In vivo potentiation of radiation response by topotecan in human rhabdomyosarcoma xenografted into nude mice

The lack of new highly efficacious drugs for cancer treatment promotes the search for innovative therapeutic modalities. The authors reported the results leading to the definition of parameters needed to demonstrate a possible radiopotentiation by topotecan (TPT) on two representative human rhabdomyosarcomas (RMSs) xenografted into nude mice. Experimental studies of radiopotentiation with different doses of topotecan showed that concomitant association of topotecan and RT for 5 consecutive days provided a synergistic therapeutic effect. Response rates were statistically higher with the radiochemotherapeutic combination (P < 0.001). Efficacy enhancement factors of this combination compared with the sum of the antitumoral activity of these treatments separately administrated were 1.54 and 1.60, respectively, on both rhabdomyosarcomas. Moreover, the efficiency of the combination of radiotherapy at the dose of 20 Gy with topotecan (12.5 mg/kg) was not statistically different from that of radiotherapy at the dose of 40 Gy. According to microscopy results, the analyses performed at different periods after topotecan treatment alone, radiotherapy alone, and their combination seemed to show that tumoral repopulation by malignant cells is as fast as the dose of radiotherapy and/or topotecan is low. Furthermore, lesions observed with the dose of 40 Gy were similar to those obtained with the association of topotecan at the dose of 12.5 mg/kg and radiotherapy at the dose of 20 Gy. In conclusion, all clinical and pathological results are consistent with a radiopotentiation effect of topotecan on the two xenografted human rhabdomyosarcomas and are currently leading to the design of clinical studies.

Combined effects of radiotherapy and angiostatin gene therapy in glioma tumor model

The objective of the present study was to evaluate the antitumor effect of a defective adenovirus expressing a secretable angiostatin-like molecule (AdK3) in combination with radiotherapy in rat C6 gliomas s.c. preestablished into athymic mice. In vitro, the combination regimen was significantly (P < 0.001) more cytotoxic for human microcapillary endothelial cells than either treatment alone, whereas survival of C6 glioma cells was not affected in the conditions used. Radiotherapy and AdK3 gene delivery was then studied on well established C6 xenografts (165 +/- 70 mm(3)). In these tumors, AdK3 intratumoral injections had only a marginal effect. Interestingly, when experimental radiotherapy was added, significantly higher (P < 0.005), and possibly synergistic, antitumoral effects were observed that tightly correlated a marked decrease of intratumoral vascularization. The combination of radiotherapy and AdK3 intratumoral injections also revealed a significant (P < 0.05) inhibition of tumor growth as compared with either treatment alone for larger tumors (467 +/- 120 mm(3)). Altogether, these data emphasize the potential of combining a destructive strategy directed against the tumor cells with an anti-angiogenic approach to fight cancer.

Consolidation with a busulfan-containing regimen followed by stem cell transplantation in infants with poor prognosis stage 4 neuroblastoma

Although infants with stage 4 neuroblastoma (NB) usually have a good prognosis, metastatic relapses after 1 year of age and amplification of the N-myc oncogene are established poor prognostic factors. In order to improve the survival of patients with such high-risk factors, we performed consolidation with a busulfan (600 mg/m2)-melphalan (140 mg/m2)-containing regimen followed by autologous stem cell transplantation (SCT). From 1986 to 1998, 12 patients were treated according to this strategy. Their median age at diagnosis was 9 months (1-11). Consolidation was performed after a metastatic relapse in five children, because of persistent bone metastases in one and as first-line consolidation in six patients whose tumor exhibited N-myc amplification. The 5-year EFS rate is 64. 5% (36-85%) with a median follow-up of 92 months (20-126). One toxicity-related death occurred in a very heavily pretreated patient. Hepatic veno-occlusive disease was the major side-effect that occurred in nine of 12 children. This busulfan-melphalan combination appears to dramatically improve the prognosis of these high-risk infants with metastatic NB. Given its high toxicity, indications for this consolidation must be restricted to high-risk infants and a lower dose of busulfan (480 mg/m2) is recommended in children weighing less than 10 kg. Bone Marrow Transplantation (2000) 25, 937-942.

Metabolism of irinotecan (CPT-11) by CYP3A4 and CYP3A5 in humans

7-Ethyl-10[4-(1-piperidino)-1-piperidino] carbonyloxy-camptothecin (CPT-11), a DNA topoisomerase I inhibitor, undergoes several metabolic pathways to generate conjugated and unconjugated derivatives that could be excreted from the body. The objective of this study was to determine the oxidative metabolites of CPT-11 recovered in human urine samples and to identify cytochrome P450 (CYP) involved in their formation. In addition to the already known metabolites of CPT-11 [SN-38, SN-38-G, 7-ethyl-10-[4-N-(5-aminopentanoic acid)-1-piperidino]carbonyloxycamptothecin (APC), and 7-ethyl-10-(4-amino-1-piperidino) carbonyloxycamptothecin (NPC)], we isolated three oxidized metabolites from the urine of two children and two adults given CPT-11. M1 and M2 (molecular weight, 602) were hydroxylated, respectively, on the CPT moiety and on the terminal piperidine ring of CPT-11. M3 had a molecular mass of 602, but its urine concentration in patients was too low to establish its chemical structure by liquid chromatography/mass spectrometry. In vitro incubations with cells expressing CYP2C8, CYP2C9, CYP1A1, CYP1A2, or CYP3A7 did not produce any detectable metabolites. Only CYP3A4 produced both APC and NPC, resulting from the oxidation of the piperidinylpiperidine side chain of CPT-11 along with metabolite M2. The metabolism of CPT-11 by CYP3A5 was markedly different because neither APC or NPC nor M2 was produced, whereas only one new metabolite, M4 (molecular weight, 558), was generated by de-ethylation of the CPT moiety. No previous study has reported the presence of the M4 metabolite. Production of APC, NPC, M2, and M4 was prevented by ketoconazole, a specific CYP3A inhibitor. The parameters of CPT-11 biotransformation into M2 and M4 were examined using cell lines expressing, respectively, with CYP3A4 and CYP3A5, indicating that CPT-11 is preferentially metabolized by CYP3A4. In conclusion, CYP3A plays a major role in the metabolism of CPT-11, with some differences of the metabolic profile exhibited by 3A4 and 3A5.

p53-dependent G2 arrest associated with a decrease in cyclins A2 and B1 levels in a human carcinoma cell line

In vivo transfer of wild-type (wt) p53 gene via a recombinant adenovirus has been proposed to induce apoptosis and increase radiosensitivity in several human carcinoma models. In the context of combining p53 gene transfer and irradiation, we investigated the consequences of adenoviral-mediated wtp53 gene transfer on the cell cycle and radiosensitivity of a human head and neck squamous cell carcinoma line (SCC97) with a p53 mutated phenotype. We showed that ectopic expression of wtp53 in SCC97 cells resulted in a prolonged G1 arrest, associated with an increased expression of the cyclin-dependent kinase inhibitor WAF1/p21 target gene. A transient arrest in G2 but not in G1 was observed after irradiation. This G2 arrest was permanent when exponentially growing cells were transduced by Ad5CMV-p53 (RPR/INGN201) immediately after irradiation with 5 or 10 Gy. Moreover, levels of cyclins A2 and B1, which are known to regulate the G2/M transition, dramatically decreased as cells arrived in G2, whereas maximal levels of expression were observed in the absence of wtp53. In conclusion, adenoviral mediated transfer of wtp53 in irradiated SCC97 cells, which are mutated for p53, appeared to increase WAF1/p21 expression and decrease levels of the mitotic cyclins A2 and B1. These observations suggest that the G2 arrest resulted from a p53-dependent premature inactivation of the mitosis promoting factor.

