Personalized pharmacokinetic targeting with busulfan in allogeneic hematopoietic stem cell transplantation in infants with acute lymphoblastic leukemia.

Individual busulfan (BU) dosing based on pharmacokinetic (PK) data is preferable for hematopoietic stem cell transplantation (HSCT) conditioning, but information on BU PK in infants is scarce. We report BU PK data on HSCT conditioning for infants with KMT2A-gene-rearrangement-positive acute lymphoblastic leukemia (MLL-r ALL). Infants showed wide variation in BU PK indices, such as clearance (CL) and volume of distribution (Vd) value, which are distributed more widely among those who received oral, rather than intravenous (IV), BU. Because the steady state concentration (Css) fluctuates readily in infants, dose re-adjustment based on PK at the initial administration was important even if the initial dose was determined by a PK test. HSCT can be performed safely within the Css range of 600-900 ng/mL per dose, although it was difficult to fit within the therapeutic index of BU. The clinical outcome of engraftment, graft-versus-host disease, adverse events, including sinusoidal obstruction syndrome, and survival did not correlate with the BU PK data, which paradoxically suggests that remaining within this Css range helped minimize transplant-related toxicities, while securing engraftment in infants with MLL-r ALL.

Super-acute onset of tumor lysis syndrome accompanied by hypercytokinemia during treatment of Hodgkin's lymphoma with ABVD chemotherapy.

BACKGROUND: Tumor lysis syndrome (TLS) is a group of life-threatening metabolic complications that can occur after initiation of cancer chemotherapy. Onset of TLS in the middle of chemotherapy, however, has not been reported previously in patients with hematologic malignancies. OBJECTIVE: We report a case of a patient who experienced TLS of super-acute onset accompanied by hypercytokinemia during chemotherapy treatment with a combination of doxorubicin (Adriamycin), bleomycin, vinblastine, and dacarbazine (ABVD). CASE SUMMARY: A 36-year-old Japanese man (height, 182 cm; weight, 83 kg; body surface area, 2.04 m(2)) was admitted to the hospital for the treatment of malignant lymphoma (clinical stage IVB Hodgkin's lymphoma). Chemotherapy was initiated using the ABVD regimen (doxorubicin [Adriamycin] 25 mg/m(2) by 30-minute infusion, bleomycin 9 mg/m(2) by 30-minute infusion, vinblastine 6 mg/m(2) by bolus injection, and dacarbazine 375 mg/m(2) by 2-hour infusion). During the dacarbazine infusion, the patient's body temperature rose from 36.5 degrees C to 42 degrees C; he experienced a convulsion and then lost consciousness. The convulsion was not suppressed despite the use of diazepam (5 mg IV twice) and phenytoin (500 mg IV). The patient was then transferred to the intensive care unit and sedated using a continuous infusion of midazolam (10 mg/h). Levels of serum lactate dehydrogenase, aspartate aminotransferase, uric acid, blood urea nitrogen, and creatinine evaluated shortly after the ABVD regimen were outside normal limits. In addition, interleukin-6 (IL-6) concentrations were elevated to 54,220 pg/mL. Continuous hemodiafiltration was immediately performed to lower the elevated levels of IL-6. The next day, IL-6 concentrations decreased to 97 pg/mL, and the patient was weaned from ventilator support and sedation. The patient had no adverse effects after the event. According to the results of an assessment using the Naranjo adverse drug reaction probability scale (score = 3), the development of TLS in this patient was possibly related to the chemotherapy regimen. CONCLUSIONS: ABVD chemotherapy was possibly associated with the super-acute onset of TLS in this patient. In addition, hypercytokinemia occurred with TLS, which led to pyrexia, convulsion, and loss of consciousness.

Probable interaction between warfarin and antitumor agents used in R-ESHAP chemotherapy.

BACKGROUND: The pharmacologic effects of warfarin might be altered by various factors, including drug-drug interaction. CASE SUMMARY: A 49-year-old Japanese man (height, 174 cm; weight, 68 kg) presented with a 20-month history of malignant lymphoma (diffuse large B cell lymphoma, clinical stage IV). He was treated with a combination of rituximab chemotherapy and etoposide, cisplatin, high-dose cytarabine, and methyl-prednisolone (R-ESHAP). He had been receiving warfarin for the secondary prevention of pulmonary embolism with deep venous thrombosis. When R-ESHAP was started, international normalized ratio (INR) increased from 1 to 5. This phenomenon was observed again in the second R-ESHAP. The INR was increased from 2.44 to 4.71 during chemotherapy but was returned to within the normal range (1.05; normal range: 0.81-1.009) 5 days after chemotherapy was completed. CONCLUSION: In this patient, R-ESHAP chemotherapy might have affected warfarin anticoagulation sensitivity; thus, careful monitoring of INR is essential, particularly in patients receiving warfarin who undergo R-ESHAP chemotherapy.

