Relation of tumor-cell ploidy to survival in children with medulloblastoma.

PURPOSE: To assess the value of tumor-cell ploidy as a predictor of survival in medulloblastoma. PATIENTS AND METHODS: Ploidy determinations were based on the flow-cytometric analysis of cellular DNA content in fresh tumor specimens taken from 34 consecutively treated children with newly diagnosed medulloblastoma. Patients were assigned a high or low risk of failure depending on tumor size and invasiveness, and the presence or absence of metastatic disease. Treatment consisted of radiotherapy, with or without chemotherapy, according to institutional or cooperative group protocols. RESULTS: Univariate analysis of candidate prognostic factors showed that only tumor-cell ploidy and clinical risk group had a statistically significant influence on survival. Patients with hyperdiploid stem lines (n = 9) had significantly longer survival times (P = .04) than did those with diploid lines (n = 20). The estimated 5-year survival probabilities (+/- SE) for these two subgroups were 89% +/- 11% and 48% +/- 13%, respectively. Although clinical risk status (high v low) showed essentially the same predictive strength as ploidy, the two features identified largely nonoverlapping subgroups. Thus, within the clinical high-risk group, it was possible to distinguish hyperdiploid patients whose 5-year survival rate (83% +/- 15%) was comparable to that of patients with localized, low-risk tumors. CONCLUSION: This prospective study indicates that both ploidy and clinical risk group are important prognostic factors in medulloblastoma. Their combined use at diagnosis would distinguish patients who require more aggressive therapeutic intervention (diploid, clinical high-risk group) from those who could be expected to benefit most from standard treatment.

Cerebrospinal fluid asparagine concentrations after Escherichia coli asparaginase in children with acute lymphoblastic leukemia.

PURPOSE: The CNS is an important sanctuary site in childhood acute lymphoblastic leukemia (ALL). CSF asparagine concentration reflects asparaginase systemic pharmacodynamics. We evaluated the time course of CSF asparagine depletion in children with ALL during and after a course of Escherichia coli asparaginase. PATIENTS AND METHODS: Thirty-one children (24 newly diagnosed and seven at relapse) received E coli asparaginase 10,000 IU/m2 intramuscularly three times weekly for six and nine doses, respectively, as part of multiagent induction chemotherapy. CSF asparagine levels were measured before, during, and after asparaginase dosing. RESULTS: The percentage of patients with undetectable (< 0.04 micromol/L) CSF asparagine was 3.2% (one of 31 patients) at baseline, 73.9% (17 of 23) during asparaginase therapy, and 56.3% (nine of 16) 1 to 5 days, 43.8% (seven of 16) 6 to 10 days, 20.0% (two of 10) 11 to 30 days and 0% (zero of 21) more than 30 days after asparaginase therapy. The proportion of patients with depleted CSF asparagine was higher during asparaginase therapy than at baseline (P < .001), 11 to 30 days (P = .003), and more than 30 days after asparaginase therapy (P < .001). Median CSF asparagine concentrations were 4.42 micromol/L before, less than 0.04 micromol/L during, and less than 0.04 micromol/L at 1 to 5 days, 1.63 micromol/L at 6 to 10 days, 1.70 micromol/L at 11 to 30 days, and 5.70 micromol/L at more than 30 days after asparaginase therapy, respectively. CSF depletion was more common in patients with low baseline CSF asparagine concentrations (P = .003). CONCLUSION: CSF asparagine concentrations are depleted by conventional doses of E coli asparaginase in the majority of patients, but they rebound once asparaginase therapy is completed.

Preirradiation chemotherapy with carboplatin and etoposide in newly diagnosed embryonal pediatric CNS tumors.

