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Treatment with the anti-CD20 antibody rituximab prior to stem cell collection may lead to tumor-free stem cell collections in patients with B-cell lymphoma undergoing autologous stem cell transplantation. To test the feasibility of obtaining polymerase chain reaction (PCR)-negative stem cell collection, 30 patients with a variety of B-cell lymphomas were enrolled in a protocol employing a common MINE (mitoxantrone/ifosfamide/etoposide) salvage regimen with rituximab (in vivo purging). Rituximab 400 mg/m2 was administered weekly for 3 weeks on days 1, 6, and 8 in relation to the last MINE cycle, which was followed by growth factor-stimulated peripheral stem cell collection. The median number of CD34(+) cells/kg was 2.5 million cells/kg collected over a median of 5 days. Polymerase chain reaction amplification for the t (14;18) or the heavy-chain gene rearrangement was performed prior to treatment and on the leukapheresis sample. Out of 15 patients who had a positive PCR signal prior to treatment, 10 had PCR-negative stem cell collections, whereas 5 had PCR-positive stem cell collections. After high-dose chemotherapy and stem cell transplant, all patients with a PCR-positive signal pretreatment became PCR negative. We conclude that rituximab may increase the yield of tumor-free stem cells. Higher rates of PCR negativity have been reported when more intense and protracted chemoimmunotherapy regimens have been employed. The magnitude of clinical benefit and the significance of the PCR analysis in stem cells after rituximab requires larger studies.

Treatment for extensive indolent lymphoma should provide optimization of efficacy while avoiding excessive toxicity. Rituximab may be an ideal agent to combine with chemotherapy because of its lack of classical myelotoxicity. In this study, 27 patients with a variety of histologies of indolent B-cell non-Hodgkin's lymphoma have been treated utilizing a novel three-drug combination. Nine patients had relapsed disease and 18 were previously untreated. Patients first received cyclophosphamide 800 mg/m(2) and mitoxantrone 8 mg/m(2) i.v. on day 1, every 3 weeks for 2 cycles. Subsequently, patients received rituximab 375 mg/m(2) followed by mitoxantrone 8 mg/m2 every 2 weeks for 4 cycles. This regimen and, in particular, the rituximab infusion were extremely well tolerated. Only two of 27 patients experienced a grade 1/2, infusion-related reaction during the first rituximab infusion. Grade 4 neutropenia was noted at some point in 16 patients who were then offered granulocyte-macrophage colony-stimulating factor support for improvement of neutropenia. No infections were noted. Alopecia was minimal. Of 27 patients, 19 achieved a complete response (CR), one achieved an unconfirmed CR (CRu), and five patients achieved a partial response, for an overall response rate of 92.5%. Molecular remissions were noted in seven of 12 tested patients in CR. We concluded that the cyclophosphamide/mitoxantrone/rituximab (CyMiR) regimen is effective and extremely well tolerated. Furthermore, rituximab infusion-associated morbidity is markedly reduced.