New Assays Open Window in Evaluating Leukemia Types

William G. Wierda, MD, PhD

Associate Professor

Medicine and Internist

Department of Leukemia

The University of Texas

MD Anderson CancerCenter

Houston, TX

Genetic markers are becoming a more integral part of diagnosing cancer and determining which patients will encounter more aggressive forms of their disease. For patients with leukemia, recently approved diagnostic tests may revolutionize the way their treating physicians evaluate their disease.

In October, the FDA approved the Vysis EGR1 fluorescence in situ hybridization (FISH) Probe Kit for detecting a chromosomal deletion in bone marrow that usually is associated with a poor prognosis for patients with acute myeloid leukemia.

It was the second new in vitro diagnostic test for leukemia that the FDA approved this year. In August, the agency approved the Vysis FISH Probe Kit for patients with chronic lymphocytic leukemia (CLL). The kit includes a panel of 5 individual FISH probes intended to detect deletion of the LSI TP53, LSI ATM, and LSI D13S319 probe targets and gain of the D12Z3 sequence in peripheral blood specimens from untreated patients with B-cell CLL.

Abbott Molecular, which developed the tests, said the assays are intended to help clinicians determine disease prognosis.

"When patients are given these tests, there are things that we can do differently in terms of treatment," said William G. Wierda, MD, PhD, of The University of Texas MD Anderson Cancer Center in Houston.

Wierda works most closely with patients who have CLL. For these patients, Wierda said that performing a FISH analysis allows him to detect deletions of the 17p, 11q, and 13q chromosomes and trisomy of chromosome 12. All of these deletions and mutations have been shown to predict poorer outcomes for patients with CLL.

For patients who have the 11q deletion, Weirda said he might use combination therapies such as fludarabine, cyclophosphamide, and rituximab (FCR) along with an alkylating agent.

In the case of patients with a chromosome 17p deletion, Wierda said that effective treatment options are very limited or nonexistent. For those patients, Wierda said the diagnostic tests can be good predictors of who would be an appropriate candidate for clinical trials of new therapies.

While these diagnostic tests are helpful to patients, Wierda said he hopes the detection of chromosomal abnormalities and other biomarkers eventually will be used to develop targeted therapies that help patients with these very specific mutations.