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Biomedical subjects

Peter D Cole

Publications and source records attributed to Peter D Cole.

11 recordsLinked to original sources
PubMed2026

Survival by Race and Ethnicity in Children and Adolescents/Young Adults With Relapsed/Refractory Hodgkin Lymphoma: A Pooled Analysis of Children's Oncology Group Trials.

PURPOSE: Despite 5-year survival rates of over 90% among children and adolescents/young adults (CAYAs) with classic Hodgkin lymphoma (cHL), 15%-20% relapse after frontline therapy. Prior analysis of frontline Children's Oncology Group (COG) clinical trials demonstrated that, despite similar rates of relapse, non-Hispanic Black (NHB) and Hispanic (vs. non-Hispanic White [NHW]) patients experienced higher post-relapse mortality. It is unknown whether post-relapse disparities persist when second-line treatment is delivered in a cooperative group trial setting. We examined overall survival (OS) by race and ethnicity in CAYAs enrolled in COG trials for relapsed/refractory (r/r) cHL. METHODS: A pooled analysis of individual-level data from CAYAs (≤ 29 years) receiving therapy for r/r cHL on COG clinical trials (2001-2016) was conducted. The Kaplan-Meier method estimated 3-year OS by racial and ethnic groups. Cox regression models examined associations of race and ethnicity and OS, adjusted for age, insurance, first versus ≥2 relapse, and time from initial diagnosis to relapse trial enrollment. RESULTS: Among 175 CAYAs treated on COG trials for r/r cHL (5.7% Asian or Pacific Islander, 14.9% Hispanic, 14.3% NHB, 61.7% NHW, 3.4% other), at median follow-up of 4.9 years, 3-year OS was 82.1% (95% confidence interval [CI], 75.3%-87.1%) and did not differ by race and ethnicity (p = 0.36). In multivariable analyses, shorter time from diagnosis to relapse trial enrollment (p = 0.01) and ≥2 relapses (vs. first, p = 0.004) conferred worse OS, with no significant effect of race and ethnicity (p = 0.43). CONCLUSION: Post-relapse survival did not differ by race and ethnicity among CAYAs enrolled in COG trials for r/r cHL, suggesting access to clinical trials may mitigate OS disparities.

Humans↗
PubMed2006

Delayed neurotoxicity associated with therapy for children with acute lymphoblastic leukemia.

Most children diagnosed today with acute lymphoblastic leukemia (ALL) will be cured. However, treatment entails risk of neurotoxicity, causing deficits in neurocognitive function that can persist in the years after treatment is completed. Many of the components of leukemia therapy can contribute to adverse neurologic sequelae, including craniospinal irradiation, nucleoside analogs, corticosteroids, and antifolates. In this review, we describe the characteristic radiographic findings and neurocognitive deficits seen among survivors of childhood ALL. We summarize what is known about the pathophysiology of delayed treatment-related neurotoxicity, with a focus on the toxicity resulting from pharmacologic disruption of folate physiology within the central nervous system. Finally, we suggest testable strategies to ameliorate the symptoms of treatment-related neurotoxicity or decrease its incidence.

Antineoplastic Agents↗
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↗
PubMed2005

Steroid-induced alterations of mood and behavior in children during treatment for acute lymphoblastic leukemia.

Despite their therapeutic utility, children may experience emotional and behavioral side effects from steroids during treatment for leukemia. However, clinical manifestations and treatment options have rarely been described in the pediatric literature. The aim of this current paper is to address this knowledge gap via four brief case examples and a review of the literature. In addition, we review recent data to indicate how concurrent use of antifolates may place these children at particular risk for adverse psychological reactions.

Affect↗
PubMed2005

Pharmacodynamic properties of methotrexate and Aminotrexate during weekly therapy.

