Clinical outcome of pretreated B-cell chronic lymphocytic leukemia following alemtuzumab therapy: a retrospective study on various cytogenetic risk categories.

BACKGROUND: Patients with B-cell chronic lymphocytic leukemia (CLL) with 17p deletion respond poorly to chemotherapy. This retrospective study evaluated the benefit of alemtuzumab monotherapy in unselected patients with advanced CLL in the various cytogenetic subgroups. PATIENTS AND METHODS: Data were collected from 105 consecutive, pretreated, cytogenetically defined patients who had received alemtuzumab. Response, progression-free survival (PFS), and overall survival (OS) were assessed. RESULTS: The hierarchic incidence of cytogenetic abnormalities was: 13q deletion (as sole abnormality), 18%; trisomy 12, 13%; 11q deletion, 19%; 17p deletion, 33%; and none of these, 16%. Overall response rate (ORR) was 43% in the total cohort and 49% in the subgroup of 17p-deleted patients (n = 35). From the start of alemtuzumab monotherapy, median PFS in the total cohort and in the subgroup of 17p-deleted patients was 7.0 and 7.1 months, respectively. Median OS in the total cohort and in 17p-deleted patients was 32.8 and 19.1 months, respectively. The poor-risk group of patients with CLL (i.e. fludarabine resistant, 17p deletion; n = 20) showed encouraging ORR, PFS, and OS (35%, 7.0 and 19.2 months, respectively). CONCLUSIONS: Alemtuzumab was effective in treating patients with CLL across the cytogenetic categories evaluated, but there were differences. In patients with CLL with 17p deletion quite favorable ORR, PFS, and OS were achieved.

Hematopoietic recovery after IEV chemotherapy for malignant lymphoma followed by different cytokines can be monitored by analysis of Galpha 16 and CD34.

The hematopoiesis-specific G protein alpha subunit Galpha16 is a specific element in the signal transduction of the early hematopoietic cytokine network. As Galpha16 mRNA can be detected in early hematopoietic progenitor cells, RT-PCR for Galpha16 can be used as a sensitive marker of hematopoietic activity. The aim of this study was to test the possible use of Galpha16 determinations for monitoring cytokine effects on hematopoietic recovery after chemotherapy in patients. We correlated presence of Galpha16 mRNA and CD34 surface antigen with hematopoietic recovery in six lymphoma patients undergoing salvage therapy with different cytokine support (IEV followed by G-CSF, IL-3, or placebo). Regardless of different cytokine schedules with different time courses, hematopoietic recovery was always preceded by transcription of Galpha16. Monitoring the expression of Galpha16 mRNA by RT-PCR is a highly sensitive diagnostic tool for analyzing hematopoietic recovery after chemotherapy and for characterizing the effects of cytokines on hematopoiesis.

In vivo and in vitro effects of cytokines and the hemoregulatory peptide dimer (pEEDCK)2 (pyroGlu-Glu-Asp-Cys-Lys)2 on G alpha16-positive hematopoiesis.

G proteins play an important role in signal transduction from cytokine receptors to intracellular effectors via different pathways, eg involving tyrosine kinases. In our previous studies, we demonstrated that mRNA expression of the hematopoiesis-specific G protein alpha-subunit G alpha16 is a sensitive marker indicating the appearance of early myeloid and lymphoid progenitors. This study was designed to investigate cytokine effects on hematopoiesis in vivo and in vitro as reflected by G alpha16 expression and sensitivity to the hemoregulatory peptide (pEEDCK)2 which harbors a structural homology to the effector domain of G alpha16. Investigations on blood samples from lymphoma patients undergoing salvage therapy with different cytokine support showed that monitoring of the expression of G alpha16 mRNA which appears to play a role in cytokine signalling via tyrosine kinases was a valuable complementation to CD34 screening for analyzing hematopoietic recovery after chemotherapy. We demonstrated that in contrast to CD34 which is only expressed in quiescent cells, G alpha16 transcription occurs independently of cell cycle state. In vitro, we could show that G alpha16 was also a valuable marker for confirming the immature state of ex vivo expanded blood stem cells from patients. A further part of the study was focused on the response of G alpha16 and CD34 expressing cells to the granulocyte-derived hemoregulatory peptide (pyroGlu-Glu-Asp-Cys-Lys)2 = (pEEDCK)2 which harbors a G alpha16-homologous sequence motif. Results obtained from in vitro assays which involved estimation of colony outgrowth from CD34-positive cells showed that the effect of (pEEDCK)2 on CD34 cells enhanced the effect of IL-3 or SCF. These data indicate that G alpha16 may co-operate with (pEEDCK)2 in triggering the cytokine response of immature hematopoietic cells.

