Idarubicin, intermediate-dose cytarabine, etoposide, and granulocyte-colony-stimulating factor are able to recruit CD34+/HLA-DR- cells during early hematopoietic recovery in accelerated and chronic phases of chronic myeloid leukemia.

A group of 46 patients with chronic myelogenous leukemia (CML) [chronic phase (CP), 24 patients; accelerated phase (AP), 22 patients] ineligible for allogeneic bone marrow transplantation were given an intensive chemotherapy regimen consisting of idarubicin, intermediate-dose cytarabine, and etoposide. All patients had previously received interferon-alpha and only 2 had shown a partial cytogenetic response. During early recovery from chemotherapy-induced aplasia, peripheral blood progenitor cells (PBPC) were harvested by leukapheresis. All metaphases were found to be Philadelphia chromosome (Ph) negative in the collection from 17 of 46 (37%) patients [CP, 12 of 24 (50%); AP, 5 of 22 (23%)], and a decrease to less than 50% Ph-positive metaphases was seen in an additional 6 (CP, 3 patients; AP, 3 patients). The percentage of patients showing complete Ph disappearance was 64% in those receiving this procedure within the first year of diagnosis. In vitro studies were performed to assess the behavior of the Ph-negative PBPC. In clonogenic cultures they responded to stem cell factor and were able to grow as mixed colonies. Moreover, long-term culture initiating cells (LTCIC) were present in many Ph-negative collections but rarely in Ph-positive PBPC. In 4 females, clonality was studied by analyzing X chromosome inactivation and methylation patterns of the DXS255 locus with the probe M27 beta. Hematopoiesis was polyclonal in all 4 patients tested. Thus far, the Ph-negative collections have been used for autografting in 16 patients (CP, 11 patients; PA, 5 patients) after conditioning with total-body irradiation, etoposide, and cyclophosphamide or idarubicin.(ABSTRACT TRUNCATED AT 250 WORDS)