Peripheral blood stem cell CD34+ autologous transplant in relapsed follicular lymphoma

To evaluate CD34+ selection of peripheral blood stem cells (PBSC) as a graft for autologous transplantation. Eight relapsing follicular lymphoma (FL) patients were submitted to CD34+ autologous stem cell transplantation (ASCT). All patients received at least two front line conventional therapies; mean time to treatment failure (TTF) was 4.5 months. Patients had disseminated stage III-IV disease after a median number of 2.1 relapses. Chemotherapy and G-CSF were used as mobilization for leukapheresis. CEPRATE SC concentrator (CellPro, Inc, Bothell, WA) was used to select CD34+ cells from leukapheresis products. With a mean of 1.8 leukaphereses per patient, 8.1 x 10⁸ mononuclear cells (MNCs)/kg were collected. After the selection process, the median number of MNCs was 9.4 x 10⁶/kg; 4.3 x 10⁶/kg CD34+ cells and 17 x 10⁴/kg CFU-GM, with a purity of 83.7% and a viability of 89.2%. Mbr bcl2/IgH PCR analysis of 5 grafts showed that initial buffy-coat, and CD34- fractions were negative in 3 cases and positive in 2 cases (from whom selected CD34+ fraction remained positive in 1 case). After a conditioning regimen including total body irradiation, cyclophosphamide and etoposide, CD34+ selected cells were reinfused. All patients but one had successful engraftment, median time to WBC > 1 x 10⁹/l was 12 days and platelets > 50 x 10⁹/l 17 days. No severe infectious complications were seen. After transplant, with a minimum follow up of 2 years, 5 patients are still in complete remission (CR). Three patients have relapsed after 1 year of transplant with a mean TTF of 15.6 months. We conclude that PBSC CD34+ selection for ASCT was a safe technique, capable of reconstituting hemopoiesis without severe complications for high risk FL patients included in this study. The effects of tumor cell purging need to be evaluated in a larger series.