Mitoxantrone/ifosfamide/etoposide salvage regimen with rituximab for in vivo purging in patients with relapsed lymphoma.

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.