Rituximab Plus CHOP Followed by Maintenance Rituximab as Initial Therapy for Advanced Stage Indolent Non-Hodgkin’s Lymphoma (NHL); Initial Results of Induction Therapy in a Phase II Study.

Background: This study was designed to investigate the activity and safety of rituximab (Rituxan®, R) plus CHOP induction therapy followed by maintenance R in patients with previously untreated advanced stage indolent NHL. The initial results of R-CHOP induction treatment are reported here.

Methods: 102 patients with Ann Arbor Stage III or IV indolent NHL (follicle center/follicular grade I/II or nodal marginal zone B-cell by REAL; Type B or C by IWF) were enrolled into this open-label, multi-center, community-based, Phase II, single-arm trial. Patients received 6 cycles of standard R-CHOP induction therapy (cyclophosphamide 750 mg/m², vincristine 1.4 mg/m², doxorubicin 50 mg/m² all IV on Day 1; prednisone 100 mg/day Days 1–5). R 375 mg/m² was given on Day 1 of each cycle except for cycle 1, when it was administered 2–3 days prior to CHOP chemotherapy. Subjects with an ongoing response (CR/CRu or PR) after induction receive maintenance R (4 weekly infusions) within 28 days after the completion of induction and repeated every 6 months for 2 years for a total of 16 maintenance R doses. The primary endpoints were CR/CRu after 6 cycles of induction and the incidence of R infusion-related toxicity during induction and maintenance therapy. Secondary endpoints included overall response rates (ORR), infusion times, serious adverse events (SAE) in induction and maintenance, and rituximab pharmacokinetics in maintenance therapy.

Results: Baseline characteristics were: median age 57y (33.3% ≥60y); 40.2% female; ECOG performance status 0: 70.6%; Ann Arbor stage III: 28.4% and IV: 71.6%. Serum β₂-microglobulin and LDH at baseline were above normal in 66.3% and 20.6%, respectively. CR/CRu at the end of induction in 102 patients was 51.0% (ORR 86.3%). 1% had progressive disease (PD) during induction. 2 subjects died during the induction period, both due to SAEs (probable pulmonary embolus, acute respiratory distress). SAEs occurred in 22.5% of subjects during induction with the most common event being febrile neutropenia (7.8%). Grade 3–4 R infusion-related toxicity occurred in 4.9% of patients in cycle 1; this decreased to 1% by cycle 2 of induction. Two subjects discontinued R for infusion-related toxicity. 44% of patients were able to receive their R dose within 3 hrs at cycle 2 and 69.2% of patients at cycle 6.

Conclusion: Patients with advanced stage indolent NHL treated in the community setting with R-CHOP induction tolerate therapy well and have an excellent response rate. The outcomes of maintenance therapy and rituximab pharmacokinetics in maintenance await further follow-up.