Bexxar Effective as First-Line Treatment for Non-Hodgkin's Lymphoma Patients When Used With Chemotherapy

New Study Shows Use of Radioimmunotherapy in Combination with Fludarabine Is Safe and Increases Rate of Complete Response

Dec 4, 1999


In a study of previously untreated patients with low-grade or follicular non-Hodgkin's lymphoma, all patients achieved a response with Bexxar (tositumomab, iodine I-131 tositumomab) in combination with fludarabine. The addition of Bexxar to fludarabine increased the rate of complete response five-fold, as compared to initial treatment with fludarabine alone, with the rate of complete response continuing to increase over time. These interim results, the first to report on the use of a radioimmunotherapy with standard-dose chemotherapy in lymphoma, were presented today at the 41st annual American Society of Hematology (ASH) meeting in New Orleans, Louisiana.

"We're extremely excited by these preliminary results which not only show a high rate of response, but also a dramatic increase in complete response over time when these low-grade or follicular non-Hodgkin's lymphoma patients are treated with the sequential combination of Bexxar following fludarabine," said John P. Leonard, M.D., assistant professor of medicine in the division of hematology and medical oncology at the Weill Medical College of Cornell University. "Bexxar not only demonstrates durable responses as a stand-alone first-line treatment in previously untreated patients and in those who've relapsed or become refractory, but now shows clinical potential when used in conjunction with conventional chemotherapy as an initial treatment regimen."

Interim Data Shows Promising Results

Conducted at the Center for Lymphoma and Myeloma at the Weill Medical College of Cornell University and New York-Presbyterian Hospital, this Phase II study enrolled 38 patients with previously untreated low-grade or follicular non-Hodgkin's lymphoma (NHL). The study was designed to evaluate the safety and efficacy of a sequential regimen of fludarabine followed by tositumomab, iodine I-131 tositumomab. Patients received three cycles of fludarabine (25 mg/m2 x 5 d every 5 weeks) followed six to eight weeks later by tositumomab, iodine I-131 tositumomab.

Fourteen of the 38 patients were evaluable for response at least six months after treatment with tositumomab, iodine I-131 tositumomab. Ninety-three percent of patients (13 out of 14) had Stage IV NHL at the time of treatment; one patient had Stage II NHL. All of the patients in the study achieved a response to treatment with fludarabine followed by tositumomab, iodine I-131 tositumomab. With the addition of tositumomab, iodine I-131 tositumomab, after six months of follow-up, the rate of complete response (elimination of the signs and symptoms of the disease) increased five-fold as compared to initial treatment with fludarabine. Following initial treatment with fludarabine, 14 percent of patients (two out of 14) experienced a complete response. At the thirteenth week, following treatment with tositumomab, iodine I-131 tositumomab, the rate of complete response increased to 43 percent (six out of 14 patients). At approximately six months, 71 percent of patients (10 out of 14) had experienced a complete response. Multicenter studies using tositumomab, iodine I-131 tositumomab in combination with fludarabine are scheduled to begin next year.

Treatment with fludarabine in combination with tositumomab, iodine I-131 tositumomab was well tolerated. The principal side effects were hematologic, including a decrease in blood counts, which was reversible. Non-hematologic side effects experienced with tositumomab, iodine I-131 tositumomab were mild-to-moderate, including nausea, fatigue, headache and rhinitis. Due to the immunosuppressive effect of fludarabine, only one patient developed human anti-mouse antibodies (HAMA).

"Helping patients achieve long, durable complete responses is our best hope until we find a cure for low-grade non-Hodgkin's lymphoma. This study suggests that use of Bexxar with chemotherapy is a promising, well-tolerated combination that may offer this patient population a much-needed new treatment option," said Dr. Leonard.

Tositumomab, iodine I-131 tositumomab is a novel radioimmunotherapy consisting of a radioisotope (iodine 131) combined with a monoclonal antibody. The monoclonal antibody attaches to a protein found only on the surface of B-cells, inhibiting tumor cells directly and/or recruiting the immune system to kill these cells. Simultaneously, a radioisotope delivers targeted, powerful radiation to destroy the cancer. As a result, the tumor cells receive a greater concentration of the therapeutic radiation while radiation to normal tissues is minimized.

Non-Hodgkin's Lymphoma

Non-Hodgkin's lymphoma (NHL) is a form of cancer that affects the blood and lymphatic tissues. The fifth leading cause of death among cancers in the United States, NHL also has the second fastest growing mortality rate. According to the National Cancer Institute, nearly 300,000 people are afflicted with NHL in the United States alone. Currently, there is no cure for advanced stage low-grade NHL. In more than 40 years, there have been no changes in the survival rates of low-grade NHL patients, who typically die from the disease or complications associated with current treatments.

Founded in 1898, Cornell University Medical College (now known as Joan and Sanford I. Weill Medical College of Cornell University) has long ranked among the leading medical schools in the U.S. From the start, the medical college has followed an educational philosophy that emphasizes the importance of combining a strong basic foundation in the medical sciences with extensive clinical training in patient care. In 1927, the Medical College and The New York Hospital (now New York-Presbyterian Hospital) entered into a major affiliation agreement, which culminated with the opening, in 1932, of a unified campus on the Upper East Side of Manhattan. Cornell physicians and scientists are engaged in both basic and clinical research in the cutting-edge areas of genetics and gene therapy, neuroscience, structural biology, AIDS, cancer, and psychiatry, among others. Cornell's biomedical investigators are delving ever deeper into the realms of cellular and molecular biology, which hold the secrets both to the normal functioning of the body and the malfunctions that lead to serious medical disorders.