In patients with previously untreated follicular lymphoma, similar outcomes were achieved with CHOP-R (cyclophosphamide, doxorubicin, vincristine, prednisone, plus six doses of rituximab [Rituxan]) and CHOP-RIT (CHOP plus one dose of tositumomab/iodine-131 tositumomab [Bexxar]) in a phase III Intergroup trial conducted by the Southwest Oncology Group (SWOG) and Cancer and Leukemia Group B (CALGB).1
SWOG S0016/CALGB 50102 compared the efficacy of two immunochemotherapy regimens for follicular lymphoma in 554 patients, over half of whom had stage IV disease.
“We found the outcomes are excellent with either CHOP-R or CHOP-RIT. They produce similar overall response rates, complete response rates, progression-free survival, and overall survival, and there are no major differences in the toxicities,” said Oliver W. Press, MD, PhD, of the Seattle Cancer Care Alliance.
At a median follow-up of 4.9 years, overall and progression-free survival rates were similar between the treatment approaches. Two-year overall survival rates were 97% with CHOP-R and 93% with CHOP-RIT (P = .08). Progression-free survival rates were 76% and 80%, respectively.
Response rates were 85% in each arm, including complete responses in 41% with CHOP-R and 46% with CHOP-RIT. Dr. Press suggested the response rates were in reality higher, since nonassessable patients (10%) were counted in the denominator in the analysis but not counted as responders.
Four prognostic factors were highly significant for progression-free and overall survival: Follicular Lymphoma International Prognostic Index (FLIPI) score, serum beta2-microglobulin plus lactate dehydrogenase (LDH), serum beta2-microglobulin alone, and LDH alone. Adverse events were similar except for more thrombocytopenia with CHOP-RIT (18% vs 2%; P < .0001). There was a trend toward more myelodysplasia and acute myeloid leukemia in the CHOP-RIT arm (7 cases [2.7%]) compared with the CHOP-R group (3 cases [1%]), but this difference was not statistically significant (P = .34). Human anti-mouse antibodies developed in 17% of evaluable patients treated with CHOP-RIT.
“It is important to emphasize that this clinical trial produced outstanding outcomes for patients on both arms of the study, with more than 60% of patients estimated to be progression-free 5 to 10 years after treatment. The flat slope of the progression-free survival curves after 3 years makes it likely that many of these patients will not relapse during their lifetimes,” Dr. Press speculated. ■
Disclosure: Dr. Press has been a consultant for Genentech/Roche and Spectrum Pharmaceuticals.
1. Press O, Unger JM, Rimsza LM, et al: A phase III randomized intergroup trial [SWOG S0016] of CHOP chemotherapy plus rituximab vs CHOP chemotherapy plus iodine-131-tositumomab for the treatment of newly diagnosed follicular non-Hodgkin’s lymphoma. 53rd American Society of Hematology annual meeting. Abstract 98. Presented December 11, 2011.
SWOG S0016, which compared treatment with CHOP-R (cyclophosphamide, doxorubicin, vincristine, prednisone, plus rituximab [Rituxan]) and CHOP-RIT (CHOP plus tositumomab/iodine-131 tositumomab [Bexxar]) in patients with follicular lymphoma, was one of the most important studies at the 2011 ASH...