Isolation and transplantation of highly purified autologous peripheral CD34⁺ progenitor cells: Purging efficacy, hematopoietic reconstitution in non-Hodgkin's lymphoma (NHL): Results of Japanese phase II study

The purging efficacy of positive selection of autologous CD34⁺ PBSC with a clinical scale method of magnetic-activated cell sorting system (CliniMACS) was investigated in 48 patients with non-Hodgkin's lymphoma (NHL). The median purity and recovery rate of the CD34⁺ cells post-selection were 93.3% (range 32.6-99.3) and 72.2% (range 20.5-309.8), respectively. The real-time PCR method to detect the patient-specific monoclonal immunoglobulin heavy chain gene rearrangement (minimal residual tumor; MRT) and CD19 and CD20 positivities were used for the detection of contaminating NHL cells before and after CD34⁺ selection. After selection, the median (range) depletion rate of MRT was 2.53 (1.52-4.78) log, and that of CD19⁺ cell and CD20⁺ cell was 2.46 (0.74-3.64) log and 2.32 (0.40-4.01) log, respectively. In 41 patients, high-dose chemotherapy was performed, followed by the transplantation of the isolated CD34⁺ cells. Rapid neutrophil recovery as well as platelet recovery was seen with a median time to reach 0.5 × 10⁹/1 neutrophils of 10 days (range 8-13) and 20 × 10⁹/1 platelets of 14 days (range 10-34), respectively. The present study demonstrated that CliniMACS is a highly effective positive selection method and a high purging efficacy could be obtained without compromising the hematopoietic reconstitution capacity of the graft in NHL patients undergoing high-dose chemotherapy.