header
 

ABL Kinase Mutation Analysis and Gleevec® Resistance

ABL G


Test Synonym:

ABL kinase domain gene sequencing

Associations:

CML, t(9;22) positive ALL

CPT Code:

83891 x3 – Isolation or extraction of highly purified nucleic acid
83892 x1 – Enzymatic digestion
83902 x1 – Reverse transcription
83898 x3 – Amplification of patient nucleic acid, single primer pair, each primer pair
83894 x1 – Separation by gel electrophoresis
83904 x5 – Mutation identification by sequencing, single segment, each segment 83912-26 – Interpretation and report

Turnaround Time:

5-7 days

Methodology:

Reverse transcriptase PCR (RT-PCR), Semi-nested PCR, Bi-directional DNA sequencing

Specimen Requirements:

  • 10.0ml (min. 9.0ml) whole blood in EDTA
  • 5.0ml (min. 2.5ml) bone marrow in EDTA

    • Causes for Rejection:

  • Specimen >48 hrs. old
  • Specimen clotted
  • Stored or shipped at incorrect temperature
  • Incorrect anticoagulant
  • Insufficient specimen volume

    Specimen Stability:

  • Specimen must be received by MPLN within 36 hrs. of collection
  • Stable at 2-8°C

    • Storage and Handling:

    Ship peripheral blood and bone marrow at ambient temperature (do not ship on ice or cold pack; do not ship to arrive after 1:00PM on Friday, or on weekends)

    Reference Range:

    ABL Kinase domain mutation(s) detected and characterized / not detected

    Indication:

    The majority of patients diagnosed with Philadelphia (Ph) chromosome-positive chronic myelogenous leukemia (CML) currently undergo therapy that includes the kinase inhibitor, Gleevec (Imatinib; STI571). Patients with chronic phase CML usually respond well to this treatment, often achieving a durable complete cytogenetic response (CCR) or a partial or complete molecular (PCR-negative) response. In contrast, patients who first receive Gleevec while in accelerated phase or blast crisis usually experience a relatively short-lived hematological response only(1).

    Studies to date indicate that Gleevec therapy eventually fails to some extent in all CML patients(2). Usually, this treatment failure is attributed to positive selection for drug-resistant leukemic cells, which carry a mutated chimeric ABL kinase gene. The majority of the known resistance-inducing mutations are single-base substitutions. These mutations can be detected in therapy-unresponsive patients when at least 20 percent of their Ph-positive leukemic cells carry a Gleevec resistance mutation(3). The present test employs bidirectional DNA sequencing to detect and characterize ABL kinase domain gene mutations in CML patients.

    References:

    1. Lahaye et al. (2005). Response and resistance in 300 patients with BCR-ABL-positive leukemias treated with imatinib in a single center: a 4.5-year follow-up. Cancer 103:1659-1669.

    2. Branford et al. (2004). Real-time quantitative PCR analysis can be used as a primary screen to identify patients with CML treated with imatinib who have BCR-ABL kinase domain mutations. Blood 104:2926-2932.
    3. Branford et al. (2003). Detection of BCR-ABL mutations in patients with CML treated with Imatinib is virtually always accompanied by clinical resistance, and mutations in the ATP phosphate-binding loop (P-loop) are associated with a poor prognosis. Blood 102:276-283.