PURPOSE: We evaluated the clinical efficacy of preirradiation carboplatin (CARBO) and etoposide (VP-16) in 25 patients with newly diagnosed embryonal CNS tumors. PATIENTS AND METHODS: Sixteen patients with high-risk medulloblastoma and nine with other embryonal tumors were treated with two daily doses of CARBO 350 mg/m2 and VP-16 100 mg/m2 (CARBO/VP) every 21 days for four cycles before standard craniospinal irradiation. Patients with disease progression (PD) before radiation therapy were additionally treated with intensive postirradiation cyclophosphamide (CYCLO) and vincristine (VINC). RESULTS: Among 23 assessable patients, 48% (95% confidence interval, 27% to 69%) had a complete response (CR) or partial response (PR) to CARBO/VP; eight had PD. Among the subgroup of 15 assessable patients with medulloblastoma, 53% had a CR or PR (95% confidence interval, 27% to 79%) and five PD. The toxicity of CARBO/VP was predominantly hematologic; although grade IV neutropenia was common, only five episodes of febrile neutropenia occurred. Only thrombocytopenia was a more common toxicity than in other reported chemotherapy regimens; ototoxicity was less common than in cisplatin (CDDP) regimens. CONCLUSION: The responses and survival associated with neoadjuvant CARBO/VP are similar to those with CDDP-containing and other neoadjuvant drug regimens. Although the rate of progression with this regimen may be higher than with similar CDDP-containing regimens, the numbers of patients in other published studies of these agents are too small to detect meaningful statistical differences. Future studies must balance the apparently comparable efficacy of CARBO and CDDP with their differing toxicities.

Urolithiasis in pediatric patients with acute lymphoblastic leukemia.

We evaluated the incidence, timing, and consequences of urolithiasis in children with acute lymphoblastic leukemia (ALL). A total of 20 patients with urolithiasis were identified from 2095 patients with ALL treated at St Jude Children's Research Hospital on consecutive protocols between 1968 and 1998. For remission induction therapy, all patients received daily prednisone; continuation chemotherapy regimens differed by protocol with some including pulses of prednisone or dexamethasone and others no glucocorticoid. Patients with urolithiasis were older at diagnosis of ALL than those without urolithiasis (median age, 7.5 vs 5.0 years; P=0.03) and less likely to be black (P=0.03) than white or Hispanic, but sex and treatment era did not differ. Presenting symptoms included abdominal or flank pain, hematuria, and dysuria. All stones analyzed biochemically were calcium stones. The incidence of urolithiasis after completion of therapy was 1.8 per 10 000 person-years. Compared to this baseline rate, the relative risk of urolithiasis was 45 (P<0.01) during induction therapy, 22 (P<0.01) during continuation therapy with glucocorticoids, and 5.1 (P>0.05) during continuation therapy without glucocorticoids. Urolithiasis occurred 4.5 times more often during continuation treatment with glucocorticoids than without (P<0.05). Seven patients (35%) had recurrent urolithiasis. Patients with ALL are at risk of developing calcium renal stones during chemotherapy, especially when a glucocorticoid is included.

Phenytoin alters the disposition of topotecan and N-desmethyl topotecan in a patient with medulloblastoma.

Topotecan undergoes both renal and hepatic elimination, with topotecan urinary recovery ranging from 60 to 70%. We evaluated the potential of phenytoin to alter the disposition of topotecan and its N-desmethyl metabolite. A 5-year-old child with high-risk medulloblastoma received the first course of topotecan with phenytoin and the second course without phenytoin. For both courses, topotecan doses were adjusted to achieve a target topotecan lactone plasma area under the curve (AUC). Serial plasma samples were obtained, and lactone and total plasma concentrations of topotecan, as well as total plasma and cerebrospinal fluid concentrations of N-desmethyl topotecan, were measured by high-performance liquid chromatography. Phenytoin coadministration increased lactone and total topotecan clearance from 43.4 +/- 1.9 L/h/m2 to 62.9 +/- 6.4 L/h/m2, and 20.8 +/- 2.8 L/h/m2 to 30.6 +/- 4.1 L/h/m2, respectively (P < 0.05). Concomitant phenytoin increased the plasma AUC of total N-desmethyl topotecan from 7.5 +/- 0.68 ng/ml x h to 16.3 +/- 0.53 ng/ml x h (P < 0.05) at plasma AUC of total topotecan of 226.0 +/- 5.5 ng/ml x h and 240.9 +/- 39.8 ng/ml x h, respectively. N-Desmethyl topotecan penetrated into the cerebrospinal fluid (0.12 +/- 0.01). The patient experienced no grade 3 or 4 toxicity. These are the first data documenting altered topotecan and N-desmethyl topotecan disposition when coadministered with phenytoin and suggests that topotecan may undergo further hepatic metabolism. Although there is an increase in exposure to the active N-desmethyl topotecan metabolite, it is less than the decrease in exposure to topotecan lactone. Therefore, patients concomitantly administered phenytoin may require an increase in topotecan dose to achieve a similar pharmacological effect as a patient not receiving phenytoin.

