NEW ORLEANS, May 22 /PRNewswire/ -- A radioimmunotherapy known as Bexxar
produced tumor shrinkage in 97 percent of 76 previously untreated patients
with advanced-stage, low-grade non-Hodgkin's lymphoma (NHL) in a new study at
the University of Michigan Comprehensive Cancer Center.
Most notably, 76 percent of patients achieved a complete remission, with
no sign of cancer. In addition, 84 percent of the 37 patients with evidence
of lymphoma at the molecular level at the start of the trial achieved
molecular remission for as long as three years with the treatment. Molecular
remissions were determined by a rigorous use of polymerase chain reaction, or
PCR, technology, arguably the most sensitive cancer detection method available
The promising results, from the first completed study of a first-line,
stand-alone radioimmunotherapy for cancer, were presented today at the meeting
of the American Society of Clinical Oncology by Mark S. Kaminski, M.D., U-M
professor of hematology/oncology and co-director of the U-M's
leukemia/lymphoma and bone marrow transplant programs.
"We are extremely excited by these findings, which showed remarkable
response rates and molecular remissions ongoing beyond three years," says
Kaminski. "Molecular remissions are seldom seen with chemotherapy in
low-grade lymphoma, and appear to coincide with prolonged, durable responses.
Furthermore, these results demonstrate the potential of this treatment as an
effective and well-tolerated first-line, single-agent treatment for low-grade
lymphoma, a disease without a known cure."
The Phase II study, conducted entirely at the U-M, enrolled 76 patients
with previously untreated, advanced-stage, low-grade follicular lymphoma. The
study was designed to evaluate the safety and efficacy of Bexxar as an NHL
treatment given alone and as the first treatment approach.
Patients received a trace dose, followed one to two weeks later with a
therapeutic dose. No further treatment was given. This is in contrast with
what patients would have experienced if given chemotherapy treatment, which is
commonly repeated every three to four weeks for several months.
Patients tolerated Bexxar treatment well. Moderate, reversible low blood
counts were seen, but no patients required hematologic supportive care.
Sixty-two percent of patients developed human anti-mouse antibodies (HAMA).
About two-thirds of these patients experienced flu-like symptoms lasting less
Virtually all patients -- 74 of 76 - responded in some way to treatment.
An impressive number of patients (58) achieved a complete response. About 70
percent of those patients are projected to continue to be disease-free for at
least three years.
PCR analyses were conducted to test for detectable signs of disease in
bone marrow among all patients before and after therapy. Of the 37 patients
who had molecular signs of the cancer before treatment, 31 achieved molecular
remissions when measured again later. About 75 percent of those 31 patients
are projected to remain in remission for at least three years.
A remission is usually measured by a patient's disease-free status based
on the absence of symptoms through examination and medical imaging. Molecular
remissions are based on tests at the DNA level to see if the disease has been
eradicated. The PCR assay can detect one cancerous cell among a million
normal cells; in non-Hodgkin's lymphoma the test looks for aberrant cells in
the bone marrow and blood and can demonstrate how completely the disease has
been destroyed by treatment.
Bexxar is a radioimmunotherapy that combines a monoclonal antibody
attached to the radioisotope iodine 131. It attaches to a protein found only
on the surface of the blood's B-cells, including those turned malignant in
non-Hodgkin's lymphoma patients. The compound is believed to work through a
combination of immune system activity involving the monoclonal antibody and
the effects from the radiation released by the iodine 131. Through this
targeted approach, the tumor cells receive a greater concentration of the
therapeutic radiation while minimizing radiation exposure to normal tissues.
The original studies in the therapeutic development of Bexxar, or Iodine I
131 tositumomab, were done at the U-M by Kaminski and his colleague Richard
Wahl, M.D., professor of nuclear medicine and radiology. The therapy is now
being jointly developed by Coulter Pharmaceutical, Inc. and SmithKline
Non-Hodgkin's lymphoma is a form of cancer that affects the blood and
lymphatic tissues. The sixth leading cause of cancer death in the U.S., NHL
also has the second fastest growing incidence rate of all cancers. According
to the National Cancer Institute, nearly 300,000 Americans have NHL, among
them 140,000 with the low-grade or transformed low-grade forms of the disease.
In more than 30 years, the survival rates of low-grade NHL patients have not
changed, and patients continue to die from the disease or complications
associated with current treatments.
SOURCE University of Michigan Comprehensive Cancer Center