Phase II Study of the Efficacy and Toxicity of Ontak(Registered Trademark) (Denileukin Diftitox) in the Therapy of Adult T-Cell Leukemia

Study Summary

Adult T-cell leukemia (ATL) is and aggressive characterized by the presence of cluster of differentiation 4 (CD4)/cluster of differentiation 25 (CD25)-expressing T cells (interleukin-2 \[IL-2\]R expressing) in the peripheral blood and in lymphoid and other tissues. Denileukin diftitox (Ontak(Registered Trademark)) is a genetically engineered fusion protein that targets IL-2-expressing malignancies. Denileukin diftitox interacts with the IL-2R on the cell surface, is internalized via endocytosis, and inhibits cellular protein synthesis, resulting in cell death within hours to days. The objectives of this study are to determine the clinical response to Denileukin diftitox of patients with adult T-cell leukemia (ATL) and the safety of Denileukin diftitox in those patients. Eligible participants must be 18 years of age or older with chronic, lymphomatous and acute forms of ATL, and must be infected with human T-cell lymphotropic virus type I (HTLV1). Patients will be treated with 9 mcg/kg/d of Denileukin diftitox intravenously for 5 days every 2 weeks. Tumor response will be evaluated after two cycles of treatment. Stable or responding patients will continue treatment for a total of 12 months, with evaluations every four cycles of treatment. Patients will be treated for two cycles beyond a complete remission. The trial uses an optimal two-stage design targeting for a true response proportion of more than 30 percent. Nine patients will be treated initially, with expansion to 29 patients if a response is seen in 1 of the initial 9 patients treated. Treatment will be discontinued if a patient experiences serious side effects. A potential benefit is that a patient may undergo partial or complete remission. The research may not directly benefit participants, but the results may aid in the treatment of others.

Primary Outcome

Response rate is based on the number of patients who achieve either a complete response (CR) or partial response (PR) to therapy. Complete response is complete disappearance of all detectable clinical and radiographic evidence of disease and disappearance of all disease related symptoms if present before therapy and normalization of those biochemical abnormalities (for example LDH) definitely assignable to the lymphoma. Partial response is reduction by \>=50% of leukemia cell count or \>=50% red

Interventions

• BIOLOGICAL Denileukin diftitox (Ontak)