High-dose chemotherapy in childhood brain tumours

New therapeutic strategies are required to improve the prognosis of malignant brain tumours in children, in terms of survival and quality of life. During the last 10 years, high-dose chemotherapy (HDCT) with autologous haematopoietic stem cell rescue has been studied in different types of paediatric brain tumours. The most frequently used combined regimens were busulfan-thiotepa and etoposide-thiotepa along with carboplatin or BCNU. High response rates have been reported in medulloblastoma and germ cell tumours, and HDCT has been further developed as salvage therapy or for consolidation in these diseases. Interesting objective tumour responses have been obtained in supratentorial high-grade glioma, but HDCT has not so far been effective either in ependymoma or in diffuse pontine brain stem tumours. This article reviews the rationale for HDCT in brain tumours and the current clinical results obtained in each tumour type. The place of HDCT in the therapeutic strategy for paediatric brain tumours, especially in young children, is discussed.

Molecular genetic studies of chromosome 11 and chromosome 22q DNA sequences in pediatric medulloblastomas

Medulloblastomas are primitive neuroectodermal tumors (PNETs) of the cerebellum with poorly understood pathogenesis. Previous molecular studies suggested a role for loci on chromosome 11 in the development of medulloblastomas-PNETs. In order to identify the frequency of loss and eventually the extent of allelic loss on chromosome 11, we have examined 23 pediatric medulloblastomas for loss of heterozygosity (LOH) with 16 polymorphic microsatellites. Our data reveal that LOH on 11p or 11q occurs rarely (13%) suggesting the unlikely involvement of chromosome 11 in most cases of medulloblastomas. The same frequency of LOH in medulloblastomas was detected using 8 microsatellites on 22q. Alterations of microsatellite length were found in only 4/594 PCR analyses using 28 markers located on chromosomes 2, 9, 11, 18, and 22, demonstrating that genomic instability is uncommon in medulloblastomas.

Combination interleukin-2 and doxorubicin in advanced adult solid tumors: circumvention of doxorubicin resistance in soft-tissue sarcoma?

Based on the likelihood of antitumor interactions between cytokines and cytotoxic drugs, we designed a pilot study to evaluate feasibility, clinical, pharmacologic, and immunologic effects of concomitantly administered subcutaneous (SQ) recombinant interleukin-2 (r-IL-2) and doxorubicin (ADR) in patients with advanced solid tumors (AST). Patients received one injection of ADR alone (70 mg/m2) and 3 weeks later a combination of r-IL-2 (18 MIU/m2 days 1-5 s.q.) and ADR at the same dose either 3-4 h after the first r-IL-2 injection (arm 1) or 2 days after the last r-IL-2 injection (arm 2). The same combination was repeated every 4 weeks according to the evolution of the disease. Pharmacokinetics were assessed over 48 h after injection of ADR alone and after the first ADR-IL-2 cycle and immunologic monitoring at days 1 and 8 of the first ADR-IL-2 cycle. Tumors were measured at baseline, after ADR alone, and after each ADR-IL-2 cycle until progression. Twenty-one adult patients with various AST including 14 soft-tissue sarcomas (STS) entered the study, 11 in arm 1 and 10 in arm 2. All patients were heavily pretreated; 16 had received an anthracycline-containing chemotherapy regimen. Eleven patients were ADR refractory and 1 ADR resistant. Grade 4 neutropenia occurred in 28, 82, and 40% of patients after ADR alone, ADR-IL-2 in arm 1 and ADR-IL-2 in arm 2, respectively. Mucitis was higher in arm 1 (7 of 11 patients) compared with arm 2 (0 of 10) and ADR alone (0 of 21). SQ injections of r-IL-2 did not affect ADR pharmacokinetics. ADR injection in arm 1 prevented IL-2-induced lymphocyte rebounds in all patients but did not alter qualitatively non-major histocompatibility complex-restricted cytotoxicity. There was no response after ADR alone. Two patients, one in each arm, experienced a prolonged (8 and 5 months) objective response after ADR-IL-2. Both had ADR-refractory STS with a local relapse and metastatic metastases. Interestingly, both patients had unusually elevated TNF-alpha levels before and after the first ADR cycle. Combination ADR-IL-2, although toxic, is feasible and manageable with routine clinical support. r-IL-2 enhanced ADR hematologic and extrahematologic toxicities. The two objective responses observed in these heavily pretreated patients refractory to ADR supports the hypothesis of a modulation of ADR resistance, possibly mediated by means of a mechanism involving TNF-alpha. Elevated baseline TNF-alpha levels could be predictive of response to ADR-IL-2 and deserves further investigation.

Prognostic factors in metastatic neuroblastoma in patients over 1 year of age treated with high-dose chemotherapy and stem cell transplantation: a multivariate analysis in 218 patients treated in a single institution

The purpose of this paper is to study prognostic factors in neuroblastoma patients treated with high-dose chemotherapy and hematopoietic stem cell transplantation. Two hundred and eighteen children over 1 year of age and treated for stage 4 neuroblastoma were enrolled in this study. The median age at diagnosis was 39 months, the sex ratio 1.5 and 84% of patients had an abdominal primary tumor. Skeletal disease was detected in 79% of cases and bone marrow involvement in 93%. N-myc oncogene amplification was present in 27% of the patients studied. The probability of event-free survival at 5 years post-diagnosis was 29% in this series. Three major favorable prognostic factors were significant and independent in the multivariate analysis: age under 2 years at diagnosis (P<0.01), absence of bone marrow metastases at diagnosis (P<0.04) and the high-dose conditioning regimen containing busulfanmelphalan combination (P = 0.001). The quality of response to conventional primary chemotherapy was close to significance (P = 0.053). We conclude that factors related to the patient (age) and extent of disease are predictive of outcome in patients with neuroblastoma treated with conventional chemotherapy followed by surgical excision of the primary and consolidation with high-dose chemotherapy. They should be taken into account in future prospective studies. Moreover, the type of conditioning regimen appears to be the most important prognostic factor. This should encourage new investigations into innovative drug combinations.

Comparative genomic hybridization detects many recurrent imbalances in central nervous system primitive neuroectodermal tumours in children

A series of 23 children with primitive neuroectodermal tumours (PNET) were analysed with comparative genomic hybridization (CGH). Multiple chromosomal imbalances have been detected in 20 patients. The most frequently involved chromosome was chromosome 17, with a gain of 17q (11 cases) and loss of 17p (eight cases). Further recurrent copy number changes were detected. Extra copies of chromosome 7 were present in nine patients and gains of 1q were detected in six patients. A moderate genomic amplification was detected in one patient, involving two sites on 3p and the whole 12p. Losses were more frequent, and especially involved the chromosomes 11 (nine cases), 10q (eight cases), 8 (six cases), X (six patients) and 3 (five cases), and part of chromosome 9 (five cases). These recurrent chromosomal changes may highlight locations of novel genes with an important role in the development and/or progression of PNET.

Busulphan is active against neuroblastoma and medulloblastoma xenografts in athymic mice at clinically achievable plasma drug concentrations

High-dose busulphan-containing chemotherapy regimens have shown high response rates in children with relapsed or refractory neuroblastoma, Ewing's sarcoma and medulloblastoma. However, the anti-tumour activity of busulfan as a single agent remains to be defined, and this was evaluated in athymic mice bearing advanced stage subcutaneous paediatric solid tumour xenografts. Because busulphan is highly insoluble in water, the use of several vehicles for enteral and parenteral administration was first investigated in terms of pharmacokinetics and toxicity. The highest bioavailability was obtained with busulphan in DMSO administered i.p. When busulphan was suspended in carboxymethylcellulose and given orally or i.p., the bioavailability was poor. Then, in the therapeutic experiments, busulphan in DMSO was administered i.p. on days 0 and 4. At the maximum tolerated total dose (50 mg kg(-1)), busulphan induced a significant tumour growth delay, ranging from 12 to 34 days in the three neuroblastomas evaluated and in one out of three medulloblastomas. At a dose level above the maximum tolerated dose, busulphan induced complete and partial tumour regressions. Busulphan was inactive in a peripheral primitive neuroectodermal tumour (PNET) xenograft. When busulphan pharmacokinetics in mice and humans were considered, the estimated systemic exposure at the therapeutically active dose in mice (113 microg h ml(-1)) was close to the mean total systemic exposure in children receiving high-dose busulphan (102.4 microg h ml(-1)). In conclusion, busulphan displayed a significant anti-tumour activity in neuroblastoma and medulloblastoma xenografts at plasma drug concentrations which can be achieved clinically in children receiving high-dose busulphan-containing regimens.

