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Biomedical subjects

John Holcenberg

Publications and source records attributed to John Holcenberg.

6 recordsLinked to original sources
PubMed2007

Substitution of oral and intravenous thioguanine for mercaptopurine in a treatment regimen for children with standard risk acute lymphoblastic leukemia: a collaborative Children's Oncology Group/National Cancer Institute pilot trial (CCG-1942).

BACKGROUND: Although mercaptopurine (MP) is conventionally used to treat childhood acute lymphoblastic leukemia (ALL), thioguanine (TG) is a more potent thiopurine in vitro and, when administered orally to patients, achieves cytotoxic drug concentrations in the cerebrospinal fluid (CSF). We performed a pilot study incorporating oral and 24-hr continuous IV infusion (CIVI) TG in children with newly diagnosed standard-risk ALL. PROCEDURE: Children with newly diagnosed standard-risk ALL (age 1-10 years, WBC<50 k) were eligible. Multi-agent chemotherapy was patterned after the Children's Cancer Group (CCG) 105 trial, with the addition of CIVI-TG (480 mg/m2) during consolidation, interim maintenance and maintenance, and substitution of oral TG (60 mg/m2/day) for oral MP during maintenance. RESULTS: Fifty-eight patients (31 female), median age 4.3 years, were enrolled. At 8 years, the relapse-free and overall survival probabilities were 83% and 88%. There were no CNS relapses. Six patients (five males) experienced reversible veno-occlusive disease (VOD) while receiving oral TG, and the study was amended to discontinue TG, changing all patients to oral MP. Red cell TG nucleotide concentrations during oral TG averaged 95 ng (570 pmol)/8x10(8) RBC, greater than concentrations reported with oral MP. CONCLUSION: Although the absence of CNS relapses in this pilot study suggests that TG may contribute to the prevention of CNS recurrences, the development of VOD negatively impacts the risk:benefit ratio of substituting TG for MP.

Administration, Oral↗
PubMed2005

Phase II trial of oral aminopterin for adults and children with refractory acute leukemia.

PURPOSE: To determine the antileukemic activity of weekly oral aminopterin in patients with refractory acute leukemia; to describe the pharmacodynamic properties of aminopterin; and to contrast the intracellular metabolism of aminopterin and methotrexate by patients' blasts in vitro. EXPERIMENTAL DESIGN: Forty-six patients were enrolled in three strata: children with acute lymphoblastic leukemia (ALL), adults with ALL, and patients with acute myeloid leukemia (AML). Aminopterin was given weekly, in two doses of 2 mg/m(2), 12 hours apart. Limited sampling pharmacokinetic analysis was done during the first week of therapy. Accumulation of [(3)H]aminopterin and [(3)H]methotrexate by leukemic blasts was studied in vitro. RESULTS: Six of 22 children with ALL (27%; 95% confidence interval, 8-47%) had clinically significant responses. None of those with AML and only two of 11 adults with ALL had responses meeting protocol definitions, although peripheral blast counts tended to decrease with therapy in all groups. Mucosal toxicity was minimal, even with limited use of leucovorin rescue. Complete bioavailability of aminopterin was confirmed, with a mean area under the curve of 0.52 +/- 0.03 micromol hour/L after oral dosing. No relationship between aminopterin pharmacokinetics and response was seen. In vitro, aminopterin showed more consistent metabolism by leukemic blasts to polyglutamates than methotrexate. Lineage-specific differences in the pattern of intracellular antifolylpolyglutamates were observed. CONCLUSIONS: Weekly oral aminopterin has significant activity among children with refractory ALL. With greater cellular accumulation and metabolism, more reliable bioavailability than methotrexate, and tolerable toxicity at this dose and schedule, aminopterin deserves further study as a potent alternative to methotrexate.

Administration, Oral↗
PubMed2004

Phase I trial and pharmacokinetics of gemcitabine in children with advanced solid tumors.

PURPOSE: To determine the maximum tolerated dose, toxicity, and pharmacokinetics of gemcitabine in children with refractory solid tumors. PATIENTS AND METHODS: Gemcitabine was given as a 30-minute infusion for 2 or 3 consecutive weeks every 4 weeks, to 42 patients aged 1 to 21 years. Doses of 1000, 1200 and 1500 mg/m(2) were administered for 3 weeks. Subsequently, gemcitabine was given for only 2 consecutive weeks at 1500, 1800, and 2100 mg/m(2). Plasma concentrations of gemcitabine and its metabolite, 2'2'-difluorodeoxyuridine, were measured in 28 patients. RESULTS: Forty patients who received 132 courses of gemcitabine were assessable for toxicity. The maximum tolerated dose of gemcitabine given weekly for 3 weeks was 1200 mg/m(2). Dose-limiting toxicity was not seen in one-third of children treated at any doses given for 2 weeks. The major toxicity was myelosuppression in three of five patients at 1500 mg/m(2) for 3 weeks, and one of seven patients at 1800 mg/m(2) for 2 weeks. Other serious adverse events were somnolence, fever and hypotension, and rash in three patients. Gemcitabine plasma concentration-time data were fit to a one- (n = 5) or two-compartment (n = 23) open model. Mean gemcitabine clearance and half-life values were 2140 mL/min/m(2) and 13.7 minutes, respectively. One patient with pancreatic cancer had a partial response. Seven patients had stable disease for 2 to 17 months. CONCLUSION: Gemcitabine given by 30-minute infusion for 2 or 3 consecutive weeks every 4 weeks was tolerated well by children at doses of 2100 mg/m(2) and 1200 mg/m(2), respectively.

Adolescent↗
PubMed2004

Toxicity and efficacy of intensive chemotherapy for children with acute lymphoblastic leukemia (ALL) after first bone marrow or extramedullary relapse.

BACKGROUND: Approximately 25% of children newly diagnosed with acute lymphoblastic leukemia (ALL) will eventually experience leukemic relapse, with bone marrow being the most common site of recurrence. The ability to achieve a durable second remission is complicated by toxicity and resistant disease. We report a novel combination of chemotherapy for relapsed pediatric ALL. PROCEDURE: Thirty pediatric patients with relapsed medullary (n = 18) and extra-medullary (n = 12) ALL were enrolled at three pediatric institutions. Following receipt of induction and the first Block A and Block B of intensification, each patient was evaluated for toxicity, efficacy in achieving remission, and long-term survival. Additionally, minimal residual disease (MRD) detection by multidimensional flow cytometry (MDF) was performed. RESULTS: During induction, the major non-hematopoeitic toxicities were mucositis (30% of patients) and bacteremia (50% of patients). Two patients (7%) died of toxicity during induction. Toxicity during intensification Block 1A and 1B was markedly reduced. Eight-nine percent of patients with marrow disease achieved a remission following induction and intensification. The event-free survival (EFS) for all patients at 2 and 4 years were 60% (95% CI: 42-78%) and 49% (95% CI: 30-68%), respectively. CONCLUSIONS: This regimen for patients with relapsed ALL was successful in achieving a second remission for the majority of patients with acceptable toxicity.

Administration, Oral↗