4-Amino-pteroyl-glutamic acid (Aminotrexate; AMT) has several advantages over the related antifolate methotrexate (MTX), including greater potency, complete oral bioavailability, and greater accumulation by leukemic blasts in vitro. We compared the pharmacodynamic properties of AMT (given orally at 4 mg/m2 in two divided doses per week) and MTX (100 mg/m2 in four divided doses per week) among children with acute lymphoblastic leukemia. We find AMT and MTX to have equivalent penetration into the bone marrow compartment of these patients, as indicated by the steady-state concentrations within mature red blood cells (RBCs). However, MTX concentrations in the cerebrospinal fluid after oral dosage are significantly greater than AMT. To confirm these clinical observations, mice were treated four weekly injections of AMT or MTX, at a 1:20 dosage ratio, and tissue antifolate content was then determined over the subsequent 22 days. We confirm the selective exclusion of AMT from the CNS compartment, while showing equivalent accumulation of AMT and MTX in the RBCs, liver, spleen, kidneys and testes. Finally, we demonstrate that AMT, MTX, and their predominant polyglutamate species are equipotent inhibitors of their target intracellular enzyme dihydrofolate reductase, emphasizing the critical nature of steady-state tissue accumulation in determining the relative cytotoxic potency of these two antifolates.

Aminopterin↗
PubMed2005

High-dose methotrexate in acute lymphoblastic leukemia: where is the evidence for its continued use?

High-dose intravenous methotrexate is an important component of many effective chemotherapeutic regimens for childhood acute lymphoblastic leukemia (ALL). Its use has a strong pharmacologic rationale: to overcome mechanisms of resistance of the malignant cells and to achieve cytotoxic concentrations in sanctuary sites for lymphoblasts. Although therapeutic progress in ALL during the past 4 decades has been closely associated with more widespread use of intravenous methotrexate and in progressively larger doses, little data exist to clearly support the use of high-dose intravenous methotrexate over a regimen of prolonged administration of low-dose methotrexate. The implied superiority of intravenous methotrexate mainly stems from studies that used identical leucovorin rescue with low-dose methotrexate or from studies of upfront window therapy in untreated children with ALL in which single standard doses of oral methotrexate were compared with high-dose intravenous methotrexate with leucovorin rescue. The evidence favoring administration of intravenous methotrexate for children with ALL is critically reviewed. Despite its extensive use, high-dose intravenous methotrexate has not been proved conclusively to be more effective than less toxic, less labor intensive, and less costly methods of methotrexate administration.

Animals↗
PubMed2004

Reduced folate carrier mutations are not the mechanism underlying methotrexate resistance in childhood acute lymphoblastic leukemia.

BACKGROUND: Although the majority of children with acute lymphoblastic leukemia (ALL) are cured with combination chemotherapy containing methotrexate (MTX), drug resistance contributes to treatment failure for a substantial fraction of patients. The primary transporter for folates and MTX is the reduced folate carrier (RFC). Impaired drug transport is a documented mechanism of MTX resistance in patients with ALL; however, to the authors' knowledge it is not known whether inactivating RFC mutations are a contributing factor. METHODS: The authors devised a genomic polymerase chain reaction-single strand conformational polymorphism assay followed by sequencing and screened the entire RFC coding region for sequence alterations in DNA from 246 leukemia specimens from patients with diverse ethnic variation, 24 at the time of recurrence and the rest at the time of diagnosis. This cohort was comprised of 203 B-precursor ALL specimens (82.5%), 32 T-lineage ALL specimens (13%), and 11 acute myeloblastic leukemia specimens (4.5%). RESULTS: Of 246 DNA samples, only 3 diagnosis B-precursor ALL specimens (1.2%) were found to harbor alterations in the RFC gene, including heterozygous single nucleotide changes resulting in D56H and D522N substitutions in the first extracellular loop and the C-terminus of this transporter, respectively. The third sample had a sequence alteration in exon 3 that could not be identified because of the lack of availability of DNA. CONCLUSIONS: Whereas inactivating RFC mutations are a frequent mechanism of MTX resistance in human leukemia cell lines and in patients with osteosarcoma, they are not common and do not appear to play any significant role in intrinsic or acquired resistance to MTX in childhood leukemia. This is the first study of RFC mutations in multiple pediatric leukemia specimens.