[Methodology and limitations of pre-clinical models for the development of anticarcinogenic chemotherapy combinations]

In chemosensitive tumors, cancer chemotherapy is active as drug combinations. During the development of new anticancer drugs, preclinical experimental models may help to design drug combinations. Indeed, in vitro models are able to define drug interactions in terms of synergism, additivity or antagonism, while in vivo models can evaluate therapeutic synergism along with toxicity in a clinical setting. The methodology for in vitro and in vivo evaluation of anticancer drug combinations is described. The limits are discussed. In conclusion, preclinical models contribute to the clinical development of drug combinations which are nevertheless designed on the basis of clinical therapeutic principles.

Pathophysiology and therapy of irinotecan-induced delayed-onset diarrhea in patients with advanced colorectal cancer: a prospective assessment

PURPOSE

Irinotecan (CPT-11), a camptothecin derivative, has shown efficacy against colorectal cancer. Delayed-onset diarrhea is its main limiting toxicity. The aim of this study was to determine the pathophysiology of CPT-11-induced delayed-onset diarrhea and assess the efficacy of combined antidiarrheal medication in a phase II, prospective, successive-cohorts, open study.

PATIENTS AND METHODS

Twenty-eight patients with advanced colorectal cancer refractory to fluorouracil (5-FU) therapy received CPT-11 350 mg/m2 every 3 weeks. The first cohort of 14 consecutive patients explored for the mechanism of diarrhea received acetorphan (a new enkephalinase inhibitor) 100 mg three times daily; the second 14-patient cohort received, in addition to acetorphan, loperamide 4 mg three times daily. Before treatment, and if late diarrhea occurred, patients underwent colon mucosal biopsies for CPT-11 and topoisomerase I levels; intestinal transit time; fecalogram; fat and protein excretion; alpha1-antitrypsin clearance; D-xylose test; blood levels for vasoactive intestinal polypeptide, glucagon, gastrin, somatostatin, prostaglandin E2, and carboxylesterase; CPT-11/SN-38 and SN-38 glucuronide pharmacokinetics; and stool cultures.

RESULTS

Delayed-onset diarrhea occurred during the first three treatment cycles in 23 patients (82%). Electrolyte fecal measurements showed a negative or small osmotic gap in nine of nine patients and an increased alpha1-antitrypsin clearance in six of six patients. There were no modifications in stool cultures or hormonal dysfunction. Four of 11 patients (36%) with delayed-onset diarrhea in the first cohort responded to acetorphan, whereas nine of 10 patients (90%) responded to the combination of acetorphan and loperamide (P < .02).

CONCLUSION

CPT-11-induced delayed-onset diarrhea is caused by a secretory mechanism with an exudative component. Early combined treatment with loperamide and acetorphan seems effective in controlling the diarrheal episodes.

Radiation dose, chemotherapy and risk of osteosarcoma after solid tumours during childhood

Osteosarcoma is the most frequent second primary cancer occurring during the first 20 years following treatment for a solid cancer in childhood. Using a cohort study of children treated for a solid cancer, we investigated the incidence and etiology of osteosarcoma as a second malignant neoplasm after childhood cancer in a cohort and a case-control study. We analysed the relationship between the local dose of radiation and the risk of osteosarcoma, taking into account chemotherapy received. A cohort study of 4,400 3-year survivors of a first solid cancer during childhood diagnosed in France or the United Kingdom, between 1942 and 1986, revealed 32 subsequent osteosarcomas. In a nested case-control study, we matched 32 cases and 160 controls for sex, type of first cancer, age at first cancer and the duration of follow-up. Parameters studied were the incidence of osteosarcoma, the cumulative local dose of irradiation and the cumulative dose of chemotherapy received by cases and controls. The risk of a osteosarcoma was found to be a linear function of the local dose of radiation (excess relative risk per gray=1.8), and was found to increase with the number of moles of electrophilic agents per square meter but not with other drugs. No interaction was noted between radiotherapy and chemotherapy. Bilateral retinoblastoma, Ewing's sarcoma and soft tissue sarcoma were found to render patients susceptible to a higher risk of developing an osteosarcoma as a second malignant neoplasm. We recommend long-term surveillance of patients who were treated during childhood for bilateral retinoblastoma, Ewing's sarcoma, soft tissue sarcoma, as well as other first cancer treated with radiotherapy plus high doses of chemotherapy, without focusing exclusively on the radiation field.

Radiation dose, chemotherapy and risk of osteosarcoma after solid tumours during childhood

Osteosarcoma is the most frequent second primary cancer occurring during the first 20 years following treatment for a solid cancer in childhood. Using a cohort study of children treated for a solid cancer, we investigated the incidence and etiology of osteosarcoma as a second malignant neoplasm after childhood cancer in a cohort and a case-control study. We analysed the relationship between the local dose of radiation and the risk of osteosarcoma, taking into account chemotherapy received. A cohort study of 4,400 3-year survivors of a first solid cancer during childhood diagnosed in France or the United Kingdom, between 1942 and 1986, revealed 32 subsequent osteosarcomas. In a nested case-control study, we matched 32 cases and 160 controls for sex, type of first cancer, age at first cancer and the duration of follow-up. Parameters studied were the incidence of osteosarcoma, the cumulative local dose of irradiation and the cumulative dose of chemotherapy received by cases and controls. The risk of a osteosarcoma was found to be a linear function of the local dose of radiation (excess relative risk per gray=1.8), and was found to increase with the number of moles of electrophilic agents per square meter but not with other drugs. No interaction was noted between radiotherapy and chemotherapy. Bilateral retinoblastoma, Ewing's sarcoma and soft tissue sarcoma were found to render patients susceptible to a higher risk of developing an osteosarcoma as a second malignant neoplasm. We recommend long-term surveillance of patients who were treated during childhood for bilateral retinoblastoma, Ewing's sarcoma, soft tissue sarcoma, as well as other first cancer treated with radiotherapy plus high doses of chemotherapy, without focusing exclusively on the radiation field.

Preclinical development of camptothecin derivatives and clinical trials in pediatric oncology

Although the prognosis of childhood cancers has dramatically improved over the last three decades, new active drugs are needed. Camptothecins represent a very attractive new class of anticancer drugs to develop in paediatric oncology. The preclinical and clinical development of two of these DNA-topoisomerase I inhibitors, i.e. topotecan and irinotecan, is ongoing in paediatric malignancies. Here we review the currently available results of this evaluation. Topotecan proved to be active against several paediatric tumour xenografts. In paediatric phase I studies exploring several administration schedules, myelosuppression was dose-limiting. The preliminary results of topotecan evaluation in phase II study showed antitumour activity in neuroblastoma (response rate: 15% at relapse and 37% in newly diagnosed patients with disseminated disease) and in metastatic rhabdomyosarcoma (40% in untreated patients). Topotecan-containing drug combinations are currently investigated. Irinotecan displayed a broad spectrum of activity in paediatric solid tumour xenografts, including rhabdo-myosarcoma, neuroblastoma, peripheral primitive neuroectodermal tumour, medulloblastoma, ependymoma, malignant glioma and juvenile colon cancer. For several of these histology types, tumour-free survivors have been observed among animals bearing an advanced-stage tumour at time of treatment. The clinical evaluation of irinotecan in children is ongoing. Irinotecan undergoes a complex in vivo biotransformation involving several enzyme systems, such as carboxylesterase, UDPGT and cytochrome P450, in children as well as in adults. Preclinical studies of both drugs have shown that their activity was schedule-dependent. The optimal schedule of administration is an issue that needs to be addressed in children. In conclusion, the preliminary results of the paediatric evaluation of camptothecin derivatives show very encouraging results in childhood malignancies. The potential place of camptothecins in the treatment of paediatric malignant tumours is discussed.

