NeoRx's Skeletal Targeted Radiotherapy -- STR -- Shows Encouraging Safety and Response Data in Multiple Myeloma Patients.

Business Editors, Health/Medical Writers

TAMPA, Fla.--(BUSINESS WIRE)--July 11, 2000

NeoRx Corporation (Nasdaq:NERX). Speaking at the International Society for Experimental Hematology meetings, Dr. William Bensinger (Fred Hutchinson Cancer Research Center, University of Washington, Seattle) a principal investigator on the study, reported that NeoRx's skeletal targeted radiotherapy (STR) product, Holmium-166 DOTMP, combined with high dose chemotherapy continued to show an excellent safety profile without serious side effects in 66 patients evaluated for safety in the Phase I/II trial. Among the 56 patients evaluated for response, three entered the trials in complete remission (CR) and retained their CR status post therapy, 20 additional patients became CRs, four were partial remissions and 29 did not respond. Complete remission requires the absence of all evidence of the characteristic myeloma protein as judged by sensitive biochemical techniques. For partial remission, at least a 75% reduction in the myeloma protein is required.

"STR enables physicians to add high radiation doses to chemotherapy without increasing side effects, and this appears to result in a substantial number of complete remissions," said Dr. Bensinger.

In this Phase I/II trial, patients received one of three high dose therapy regimens and escalating doses of STR. To date, 24 patients have been treated at the highest dose level of STR (i.e., the dose that will be used in the Phase III Trial). Of the 14 patients in this group evaluable for response, two entered the trials in complete remission (CR) and retained their CR status post therapy, six additional patients became CRs, and six did not respond. The number of patients in this group is too small to predict the eventual response rate in the Phase III trial.

"Previously reported safety and efficacy trends appear to be continuing," said Paul Abrams, MD, JD, NeoRx's chief executive officer. "Results on patients not yet completed cannot be predicted. We are moving forward to initiate the Phase III trial that will randomize patients to standard therapy with STR versus standard therapy alone. This is an exciting time for patients and for the company."

Multiple myeloma is a malignancy of plasma cells, a type of blood cell that arises in the bone marrow and is responsible for making antibodies. These myeloma cells can result in destructive bone lesions, kidney failure, and anemia. Patients with multiple myeloma typically have a single protein present in their blood that represents the antibody made by the myeloma cells. The presence or absence of this protein can be measured by sophisticated biochemical techniques, and it must be undetectable for a patient to be deemed a complete remission.

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