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Release: Aug. 13, 2001

UI only U.S. center to study tumor treatment in children

IOWA CITY, Iowa -- University of Iowa Health Care physicians have received a two-year, $500,000 National Cancer Institute grant for a Phase I clinical trial to study a potential treatment for nervous system tumors in children. Phase I trials are designed to determine the maximum drug dosage at which children with relapsed cancer can safely be treated.

The UI will be the only institution in the United States where children can participate in this treatment trial. The UI already is one of three hospitals nationwide offering the treatment to adults with neuroendocrine tumors such as carcinoid.

The approach involves adapting a radioactive imaging method used to diagnose nervous tumors for use as a treatment that involves tumor-targeted radiation. Both the diagnostic test and the new therapy have been approved by the Food and Drug Administration.

Over the next two years, UI investigators expect to treat up to 20 children who have brain tumors such as meduloblastoma or peripheral nervous system tumors such as neuroblastoma.

The treatment may have several advantages, said lead investigator M. Sue O'Dorisio, M.D., Ph.D., UI Foundation Professor of Pediatrics and director of the UI Division of Pediatric Hematology/Oncology.

"Children whose tumors have become resistant to chemotherapy may respond to this radiation therapy. Previous research on adults shows that the treatment has fewer side effects than other treatments," O'Dorisio said. "However, children whose tumors do not 'light up' in the diagnostic test will not be given the therapy and therefore not exposed to radiation that will not work for them."

Previous research has shown that a particular hormone, somatostatin, is used by both the central and peripheral nervous systems to regulate nerve growth. The cancerous tumors also use this hormone.

Based on this knowledge, European researchers in the mid-1990s developed a diagnostic test of the brain, spine, chest and other organs where tumors might be located. The test involves adding a radioactive compound to a synthetic version of the hormone, which then is given internally to a person. The radioactive hormone is taken up by tumors at a much higher rate than by other tissues. As a result, if tumors are present, they will appear in images as much brighter areas than normal tissue.

Because this method was so successful in providing images of tumors for diagnostic purposes, researchers decided to put a different type of radioactive compound on the hormone in an attempt to deliver radiation therapy to tumors, O'Dorisio said.

"We can give a patient who has a tumor one form of the radioactive hormone, then take a picture," O'Dorisio said. "If their tumor takes up the hormone, then they may be eligible for the study and actually be treated with the other radioactive form of the hormone."

The diagnostic technique is known as OctreoScan, and the treatment method is known as OctreoTher.

O'Dorisio emphasized, "In both cases, it's the same hormone. However, in one case it has a radioactive compound that is good for taking pictures, and in the second case it has a radioactive compound that gives highly focused radiation therapy."

Based on earlier studies performed in the laboratory of Sue O'Dorisio and Thomas M. O'Dorisio, M.D., UI professor of internal medicine, approximately 95 percent of all neuroblastomas and 100 percent of all meduloblastomas take up the hormone because they have somatostatin receptors.

To date, 12 adults with metastatic neuroendocrine and carcinoid tumors have been treated at UI Hospitals and Clinics and the Veterans Affairs Medical Center (VAMC) in Iowa City by Thomas O'Dorisio, who also is a VAMC researcher and staff physician, and David Bushnell, M.D., UI associate professor of radiology.

Sue O'Dorisio said there have been no serious side effects, and some improvement in symptoms and tumor shrinkage has been seen in these patients to date. However, the researchers caution that the study is in early stages, and no analysis of either toxicity or efficacy can be made at this time.

The immediate goal in the new UI study involving children is to determine the dosage at which side effects remain low; therefore, only children who have failed other treatments will be eligible.

However, if side effects are low, researchers hope eventually to treat children who are newly diagnosed with a neuroblastoma or a meduloblastoma, in conjunction with other chemotherapy or radiation therapy, O'Dorisio said.

She added, "The hope is we'll be able to use lower doses of therapy if we can treat the children immediately after diagnosis."

All patients in the study will be referred by physicians. Novartis, which supports the Phase II adult study at the UI, will provide the radioactive hormone drug for the study, and the National Cancer Institute will pay other treatment charges.

University of Iowa Health Care describes the partnership between the UI College of Medicine and the UI Hospitals and Clinics and the patient care, medical education and research programs and services they provide.