Biomedical subjects

S M Blaney

Publications and source records attributed to S M Blaney.

At least 19 recordsLinked to original sources

PubMed2006

A phase I study of irinotecan administered on a weekly schedule in pediatric patients.

BACKGROUND: The objectives of this study were to determine the maximum tolerated dose (MTD), dose-limiting toxicities (DLTs), pharmacokinetics, and anti-tumor effect of irinotecan in pediatric patients with recurrent or refractory malignancies. PROCEDURE: Twenty-three patients between 1 and 21 years of age, with a solid tumor refractory to standard therapy or for which there was no standard therapy were enrolled. Irinotecan was administered over 90 min weekly 4x, every 6 weeks. The initial dose level was 125 mg/m(2)/day, with subsequent escalations to 160 and 200 mg/m(2)/day. A MTD was defined in heavily-pretreated and less-heavily-pretreated (< or =2 prior chemotherapy regimens, no prior bone marrow transplantation, and no central axis radiation) patients. Pharmacokinetic studies were also performed. RESULTS: Neutropenia and diarrhea were the DLTs in heavily pretreated patients; the MTD was 125 mg/m(2)/day. Neutropenia was the DLT in less-heavily pretreated; the MTD was 160 mg/m(2)/day. Five patients had stable disease for two to four cycles including one patient each with rhabdomyosarcoma, Ewing sarcoma, neuroblastoma, and two patients with ependymoma. Irinotecan clearance was greater that that previously reported for children receiving high dose irinotecan. CONCLUSIONS: The recommended phase II dose of irinotecan administered weekly 4x, every 6 weeks in children with solid tumors is 125 mg/m(2)/dose for heavily pretreated patients and 160 mg/m(2)/dose for less heavily pretreated patients.

Adolescent↗

PubMed2004

Phase I trial of intrathecal liposomal cytarabine in children with neoplastic meningitis.

PURPOSE: We performed a phase I trial of intrathecal (IT) liposomal cytarabine (DepoCyt; Enzon Pharmaceuticals, Piscataway, NJ and SkyePharma Inc, San Diego, CA) to determine the maximum-tolerated dose, the dose-limiting toxicities, and the plasma and CSF pharmacokinetics of IT lipsomal cytarabine in children >/= 3 years of age with advanced meningeal malignancies. PATIENTS AND METHODS: Eighteen assessable patients received IT liposomal cytarabine through either an indwelling ventricular access device or via lumbar puncture. Liposomal cytarabine was given once every 2 weeks during induction, once every 4 weeks during consolidation, and once every 8 weeks during the maintenance phase of treatment. The initial dose was 25 mg, with subsequent escalations to 35 and 50 mg. CSF pharmacokinetic samples were obtained in a subset of patients. RESULTS: Arachnoiditis, characterized by fever, headache, nausea, vomiting, and back pain was noted in the first two patients at the 25 mg dose level. Therefore, subsequent patients were treated with dexamethasone, beginning the day of liposomal cytarabine administration and continuing for 5 days. Headache (grade 3) was dose limiting in two of eight patients enrolled at the 50 mg dose level. Eight of the 14 patients assessable for response demonstrated evidence of benefit manifest as prolonged disease stabilization or response. CONCLUSION: The maximum-tolerated dose and recommended phase II dose of liposomal cytarabine in patients between the ages of 3 and 21 years is 35 mg, administered with dexamethasone (0.15 mg/kg/dose, twice a day for 5 days). A phase II trial of IT liposomal cytarabine in children with CNS leukemia in second or higher relapse is in development.

Adolescent↗

PubMed2004

Pediatric phase I trial and pharmacokinetic study of the platelet-derived growth factor (PDGF) receptor pathway inhibitor SU101.

