Molecular Pathology Laboratory Network

A small study found that patients who had a complete remission of myelodysplastic syndrome (MDS) after treatment with lenalidomide (Revlimid) still had circulating drug-resistant malignant stem cells; and the disease resumed its progression in most patients despite continued treatment.

The study, published in a recent issue of the New England Journal of Medicine, tracked seven patients with MDS marked by the 5q genomic deletion who experienced complete clinical responses to lenalidomide -- two of whom also had complete chromosome responses -- along with an eighth patient with similar disease who failed lenalidomide therapy.

Researchers found that all seven patients who achieved remission, including those with complete chromosome responses, had MDS-associated stem cells with the 5q deletion still in circulation; and the surviving malignant stem cells tended to be "distinctly resistant" to lenalidomide.

The results, according to researchers, may help explain why lenalidomide eventually loses effectiveness in many MDS cases.

To identify chromosome abnormalities in MDS such as a 5q deletion, MPLN offers a MDS FISH profile, which includes probes for chromosomes 5, 7, 8 and 20. For more information, contact a technical service specialist at 800.932.2943.