A comparison of CD34(+) cell selected and unselected autologous peripheralblood stem cell transplantation for multiple myeloma: a case controlled analysis

Following ASCT for multiple myeloma, it is unclear whether relapse is due s olely to the presence of residual myeloma cells after myeloablation, or whe ther it is in part attributable to contamination of the stem cell harvest w ith viable malignant cells. Positive selection of CD34(+) cells markedly re duces plasma cell contamination. We performed a case controlled analysis in which 15 patients with myeloma who underwent autologous PBSCT with CD34(+) cell selection using the Ceprate System tinder group), were compared with 15 matched controls, All subjects received an identical preparative regimen , The median times to neutrophils greater than or equal to 0.5 x 10(9)/l an d unsupported platelets greater than or equal to 50 x 10(9)/l mere 11 and 2 3 days for the CD34(+) cell selected group and 11 (P = 0.03) and 14 (P = 0. 029) for the case controls, Median follow-up of purged patients from autolo gous PBSCT was 32 months (range 18-43). At 36 months, the probability of PF S was 47 +/- 14% and 46 +/- 14% in the index and control groups (P = 0.44). The 3 year probability of OS was 69 +/- 13% for the CD34(+) cell selected arm and 66 +/- 12.4% in unpurged patients (P = 0.91), Median PFS for the ce ll selected group is 24 months (CI 19.1-36.0), and 29 months for controls ( CI 7.1-50.9. Eleven patients undergoing cell selection remain alive, seven of whom are progression free. At the same time-point after unpurged autolog ous PBSCT, the corresponding figures are 12 patients alive, with seven rema ining progression free. Autologous PBSCT with CD34(+) cell selection is bot h feasible and safe, but results in delayed engraftment as compared to case controls. The 3 year probability of PFS and OS in the cell selected arm wa s similar to that of the unpurged controls, Our findings indicate that auto logous PBSCT with CD34(+) cell selection appears not to have any favourable effect on disease progression, However, the results of this case controlle d analysis should be cautiously interpreted, and the role of CD34(+) select ion in autologous PBSCT should be further investigated by large randomised trials.