Phase II study of R-CVP followed by rituximab maintenance therapy for patients with advanced marginal zone lymphoma: consortium for improving survival of lymphoma (CISL) study.

Background: The response rate and survival improvement for rituximab, a CD20-targeting monoclonal antibody, have been demonstrated in marginal zone lymphoma (MZL) as monotherapy and in combination with chemotherapeutic regimens, yet relapses still occur despite treatment completion. Thus, extending the period of remission in MZL patients remains an essential goal. This multicenter, single-arm, open-label phase II study evaluated the survival efficacy of 2 years of rituximab-maintenance therapy in patients with stage III-IV CD20-positive MZL who had responded to first-line R-CVP (rituximab, cyclophosphamide, vincristine, and prednisolone). The objective of this study was to determine whether rituximab maintenance following R-CVP warrants further investigation.

Methods: Prior to rituximab-maintenance therapy, patients received 6-8 cycles of first-line R-CVP therapy for stage III-IV MZL. Rituximab (375 mg/m), cyclophosphamide (750 mg/m), and vincristine (1.4 mg/m; maximum 2 mg) were administered via an intravenous infusion on day 1 of each 3-week cycle, while oral prednisolone (100 mg) was given on days 1-5 of each 3-week cycle. The patients who achieved complete response (CR), partial response (PR), or stable disease (SD) to R-CVP treatment, were prescribed rituximab-maintenance therapy which was administered intravenously at a dose of 375 mg/m every 8 weeks for up to 12 cycles. The primary endpoint was progression-free survival (PFS). Secondary endpoints were overall survival (OS) and treatment safety.

Results: 47 patients were enrolled, of whom, 45 (96%) received rituximab-maintenance treatment. Fifteen (33%) patients had nodal MZL. Following R-CVP first-line therapy, 20 (44%), 22 (49%), and 3 (7%) patients achieved CR, PR, and SD, respectively. After a median follow-up of 38.2 months, their observed 3-year PFS rate was 81%. During the rituximab-maintenance, 6 PR and 1 SD patients achieved CR following the administration of R-CVP. Elevated LDH and the presence of B symptoms were found to be significant prognostic factors for PFS (P = 0.003) and demonstrated a 3-year OS rate of 90%. Rituximab-maintenance therapy was well tolerated, and the common treatment-emergent adverse events were sensory neuropathy (18%), myalgia (13%), fatigue (9%), and neutropenia (9%).

Conclusion: Rituximab-maintenance therapy following first-line R-CVP demonstrated good PFS in patients with stage III-IV MZL, in addition to a favorable toxicity profile. Trial registration clinicaltrials.gov: NCT01213095.