Rituximab (anti-CD20 monoclonal antibody) as single first-line therapy for patients with follicular lymphoma with a low tumor burden: clinical and molecular evaluation

The clinical activity of rituximab, a chimeric monoclonal antibodywhich binds to the CD20 antigen, was evaluated as a single first-linetherapy for patients with follicular non-Hodgkin lymphoma (NHL). Fiftypatients with follicular CD20⁺ NHL and a low tumor burdenwere analyzed for clinical and molecular responses. They received 4 weekly infusions of rituximab at a dose of 375 mg/m². Theresponse rate a month after treatment (day 50) was 36 of 49 (73%),with 10 patients in complete remission, 3 patients in completeremission/unconfirmed, and 23 patients in partial remission. Tenpatients had stable disease, and the disease progressed in 3 patients. One of 13 (8%) patients in complete remission, 9 of 23 (39%) patients in partial remission, and 5 of 10 (50%) patients withstable disease exhibited disease progression during the first year.Within the study population, 32 patients were initially informative forpolymerase chain reaction (PCR) data on bcl-2-J_H rearrangement. On day 50, 17 of 30 patients (57%) were negative forbcl-2-J_H rearrangement in peripheral blood, and 9 of 29 (31%) were negative in bone marrow; a significant association wasobserved between molecular and clinical responses(P < .0001). At month 12, 16 of 26 patients (62%) werePCR negative in peripheral blood. These results indicate that earlymolecular responses can be sustained for up to 12 months and that thisresponse is highly correlated with progression-free survival. Rituximabhas a high clinical activity and a low toxicity and induces a highcomplete molecular response rate in patients with follicular lymphomaand a low tumor burden.