Resistance to Methotrexate in Patients With Acute Lymphoblastic Leukemia in Relapse or Remission

Children's Oncology Group135 enrolled

Overview

RATIONALE: Studying samples of blood from patients with cancer in the laboratory may help doctors learn more about cancer and the development of drug resistance in patients. PURPOSE: This laboratory study is looking at resistance to methotrexate in patients with acute lymphoblastic leukemia in relapse or remission.

OBJECTIVES: * Determine the mechanisms of intrinsic and acquired methotrexate resistance using in vitro assays of matched initial diagnosis, relapsed, and nonrelapsed (control) leukemic blast samples from patients with acute lymphoblastic leukemia in relapse or remission. * Determine if the mechanisms of acquired methotrexate resistance are related to dosage or timing of methotrexate administration or other clinical factors in these patients. OUTLINE: Random samples of frozen leukemic blasts from relapsing patients at initial diagnosis and relapse are selected. A corresponding sample from nonrelapsing patients (control) at initial diagnosis is also randomly selected. Reduced folate carrier (RFC) and dehydrofolate reductase (DHFR) expression is measured using a quantitative reverse transcriptase-polymerase chain reaction assay of prepared RNA. DHFR gene amplification is measured by a dot blot analysis of prepared DNA. Results of these assays are used to determine if a particular mechanism of acquired methotrexate resistance is associated with a particular subset of acute lymphoblastic leukemia patients. Data are collected regarding the actual timing and dosage of methotrexate received by each patient and are correlated with the mechanisms of resistance. PROJECTED ACCRUAL: A total of 135 paired samples will be accrued for this study.

Study Type

OBSERVATIONAL

Enrollment

135

Conditions

Leukemia

Interventions

microarray analysisGENETIC

reverse transcriptase-polymerase chain reactionGENETIC

laboratory biomarker analysisOTHER

Eligibility

Sex: ALLMax age: 120 Years

Medical Language ↔ Plain English

DISEASE CHARACTERISTICS: * Meets 1 of the following criteria: * Acute lymphoblastic leukemia (ALL) in relapse, including all risk groups and leukemia subtypes, with frozen leukemic blast samples stored from the time of initial diagnosis and relapse * Non-relapsing ALL (as control) PATIENT CHARACTERISTICS: * Not specified PRIOR CONCURRENT THERAPY: * Not specified

Outcomes

Primary Outcomes

Mechanisms of intrinsic and acquired methotrexate resistance

Correlation of acquired methotrexate resistance with dosage or timing of methotrexate administration

Correlation of acquired methotrexate resistance with other clinical factors

Data from ClinicalTrials.gov

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