A four-hour topotecan infusion achieves cytotoxic exposure throughout the neuraxis in the nonhuman primate model: implications for treatment of children with metastatic medulloblastoma.

The purpose of this study was to define the length of topotecan (TPT) i.v. infusion necessary to attain a cytotoxic exposure for medulloblastoma cells throughout the neuraxis. In vitro studies of human medulloblastoma cell lines (Daoy, SJ-Med3) were used to estimate the length and extent of TPT systemic exposure associated with inhibition of tumor cell growth or the exposure duration threshold (EDT). We evaluated TPT systemic and cerebrospinal fluid (CSF) disposition in six male rhesus monkeys (8-12 kg) that received TPT 2.0 mg/m2 i.v. as a 30-min or 4-h infusion. Plasma and CSF samples were assayed for TPT lactone by high-performance liquid chromatography, and the CSF exposures were compared with the estimated EDT. Results of the in vitro studies defined an EDT as a TPT lactone concentration of > 1 ng/ml for 8 h (IC99) daily for 5 days. The mean +/- SD for systemic clearance (CL(SYS)), penetration into fourth ventricle (%CSF(4th)), and penetration into lumbar space (%CSF(LUM)) were similar for the 30-min and the 4-h infusions. At a TPT lactone systemic exposure (AUC(PL)) of 56.7 +/- 19.9 ng/ml x h, time above 1 ng/ml in the fourth ventricle was 1.4-fold greater for a 4-h infusion compared with a 30-min infusion. At a TPT lactone AUC(PL) of 140 ng/ml x h, the 4-h infusion achieved the desired TPT exposure throughout the neuraxis (lateral and fourth ventricles and lumbar space), whereas the 30-min infusion failed to achieve it in the lumbar space. In conclusion, prolonging TPT i.v. infusion from 30-min to 4-h at a targeted AUC(PL) achieves the EDT throughout the neuraxis and represents an alternative method of TPT administration that will be tested prospectively in patients with high-risk medulloblastoma.

Topotecan-filgrastim combination is an effective regimen for mobilizing peripheral blood stem cells.

We compared the efficacy, toxicity, and cost of topotecan-filgrastim and filgrastim alone for mobilizing peripheral blood stem cells (PBSCs) in 24 consecutive pediatric patients with newly diagnosed medulloblastoma. PBSCs were mobilized with an upfront window of topotecan-filgrastim for 11 high-risk patients (residual tumor > or =1.5 cm2 after resection; metastases limited to neuraxis) and with filgrastim alone for 13 average-risk patients. All patients subsequently underwent craniospinal irradiation and four courses of high-dose chemotherapy with stem cell rescue. Target yields of CD34+ cells (> or =8 x 10(6)/kg) were obtained with only one apheresis procedure for each of the 11 patients treated with topotecan-filgrastim, but with a mean of 2.3 apheresis procedures for only six (46%) of the 13 patients treated with filgrastim alone (P = 0.0059). The median peak and median total yield of CD34+ cells were six-fold higher for the topotecan-filgrastim group (328/microl and 21.5 x 10(6)/kg, respectively) than for the filgrastim group (54/microl and 3.7 x 10(6)/kg, respectively). Mean times to neutrophil and platelet engraftment were similar. Myelosuppression was the only grade 4 toxicity associated with topotecan-filgrastim mobilization and lasted a median of 5 days. Compared with filgrastim mobilization, topotecan-filgrastim mobilization resulted in a mean cost saving of $3966 per patient. Topotecan-filgrastim is an efficacious, minimally toxic, and cost-saving combination for PBSC mobilization.

Interpatient variability in bioavailability of the intravenous formulation of topotecan given orally to children with recurrent solid tumors.

