Molecular Imaging News
May 17, 2005
USC Researchers Find Way to Streamline Radioimmunotherapy
University of Southern California
Researchers at the Keck School of Medicine of the University of Southern California and colleagues have found a way to streamline Zevalin radioimmunotherapy for patients with non-Hodgkin's lymphoma.
The radiologists presented findings at the 2005 Annual Meeting of the American Society of Clinical Oncology (ASCO) on May 17.
Radioimmunotherapy joins radioactive atoms to special antibodies. These antibodies are injected into the body where they deliver their radioactive payload by seeking out and binding to proteins found on cancer cells. Selected institutions have been offering this treatment to non-Hodgkin's lymphoma patients since the early 2000s.
However, in a few patients, the medication goes to the wrong tissues. That means that physicians are required to perform imaging scans at the start of therapy to determine where the antibodies go, a process that lengthens and complicates treatment. If physicians could quickly confirm that medication is going where it should, that would speed treatment while maintaining quality care for patients.
"This treatment approach is growing and is a new and realistic alternative to conventional chemotherapy. Making it easier for physicians to administer the treatment by avoiding unnecessary steps will lead to higher utilization and better patient compliance," said Peter Conti, MD, professor of radiology at the Keck School, director of the USC PET Imaging Center, first author on the ASCO presentation, and president-elect of the SNM. He noted that patients receive injections on an outpatient basis and have an overall high level of satisfaction with the procedure.
Researchers from the Keck School of Medicine and San Diego-based Biogen Idec Inc., developer of Zevalin, studied about 400 patients who had received Zevalin between 2002 and 2003 after unsuccessfully trying conventional therapy first. Zevalin consists of a series of steps. In the first line of attack, physicians infuse rituximab, a monoclonal antibody that hones in on B cells, the immune cell most often involved in non-Hodgkin's lymphoma. Next, for the imaging sessions, physicians inject another monoclonal antibody, ibritumomab tiuxetan, which is tagged with the radioactive isotope 111In (indium 111). Finally, a week later—and only if imaging sessions have shown the medication accumulating in the right areas—they inject ibritumomab tiuxetan that has been tagged with 90Y (yttrium 90), the treatment isotope.
Physicians perform an initial imaging scan within 24 hours of the ibritumomab tiuxetan/111In injection and another within two to three days to verify that the antibody is carrying the radioactivity to the cancer sites. Sometimes another scan is performed four to five days later.
But Conti and colleagues found that most of those scans are unnecessary. In their study, they found that 16 patients had treatment discontinued due to results of imaging scans. Of these, only six actually had medication going to the wrong tissues. And most important, all of these cases were apparent after the very first imaging scan.
The findings suggest that physicians and patients can confidently proceed with treatment if radioimmunotherapy is correctly targeting cancer-ridden areas within 24 hours of the 111In-labeled injection.
Conti is currently planning further radioimmunotherapy trials at USC, including a potential trial for AIDS-related lymphoma done in conjunction with hematology faculty.
Because Conti reviewed patient data from Biogen Idec's original clinical trials with Zevalin, the research was supported in part by Biogen Idec.
Abstract: Peter Conti, Christine White, Peter Pieslor, Gene Menendez, V. Douglas Harrough, Dan Matso, Jacqueline Aussie, Thomas Ryskamp and Paul A. Foster, "Low Frequency of Altered Biodistribution Detected by Indium 111 (111In) Imaging Prior to Yttrium 90 (90Y) Ibritumomab Tiuxetan (Zevalin) Radioimmunotherapy: Results from a Zevalin Imaging Registry," American Society of Clinical Oncology 2005 Annual Meeting, May 13-17, 2005, Poster Session Abstract No. 6589.