PURPOSE: To determine the maximum tolerated dose and the toxicity profile of the PDGF receptor pathway inhibitor SU101 in pediatric patients with refractory solid tumors, and to define the plasma pharmacokinetics of SU101 and its active metabolite SU0020 in children. EXPERIMENTAL DESIGN: Patients between 3 and 21 years of age with CNS malignancy, neuroblastoma, or sarcoma refractory to standard therapy were eligible. The starting dose of SU101 was 230 mg/m(2) per day administered as a 96-h continuous infusion every 21 days. Blood for pharmacokinetic analysis was obtained during the first cycle. RESULTS: Entered into the trial were 27 patients, and 24 were fully evaluable for toxicity. Dose-limiting central nervous system toxicity was observed in two patients at the 440 mg/m(2) per day dose level. Non-dose-limiting toxicities included nausea, vomiting, headache, fatigue, abdominal discomfort, diarrhea, pruritus, anorexia, constipation, and paresthesias. There were no complete or partial responses. One patient with rapidly progressive desmoplastic small round-cell tumor experienced symptomatic improvement and prolonged stable disease. Steady-state concentrations of SU101 were rapidly achieved and proportional to dose. The concentration of SU0020 was 100- to 1000-fold greater than that of SU101. The median clearance of SU0020 was 0.19 l/day per m(2) and its terminal elimination half-life was 14 days. CONCLUSIONS: SU101 administered on this schedule was generally well tolerated. The maximum tolerated dose of SU101 is 390 mg/m(2) per day for 4 days repeated every 3 weeks. The neurotoxicity observed at the 440 mg/m(2) per day dose level suggests that patients receiving repetitive cycles must be monitored closely, as SU0020 may accumulate over time.

Adolescent↗

PubMed2001

Recombinant urate oxidase for the prophylaxis or treatment of hyperuricemia in patients With leukemia or lymphoma.

PURPOSE: To improve the control of hyperuricemia in patients with leukemia or lymphoma, we tested a newly developed uricolytic agent, recombinant urate oxidase (SR29142; Rasburicase; Sanofi-Synthelabo, Inc, Paris, France), which catalyzes the oxidation of uric acid to allantoin, a highly water-soluble metabolite readily excreted by the kidneys. PATIENTS AND METHODS: We administered Rasburicase intravenously, at 0.15 or 0.20 mg/kg, for 5 to 7 consecutive days to 131 children, adolescents, and young adults with newly diagnosed leukemia or lymphoma, who either presented with abnormally high plasma uric acid concentrations or had large tumor cell burdens. Blood levels of uric acid, creatinine, phosphorus, and potassium were measured daily. The pharmacokinetics of Rasburicase, the urinary excretion rate of allantoin, and antibodies to Rasburicase were also studied. RESULTS: At either dosage, the recombinant enzyme produced a rapid and sharp decrease in plasma uric acid concentrations in all patients. The median level decreased by 4 hours after treatment, from 9.7 to 1 mg/dL (P =.0001), in the 65 patients who presented with hyperuricemia, and from 4.3 to 0.5 mg/dL (P =.0001) in the remaining 66 patients. Despite cytoreductive chemotherapy, plasma uric acid concentrations remained low throughout the treatment (daily median level, 0.5 mg/dL). The urinary excretion rate of allantoin increased during Rasburicase treatment, peaking on day 3. Serum phosphorus concentrations did not change significantly during the first 3 days of treatment, decreased significantly by day 4 in patients presenting with hyperuricemia (P =.0003), and fell within the normal range in all patients by 48 hours after treatment. Serum creatinine levels decreased significantly after 1 day of treatment in patients with or without hyperuricemia at diagnosis (P =.0003 and P =.02, respectively) and returned to normal range in all patients by day 6 of treatment. Toxicity was negligible, and none of the patients required dialysis. The mean plasma half-lives of the agent were 16.0 +/- 6.3 (SD) hours and 21.1 +/- 12.0 hours, respectively, in patients treated at dosages of 0.15 or 0.20 mg/kg. Seventeen of the 121 assessable patients developed antibodies to the enzyme. CONCLUSION: Rasburicase is safe and highly effective for the prophylaxis or treatment of hyperuricemia in patients with leukemia or lymphoma.

Adolescent↗

PubMed2001

Intrathecal chemotherapy.

An unforeseen consequence of improved disease-free survival in many hematologic and solid tumor malignancies has been an increase in the incidence of disease recurrence in the leptomeninges. The recognition of the central nervous system (CNS) as a unique 'sanctuary' site has resulted in the development of therapeutic strategies specifically directed at the leptomeninges. Although therapeutic strategies have been successful in the prevention and treatment of CNS leukemia, there are still a paucity of therapeutic options for patients with neoplastic meningitis due to solid tumors or recurrent CNS leukemia. This article provides an overview of the pharmacology and toxicity of intrathecal agents that are commonly employed in the treatment and prevention of leptomeningeal disease, and describes new agents that are in the early stages of clinical development.

