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Unit Code 87995:
Imatinib Mesylate Responsive Genes, Locus Anomalies, FISH

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Useful For

Detecting a neoplastic clone associated with the common

chromosome anomalies seen in patients with acute leukemia

or other myeloid malignancies.

 

This panel is particularly useful for specimens in which standard

cytogenetic analysis is unsuccessful.

 

Individual probes can also be utilized to track down known

chromosome anomalies in patients with myeloid malignancies

and, therefore, assess response to therapy.

Clinical Information

Myeloid neoplasms are primary disorders of the bone marrow cells.

These malignancies encompass several entities with extremely varied

clinical courses, including acute myeloid leukemias (AML), chronic

myeloproliferative disorders (CMPD), and myelodysplastic syndromes.

The underlying genetic mechanisms associated with these malignancies

are varied and only a portion of the genetic anomalies have targeted

therapies clinically available.

 

One group of genes, including ABL (Abelson murine leukemia viral

oncogene homolog 1), ARG (Abelson murine leukemia viral oncogene

homolog 2, also called ABL2), PDGFRA (platelet-derived growth factor

receptor, alpha), and PDGFRB (platelet-derived growth factor receptor,

beta) can be inappropriately activated via various genetic mechanisms

and result in overexpression of their tyrosine kinase activity. Tyrosine

kinase activity plays an important role in cellular signaling, division, and

differentiation; overexpression may cause some cancers. The myeloid

malignancies associated with these aberrantly expressed genes include

AML, chronic myelogenous leukemia (CML), hypereosinophilic

syndrome/systemic mast cell disease (HES/SMCD), and atypical CMPD.

These translocations can also be seen in lymphoid neoplasms, including

acute lymphoblastic leukemia (ALL) and lymphomas, and they can also

possess a varied genetic etiology. Several clinical studies have

demonstrated that the malignancies displaying overexpression of

these genes are responsive to imatinib mesylate (Gleevec), a drug that

specifically targets these genes.

Reference Values

An interpretive report will be provided.

Interpretation

A neoplastic clone is detected when the percent of cells with an

abnormality exceeds the normal cutoff for any given probe.

 

The presence of a positive clone supports a diagnosis of malignancy.

 

The absence of an abnormal clone does not rule out the presence

of neoplastic disorder.

Cautions

This test is not approved by the Food and Drug Administration (FDA) and

it is best used as an adjunct to existing clinical and pathologic information.

Special Instructions and Forms

• Cytogenetics Hematologic FISH Panel Patient Information Sheet 

Clinical Reference

1.   Trempat P, Villalva C, Laurent G, et al:  Chronic myeloproliferative

      disorders with rearrangement of the platelet-derived growth factor

      alpha receptor; a new clinical target for STI571/Glivec. Oncogene

      2003 Aug 28;22(36):5702-5706

 

2.   Dave BJ, Wiggins M, Higgeins CM, et al:  9q34 rearrangements in

      BCR/ABL fusion-negative acute lymphoblastic leukemia. Cancer

      Genet Cytogenet 2005 Oct 1;162:30-37

 

3.   Pardanani A, Reeder T, Porrata LF, et al:  Imatinib therapy for

      hypereosinophilic syndrome and other eosinophilic disorders.

      Blood 2003 May 1;101(9):3391-3397

 

4.   Pardanani A, Tefferi A:  Imatinib targets other than bcr/abl and their

      clinical relevance in myeloid disorders. Blood 2004 Oct 1;104(7):

      1931-1939 

Key