Outpatient radioimmunotherapy with Bexxar

BACKGROUND Radioimmunotherapy (RIT) with Bexxar (tositumomab and iodine‐131 tositumomab; Coulter Pharmaceutical, South San Francisco, CA) has been shown to be effective in the treatment of low‐grade and transformed low‐grade non‐Hodgkin lymphoma (NHL). METHODS Patient‐specific dosimetry with 5 mCi of iodine‐131 tositumomab preceded by 450 mg of tositumomab was utilized to calculate the radionuclide dose needed to deliver 75 cGy whole‐body radiation (65 cGy for platelet counts of 100,000–149,000/mm 3 ). To safely infuse the approximately 95 mCi (range, 52–211mCi) of iodine‐131 needed for this treatment, a shielded, closed system was developed to minimize radiation exposure for personnel administering the treatment infusions and to eliminate possible release of aerosolized iodine‐131. RESULTS Twenty‐five patients who could be evaluated were infused with a single course of iodine‐131 tositumomab therapy and achieved a 76% total response rate at 3 months (32% complete response [CR], 44% partial response [PR]); 59% total response at 6 months (40% CR, 18% PR); and 38% total response at 12 months (31% CR, 6% PR). Administration of RIT using our unique, totally closed system significantly reduced personnel exposure and potential for radioactive spills. The sum of all individuals who administered and monitored the infusions was < 120 mRem whole body exposure over 22 months, well within the ALARA (as low as reasonably achievable) Level I guideline limits. No radioiodide was detectable in the thyroid of any staff member. CONCLUSIONS In NHL patients who had experienced failure with conventional therapy, RIT with iodine‐131 tositumomab therapy was safe and effective. Response rates obtained were equivalent to those obtained at the university medical centers where the Phase I–III clinical trials were performed. Cancer 2002;94:1358–62. © 2002 American Cancer Society. DOI 10.1002/cncr.10306