Conduct of phase I trials in children with cancer

PURPOSE AND METHODS

Future progress in the care of children with cancer requires appropriate evaluations of promising new agents for pediatric indications, beginning with well-conducted phase I trials. This report summarizes current guidelines for the conduct of pediatric phase I trials and represents a consensus between American and European investigators. The primary objective of pediatric phase I trials is to define safe and appropriate doses and schedules of new agents that can subsequently be used in phase II trials to test for activity against specific childhood malignancies. Prioritization of agents for evaluation in children is critical, since many more investigational agents are evaluated in adult patients than can be systematically evaluated in children. Considerations used in prioritizing agents include activity in xenograft models, novel mechanism of action, favorable drug-resistance profile, and activity observed in adult trials of the agent.

RESULTS AND CONCLUSION

Distinctive characteristics of pediatric phase I trials, in comparison to adult phase I trials, include the necessity for multiinstitutional participation and their higher starting dose (typically 80% of the adult maximum-tolerated dose [MTD]), both of which reflect the relative unavailability of appropriate patients. The application of uniform eligibility criteria and standard definitions for MTD and dose-limiting toxicity (DLT) help to assure that pediatric phase I trials are safely conducted and reliably identify appropriate doses and schedules of agents for phase II evaluation. Where possible, pediatric phase I trials also define the pharmacokinetic behavior of new agents in children.

Activity of fotemustine in medulloblastoma and malignant glioma xenografts in relation to O6-alkylguanine-DNA alkyltransferase and alkylpurine-DNA N-glycosylase activity

Fotemustine is a chloroethylnitrosourea with antitumor activity in disseminated melanoma and adult primary brain tumors. Because new drugs are required for the treatment of medulloblastoma in children, we evaluated the preclinical antitumor activity of fotemustine in four s.c. medulloblastoma xenografts, in comparison with 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). Both drugs were administered as a single i.p. injection to nude mice bearing advanced-stage tumor. Fotemustine displayed significant antitumor activity in three of four medulloblastoma xenografts; two, IGRM34 and IGRM57, were highly sensitive, with 37 and 100% tumor-free survivors, respectively, more than 120 days after treatment at the highest nontoxic dose (50 mg/kg). Fotemustine was also highly active in a malignant glioma xenograft (IGRG88; five of six tumor-free survivors on day 177). Fotemustine proved to be significantly more active than BCNU in IGRM34 and the glioma xenograft IGRG88. The DNA repair protein O6-alkylguanine-DNA alkyltransferase (ATase) was detected in all tumor xenografts, ranging in activity from 6 to 892 fmol/mg protein. The high in vivo sensitivity to fotemustine and BCNU observed in three xenografts was clearly associated with a low ATase activity (> 20 fmol/mg), whereas the two poorly sensitive or refractory medulloblastoma xenografts showed high ATase activity (> 500 fmol/mg). Alkylpurine-DNA N-glycosylase activity was detected in all tumor xenografts but at levels ranging only from 513 to 1105 fmol/mg/h; no consistent relationship was found between alkylpurine-DNA N-glycosylase activity and the in vivo sensitivity to the two chloroethylnitrosoureas. The improved activity and tolerance of fotemustine in comparison with BCNU in pediatric medulloblastoma xenografts strongly support the clinical development of this agent in children with brain tumors, in which ATase should be examined as a potential prognostic indicator.

Benefits of pharmacological knowledge in the design and monitoring of cancer chemotherapy

Prescribing chemotherapy is a difficult task, because of drug resistance, which prevents all tumors to respond to a given protocol and because of drug toxicity, which is generally unavoidable but which must be limited to acceptable levels. The therapeutic window of anticancer drugs is very narrow and clinicians have to try to optimize the individual doses and schedules of the drugs to be administered. They can rely upon simple anthropometric features, such as body weight or surface area; they can also take into account the physiological status of the patient: age, liver and kidney function, genetic characteristics of drug metabolism, etc. The best way for dose adaptation lies in the establishment of pharmacokinetic/pharmacodynamic relationships, i.e., between the behavior of a drug in the body and its efficacy and toxicity. When it is established that the optimal effect of a drug is related to a given parameter, such as the area under the curve plotting plasma concentration vs. time (AUC), it becomes possible to administer the drug with the dose allowing to obtain the target parameter value. Individual dose adaptation can be achieved thanks to the study of the pharmacokinetics of a test dose preceding that of the therapeutic dose, or by the measure of drug plasma levels, either at steady state during a protracted infusion, or from cycle to cycle during repetitive protocols. Population analysis now allows the adaptation of anticancer drug dosing from a minimum knowledge of individual pharmacokinetic features, together with other characteristics of the patients such as age, gender or physiological functions.

Stage IV neuroblastoma in patients over 1 year of age at diagnosis: consolidation of poor responders with combined busulfan, cyclophosphamide and melphalan followed by in vitro mafosfamide-purged autologous bone marrow transplantation

In an attempt to improve the poor prognosis of poor responders with stage IV neuroblastoma, a new combined high-dose chemotherapy conditioning regimen was tested. Event-free and overall survival, as well as the incidence of complications, were analysed. Twenty-five children aged 12-146 months at diagnosis entered this study. All were in complete remission (CR) at the time of high-dose chemotherapy. Two or three different protocols had been necessary for them to achieve a CR. High-dose chemotherapy consisted of a combination of busulfan (600 mg/m2), cyclophosphamide (4400 mg/m2) and melphalan (140 mg/m2). It was followed by autologous bone marrow transplantation (ABMT). The bone marrow graft was purged in vitro with mafosfamide. The probability of event-free survival (EFS) at 5 years post-ABMT was 34%, compared to < 8% in a historical series. Toxicity was severe but manageable and 2 complication-related deaths were observed. Veno-occlusive disease was the most frequent extrahaematopoietic complication encountered, but its outcome was always favourable. By using a very intensive conditioning regimen consisting of a combination of three alkylating agents, the EFS of poor responders with metastatic neuroblastoma was improved and similar to that of good responders. When compared with a previously published similar series of patients, the improvement in survival appears probably related to intensification of the conditioning regimen.

DNA-topoisomerase I, a new target for the treatment of neuroblastoma

DNA-topoisomerase I is the nuclear target of new anticancer drugs, namely camptothecin and its derivatives. In order to establish the rational basis for their clinical development in paediatric oncology, the antitumour activity of irinotecan (CPT-11) and topotecan, two camptothecin water-soluble derivatives, was studied in nude mice bearing neuroblastoma xenografts. The panel was composed of 4 previously established subcutaneous xenograft lines (IGR-N835, IGR-N91, IGR-NB3, IGR-NB8) that exhibited the common biological markers of poor prognosis in children (MYCN amplification, 1p deletion, paradiploidy and/or MDR1 overexpression). Irinotecan and topotecan were administered i.v. or i.p. over 5 consecutive days in animals bearing tumours. Irinotecan (40 mg/kg/day) induced 20-100% complete regressions with tumour growth delays ranging from 20 to 46 days. Two out of 10 IGR-N91 bearing animals were tumour free more than 120 days after treatment with the top dose (50 mg/kg/day). Topotecan (2.7 mg/kg/day) induced 0-67% complete regressions with tumour growth delays ranging from 23 to 50 days. One out of 8 IGR-NB3 bearing mice was tumour free at the end of the experiment. The antitumour activity of both drugs was clearly sustained at a lower dose level. Topoisomerase I activity was assayed in 15 neuroblastomas, 3 ganglioneuroblastomas and 2 normal adrenal glands, using a DNA relaxation assay. Topoisomerase I activity ranged from 69 to 1304 arbitrary units/mg of protein, and was significantly higher in immature neuroblastomas than in ganglioneuroblastomas and adrenal glands. In conclusion, irinotecan and topotecan are active against neuroblastoma xenografts. Their target is expressed in patients' tumour samples. Clinical development of topoisomerase I inhibitors in children with neuroblastoma is warranted.