Antimetabolites, Antineoplastic↗
PubMed2002

Osteosarcoma cells, resistant to methotrexate due to nucleoside and nucleobase salvage, are sensitive to nucleoside analogs.

PURPOSE: To test a novel strategy for overcoming intrinsic resistance to methotrexate (MTX) in osteosarcoma (OS) due to nucleoside and nucleobase salvage (NS). METHODS: Four OS cell lines, found to be highly resistant to MTX, were tested to determine the dominant mechanism of resistance. Sensitivity to MTX was tested in the presence of dialyzed serum or the transport inhibitor dipyridamole (DP) to confirm the contribution of NS to MTX resistance. We then investigated whether increased NS activity could be exploited using cytotoxic nucleoside analogs. RESULTS: Like other cell types, OS cells are capable of circumventing inhibition of de novo nucleotide synthesis by relying on NS. MTX, at concentrations as high as 1 m M did not inhibit cell growth in culture medium supplemented with undialyzed serum. In contrast, when NS was inhibited by DP or in medium depleted of nucleosides and nucleobases, sensitivity to MTX was seen at nanomolar concentrations. In medium with dialyzed serum, thymidine and hypoxanthine provided dose-dependent protection from MTX toxicity at concentrations similar to those seen in human plasma. No evidence of other significant mechanisms of resistance were found. All four cell lines were sensitive to 3-day exposures to cytarabine (IC50 0.22 to 2.88 micro M) and vidarabine (IC50 0.09 to 0.95 micro M). CONCLUSIONS: Salvage of de novo nucleotide synthesis inhibition by extracellular thymidine and hypoxanthine, at physiologically relevant concentrations, contributes to resistance to MTX in OS. However, this same process may impart a collateral sensitivity to nucleoside analogs. These findings support clinical trials for patients with OS using nucleoside analogs, either alone or in combination.

Animals↗
PubMedDate not supplied

Dextromethorphan is effective in the treatment of subacute methotrexate neurotoxicity.

Methotrexate-induced neurotoxicity (MTX-Ntox) is a frequent complication of methotrexate (MTX) therapy for patients with both malignant and inflammatory diseases. MTX-Ntox can occur after intrathecal MTX or after low-, intermediate-, or high-dose systemic administration. Symptoms can present in the acute, subacute, or late setting form, and can range from affective disorders, malaise, and headaches, to somnolence, focal neurologic deficits, and seizures. While the pathogenesis of MTX-Ntox is likely multifactorial, one potential biochemical pathway leading from MTX to neurotoxicity involves the folate dependent remethylation of homocysteine (Hcy). MTX therapy is known to cause elevations of both plasma and CSF Hcy. Hcy is directly toxic to vascular endothelium and it and its metabolites are excitatory agonists of the N-methyl-D-aspartate (NMDA) receptor. Competitive or noncompetitive antagonists might afford protection from or reversal of MTX-Ntox. Using high-performance liquid chromatography (HPLC) with coulometric electrochemical detection, the authors measured CSF Hcy in sequential patients with severe subacute MTX-Ntox. CSF Hcy was higher in these patients (n = 9, median = 0.93 microM) than in asymptomatic patients (n = 11, median 0.2 microM, p < .01). Five patients with severe subacute MTX-Ntox (most with dysarthria and/or hemiplegia) were treated with 1-2 mg/kg oral dextromethorphan (DM), a noncompetitive antagonist of the N-methyl-1-aspartate (NMDA) receptor. All five had resolution of symptoms. These data provide additional clinical support for elevated CSF Hcy in the induction of MTX-Ntox through activation of the NMDA-receptor. These data provide support for a placebo-controlled clinical trial to examine the ability of DM to prevent or alleviate MTX-Ntox.

Adolescent↗