ur patients had disease that did not respond to their last treatment with Rituximab, 11 patients had disease that responded to Rituximab for less than 6 months, and five patients had disease that responded to Rituximab, with a duration of response of 6 months or greater. Overall, 35 of the 40 patients met the definition of “Rituximab refractory”, defined as no response or a response of less than 6 months duration. In this subset of patients the overall objective response was 63% (95% confidence interval 45%, 79%) with a median duration of 25 months (range of 4 - 38+ months). The complete response in this subset of patients was 29% (95% CI of 15%, 46%) with a median duration of response not yet reached (range of 4 - 38+ months).
Study 2 was a multicenter, single arm, open-label study of 60 chemotherapy refractory patients. The median age was 60 (range 38-82), the median time from diagnosis to protocol entry was 53 months (range: 9-334), and the median number of prior chemotherapy regimens was 4 (range 2-13). Fifty-three patients had not responded to prior therapy and 7 patients had responded with a duration of response of<6 months. The efficacy outcome data from this study, as determined by an independent panel that reviewed patient records and radiologic studies are also summarized in Table 4. Investigators continued to follow eight patients with complete response after the last independent review panel assessment. The updated duration of ongoing response as per investigators was reported to range from 42 to 85 months.
Table 4: Efficacy Outcomes in BEXXAR Clinical Studies Study 1
(n = 40)
Study 2
(n = 60)
Overall Response
Rate
95% CI a
68%
(51%, 81%)
47%
(34%, 60%)
Response Duration (mos)
Median
95% CI a
Range
16
(10, NRb)
1+ to 38+
12
(7, 47)
2 to 47
Complete Response c
Rate
95% CI a
33%
(19%, 49%)
20%
(11%, 32%)
Complete response c duration (mos)
Median
95% CI a
Range
NR b
(15, NR)
4 to 38+
47
(47, NR)
9 to 47
aCI = Confidence Interval
bNR = Not reached, Median duration of follow up: Study 1 = 26 months; Study 2 = 30 months
cComplete response rate = Pathologic and clinical complete responses
The results of these studies were supported by demonstration of durable objective responses in three single-arm studies. In these studies, 130 patients with Rituximab-naïve follicular non-Hodgkin’s lymphoma with or without transformation were eva luated for efficacy. All patients had relapsed following, or were refractory to, chemotherapy. The overall response rates ranged from 49% to 64% and the median durations of response ranged from 13 to 16 months. Due to small sample sizes in the supportive studies, as in studies 1 and 2, the 95% confidence intervals for the median durations of response are wide.
INDICATIONS AND USAGE
The BEXXAR therapeutic regimen (Tositumomab and Iodine I 131 Tositumomab) is indicated for the treatment of patients with CD20 antigen-expressing relapsed or refractory, low grade, follicular, or transformed non-Hodgkin's lymphoma, including patients with Rituximab-refractory non-Hodgkin’s lymphoma. Determination of the effectiveness of the BEXXAR th