Antineoplastic Agents↗

PubMed2001

Treatment controversies in medulloblastoma.

Medulloblastoma, the most common primary malignant brain tumor in children, is a radiosensitive and chemosensitive tumor. Nevertheless, medulloblastoma remains a management challenge for the clinical oncologist, because the optimal sequence and dosage for each treatment modality has not yet been defined. In addition, effective management strategies for medulloblastoma may result in profound neuroendocrine and neuropsychologic sequelae. In this article, we review the clinical and biologic prognostic factors for classifying medulloblastoma, current strategies for the management of this disease, and potential strategies to prevent or minimize long-term treatment sequelae.

Cerebellar Neoplasms↗

PubMed2001

The development of camptothecin analogs in childhood cancers.

Camptothecin analogs, agents that target the intranuclear enzyme topoisomerase I, represent a promising new class of anticancer drugs for the treatment of childhood cancer. In preclinical studies, camptothecins, such as topotecan and irinotecan, are highly active against a variety of pediatric malignancies including neuroblastomas, rhabdomyosarcomas, gliomas, and medulloblastomas. In this paper, we review the status of completed and ongoing clinical trials and pharmacokinetic studies of camptothecin analogs in children. These and future planned studies of this novel class of cytotoxic agents are critical to defining the ultimate role of topoisomerase I poisons in the treatment of childhood cancer.

Adolescent↗

PubMed2000

Neoplastic meningitis: diagnosis and treatment considerations.

Neoplastic meningitis is an increasingly recognized complication of advanced metastatic cancer and, if left undiagnosed or untreated, is characterized by rapid neurologic deterioration and death. Thus, the diagnosis and treatment of neoplastic meningitis present challenges for the clinical oncologist. The diagnosis of neoplastic meningitis is based on clinical signs and symptoms, laboratory analysis of cerebrospinal fluid to determine cell count and cytology, and analysis of neuroimaging studies for evidence of leptomeningeal or cranial nerve enhancement. Once diagnosed, conventional treatment regimens may include radiotherapy combined with systemic or intrathecal chemotherapy, often with the antimetabolites cytarabine and/or methotrexate. However, the prognosis for neoplastic meningitis secondary to an underlying solid tumor or recurrent leukemia is poor with conventional treatment regimens. Therefore, novel agents for intrathecal administration, including DepoCyttrade mark, mafosfamide, and topotecan, or novel therapeutic approaches, including conjugated monoclonal antibodies and immunotoxins or gene therapy, are currently under investigation. Such new agents and therapeutic approaches will facilitate the development of effective treatment strategies and will ultimately improve the outcome for patients with this devastating disease. This article provides an overview of the approaches to the diagnosis, evaluation, and treatment of neoplastic meningitis.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2000

Methotrexate distribution within the subarachnoid space after intraventricular and intravenous administration.

PURPOSE: Intrathecal methotrexate achieves high concentrations in cerebrospinal fluid (CSF), but drug distribution throughout the subarachnoid space after an intralumbar dose is limited. The objective of this study was to quantify methotrexate distribution in CSF after intraventricular and intravenous administration and to identify factors that influence CSF distribution. METHODS: Nonhuman primates (Macaca mulatta) with permanently implanted catheters in the lateral and fourth ventricles received methotrexate by bolus injection (0.5 mg) and infusion (0.05 to 0.5 mg/day over 24 to 168 h) into the lateral ventricle, as well as intravenous infusions. CSF was sampled from the lumbar space, fourth ventricle and the subarachnoid space at the vertex. Methotrexate in CSF and plasma was measured with the dihydrofolate reductase inhibition assay. RESULTS: After bolus intraventricular injection, methotrexate exposure in lumbar CSF ranged from 11% to 69% of that achieved in the fourth ventricle. During continuous intraventricular infusions, methotrexate steady-state concentrations (C(ss)) in lumbar CSF and CSF from the vertex were only 20% to 25% of the ventricular CSF C(ss). The dose, duration of infusion, and infusate volume did not influence drug distribution to the lumbar CSF, but probenicid increased the lumbar to ventricular C(ss) ratio, suggesting the involvement of a probenicid-sensitive transport pump in the efflux of MTX from the CSF. During the intravenous infusions, the ventricular methotrexate C(ss) was lower than the lumbar C(ss) and the C(ss) in CSF from the vertex. CONCLUSION: Methotrexate CSF distribution after intraventricular injection was uneven, and at steady-state CSF methotrexate concentrations were lower at sites that were more distant from the injection site.

