BEXXAR(R) Demonstrates Improved Clinical Responses in Chemotherapy Refractory
Non-Hodgkin's Lymphoma (NHL) Patients
Study in `Journal of Clinical Oncology' Suggests Radioimmunotherapy
Improves Outcome Following Treatments
SEATTLE and PHILADELPHIA, Oct. 2 /PRNewswire/ -- An investigational
radioimmunotherapy, BEXXAR(R) (tositumomab and iodine I 131 tositumomab),
demonstrates more durable complete or partial clinical responses in patients
with low-grade and transformed low-grade non-Hodgkin's lymphoma (NHL) as
compared to their last round of chemotherapy, according to a new study
published in the "Journal of Clinical Oncology." All of the patients in the
study had chemotherapy refractory NHL. Typically, refractory patient response
rates and durations of response decline with each successive therapy, but in
this study BEXXAR was shown to reverse this expected outcome.
"BEXXAR therapy has resulted in durable remissions in a low-grade NHL
population refractory to chemotherapy, and in those with transformed low-grade
NHL -- an aggressive form of lymphoma that is associated with a very poor
prognosis," said Mark. S. Kaminski, M.D., professor of internal medicine and
co-director of the leukemia/lymphoma bone marrow transplant program at the
University of Michigan Cancer Center. "The results of this study demonstrate a
measurable improvement over previous therapy and suggest a reversal of the
downward trend seen in relapsed and refractory patients following prior
treatments."
The study explored the safety and efficacy of BEXXAR in comparison to the
patient's previous chemotherapy. Researchers observed a partial or complete
response (CR) to BEXXAR in 65 percent of patients, as compared to a 28 percent
response rate from the patient's last chemotherapy agent. Results for
patients obtaining a CR were 20 percent after BEXXAR, in comparison to 3
percent after treatment with their previous agent. For those patients who
achieved a CR with BEXXAR, the median duration of response (MDR) has not yet
been reached and nine of the twelve patients with CRs have ongoing responses
ranging from 32.3 - 47.4 months at time of the last data analysis.
"BEXXAR demonstrated a high rate of response and a low rate of
hematological toxicity in a heavily treated patient population," said Dr.
Kaminski.
BEXXAR combines the targeting ability of a monoclonal antibody and the
therapeutic potential of radiation, with patient-specific dosing. The
radiolabeled monoclonal antibody attaches to the target marker CD20 found on
NHL cells, thereby eliciting an immune response and delivering a dose of
iodine I 131 radiation to tumor cells. BEXXAR is the only NHL therapy that is
precisely dosed based on individual drug clearance rates.
"This targeted approach was designed to ensure that the tumor cells will
receive a greater concentration of the therapeutic radiation than normal
tissues, and the radioactive component is probably a major factor in the
drug's anti-tumor effect," explained Dr. Kaminski.
Most side effects reported from this study were transient and mild to
moderate. In addition, the BEXXAR infusions were well tolerated. The
principal toxicity was hematologic, with 18 percent of patients experiencing
reversible Grade IV decrease in white blood cells, which was effectively
managed with hematological supportive therapy.
Study of Patients with Especially Poor Prognosis
The pivotal, multi-center study investigated the safety and efficacy of
BEXXAR in 60 patients who had been treated with at least two (median of 4)
protocol-specified qualifying chemotherapy regimens and had not responded or
progressed within six months after treatment. The investigation was conducted
at seven clinical sites in the United States and one in the United Kingdom.
"The results of the present study are promising," said Dr. Kaminski. "We
treated patients with extremely chemotherapy refractory disease for whom the
prognosis is usually very poor. The fact that a positive response was seen
with BEXXAR provides hope for patients with limited therapeutic options."
Dosages Tailored to Each Patient's Needs
In this study, BEXXAR was administered over two sessions usually spaced
one week apart. In the first session, patients received a 60-minute infusion
of non-radioactive antibody (tositumomab). Second, a trace amount of the
radiolabeled antibody was administered to determine the patient-specific body
clearance of the radiation, which was used to accurately determine the precise
therapeutic dose appropriate for each patient. During the next session,
patients received another 60-minute infusion of non-radiolabeled tositumomab
followed by 20-minute infusion of patient-specific dose of iodine I 131
tositumomab.
Non-Hodgkin's Lymphoma
Non-Hodgkin's lymphoma is a form of cancer that affects the blood and
lymph tissues. NHL currently is the sixth leading cause of death among cancers
in the United States and has the second fastest growing mortality rate.
According to statistics from the National Cancer Institute (NCI),
approximately 300,000 people are afflicted with NHL in the United States
alone. Of the total, the NCI estimates that approximately 140,000 people have
low-grade (LG) or transformed LG disease.
BEXXAR is currently under review by the U.S. Food and Drug Administration
(FDA). To date, BEXXAR has been studied in more than 1,000 LG NHL patients at
more than 80 centers. It is being co-developed by Corixa Corporation and
GlaxoSmithKline.<snip> |
