ALso important is the following abstact providing an initial indiation that Bexxar can follow patients who have failed Rit. This is from the expanded access program.
[397] BEXXAR? (TOSITUMOMAB, IODINE I 131 TOSITUMOMAB) CAN BE SAFELY ADMINISTERED IN RELAPSED LOW-GRADE OR TRANSFORMED LOW-GRADE NON-HODGKIN'S LYMPHOMA (NHL) PATIENTS AFTER PRIOR TREATMENT WITH RITUXIMAB: INITIAL EXPERIENCE FROM THE EXPANDED ACCESS STUDY. S. A. Gregory, J. Leonard, M. Coleman, L. Fehrenbacher, A. Bhatnagar, D. Magnuson, S. Kroll, G. Tidmarsh. Rush Cancer Institute, Chicago, IL; Cornell Medical Center, New York, NY; Kaiser, Vallejo, CA; Coulter Pharmaceutical, South San Francisco, CA.
Bexxar is a new radioimmunotherapy for the treatment of relapsed and refractory low-grade and transformed low-grade NHL. Iodine I 131 tositumomab is a radiolabeled murine IgG2a monoclonal antibody directed against the CD20 antigen. With the availability of two monoclonal antibodies containing murine protein and both directed against the CD20 antigen (Bexxar and rituximab), it is important to establish the safety of using Bexxar in rituximab treated pts. As of April 8, 1999, 30 pts enrolled in the Expanded Access Study had previously received treatment with rituximab. At study entry, 21 of 30 pts (70%) had low-grade and 9 (30%) had transformed low-grade NHL. Pts had received a median of 3 (range:1-9) prior chemotherapy regimens. Baseline pt characteristics were: median age was 57 yrs; 16 pts were male; median time from diagnosis was 59 mo; 27 (90%) pts had stage III or IV disease; median IPI at entry was 3.0; 20 (67%) pts had elevated LDH; and 14 (47%) pts had a tumor diameter 5 cm. Ten pts had positive bone marrow biopsies with <25% lymphoma involvement. All pts received SSKI or Lugol's solution and a single dosimetric dose (450 mg tositumomab IV over 1 hr followed by 35 mg of tositumomab radiolabeled with 5 mCi of Iodine-131 over 1/2 hr) and then had 3 whole body counts obtained over the next 7 days. The whole body counts were used to calculate the required activity (mCi) to deliver the desired therapeutic dose (65 cGy for platelets 100,000-149,999 and 75 cGy for platelets 150,000). Twenty-eight pts received a single therapeutic dose (450 mg tositumomab IV over 1 hr followed by 35 mg tositumomab containing an appropriate activity (mCi) of Iodine-131 to deliver the specified total body dose (cGy) over 1/2 hr) 7-14 days after the dosimetric dose. Two pts experienced transient Grade I adverse experiences (AE) during the dosimetric infusion, and no pt required infusion rate adjustments. Median duration of the tositumomab pre-dose infusion during the dosimetric dose was 1.0 hr (range:1.0-1.1 hr). Two pts did not receive the therapeutic infusion because of progressive NHL. No pt experienced an AE, required an adjustment or discontinuation of the therapeutic infusion, and median duration of tositumomab pre-dose infusion was 1.0 hr (range: 0.9 - 1.1 hr). One pt was positive for human anti-mouse antibody (HAMA) at time of study entry and was treated without complications. Two pts have developed HAMA followed Bexxar. Conclusion: Bexxar has been safely administered to pts with relapsed low-grade or transformed low-grade NHL who had previously been treated with rituximab.
Poster Session: Indolent Lymphoid Malignancies and Additional Therapeutic Approaches (9:45 AM-7:30 PM)
Presentation Date: Saturday, December 4, 1999, Time: 9:45AM, Room: Hall B, Poster Board Number: 397
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