Animals↗

PubMed2000

Clinical pharmacology of encapsulated sustained-release cytarabine.

BACKGROUND: The therapeutic effectiveness of chemotherapy is often limited by the inability to sustain cytotoxic concentrations at the tumor site. Cytarabine liposome injection (DepoCyt), a sterile, injectable suspension of the antimetabolite cytarabine, encapsulated into multivesicular, lipid-based particles, has been developed to improve the treatment of neoplastic meningitis (NM) through sustained release of cytarabine. OBJECTIVE: To review the pharmacokinetics, efficacy, and safety of intrathecal DepoCyt for the treatment of NM secondary to lymphoma or solid tumors. RESULTS: In preclinical and clinical studies, DepoCyt markedly extended the duration of tumor exposure to cytotoxic concentrations of cytarabine compared with administration of unbound cytarabine. Data from recent clinical studies demonstrate that DepoCyt improves complete response rates among patients with NM secondary to lymphoma. Trends in time to neurologic progression and median survival also favored DepoCyt over unbound cytarabine in these studies. Data have also been presented that suggest that patients with NM secondary to solid tumors benefit more from DepoCyt than from conventional treatment approaches. Chemical arachnoiditis (i.e., headache, fever, nausea, vomiting) was common in patients receiving DepoCyt, however, symptoms were manageable with oral dexamethasone. CONCLUSIONS: Encapsulation of cytarabine into liposomes for sustained release prolongs tumor exposure to cytotoxic concentrations of cytarabine, which may improve therapeutic efficacy in patients with NM secondary to lymphoma or solid tumors.

Animals↗

PubMed2000

Pharmacokinetics and cerebrospinal fluid penetration of CI-994 (N-acetyldinaline) in the nonhuman primate.

CI-994 is a substituted benzamide derivative that has demonstrated significant antitumor activity in vitro and in vivo against a broad spectrum of murine and human tumor models. Its mechanism of action is still unknown but seems to be novel compared with existing anticancer drugs. We studied the plasma and cerebrospinal fluid (CSF) pharmacokinetics of CI-994 in nonhuman primates. Three animals (total 4 doses) received an 80 mg/m2 dose of CI-994 administered over 20 min, and one animal received a dose of 100 mg/m2. Serial plasma and fourth ventricular CSF samples were obtained from 0 to 4320 min after administration of the 80-mg/m2 dose, and only plasma samples were obtained after the 100-mg/m2 dose. CI-994 was measured using a previously validated reverse-phase high-performance liquid chromatography assay. Elimination of CI-994 from plasma was triexponential (4 of 5 cases) or biexponential (1 of 5 cases), with a terminal half life (t1/2) of 7.4 +/- 2.5 h, volume of distribution of 15.5 +/- 1.8 L/m2, and clearance of 40 +/- 6 ml/min/m2. The area under the concentration-time curve (AUC) for the 80-mg/m2 dose was 125 +/- 17 microM x hr. CI-994 was first detected in CSF at the completion of the i.v. infusion. Peak concentrations of CI-994 in CSF were 3.4 +/- 0.3 microM. Elimination from CSF was monoexponential (2 of 4 cases) or biexponential (2 of 4 cases) with a terminal t1/2 in CSF of 12.9 +/- 2.5 h and AUC of 55 +/- 18 microM x hr. The AUC(CSF):AUCplasma ratio was 43 +/- 10%. This study demonstrates that there is excellent CSF penetration of CI-994 after i.v. administration. Additional studies are needed to evaluate the potential role of CI-994 in the treatment of central nervous system neoplasms.

Animals↗

PubMed2000

Modified procedure for implantation of subcutaneous central venous access devices in macaques (Macaca mulatta).

