Efficacy and safety of tositumomab and iodine-131 tositumomab (Bexxar) in B-cell lymphoma, progressive after rituximab.
OBJECTIVE
To determine overall response (OR) and complete response (CR) rates, response duration, progression-free (PFS) and overall survival and safety with the tositumomab and iodine-131 tositumomab ((131)I tositumomab) therapeutic regimen in patients with indolent, follicular large-cell, or transformed B-cell lymphoma, progressive after rituximab.


METHODS
From July 1998 to November 1999, 40 patients (24 rituximab nonresponders: 11 with response < 6 months, and five with response > or = 6 months) received a therapeutic dose (0.65 to 0.75 Gy per platelet count) of (131)I tositumomab based on total-body dosimetry in this prospective phase II study. The median number of prior treatments was four; 59% of patients were chemotherapy-resistant.


RESULTS
Confirmed OR (65%) and CR (38%) rates were not significantly associated with prior rituximab response. With a median follow-up of 3.3 years, the median PFS was 10.4 months, 24.5 months for responders, and not reached for CR patients. Among follicular grade 1 or 2 patients with tumors < or = 7 cm (n = 21), the OR and CR rates were 86% and 57%. Estimated 3-year PFS in this subgroup was 48%, compared with 11% for all others (P = .002). Transient grade 3 to 4 marrow toxicity was seen in 50% of patients. Two patients, one of whom received two subsequent chemotherapy regimens, developed secondary myelodysplasia.


CONCLUSIONS
(131)I tositumomab is effective in CD20-positive lymphoma progressive after rituximab, with a 65% OR rate and median PFS of 24.5 months for responders. Patients with follicular grade 1 or 2 histology and tumors < or = 7 cm achieved very high OR and CR rates, with 48% PFS at 3 years.
Horning
Sandra J
SJ
Stanford University, Stanford, CA 94305-5821, USA. sandra.horning@stanford.edu
Younes
Anas
A
Jain
Vinay
V
Kroll
Stewart
S
Lucas
Jennifer
J
Podoloff
Donald
D
Goris
Michael
M
D000328:Adult; D000368:Aged; D000911:Antibodies, Monoclonal / Q000009:adverse effects / Q000627:therapeutic use*; D058846:Antibodies, Monoclonal, Murine-Derived; D005260:Female; D006801:Humans; D016393:Lymphoma, B-Cell / Q000401:mortality / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D016499:Radioimmunotherapy; D000069283:Rituximab
D000911:Antibodies, Monoclonal; D058846:Antibodies, Monoclonal, Murine-Derived; D000069283:Rituximab; C119496:tositumomab I-131