Blood
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Donor lymphocyte infusions (DLIs) induce effective graft-versus-tumor responses in patients with multiple myeloma who relapse after allogeneic hematopoietic stem-cell transplantation. The graft-versus-myeloma response is presumably mediated primarily by donor T cells, but recent studies have also demonstrated the presence of antibodies specific for a variety of myeloma-associated antigens in patients who achieve complete remission after DLI. One of the B-cell antigens identified in these studies was B-cell maturation antigen (BCMA), a transmembrane receptor of the tumor necrosis factor (TNF) superfamily that is selectively expressed by mature B cells. ⋯ BCMA antibodies were only found in post-DLI responders and not in other allogeneic transplant patients or healthy donors. These results demonstrate that BCMA is a target of donor B-cell immunity in patients with myeloma who respond to DLI. Antibody responses to cell-surface BCMA may contribute directly to tumor rejection in vivo.
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Imatinib mesylate is highly effective in newly diagnosed chronic myeloid leukemia (CML), but BCR/ABL (breakpoint cluster region/abelson murine leukemia)-positive progenitors persist in most patients with CML treated with imatinib mesylate, indicating the need for novel therapeutic approaches. In this study, we have used the murine CML-like myeloproliferative disorder as a platform to characterize the pharmacokinetic, signal transduction, and antileukemic properties of PD166326, one of the most potent members of the pyridopyrimidine class of protein tyrosine kinase inhibitors. In mice with the CML-like disease, PD166326 rapidly inhibited Bcr/Abl kinase activity after a single oral dose and demonstrated marked antileukemic activity in vivo. ⋯ PD166326 also prolonged the survival of mice with imatinib mesylate-resistant CML induced by the Bcr/Abl mutants P210/H396P and P210/M351T. Altogether, these findings demonstrate the potential of more potent Bcr/Abl inhibitors to provide more effective antileukemic activity. Clinical development of PD166326 or a related analog may lead to more effective drugs for the treatment of de novo and imatinib mesylate-resistant CML.
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A total of 21 patients with myelofibrosis with myeloid metaplasia (MMM), with a median age of 54 years (range, 27-68 years), were prepared with a reduced-intensity conditioning (RIC) regimen. The patients received an allogeneic marrow (n = 3) or peripheral blood stem-cell (n = 18) transplant from HLA-matched related (n = 18) or unrelated (n = 2), or 1 Ag-mismatched related (n = 1), donors. RIC regimens included fludarabine/total body irradiation 200 cGy (n = 5) or 450 cGy (n = 1), fludarabine/melphalan (n = 7), thiotepa/cyclophosphamide (n = 7), and thiotepa/fludarabine (n = 1). ⋯ There were 3 patients who died from acute GVHD, infection, and relapse. There are 18 patients alive 12 to 122 months (median, 31 months) after transplantation, and 17 are in remission (1 after a second transplantation). The use of RIC regimens in allogeneic stem cell transplantation results in prolonged survival in intermediate/high-risk MMM patients.
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Previously, we suggested that imatinib incorporation into conventional chemotherapy as an alternative (imatinib interim therapy) might be a useful strategy for bridging the time to allogeneic stem cell transplantation (SCT) for newly diagnosed Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph(+) ALL). Here, we provide an updated report on this strategy in 29 patients. At the time of enrollment, 23 patients (79.3%) achieved complete remission (CR). ⋯ With a median follow-up duration of 25 months after SCT, the 3-year estimated probabilities of relapse, nonrelapse mortality, disease-free survival, and overall survival were 3.8%, 18.7%, 78.1%, and 78.1%, respectively. In comparison to our historical control data, first-line imatinib interim therapy appears to provide a good quality of CR and a survival advantage for patients with Ph(+) ALL. Further long-term follow-up is needed to validate the results of this study.