A nonhuman primate model comprising adult male rhesus monkeys (Macaca mulatta) with chronically indwelling subcutaneous central venous access devices provides a unique opportunity to determine plasma pharmacokinetics of new drugs such as anticancer and anti- retroviral agents. The central venous access we use is a low-profile, single-septum, titanium port that is attached to a radiopaque, indwelling catheter; the catheter is implanted in an internal jugular vein. A common complication following placement of the venous access device was migration of the catheter tip. We therefore modified the standard procedure by cutting the silicone catheter and introducing the rigid connector to secure the catheter to the vessel at the insertion site (approximately 9 to 13 cm from the distal end of the catheter). Prior to the use of the connector, three of five catheters migrated within 4 weeks after placement. In contrast, all 13 internal jugular catheters with connectors have remained patent without migration of the catheter tip. Therefore, incorporation of the catheter connector appears to have eliminated the problem of catheter migration.

Analgesics, Opioid↗

PubMed1999

Plasma and CSF pharmacokinetics of ganciclovir in nonhuman primates.

PURPOSE: The antiviral nucleoside analogue ganciclovir is a potent inhibitor of replication in herpes viruses and is effective against cytomegalovirus infections in immunocompromised patients. Ganciclovir is also used in cancer gene therapy studies that utilize the herpes simplex virus thymidine kinase gene (HSV-TK). The pharmacokinetics of ganciclovir in adults and children have been described previously but there are no detailed studies of the CNS pharmacology of ganciclovir. We studied the pharmacokinetics of ganciclovir in plasma and CSF in a nonhuman primate model that is highly predictive of the CSF penetration of drugs in humans. METHODS: Ganciclovir, 10 mg/kg i.v., was administered over 30 min to three animals. Ganciclovir concentrations in plasma and CSF were measured using reverse-phase HPLC. RESULTS: Peak plasma ganciclovir concentrations ranged from 18.3 to 20.0 microg/ml and the mean plasma AUC was 1075+/-202 microg/ml x min. Disappearance of ganciclovir from the plasma was biexponential with a distribution half-life (t(1/2)alpha) of 18+/-7 min and an elimination half-life (t(1/2)beta) of 109+/-7 min. Total body clearance (ClTB) was 9.4+/-1.6 ml/min/kg. The mean CSF ganciclovir AUC was 168+/-83 microg/ml x min and the mean peak CSF concentration was 0.7+/-0.3 microg/ml. The ratio of the AUCs in CSF and plasma was 15.5+/-7.1%. CONCLUSIONS: Ganciclovir penetrates into the CSF following i.v. administration. This finding will be useful in the design of gene therapy trials involving the HSV-TK gene followed by treatment with ganciclovir in CNS or leptomeningeal tumors.

Animals↗

PubMed1999

Phase I trial of docetaxel with filgrastim support in pediatric patients with refractory solid tumors: a collaborative Pediatric Oncology Branch, National Cancer Institute and Children's Cancer Group trial.

Neutropenia is the dose-limiting toxicity of docetaxel in children. This Phase I trial was designed to determine the maximum tolerated dose, the dose-limiting toxicities, and the incidence and severity of other toxicities of docetaxel with filgrastim (G-CSF) support in children with refractory solid tumors. Docetaxel was administered as an i.v. infusion for 1 h every 21 days with a starting dose of 150 mg/m2 and an escalation to 185 mg/m2 and 235 mg/m2 in subsequent patient cohorts. G-CSF (5 microg/kg/day) was administered s.c., starting 48 h after docetaxel and continuing until the post-nadir neutrophil count reached 10,000/microl. Seventeen patients received 27 courses of docetaxel with G-CSF support. Generalized erythematous desquamating skin rash and myalgias were dose-limiting at 235 mg/m2. Localized and generalized rashes were seen at all of the three dose levels. Neutropenia (median nadir, 95/1microl) occurred at all of the dose levels but was brief in duration and not dose-limiting. Thrombocytopenia was minimal (median platelet count nadir, 139,000/microl), and the severity of neutropenia and thrombocytopenia did not seem to be related to the docetaxel dose. Other docetaxel-related toxicities included hemorrhage (associated with mucositis), sepsis, hypersensitivity reaction, transient elevation of liver enzymes, stomatitis, back pain, asthenia, and neuropathy. One minor response was observed in a patient with colon cancer. The maximum tolerated dose of docetaxel with G-CSF support in children is 185 mg/m2, which is 50% higher than the maximum tolerated dose of docetaxel alone in children and 85 % higher than the recommended adult dose.

