Addition of Rituximab to Chlorambucil Produces Superior Event-Free Survival in the Treatment of Patients With Extranodal Marginal-Zone B-Cell Lymphoma: 5-Year Analysis of the IELSG-19 Randomized Study

Abstract

Purpose Apart from localized gastric disease, there is no consensus on standard initial treatment of mucosa-associated lymphoid tissue lymphoma. The IELSG-19 study (Randomized Trial of Chlorambucil Versus Chlorambucil Plus Rituximab Versus Rituximab in MALT Lymphoma) was launched to compare chlorambucil alone versus chlorambucil plus rituximab in patients not previously given systemic anticancer therapy. Patients and Methods Patients not responding to or not suitable for local therapy were eligible. In arm A, chlorambucil was given daily 6 mg/m2 orally (PO) for 6 weeks. Responding patients and those with stable disease continued to be given daily chlorambucil 6 mg/m2 PO for 14 consecutive days every 28 days for four cycles. In arm B, intravenous rituximab 375 mg/m2 per day was added on days 1, 8, 15, 22, 56, 84, 112, and 140. After completion of the planned accrual, the protocol was amended to introduce a third arm with rituximab alone. We report the planned final analysis of the first two arms (113 patients in arm A and 114 in arm B). Results At a median follow-up of 62 months, the 5-year event-free survival (EFS) was significantly better for the patients treated in arm B (68% v 50%; P = .002) who, despite similar overall response rates (90% v 87%), achieved a higher complete remission rate (78% v 65%; P = .025). Progression-free survival was also improved but it did not reach statistical significance (P = .057). Five-year overall survival (OS) was 89% in both arms. Both treatments were well tolerated without unexpected toxicities. Conclusion Both treatments were active; the better response rate and EFS obtained with the addition of rituximab did not translate into improved OS.