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Key Words

Myelodysplastic syndrome, lenalidomide (Revlimid™). (Definitions of many terms related to cancer can be found in the Cancer.gov Dictionary.)

Summary

Lenalidomide (Revlimid™) was highly effective in a phase II study of previously treated patients with myelodyspastic syndromes (MDS) who had a particular gene abnormality. Nearly two in three patients no longer required regular blood transfusions after a median period of only four weeks on the drug. Their blood cells also reflected other positive changes.

Source

American Society of Clinical Oncology (ASCO) annual meeting. Orlando, May 15, 2005.

Background

Myelodysplastic syndromes (MDS) are a group of cancers in which bone marrow does not make enough mature, healthy blood cells. They are the most common blood cancers in adults, affecting nearly 50,000 Americans every year. MDS patients often need regular blood transfusions to help them fight fatigue and anemia.

One type of MDS involves a missing or defective gene located at chromosome 5, so-called 5q-minus syndrome. Between 18 and 25 percent of all MDS patients have this form of the disease; they are the largest subgroup. In addition to needing regular blood transfusions, patients with this type of MDS do not respond well to cytokines that otherwise might be given to boost their immune system and increase the number of red and white blood cells and platelets (their blood count).

Lenalidomide is an anticancer compound related to, and less toxic than, thalidomide. A previous phase I/II study had found lenalidomide to be extremely effective in this subgroup of MDS patients: 10 of 11 patients no longer required transfusions, and their blood counts dramatically improved. The current phase II study was designed by some of the same researchers to further investigate the safety and efficacy of lenalidomide with this subgroup of MDS patients.

The Study

In this multicenter, randomized phase II study of 146 patients with 5q-minus MDS, one group received lenalidomide for 21 days and then nothing for the next seven days, while the remaining patients got the same dosage daily. The study began in July 2003 and researchers are continuing to monitor the patients.

The study’s lead author is Dr. Alan F. List from the H. Lee Moffitt Cancer Center and Research Institute in Tampa, Florida.

Results

After a median time of 4.4 weeks, 97 patients from both arms of the trial no longer required blood transfusions; the rate was better (69 percent) among those who took the drug daily than the group that had a seven-day break (58 percent).

For patients in both arms, the lenalidomide improved the hemoglobin levels from 7.8 grams before treatment to an average of 13.4 grams after six months of treatment. As time has continued, 71 patients still needed no transfusion after 48 weeks.

In 81 patients there was a significant reduction in the number of bone marrow cells containing the abnormality; in 51 patients the abnormal cells were undetectable. These patients no longer needed blood transfusions. Among those whose abnormal cells remain unaffected by lenalidomide, their need for blood transfusions was still reduced by 50 percent.

The drug did cause some adverse reactions. Thirty-nine percent of the patients experienced serious drops in their white blood cell counts, and 35 percent a drop in their platelets.

The disease also progressed in some patients. In nine patients, the MDS progressed to acute myeloid leukemia or refractory anemia with excess blasts. Twelve patients died from disease complications or infection from low white blood cell counts.

Comments

These results indicate a “major change for us in treating MDS, particularly for the so-called 5q-minus syndrome patients,” said List. Not only does the reduction in transfusion herald a major improvement in the quality of life and health of some MDS patients, but the changes at the genetic and cellular level in blood cells are unprecedented. “This might not only change the natural history of the disease, but also guide us to treatments for other myeloid malignancies with similar chromosome abnormalities, such as acute myeloid leukemia.”

James Zwiebel, M.D., of the National Cancer Institute’s Investigational Drug Branch, agreed that “these are heartening results” but cautions that more study is required before researchers can say whether lenalidomide will help MDS patients live longer.

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