Adolescent↗

PubMed1999

Thioguanine administered as a continuous intravenous infusion to pediatric patients is metabolized to the novel metabolite 8-hydroxy-thioguanine.

Thiopurine antimetabolites have been in clinical use for more than 40 years, yet the metabolism of thiopurines remains only partially understood. Data from our previous pediatric phase 1 trial of continuous i.v. infusion of thioguanine (CIVI-TG) suggested that TG was eliminated by saturable mechanism, with conversion of the drug to an unknown metabolite. In this study we have identified this metabolite as 8-hydroxy-thioguanine (8-OH-TG). The metabolite coeluted with the 8-OH-TG standard on HPLC and had an identical UV spectrum, with a lambda(max) of 350 nm. On mass spectroscopy, the positive ion, single quad scan of 8-OH-TG yielded a protonated molecular ion at 184 Da and contained diagnostic ions at m/z 167, 156, 142, and 125 Da. Incubation of TG in vitro with partially purified aldehyde oxidase resulted in 8-OH-TG formation. 8-OH-TG is the predominant circulating metabolite found in patients receiving CIVI-TG and is likely generated by the action of aldehyde oxidase.

Aldehyde Oxidase↗

PubMed1998

Plasma and cerebrospinal fluid pharmacokinetics of 9-aminocamptothecin (9-AC), irinotecan (CPT-11), and SN-38 in nonhuman primates.

PURPOSE: The plasma and cerebrospinal fluid (CSF) pharmacokinetics of the camptothecin analogs, 9-aminocamptothecin (9-AC) and irinotecan, were studied in a nonhuman primate model to determine their CSF penetration. METHODS: 9-AC, 0.2 mg/kg (4 mg/m2) or 0.5 mg/kg (10 mg/m2), was infused intravenously over 15 min and irinotecan, 4.8 mg/kg (96 mg/m2) or 11.6 mg/kg (225 mg/m2), was infused over 30 min. Plasma and CSF samples were obtained at frequent intervals over 24 h. Lactone and total drug forms of 9-AC, irinotecan, and the active metabolite of irinotecan, SN-38, were quantified by reverse-phase HPLC. RESULTS: 9-AC lactone had a clearance (CL) of 2.1 +/- 0.9 l/kg per h, a volume of distribution at steady state (Vd[ss]) of 1.6 +/- 0.7 l/kg and a half-life (t1/2) of 3.2 +/- 0.8 h. The lactone form of 9-AC accounted for 26 +/- 7% of the total drug in plasma. The CSF penetration of 9-AC lactone was limited. CSF 9-AC lactone concentration peaked 30 to 45 min after the dose at 11 to 21 nM (0.5 mg/kg dose), and the ratio of the areas under the CSF and plasma concentration-time curves (AUC(CSF):AUC[P]) was only 3.5 +/- 2.1%. For irinotecan, the CL was 3.4 +/- 0.4 l/kg per h, the Vd(ss) was 7.1 +/- 1.3 l/kg, and the t1/2 was 4.9 +/- 2.2 h. Plasma AUCs of the lactone form of SN-38 were only 2.0% to 2.4% of the AUCs of irinotecan lactone. The lactone form of irinotecan accounted for 26 +/- 5% of the total drug in plasma, and the lactone form of SN-38 accounted for 55 +/- 6% of the total SN-38 in plasma. The AUC(CSF):AUC(P) ratio for irinotecan lactone was 14 +/- 3%. SN-38 lactone and carboxylate could not be measured (< 1.0 nM) in CSF. The AUC(CSF):AUC(P) ratio for SN-38 lactone was estimated to be < or = 8%. CONCLUSION: Despite their structural similarity, the CSF penetration of 9-AC and SN-38 is substantially less than that of topotecan which we previously found to have an AUC(CSF):AUC(P) ratio of 32%.

Animals↗

PubMed1998

Phase I trial and pharmacokinetic study of pyrazoloacridine in children and young adults with refractory cancers.

