Name of the Trial
Phase II Study of Denileukin Diftitox in Patients with Tac-Expressing HTLV-1-Associated Adult T-Cell Leukemia/Lymphoma (NCI-05-C-0185). See the protocol summary at http://cancer.gov/clinicaltrials/NCI-05-C-0185.

Principal Investigators
Drs. John Janik and Deirdre O'Mahony (Protocol Chair), NCI CCR

Why This Trial Is Important
Adult T-cell leukemia/lymphoma (ATLL) is an aggressive form of non-Hodgkin's lymphoma caused by the human T-cell leukemia virus type 1 (HTLV-1). Patients with ATLL may experience bone and skin lesions; high calcium levels; or enlargement of the lymph nodes, spleen, or liver. Most patients die within a year of diagnosis. The development of effective therapies for the treatment of this aggressive cancer serves as a model for the treatment of other forms of lymphoma.

In ATLL, HTLV-1 causes abnormal and uncontrolled growth of T cells (immune system cells that normally fight infections and disease). These malignant T cells often express high amounts of a protein called Tac, which is a receptor protein for the immune system hormone interleukin-2.

Denileukin diftitox (Ontak) is a genetically engineered protein that combines segments of interleukin-2 and diphtheria toxin. Diphtheria toxin is a poison made by the same bacterium that causes the disease diphtheria, which can be fatal.

Denileukin diftitox binds to the Tac protein on ATLL cells and is subsequently absorbed by them, causing the cells to die. Researchers hope that administering denileukin diftitox to patients with ATLL will help these patients survive longer.

"Denileukin diftitox is approved by the Food and Drug Administration to treat cutaneous T-cell lymphoma, and it is fairly well tolerated by patients," said Dr. O'Mahony. "We hope that this drug will prove to be a more effective treatment than traditional chemotherapy for patients with ATLL, a rare disease that is usually associated with a poor outcome."

Who Can Join This Trial
Researchers seek to enroll 29 patients aged 18 or over with Tac-expressing ATLL. See the list of eligibility criteria at http://cancer.gov/clinicaltrials/NCI-05-C-0185.

Study Site and Contact Information
This study is taking place at the NIH Clinical Center in Bethesda, Md. For more information, call the NCI Clinical Studies Support Center (CSSC) at 1-888-NCI-1937. The call is toll free and confidential.