Potent therapeutic activity of irinotecan (CPT-11) and its schedule dependency in medulloblastoma xenografts in nude mice

The anti-tumor activity of irinotecan (CPT-11), a DNA-topoisomerase 1 inhibitor, was evaluated in 5 advanced stage subcutaneous medulloblastoma xenografts in nude mice, using different schedules of administration. With a 5-day schedule, the highest i.v. dose tested (40 mg kg-1 day-1) induced complete regressions in all xenografts but 1, and delays in tumor growth always exceeded 30 days. Two xenografts, IGRM11 and IGRM33, were highly sensitive, and animals survived tumor-free beyond 120 days after treatment. CPT-11 clearly retained its anti-tumor activity at a lower dosage (27 mg kg-1 day-1). CPT-11 was significantly more active than cyclophosphamide, thiotepa and etoposide against the 3 xenografts evaluated. To study the schedule dependency of its anti-tumor activity, CPT-11 was given i.v. at the same total doses over the same period (33 days) using either a protracted or a sequential schedule in IGRM34-bearing mice. With a dose of 10 mg kg-1 day-1 given on days 0-4, days 7-11, days 21-25 and days 28-32 (total dose, 200 mg kg-1), 3 of 6 animals were tumor free on day 378. The same total dose given with a sequential schedule, i.e., 20 mg kg-1 day-1 on days 0-4 and days 28-32, failed to induce complete regression. The plasma pharmacokinetics of CPT-11 and SN-38 were studied in IGRM34-bearing animals after a single i.v. dose of 10 and 40 mg kg-1. The plasma clearance rate of CPT-11 was dose dependent. The ratio between the SN-38 and CPT-11 area under the curve in plasma was 0.4-0.65, i.e., significantly higher than that observed in humans at the maximum tolerated dose (0.01-0.05). Conversely, this ratio was 10-fold lower in tumor than in plasma. Clinical development of irinotecan is warranted in pediatric malignancies.

Previous conventional chemotherapy is the principal risk factor for immunoglobulin deficiency during the early post-ABMT period in children

Humoral immunodeficiency after ABMT may worsen the course of infectious complications as already described in this clinical setting; children with low Ig values of the three isotypes during the first week after ABMT experienced more severe infections during the procedure than those with normal values. The aim of the study was to establish the prevalence, the duration and the risk factors of Ig deficiency after ABMT. Serum Ig levels of 160 children treated with high-dose chemotherapy (HDCT) followed by ABMT for solid tumors were studied prospectively before HDCT and weekly from the day after transplantation until the patients were discharged from the unit, as were the associations of the following covariates: patient characteristics, previous conventional chemotherapy (CCT), conditioning regimens, marrow graft and complications following ABMT. Serum Ig deficiency for at least one isotype was already present before HDCT in half of the children and mean serum Ig values decreased after HDCT. Serum Ig deficiency was early (day 7), inconstant, heterogeneous (IgM deficiency was more frequent and lasted longer) and brief (< 1 month). Children with low Ig values before HDCT were at high risk of profound and prolonged humoral immune deficiency. Previous CCT with more than six different drugs was the main risk factor for low serum IgM values before HDCT, on day 7 and on day 21 post-HDCT. This study shows that Ig replacement therapy could be useful after ABMT provided it is given to the patients defined on the basis of these specific risk factors and serum Ig levels before HDCT.

Therapeutic activity of CPT-11, a DNA-topoisomerase I inhibitor, against peripheral primitive neuroectodermal tumour and neuroblastoma xenografts

The anti-tumour activity of CPT-11, a topoisomerase I inhibitor, was evaluated in four human neural-crest-derived paediatric tumour xenografts; one peripheral primitive neuroectodermal tumour (pPNET) (SK-N-MC) and three neuroblastomas. Two models, SK-N-MC and IGR-N835, were established in athymic mice from a previously established in vitro cell line. Two new neuroblastoma xenograft models, IGR-NB3 and IGR-NB8, were derived from previously untreated non-metastatic neuroblastomas. They exhibited the classic histological features of immature neuroblastoma along with N-myc amplification, paradiploidy, chromosome 1p deletions and overexpression of the human mdr 1 gene. These tumour markers have been shown to be poor prognostic factors in children treated for neuroblastoma. CPT-11 was tested against advanced stage subcutaneous tumours. CPT-11 was administered i.v. using an intermittent (q4d x 3) and a daily x 5 schedule. The optimal dosage and schedule was 40 mg kg-1 daily for 5 days. At this highest non-toxic dose, CPT-11 induced 100% tumour-free survivors on day 121 in mice bearing the pPNET SK-N-MC xenograft. For the three neuroblastoma xenografts, 38-100% complete tumour regressions were observed with a tumour growth delay from 38 to 42 days, and anti-tumour activity was clearly sustained at a lower dosage (27 mg kg-1 day-1). The efficacy of five anti-cancer drugs commonly used in paediatric oncology or in clinical development was evaluated against SK-N-MC and IGR-N835. The sensitivity of these two xenografts to cyclophosphamide, thiotepa and cisplatin was of the same order of magnitude as that of CPT-11, but they were refractory to etoposide and taxol. In conclusion, CPT-11 demonstrated significant activity against pPNET and neuroblastoma xenografts. Further clinical development of CPT-11 in paediatric oncology is warranted.

Tumorigenicity of cerebellar primitive neuro-ectodermal tumors in athymic mice correlates with poor prognosis in children

The histogenesis of medulloblastoma, also described as a cerebellar primitive neuro-ectodermal tumor (PNET), remains controversial and unresolved. In addition, genetic markers which characterize cerebellar PNETs with poor prognosis in children have not been identified. Since xenografts can be valuable tools for better understanding the genetic events involved in cerebellar PNETs, small fragments of tumor samples from 17 children with newly diagnosed cerebellar PNETs were transplanted s.c. into female athymic Swiss mice. Eleven were non-metastatic and 6 were metastatic PNETs. Eight tumors (47%) were tumorigenic. Histological analysis showed 6 typical medulloblastomas, 1 PNET with melanin pigment and 1 PNET with a rhabdoid phenotype. Wide heterogeneity was observed in tumor growth, with a doubling time ranging from 8 to 81 days after the first passage. Tumorigenicity was correlated with the metastatic phenotype of the tumor (p < 0.001). All the patients but one with a tumorigenic tumor relapsed and died. The survival of patients with a non-tumorigenic PNET (67%) was significantly higher than that of patients with a tumorigenic PNET (13%) (p < 0.02). None of the xenografts or tumors from patients exhibited N-myc-gene alteration. Only one xenograft showed c-myc amplification, with an abnormal 15-kilobase fragment. None of the 17 tumors from patients showed amplification or c-myc-gene rearrangement. In conclusion, tumorigenicity of cerebellar PNETs strongly correlates both with the metastatic phenotype of the tumors and with the disease-free survival of the patients. In addition, genetic events other than c-myc-gene amplification might be involved in cerebellar PNETs with poor prognosis.