PURPOSE: Evaluation of inter- and intrapatient variability of topotecan oral bioavailability and disposition was performed in children with malignant solid tumors. PATIENTS AND METHODS: Topotecan i.v. formulation was given orally on schedules of daily for 21 consecutive days (d x 21) or daily for 5 days per week for 3 weeks [(d x 5)3], in both cases repeated every 28 days. Topotecan doses of 0.8 and 1.1 mg/m2 per day were evaluated on both schedules. Serial plasma samples were obtained after oral and i.v. administration of topotecan at the beginning and end of the first course of therapy. Topotecan lactone and total concentrations were measured by a high-performance liquid chromatography (HPLC) assay, and a one-or two-compartment model was fit to the plasma concentration-time data after oral or i.v. administration, respectively. Topotecan oral bioavailability (F) was calculated as the ratio of the AUC determined after oral treatment (AUCpo) divided by the AUC calculated after i.v. administration. RESULTS: Pharmacokinetics studies were performed on 15 and 11 patients receiving 0.8 and 1.1 mg/m2 per day, respectively. After oral administration the topotecan lactone AUCpo and F determined for 0.8 and 1.1 mg/m2 per day were 13.6 +/- 5.8 and 25.1 +/- 12.9 ng ml(-1) h and 0.34 +/- 0.14 and 0.34 +/- 0.16, respectively. The within-patient variance for AUCpo and F was much smaller than the between-patient variance. The ratio of topotecan lactone to total concentration was consistently higher after oral as compared with i.v. administration. CONCLUSIONS: Large interpatient variability was noted in topotecan pharmacokinetics, whereas intrapatient variability was relatively small. Further studies of oral topotecan are warranted to evaluate the tolerance of shorter courses and to define further the interpatient variability.

A mechanistic mathematical model of temozolomide myelosuppression in children with high-grade gliomas.

Temozolomide (TMZ) is currently being evaluated for the treatment of high-grade gliomas in children. Myelosuppression (the suppression of bone marrow activity) is the dose-limiting toxicity for TMZ in adults and children. Empirical methods (i.e. relations between the percent change in absolute neutrophil count (ANC) and the area under the plasma concentration curve (AUC) of TMZ or its active metabolite MTIC) showed poor results when attempting to describe myelosuppression from serial data derived during TMZ therapy in a Phase II study of children with high-grade glioma. Therefore, to improve our understanding of the myelosuppressive effects of TMZ and MTIC in children we developed a mechanistic mathematical model. The model describes the progression of neutrophils from their production in the bone marrow to their release in the plasma. Included in the model are the feedback effects of granulocyte colony stimulating factor (G-CSF), which stimulates neutrophil production when there is a decrease in circulating neutrophils. The model is fit to serial ANC measurements obtained after TMZ dosing and it is able to explain, among other things, the lag in ANC reduction following a dose of TMZ, the ANC nadir, and the 'rebound effect' observed where the ANC recovers to levels greater than that observed pre-TMZ dose. This model will be useful for the prospective design of clinical trials of TMZ in children with cancer.

Supratentorial malignant gliomas in childhood: a single institution perspective.

BACKGROUND: A retrospective study evaluated the clinical characteristics, prognostic factors, and outcome of patients with newly diagnosed supratentorial malignant gliomas treated with preirradiation chemotherapy. METHODS: Of 41 patients with supratentorial malignant gliomas accrued between 1984-1994, all had neuroimaging documentation of the extent of resection and 37 had complete neuraxis staging prior to treatment; 80% were treated with one of a variety of neoadjuvant chemotherapy regimens. RESULTS: Thirteen patients had anaplastic astrocytoma (AA), 25 had glioblastoma multiforme (GBM), and 3 had anaplastic oligodendroglioma. Gross total resection (GTR) was performed in 10 patients, subtotal resection (STR) in 22 patients, and biopsy (Bx) alone in 9 patients. For the entire group the 3-year overall and progression free survivals were 35 +/- 8% and 18 +/- 6%, respectively. Tumor recurrence was dominantly local. However, 9 patients with initially local disease failed at a distant neuraxis site, giving a 26 +/- 7% actuarial risk of dissemination at 3 years. The only significant prognostic factor was extent of tumor resection: patients who underwent GTR survived longer than those who underwent STR or Bx (P = 0.004). Histology (GBM vs. AA), age, and the use of enhanced local dose radiation therapy (brachytherapy or stereotactic irradiation) did not affect survival. CONCLUSIONS: Neoadjuvant chemotherapy was not associated with a survival rate significantly different from that observed in adjuvant chemotherapy studies. Systematic neuraxis staging at diagnosis and recurrence revealed a rate of neuraxis dissemination as a component of recurrence that was higher than previously reported; the utility of craniospinal irradiation in preventing isolated dissemination remains uncertain.