Tositumomab and iodine-131 tositumomab produces durable complete remissions in a subset of heavily pretreated patients with low-grade and transformed non-Hodgkin's lymphomas.
OBJECTIVE
This study is an integrated efficacy analysis of the five clinical trials of tositumomab and iodine-131 tositumomab in patients with relapsed or refractory low-grade, follicular, or transformed low-grade non-Hodgkin's lymphoma (NHL) that resulted in the regulatory approval of the iodine-131 tositumomab by the US Food and Drug Administration.


METHODS
This integrated analysis included 250 patients. Patients received a single course of iodine-131 tositumomab. Responses were assessed by an independent panel of radiologists and oncologists.


RESULTS
Response rates in the five trials ranged from 47% to 68%; complete response rates ranged from 20% to 38%. With a median follow-up of 5.3 years, the 5-year progression-free survival was 17%. Eighty-one (32%) of 250 patients had a time to progression of > or = 1 year (termed durable response population). For the durable response population, 44% had not progressed at > or = 2.5 to > or = 9.5 years and had a median duration of response of 45.8 months. The median duration of complete response was not reached. The durable response population had many poor prognostic characteristics, including bone marrow involvement (41%), bulky disease > or = 5 cm (49%), and transformed histology (23%). Forty-three percent of the patients had been treated with more than four prior therapies and 36% had not responded to their most recent therapy.


CONCLUSIONS
The tositumomab and iodine-131 tositumomab therapeutic regimen produces high response rates in patients with relapsed or refractory low-grade, follicular, and transformed low-grade NHL, with a sizable subgroup of patients achieving long-term durable responses.
Fisher
Richard I
RI
University of Rochester School of Medicine, James P. Wilmot Cancer Center, 601 Elmwood Ave, Box 704, Rochester, NY 14642, USA. richard_fisher@urmc.rochester.edu
Kaminski
Mark S
MS
Wahl
Richard L
RL
Knox
Susan J
SJ
Zelenetz
Andrew D
AD
Vose
Julie M
JM
Leonard
John P
JP
Kroll
Stewart
S
Goldsmith
Stanley J
SJ
Coleman
Morton
M
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D019008:Drug Resistance, Neoplasm; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008224:Lymphoma, Follicular / Q000188:drug therapy / Q000276:immunology / Q000532:radiotherapy*; D020522:Lymphoma, Mantle-Cell / Q000188:drug therapy / Q000276:immunology / Q000532:radiotherapy; D008228:Lymphoma, Non-Hodgkin / Q000188:drug therapy / Q000276:immunology / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000188:drug therapy / Q000276:immunology / Q000532:radiotherapy*; D016499:Radioimmunotherapy; D012074:Remission Induction; D016879:Salvage Therapy; D015996:Survival Rate
D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; D007457:Iodine Radioisotopes; C119496:tositumomab I-131