Phase I study of high-dose continuous intravenous infusion of VP-16 in combination with high-dose melphalan followed by autologous bone marrow transplantation in children with stage IV neuroblastoma

The purpose of the study was to determine the maximum tolerated dose of continuous infusion of high-dose VP-16 in combination with high-dose melphalan (HDM) for conditioning before autologous bone marrow transplantation (ABMT). Thirteen children (median age 27 months) with stage IV neuroblastoma were treated with high-dose VP-16 and HDM followed by ABMT as consolidation treatment. All had previously received conventional chemotherapy with a mean number of six drugs. Surgery of the primary tumor had been performed in 12/13. We performed a dose-escalating study of VP-16 from 1800 mg/m2/72 h with 300 mg/m2/72 h dose increments according to toxicity. VP-16 was administered as a 72-h i.v. infusion. Melphalan (140 mg/m2/day) was administered once as an i.v. push. VP-16 pharmacokinetics were analyzed in 12 patients. Five children received 1800 mg/m2/72 h of VP-16, five received 2100 mg/m2/72 h and three, 2400 mg/m2/72 h. The mean duration of granulocytopenia (< 0.5 x 10(9)/1) was 24 days and thrombocytopenia (< 50 x 10(9)/1) was 36 days. No major infectious complications occurred. Gastrointestinal (GI) toxicity was the dose-limiting toxicity. Five severe manifestations of GI toxicity in three patients led us to consider 2400 mg/m2/72 h as the MTD. The mean VP-16 clearance rate was 17.3 ml/min/m2 with continuous infusion. A mean steady-state plasma concentration of 24.2 micrograms/ml (s.d. = 2) and 28.3 micrograms/ml (s.d. = 1.9) was achieved at the 1800 mg/ml and 2100 mg/m2 dose levels, respectively, GI toxicity is dose limiting when VP-16 at 2400 mg/m2/72 h, is associated with HDM. When given as a continuous i.v. infusion, at 2100 mg/m2/72 h, VP-16 associated with HDM is well tolerated before ABMT in young heavily pre-treated children.

Pharmacokinetics and antitumor effects of mitoxantrone after intratumoral or intraarterial hepatic administration in rabbits

The intratumoral (i.t.) delivery of anticancer drugs aims at controlling tumor growth and thereby provides palliative treatment for liver neoplasms. Mitoxantrone is a good candidate for local or regional administration because (1) its metabolism is mainly hepatic, (2) it has a steep dose-response curve for multiple solid tumors, and (3) its fixation in tissues is sustained without vesicant effects after extravasation. We compared the tolerance, pharmacokinetics, and antitumor effects of mitoxantrone on hepatic VX2 tumors in rabbits treated with i.t. intraarterial hepatic (i.a.h.) or i.v. mitoxantrone, i.t. ethanol; or i.t. 0.9% NaCl and in control animals. Tumor growth rates (TGRs) were evaluated at 9 days after treatment. Myelosuppression was the limiting toxicity of i.v. mitoxantrone at 1.5 mg/kg (maximal tolerated dose, MTD), but neither i.t. nor i.a.h. administration led to hematologic toxicity at the same dose. The mitoxantrone retained in tumors after i.t. administration was seen as blue-stained areas of complete necrosis according to histologic analysis. Pharmacokinetic parameters showed a significantly decreased systemic exposure to the drug after both regional treatments, although the i.a.h. route appeared to have an edge over the i.t. route. TGRs were significantly reduced after i.t. mitoxantrone (81 +/- 62%), i.a.h. mitoxantrone (337 +/- 110%), and i.t. ethanol treatments (287 +/- 117%) as compared with control values (886 +/- 223%; p < 0.01). Treatment with i.v. mitoxantrone (816 +/- 132%) had no antitumor effect, nor did NaCl injections (868 +/- 116%). Mitoxantrone given i.t. induced the highest antitumor effects, resulting in a 3.5-fold reduction in TGRs as compared with i.a.h. mitoxantrone and i.t. ethanol treatments (p < 0.02). Treatment with i.t. mitoxantrone provided efficient antitumor therapy without producing major side effects. This method should be considered as palliative treatment for nonresectable liver tumors and other localized malignancies.

[Pediatric aspects of anthracycline cardiotoxicity and practical implications for prevention]

Discovered during the sixties, anthracycline antibiotics are today widely used anti-cancer drugs. Their potentially fatal cardiac toxicity, which is related in part to the total cumulative dose, has been described since 1967. The aim of this paper is to describe their biological and clinical toxic effects on the heart, especially of children, and to propose prevention guidelines. The mechanisms of cardiac toxicity, with their destructive consequences on functional myocytes reserve, are shortly recalled. Acute, sub-acute and chronic clinical aspects of anthracycline's cardiomyopathy are the subject of a literature review. In Pediatric Oncology, the prolonged survival usually observed allows delayed congestive heart failure to occur by myocardial reserve insufficiency, as hemodynamic needs are quickly increasing, especially at the end of the somatic growth. Furthermore, the frequency of cardiac abnormalities is increasing with time after therapy, reaching about half of the explored patients after 15 years. The main known methods to prevent such a toxicity are reviewed. The parcimonious use of anthracyclines is already seen in children. Every method to decrease the maximal plasma concentration of the drug (weekly schedule or prolonged infusion) has to be considered. The active cardioprotectant agent such as ICRF-187, is in clinical development. Detection, prevention, and therapy of cardiac abnormalities, which are likely to precede delayed heart failure, still remains a difficult problem in these more and more numerous children to be cured of cancer.

Neurofibromatosis 1 (NF1) mRNAs expressed in the central nervous system are differentially spliced in the 5' part of the gene

The neurofibromatosis 1 gene seems to play essential roles at several different stages of life. During embryogenesis, it is involved in cardiac development while in the adult, neurofibromin (the corresponding protein) is mainly expressed in the nervous system, and therein, essentially in neurons, non-myelinating Schwann cells and oligodendrocytes. In addition, the NF1 gene is considered a tumor suppressor gene, since mutations have been associated with the occurrence of benign and malignant tumors in neuralcrest-derived tissues. Using reverse transcription-polymerase chain reaction (RT-PCR) analyses with primers located in exons 7 and 13, we have identified evidence of alternative splicing in this region of the NF1 gene. Cloning and sequencing of cDNA allowed the characterization of an isoform bearing an extra 30 bp sequence between exons 9 and 10a, leading to the insertion of 10 amino acids between residues 420 and 421 of neurofibromin. The insertion is conserved in the mouse. Examination of the pattern of expression of this isoform demonstrated a high level of expression in the central nervous system and an absence of expression in all the other normal tissues tested including peripheral nervous tissues derived from the neural crest. Analysis of brain tumors indicated a reduced expression of the alternative exon in medulloblastomas and oligodendrogliomas. The results presented here are consistent with tissue-specific expression of this alternative exon which we propose to call exon 9br.

Busulfan disposition and hepatic veno-occlusive disease in children undergoing bone marrow transplantation

Hepatic veno-occlusive disease (HVOD) is a frequent life-threatening toxicity in patients undergoing bone marrow transplantation (BMT) after the administration of a high-dose busulfan-containing regimen. Recent studies have shown that the morbidity and mortality of HVOD may be reduced in adults by pharmacologically guided dose adjustment of busulfan. We analyzed the pharmacodynamic relationship between busulfan disposition and HVOD in 61 children (median age, 5.9 years) with malignant disease. Busulfan, given at a dose ranging from 16 mg/kg to 600 mg/m2, was combined with one or two other alkylating agents (cyclophosphamide, melphalan, thiotepa). Only 3 patients received the standard busulfan/cyclophosphamide (BUCY) regimen. A total of 24 patients (40%) developed HVOD, which resolved in all cases. A pharmacokinetics study confirmed the previously reported wide interpatient variability in busulfan disposition but did not reveal any significant alteration in children with HVOD. The mean area under the concentration-time curve (AUC) after the first dose of busulfan was higher in patients with HVOD (6,811 +/- 2,943 ng h ml-1) than in patients without HVOD (5,760 +/- 1,891 ng h ml-1., P = 0.10). This difference reflects the higher dose of busulfan given to patients with HVOD. No toxic level could be defined and, moreover, none of the toxic levels identified in adults were relevant. The high incidence of HVOD in children given 600 mg/m2 busulfan may be linked to the use of more intensive than usual high-dose chemotherapy regimens and/or drug interactions. Before the prospective evaluation of busulfan dose adjustment in children, further studies are required to demonstrate firmly the existence of a pharmacodynamic relationship in terms of toxicity and allogeneic engraftment, especially when busulfan is combined with cyclophosphamide. The maximal tolerated and minimal effective AUCs in children undergoing BMT are likely to depend mainly upon the disease, the nature of the combined high-dose regimen, and the type of bone marrow transplant.