Population pharmacokinetics of oral busulfan in young Japanese children before hematopoietic stem cell transplantation.

The objectives of this study were to develop a population pharmacokinetic model and to determine the covariates affecting the pharmacokinetics of busulfan in Japanese pediatric patients who received high-dose oral busulfan as a conditioning regimen before hematopoietic stem cell transplantation. Population analysis was performed using retrospective therapeutic drug monitoring data (including test dose data) from 103 children. Their ages ranged from 2 months to 11 years old (mean age, 30 months; median age, 18 months). The plasma concentration of busulfan in all 1028 samples was measured with the same high-performance liquid chromatography method. Maximum likelihood estimates were sought for pharmacokinetic parameters with the NONMEM program. The best structural covariate-free model for busulfan was a one-compartment model with an exponential error model to account for intersubject variability and a proportional error model to account for intrasubject variability. The apparent oral clearance was found to be correlated with age, aspartate transaminase, and type of disease (malignant disease or other). The apparent volume of distribution was related to body weight. The busulfan formulation (1% powder form or crystal form) and dose (milligrams per kilogram) influenced the absorption rate constant. It was estimated that oral clearance expressed per kilogram of body weight is low at early infancy, then increases to a maximum at approximately 2 years of age and, thereafter, decreases. In conclusion, we have developed a population pharmacokinetic model of oral busulfan in children, particularly for those younger than 4 years old, that takes into consideration not only body size, but also several other covariates.

[A case of subacute idiopathic interstitial pneumonia resistant to steroids, successfully treated with cyclophosphamide].

A 47-year-old woman was admitted to our hospital because of dry cough, fever, and subacute, progressive dyspnea. Chest radiography and computed tomography showed ground glass opacities in the lower lung fields. We suspected pneumonia caused by atypical pathogens and administered antibiotics, but they had no effect at all. Histopathologic findings from a transbronchial lung biopsy (TBLB) included intensive infiltration of mononuclear cells and edema on the alveolar wall with no evidence of fibrosis, fibroblasts, hyaline membrane, or granuloma. On the basis of these findings, we suspected interstitial pneumonia, but a surgical lung biopsy was not possible because the patient would not give her consent. After TBLB, corticosteroid was administered repetitively, but dyspnea was deteriorating as the ground glass opacities became more widespread, and tractional bronchiectasis appeared throughout the lung fields. Therefore, we decided to administer cyclophosphamide (CPA). This was very effective: all of her symptoms improved and the ground glass opacities and tractional bronchiectasis disappeared. Though we tapered and then discontinued corticosteroids a few months after CPA, there was no recurrence whatever. No signs suggesting the association of collagen vascular diseases were detected. The effectiveness of CPA in interstitial pneumonia associated with collagen vascular disease is occasionally reported, but the effect on idiopathic interstitial pneumonia, especially in acute and subacute progressive cases, is rarely reported. We think this is an interesting case to consider the availability of CPA in idiopathic interstitial pneumonia with subacute progression.

Direct interaction between substrates and endogenous steroids in the active site may change the activity of cytochrome P450 3A4.

CYP3A4 exhibits unusual kinetic characteristics that result from the metabolism of multiple substrate including endogenous steroids and some drugs that coexist at the active site. To clarify the mechanism of the effect of endogenous steroids on the drug metabolism, the interaction between substrates, nevirapine (NVP) and carbamazepine (CBZ), and endogenous steroids was investigated by theoretical calculations. When the activities of NVP 2-hydroxylation and CBZ 10,11-epoxidation by expressed CYP3A4 were measured in the presence of steroids, NVP 2-hydroxylation was found to be remarkably increased by aldosterone and inhibited by estradiol. CBZ 10,11-epoxidation was increased by androstenedione. Three-dimensional computer modeling has shown that the active site of CYP3A4 is especially large, permitting access of two substrate molecules. The interactions between NVP and aldosterone and between CBZ and androstenedione were estimated by theoretical calculations assuming the substrate and steroids to be present in the active site at the same time. It was shown that NVP or CBZ would be stably fixed close to the oxygen atom at the sixth ligand of heme by interaction with steroids, suggesting that NVP and CBZ may be hydroxylated more easily due to the interaction with steroids. Estradiol was also expected to interact with NVP via a pi/pi interaction between a benzene ring, in which the NVP hydroxylation site is located, and a benzene ring of estradiol, suggested to inhibit the reaction. From these results, interactions between the substrate and endogenous steroids in the active site may change the activity of CYP3A4.