A comparison of chimerism and minimal residual disease between four different allogeneic transplantation methods in patients with chronic myelogenousleukemia in first chronic phase

The detection of chimerism, residual molecular and cytogenetic disease foll owing transplantation of peripheral blood stem cells (PBSCT) with a nonmyel oablative conditioning (n = 9) and the transplantation of highly purified C D34(+) stem cells (CD34(+) PBSCT) (n = 16) were compared to unmanipulated b one marrow transplantation (BMT) (n = 69) and unmanipulated PBSCT (n = 50) after myeloablative conditioning in patients with first chronic phase of ch ronic myelogenous leukemia (CML) (n = 137), second chronic phase of CML (n = 4), acute lymphoblastic leukemia (n = 2) and acute myeloid leukemia (n = 1). A molecular relapse (MR) as defined by two consecutive positive polymer ase chain reaction assays for the detection of M-bcr-abl transcripts (n = 1 41) and cbf beta -myh11 transcripts (n = 1) in a 4-week interval was found in 10 of 16 patients (63%) after CD34(+) PBSCT, and in 27 of 69 patients (3 9%) after BMT, whereas only three of 50 patients (6%) after PBSCT (P < 0.00 1) and one of eight patients (13%) after PBSCT with reduced conditioning su ffered from a MR. A cytogenetic relapse occurred in five of 16 patients (31 %) after CD34(+) PBSCT and 21 of 69 patients (30%) after BMT (NS) compared to two of 50 patients (4%) after PBSCT and none of the eight patients after PBSCT with reduced conditioning (P < 0.05). The lowest treatment-related m ortality was seen in the 16 patients after CD34(+) PBSCT, who are all curre ntly alive with a median follow-up of 15 months, whereas the survival rate for BMT, PBSCT and PBSCT with reduced conditioning were 65%, 63% and 58%, r espectively. Multivariate analysis including all potential influential fact ors of post-transplant residual disease recurrence showed that patients aft er CD34(+) PBSCT had a significantly higher risk (two times) to develop a M R than patients after BMT (P < 0.03), whereas patients after unmanipulated PBSCT had a significant lower risk (eight times) for the occurrence of a MR post transplant (P < 0.001). Patients after BMT and CD34(+) PBSCT had the lowest rates of complete chimerism (CC) at 3 months after transplant, Only five of nine patients (55%) after CD34(+) PBSCT and 19 of 33 patients (58%) after BMT achieved CC compared to 19 of 22 (86%) patients after PBSCT and seven of eight (88%) patients after PBSCT with reduced conditioning (P < 0. 05).