Pharmacologically-guided dose adjustment of busulfan in high-dose chemotherapy regimens: rationale and pitfalls (review)

High-dose busulfan is used in conditioning regimens before allogeneic or autologous bone marrow transplantation (BMT) in adults and children. During the last six years, several studies have established the wide inter- and intrapatient variability of high-dose busulfan disposition. Clearance rate ranges from 0.8 to 20 ml/min/kg. Some factors of variability have been identified: age, alteration in hepatic functions, disease, circadian rhythmicity, drug interactions. Using a fixed dose of busulfan, wide interpatient variability in systemic exposure is thus expected, with eventual consequences on toxicity and efficacy. In adults, a pharmacodynamic relationship between a high busulfan systemic exposure and the occurrence of hepatic veno-occlusive disease (HVOD) has been established. A prospective controlled study demonstrated that busulfan dose-adjustment decreased the morbidity and mortality of HVOD in adults. So far, pharmacodynamic studies in children have failed to establish a toxic level. The present paper analyses the rationale for busulfan dose adjustment, and focuses on the eventual pitfalls that may jeopardize its reliability (drug absorption, chronopharmacology, drug interaction within the conditioning regimen, complex pathophysiology of HVOD). Further pharmacodynamic studies are required to establish a minimum therapeutic threshold in systemic exposure for bone marrow engraftment, especially in children undergoing HLA-compatible or incompatible allogeneic BMT for non malignant disease. The definition of a therapeutic window according to the disease and the type of BMT, along with the development of iv-busulfan, will allow accurate and effective pharmacologically-guided dose adjustment of high-dose busulfan. By the end of the century, busulfan plasma level monitoring and dose adjustment at the individual level may improve the outcome of patients undergoing BMT.

Busulfan disposition below the age of three: alteration in children with lysosomal storage disease

Busulfan disposition is age-dependent with a higher clearance and a larger volume of distribution in children than in adults. The optimal dosage of busulfan needed to achieve bone marrow (BM) displacement in young children with malignant or nonmalignant disease remains to be defined. Using a gas chromatography-mass spectrometry assay, we evaluated plasma pharmacokinetics of busulfan in 33 children (median age, 9 months; range, 2 months to 2.75 years) with immune deficiencies, lysosomal storage diseases, acute leukemias, and malignant lymphohistiocytosis after an oral dose ranging from 0.9 to 2.6 mg/kg. The busulfan clearance (assuming a bioavailability of 1) ranged from 2.1 to 13.4 mL/min/kg with a mean of 6.8 mL/min/kg, which is higher than that reported in older children (4.5 mL/min/kg) and adults (2.9 mL/min/kg). Six children with lysosomal storage disease (5 with Hurler's disease, 1 with San Filippo's disease) had a prolonged elimination half-life (4.9 v 2.4 hours), a larger volume of distribution (3.4 v 1.2 L/kg) and a faster clearance (8.7 v 6.3 mL/min/kg) than the other 27 children. This suggests that a higher dose of busulfan will be required to achieve BM displacement in children with lysosomal storage disease. Over the dose range of 0.9 to 2.6 mg/kg, busulfan pharmacokinetics were linear. However, only 46% of the interpatient variation in systemic exposure could be ascribed to the dose. Given the wide interpatient variability in busulfan disposition, dose adjustment and drug monitoring will be needed to achieve the optimal dosage of busulfan in young children. The plasma busulfan levels required to achieve BM displacement need to be defined, especially in lysosomal storage diseases.

Chronopharmacology of high-dose busulfan in children

In bone marrow transplantation, high-dose busulfan is given p.o., usually every 6 h over 4 consecutive days. Since this repeated administration might alter busulfan disposition, fluctuations in busulfan plasma levels were studied over the 4-day treatment period in 21 children (median age, 5 years) with malignant solid tumors. In addition, urinary excretion of unchanged busulfan was measured every 6 h in 4 patients. Busulfan (37.5 mg/m2 for 16 doses) was given on an empty stomach at 12 p.m., 6 p.m., midnight, and 6 a.m. for 4 consecutive days, starting at 12 p.m. Trough plasma levels, i.e., concentration 6 h after each dose and just before the next one, and urinary excretion of busulfan were measured using a gas chromatography-mass spectrometry assay. Busulfan trough plasma levels exhibited a significant circadian rhythm with a higher mean level at 6 a.m. compared to that at 12 p.m., 6 p.m., and midnight. This rhythm was characterized by a double amplitude (mean +/- SD) of 42 +/- 14% and an acrophase (maximum) occurring at 5:48 a.m. +/- 115 min. In addition, once the steady state was reached, no decreasing trend was observed in any patient. Busulfan renal clearance proved to be low since only 5.4 +/- 1.2% of the given dose were excreted unchanged in urine. In the 4 patients studied, busulfan urinary excretion exhibited a significant circadian rhythm which was apparently linked to the physiological circadian rhythm in urinary output. Ten of 20 evaluable patients developed hepatic venoocclusive disease (HVOD). A significant circadian rhythm in the plasma level was found in both HVOD and non-HVOD patients with no difference between the two groups with regard to the 24-h mean, amplitude, or acrophase. Thus, the circadian changes in busulfan trough plasma levels observed at the steady state were not related to the occurrence of HVOD in these children with solid tumors. Moreover, since this rhythm was stable from day 2 to day 4, it should not compromise dose adjustment.

Combined continuous infusion etoposide with high-dose cyclophosphamide for refractory neuroblastoma: a phase II study from the Société Française d'Oncologie Pédiatrique

PURPOSE

Patients older than 1 year with stage IV neuroblastoma who fail to achieve complete remission (CRem) have a particularly poor long-term prognosis. In an attempt to improve the outcome of these refractory patients, we tested a new drug combination.

PATIENTS AND METHODS

Twenty-nine children with advanced neuroblastoma (27 stage IV and two stage III) were entered onto this phase II study. All were refractory to conventional chemotherapy and had measurable disease at the time of the trial. The regimen was a combination of high-dose cyclophosphamide (2 g/m2/d) on days 2, 3, and 4, and etoposide (VP16; 50 mg/m2/d) by continuous intravenous (IV) infusion on days 1 to 5. A pharmacokinetic study of VP16 was conducted in eight patients to determine whether the goal of persistent plasma levels between 1 and 5 micrograms/mL was achieved.

RESULTS

Patients received a median of two courses, for a total of 58 courses. The median interval between each course was 32 days. In the 28 assessable patients, the overall response rate was 43%, with one CRem and 11 partial remissions (PRems). No life-threatening complication was observed in these heavily pretreated patients. The median duration of neutropenia (< 5 x 10(9)/L) was 14 days, and that of thrombocytopenia (< 50 x 10(9)/L) was 11 days. The overall incidence of sepsis was 27%. Gastrointestinal toxicity was frequent, but mild. Electrolyte disturbance with antidiuretic hormone (ADH)-like syndrome occurred in eight courses, but resolved rapidly. Grade > or = 2 hemorrhagic cystitis was observed in three courses. No cardiac toxicity was observed. There were no treatment-related deaths. Pharmacokinetic analysis showed that mean steady-state plasma levels (Css) of VP16 were greater than 1 microgram/mL during all the courses.