PURPOSE: To define the maximum-tolerated dose (MTD), quantitative and qualitative toxicities, recommended phase II dose, and pharmacokinetics of pyrazoloacridine (PZA) administered as a 1- or 24-hour infusion in children and young adults with refractory cancers. PATIENTS AND METHODS: Twenty-two patients received PZA as a 1-hour infusion at doses of 380 mg/m2 (n = 3), 495 mg/m2 (n = 6), 640 mg/m2 (n = 6), and 835 mg/m2 (n = 7). An additional four patients received PZA as a 24-hour infusion at the MTD (640 mg/m2) for the 1-hour infusion schedule. Plasma samples were obtained for pharmacokinetic analysis in 17 patients. PZA concentration in plasma was measured by reverse-phase high-performance liquid chromatography (HPLC). A two-compartment pharmacokinetic model was fit to the PZA plasma concentration data. RESULTS: On the 1-hour infusion schedule, dose-limiting myelosuppression (neutropenia more than thrombocytopenia) was observed in two of seven patients at the 835-mg/m2 dose level. Myelosuppression did not appear to be ameliorated by prolonging the infusion to 24 hours. Nonhematologic toxicities were minor. Significant neurotoxicity, which was dose-limiting in adults treated with a 1-hour infusion of PZA, was observed in one patient treated at 640 mg/m2, but was not dose-limiting. There was marked interpatient variability in plasma PZA concentrations at all dose levels. The pharmacokinetic profile of PZA was characterized by an initial rapid decline (alpha half-life [t(1/2)alpha], 0.5 hours) followed by a prolonged elimination phase (t(1/2)beta, 30 hours). The volume of distribution at steady-state (Vd(ss)) was 700 L/m2 and the clearance was 300 mL/min/m2. There was no evidence of dose-dependent clearance. The area under the PZA concentration-time curve (AUC) correlated poorly with dose and was more predictive of the degree of myelosuppression than was PZA dose. CONCLUSION: PZA administered as 1- or 24-hour infusion is well tolerated by children and young adults. The dose-limiting toxicity (DLT) is myelosuppression. Neurotoxicity is not prominent in this age group. There was marked interpatient variation in plasma concentrations of PZA. The recommended dose for phase II studies is 640 mg/m2.

Acridines↗

PubMed1998

Phase II trial of topotecan administered as 72-hour continuous infusion in children with refractory solid tumors: a collaborative Pediatric Branch, National Cancer Institute, and Children's Cancer Group Study.

The antitumor activity of topotecan administered as a 72-h continuous i.v. infusion was evaluated in children with refractory neuroblastoma and sarcomas of soft tissue and bone. We also attempted to increase the dose intensity of topotecan by including an intrapatient dose escalation in the trial design. Ninety-three children (85 eligible and evaluable for response) with recurrent or refractory neuroblastoma, osteosarcoma, Ewing's sarcoma/peripheral neuroectodermal tumor, rhabdomyosarcoma, or other soft-tissue sarcomas received topotecan administered as a 72-h i.v. infusion every 21 days. The initial dose was 1.0 mg/m2/day, with subsequent intrapatient dose escalation to 1.3 mg/m2/day for those patients who did not experience dose-limiting toxicity after their first cycle of topotecan. There was one complete response in a patient with neuroblastoma (n = 26) and one partial response in a patient with Ewing's sarcoma/peripheral neuroectodermal tumor (n = 25). No complete or partial responses were observed in 17 patients with osteosarcoma, 15 patients with rhabdomyosarcoma, or 2 patients with other soft-tissue sarcomas; however, 8 patients had prolonged (15-48 weeks) stable disease while receiving topotecan. Topotecan was well tolerated. The most commonly observed toxicities were myelosuppression (dose-limiting) and nausea and vomiting. Intrapatient dose escalations were performed in 68% of the patients who received more than one cycle of topotecan, and 1.3 mg/m2/day was tolerated by 79% of the patients who received the higher dose and were evaluable for hematological toxicity. In conclusion, topotecan administered as a 72-h continuous infusion every 21 days is inactive (objective response rate, < 20%) in children with refractory or recurrent neuroblastoma and sarcomas of soft tissue or bone.

Adolescent↗