Frequency of Response Rate at 12 Weeks vs. Patient and Disease Characteristics
| Response rate | |||
|---|---|---|---|
| Characteristic | All patients (n = 30) | 131I-Tositumomab (n = 18) | 90Y-Ibritumomab tiuxetan (n = 12) |
| Age at radioimmunotherapy (y) | |||
| ≤60 | 6/12 (50%) | 4/9 (44%) | 2/3 (67%) |
| >60 | 8/18 (44%) | 4/9 (44%) | 4/9 (44%) |
| P | 1.00 | 1.00 | 1.00 |
| Sex (n) | |||
| Male | 11/20 (55%) | 6/13 (46%) | 5/7 (71%) |
| Female | 3/10 (30%) | 2/5 (40%) | 1/5 (20%) |
| P | 0.26 | 1.00 | 0.24 |
| Histology at radioimmunotherapy (n) | |||
| Indolent | 12/20 (60%) | 7/13 (54%) | 5/7 (71%) |
| Aggressive | 2/10 (20%) | 1/5 (20%) | 1/5 (20%) |
| P | 0.06 | 0.31 | 0.24 |
| Transformed from original histology (n) | |||
| Yes | 2/4 (50%) | 1/3 (33%) | 1/1 (100%) |
| No | 12/26 (46%) | 7/15 (47%) | 5/11 (45%) |
| P | 1.00 | 1.00 | 1.00 |
| Stage at radioimmunotherapy (n) | |||
| I–II | 3/5 (60%) | 2/4 (50%) | 1/1 (100%) |
| III–IV | 11/25 (44%) | 6/14 (43%) | 5/11 (45%) |
| P | 0.64 | 1.00 | 1.00 |
| Chemotherapy regimens before radioimmunotherapy (n) | |||
| 1–2 | 6/14 (43%) | 3/6 (50%) | 3/8 (38%) |
| 3+ | 8/16 (50%) | 5/12 (42%) | 3/4 (75%) |
| P | 0.73 | 1.00 | 0.55 |
| Refractory to rituximab* (n) | |||
| Yes | 8/14 (57%) | 4/6 (67%) | 4/8 (50%) |
| No | 5/15 (33%) | 3/11 (27%) | 2/4 (50%) |
| P | 0.27 | 0.16 | 1.00 |
| LDH at radioimmunotherapy† (n) | |||
| Normal (118–273 mg/dL) | 10/15 (67%) | 6/9 (67%) | 4/6 (67%) |
| Elevated | 0/10 (0%) | 0/6 (0%) | 0/4 (0%) |
| P | <0.01 | 0.03 | 0.08 |
| Bone marrow involvement at radioimmunotherapy (n) | |||
| Yes | 0/5 (0%) | 0/4 (0%) | 0/1 (0%) |
| No | 14/25 (56%) | 8/14 (57%) | 6/11 (55%) |
| P | 0.04 | 0.09 | 1.00 |
| Prior bone marrow transplantation (n) | |||
| Yes | 1/3 (33%) | 1/3 (33%) | 0/0 (0%) |
| No | 13/27 (48%) | 7/15 (47%) | 6/12 (50%) |
| P | 1.00 | 1.00 | 1.00 |
| Prior radiation therapy (n) | |||
| Yes | 3/7 (43%) | 2/6 (33%) | 1/1 (100%) |
| No | 11/23 (48%) | 6/12 (50%) | 5/11 (45%) |
| P | 1.00 | 0.64 | 1.00 |
| IPI score (n) | |||
| 0–2 | 10/14 (71%) | 7/10 (70%) | 3/4 (75%) |
| 3–5 | 4/16 (25%) | 1/8 (13%) | 3/8 (38%) |
| P | 0.03 | 0.02 | 0.55 |
| Full-dose treatment‡ (n) | |||
| Yes | 9/20 (45%) | 5/12 (42%) | 4/8 (50%) |
| No | 5/10 (50%) | 3/6 (50%) | 2/4 (50%) |
| P | 1.00 | 1.00 | 1.00 |