leuprorelin, megestrol, gefitinib, erlotinib, trastuzumab, leucovorin, granulocyte colony-stimulating factor, erythropoietin, ondansetron, granisetron, palonosetron, tropisetron, dolasetron, aprepitant, dexamethasone, lorazepam, and diazepam). We also review the formulae commonly used to estimate creatinine clearance, including Cockcroft-Gault, Chatelut, Jelliffe, Wright, and the Modification of Diet in Renal Disease study formulae.