High Efficacy and Good Tolerability with Rituximab In Vivo Purging Followed by High Dose Chemotheraphy and Autologous Peripheral Blood Stem Cell Transplantation (APBSCT) in Non-Hodgkin’s Lymphoma (NHL).

Purpose: High-dose chemotherapy (HDC) supported by APBSCT has been shown to be superior to standard therapy in NHL. However, many patients relapse due to minimal residual disease (MRD) in vivo or in the graft. Rituximab has the potential to clear both blood and bone marrow of malignant CD20+ cells, prompting this multicenter trial of in vivo purging with rituximab and HDC with APBSCT in China.

Methods: Cyclophosphamide 4g/m² was used as the mobilization regimen, CY/TBI, BEAM or CBV could be used as HDC at the discretion of the institution. Four infusions of rituximab (375 mg/m²) were given: one day before mobilization, one day before harvesting, one day before transplantation and on day 8 after transplantation. BCL-2/Ig-H translocation was measured as a marker of minimal residual disease in blood or bone marrow before mobilization and during transplantation using real-time quantitative PCR.

Results: Thirty-one patients from 12 centers with histologically proven CD20+ NHL (28 aggressive, 3 indolent NHL) were enrolled. Twenty-four patients were previously untreated, and 7 patients had relapsed disease. Median yields of CD34⁺ cells and mononuclear cells were 5.9×10⁶/kg and 4.4×10⁸ /kg respectively. Median time to recovery of WBC >1.5×10⁹/L, ANC >0.5×10⁹/L and platelets >20×10⁹/L after APBSCT was 10 days in each case. Median time to platelet recovery >50×10⁹/L was 13 days. Generally, this therapeutic strategy was well tolerated with few side effects attribute to rituximab. All patients achieved a complete remission after APBSCT. At a median-follow-up of 12 months, overall survival and progression-free survival (PFS) are 87% and 73% respectively for all patients. In patients with aggressive NHL, overall survival and PFS are 85% and 73% respectively and in indolent NHL are 100% and 67% respectively. PFS and overall survival were slightly higher in previously untreated compared with relapsed patients (88% vs. 83% for PFS, 73% vs. 69% for overall survival). One of five 5 patients who were initially found to be PCR-positive and achieved PCR-negative status subsequently experienced progression accompanied by a return to PCR positivity. The remaining four patients are still in complete remission and are PCR negative.

Conclusion: These results suggest that the regimen of rituximab combined with HDCT and APBSCT is effective and well tolerated for the treatment of patients with NHL.