Breakthrough in Ovarian Cancer Therapy

Scientists are evaluating a unique treatment for ovarian cancer by utilizing an intravenous agent called Ontak to destroy the lethal cells that suppress the body's natural immune response to combat cancer.

Ontak (denileukin diftitox, DAB389IL-2), developed by Ligand Pharmaceuticals, Inc. (San Diego, CA, USA), is a fusion protein, consisting of a fragment of diphtheria toxin genetically fused to interleukin-2. Ontak targets IL-2 receptors on the surface of malignant cells and some normal lymphocytes, leading to the death of these cells.

"This study [phase II trial] will test the hypothesis that Ontak improves tumor immunity by killing regulatory T cells (Tregs) in patients with advanced-stage ovarian cancer,” said lead investigator Dr. Tyler Curiel, professor of medicine and chief of hematology and medical oncology at Tulane University (New Orleans, LA, USA). "When a patient has cancer, some of the immune cells in the body begin to kill the body's tumor-killing immune cells instead of killing the tumor. So it's like friendly fire--soldiers, instead of going out and shooting the enemy, shoot their own soldiers instead.”

The researchers reported how Tregs hinder the body's capability to fight ovarian cancer. They demonstrated in the study that human tumor Treg cells inhibit tumor immunity and contribute to growth of tumors. Consequently, killing Treg cells may help treat cancer, according to Dr. Curiel. The study was published in the August 2005 issue of the journal Nature Medicine.

The U.S. National Cancer Institute (Bethesda, MD, USA) awarded a four-year grant of more than US$1.2 million for the Tulane scientists to continue studying how ovarian tumors weaken immunity and continue to grow. The researchers hope this novel treatment approach, using Ontak to deplete Tregs, will prove helpful not only for ovarian cancer, but also for other cancers in the near future, including breast and lung cancer, according to Dr. Curiel.

Ontak has received U.S. Food and Drug Administration (FDA) approval for the treatment of patients with cutaneous T-cell leukemia/lymphoma. Patients with advanced-stage ovarian cancer meeting all eligibility criteria and selected for this study will be treated with Ontak once a month.





Related Links:
Tulane University
Ligand Pharmaceuticals