CONCLUSION

This new drug combination appears to be effective in advanced neuroblastoma. Its toxicity remains manageable, with no life-threatening complications. Further evaluation in patients with less-advanced disease is warranted.

[Granulosa cell tumors of the ovary in children and adolescents. Multicenter retrospective study in 40 patients aged 7 months to 22 years]

BACKGROUND

Juvenile granulosa cell tumors (JGCT) of the ovary are rare in children. The over-all outcome after surgery is relatively good, but the indication and type of complementary treatment for severe forms are still unclear.

POPULATION

A retrospective survey of the majority of patients with JGCT of the ovary admitted between 1965 and 1990 to 11 French oncologic pediatric centers was carried out. Medical records including surgical and histological data, were analyzed and each tumor was retrospectively classified by the same pathologist according to the Wollner classification.

RESULTS

There were 40 patients aged 7 months to 22 years (mean: 6 years); 28 were less than 10 year old at diagnosis. Three had enchondromatosis (Ollier's disease). At diagnosis, all patients presented with an abdominal tumor, 23 had developed manifestations of precocious pseudopuberty, 2 had signs of virilization after a normal puberty and 2 had secondary amenorrhea. Surgery was always the primary treatment: unilateral ovariectomy in 35 cases, bilateral in 4 and biopsy alone in 1 case. There were 21 stage I, 1 stage II, 16 stage III and 2 stage IV cases. 13 patients received combined chemotherapy and 2 abdominal radiotherapy. 34 patients were alive and disease-free 10 months to 26 years after surgery and 6 died. All 23 patients with precocious pseudopuberty had a favorable outcome.

CONCLUSIONS

This study confirms earlier reports. Unilateral ovariectomy is the first-choice therapy. There is no evidence that tumors complicated by rupture and hemoperitoneum require chemotherapy. Combined chemotherapy does not appear to improve the prognosis for the rare malignant forms. The factors of good prognosis are age less than 10 years and the presence of precocious pseudopuberty.

Risk factors for hepatic veno-occlusive disease after high-dose busulfan-containing regimens followed by autologous bone marrow transplantation: a study in 136 children

Risk factors for hepatic veno-occlusive disease (HVOD) were analysed in a population of 136 autografted children who received high-dose busulfan (BU) as part of a conditioning regimen. HVOD was diagnosed according to McDonald's clinical criteria. The incidence of HVOD was particularly high in this series (22%) compared with series with other conditioning regimens but the outcome was favorable in 26 patients (87%). Four deaths occurred (13%), one of which was HVOD related. The clinical presentation of HVOD was similar to that described in previous reports. Although statistical analysis failed to demonstrate any factors predictive of outcome, it did identify risk factors for the occurrence of HVOD: these were (1) a total dose of BU exceeding the standard 16 mg/kg dose; (2) the use of three as opposed to two alkylating agents; (3) the sequence of BU administration when given in the conditioning regimen containing three alkylating agents; and (4) concomitant ketoconazole therapy.

Is 600 mg/m2 the appropriate dosage of busulfan in children undergoing bone marrow transplantation?

Recent studies have reported that the pharmacokinetics of high-dose busulfan in bone marrow transplantation (BMT) are age-dependent: with the usual dosage of 16 mg/kg over 4 days, systemic exposure is two to four times lower in children than in adults. Data suggested that the dose of busulfan should rather be calculated on the basis of the body surface area (BSA). We measured plasma pharmacokinetics of busulfan in 27 children (mean age, 5.4 years) who were administered a new dosage of 600 mg/m2 over 4 days, ie, 17.8 to 29.2 mg/kg (mean, 24.8 mg/kg), using a gas chromatography-mass spectrometry assay. Our results demonstrate that, with this new dosage, systemic exposure is significantly increased in children compared with that achieved with the usual dosage of 16 mg/kg (6,404 +/- 2,378 v 3,918 +/- 1,170 ng.h/mL; P = .003). Moreover, there is no longer a significant difference in systemic exposure between children treated with this new dosage and adults given a dose of 16 mg/kg of busulfan. However, despite the use of a dosage normalized to the BSA, there is still a wide interindividual variation in systemic exposure, ranging from 3,566 to 13,129 ng.h/mL, which may account for the high incidence of venoocclusive disease (VOD) of the liver that we have already reported. The optimal dosage and schedule of busulfan in children requires a more individual approach that could be based on dose adjustment and plasma level monitoring.

High-dose busulfan and thiotepa with autologous bone marrow transplantation in childhood malignant brain tumors: a phase II study

In order to evaluate the effect of intensive combined chemotherapy in pediatric brain tumors, we designed a phase II study of high-dose busulfan and thiotepa followed by bone marrow transplantation (BMT) in children with measurable recurrent brain tumors. As alkylating agents, busulfan and thiotepa were expected to exhibit a steep dose effect and no overlapping extramedullary toxicity. Moreover, both drugs have an excellent distribution into the central nervous system in humans. Since May 1988, 20 children (median age 6 years) have been treated. Busulfan (150 mg/m2/day x 4) given orally was followed by thiotepa (350 mg/m2/day x 3), given as a 1 h i.v. infusion. Cryopreserved bone marrow was reinfused 48 h after completion of chemotherapy. Tumor response was assessed by computed tomography and magnetic resonance imaging 4 to 6 weeks after BMT. Five partial responses were observed (three of six medulloblastomas, one of five ependymomas, one of two primitive neuroectodermal tumors); two patients with medulloblastoma and one with brain stem tumor achieved an objective response. Ten patients had stable disease and one progressive disease. One patient is not evaluable because of early toxic death. Toxicity was high in terms of aplasia and cutaneous, hepatic and neurological complications. The overall response rate of 26% is encouraging since all patients had disease refractory to all conventional therapies.

High-dose chemotherapy containing busulfan followed by bone marrow transplantation in 24 children with refractory or relapsed non-Hodgkin's lymphoma

Twenty-four children with relapsed or refractory non-Hodgkin's lymphoma underwent high-dose chemotherapy (HDC) with bone marrow transplantation (BMT). HDC comprised in all cases busulfan (16 mg/kg or 600 mg/m2), with either cyclophosphamide (200 mg/kg or 4.4 g/m2) and/or melphalan (140 mg/m2). Twenty-three of these children had received second-line therapy before receiving HDC. There were 16 B cell and eight T cell lymphomas. Twenty-three patients were evaluable at day 30 post-BMT; 19 were in complete remission, four did not respond. Eight patients are long-term survivors between 62 and 296 weeks after BMT. Among the seven children with resistant disease before HDC, only one is a long-term survivor. No toxic deaths occurred. The main adverse side effect was hepatic veno-occlusive disease which occurred in four patients, but resolved completely in all cases. Comparisons with other classic HDC regimens in relapsed childhood lymphomas show that HDC containing busulfan with BMT appears reasonably safe and is effective in refractory or relapsed lymphomas, even in these highly previously treated patients.

Streptococcal septicaemia following autologous bone marrow transplantation in children treated with high-dose chemotherapy

A total of 251 patients were given 326 courses of high-dose chemotherapy followed by autologous bone marrow transplantation between February 1979 and August 1988. Ninety-one cases of septicaemia developed in 84 patients, 33 of these cases (36%) were due to streptococci. The outcome was fatal for four patients (12.1%). No specific risk factors were identified which might account for this septicaemia and no clinical feature was significantly associated with these cases of bacterial infection. Pulmonary and neurologic septic complications, however, were of very poor prognosis since all patients with these complications died. The high rate of streptococcal septicaemia and the poor outcome for patients with prolonged and profound neutropenia led us to modify our choice of initial broad-spectrum antibiotic therapy.