Monitoring of hematopoietic recovery after autologous stem cell transplantation by analysis of G alpha 16 mRNA and CD34 surface glycoprotein.

The hematopoiesis-specific G protein alpha subunit G alpha16 was shown to be expressed in early normal and malignant hematopoietic cell lines and has been suggested to play an important role in signal transduction of hematopoiesis. We previously demonstrated a strict correlation of G alpha16 mRNA and CD34 antigen expression in peripheral blood stem cells (PBSC). In PBSC mobilization, both markers are detectable at the time of hematopoietic recovery and progenitor cell release. In this study the possible use of G alpha16 determination in peripheral blood samples for monitoring patients undergoing stem cell transplantation was investigated. Normal peripheral blood is negative for G alpha16 expression. In all five patients G alpha16 mRNA expression appeared shortly before the time of blood cell recovery. When tested together with CD34 (three cases) a pattern different from CD34 antigen expression was found, reflecting a different mechanism of action. In two cases with different time points of leukocyte and platelet recovery G alpha16 mRNA was detected at both time points but not in the interval, thus suggesting a role of G alpha16 in multipotent precursor cells. CD34 mRNA tested in three patients was not detected at any time; this argues for different regulation of CD34 and G alpha16 mRNA. G alpha16 may be used as an indicator of hematopoietic recovery after autologous stem cell transplantation, suggesting that there are cell type-specific G protein-mediated signal transduction pathways of early hematopoiesis.

Expression of G alpha 16, a G-protein alpha subunit specific for hematopoiesis in acute leukemia.

G-proteins are essential in signal transduction pathways. A G-protein alpha subunit termed G alpha 16 was found to be exclusively expressed in hematopoietic cell lines. In cells derived from patients, G alpha 16 expression has been detected in progenitor- and pre-B ALL cells and also in peripheral blood stem cells (PBSC). In this study, we analyzed G alpha 16 expression using a RT-PCR technique by testing elutriated blood cells from normal donors, PBSC from breast cancer patients and bone marrow or peripheral blood cells from acute leukemia patients. Both of two ALL patients and 15/16 AML patients expressed G alpha 16. In elutriation experiments, G alpha 16 expression was found in fractions containing the highest number of precursor cells but was absent in mature T and B cell fractions. In addition, CD34-enriched PBSC were positive for G alpha 16 expression. Further in vitro experiments using the cell line KG1 showed that G alpha 16 expression was not affected by the growth inhibiting hemoregulatory peptide pEEDCK which has a sequence homology present within G alpha 16. Taken together, these data demonstrate that G alpha 16 is expressed in various normal and malignant hematopietic progenitors but not in their differentiated counterparts. G alpha 16 could play a vital role in signal transduction pathways controlling proliferation in early normal and malignant hematopoiesis.

Analysis of peripheral blood progenitor cells demonstrates limitations of minimal residual disease diagnosis in a case of acute promyelocytic leukemia.

Detection of minimal residual disease (MRD) by analysis of the PML-RAR alpha fusion transcript using the RT-PCR method is routinely carried out on peripheral blood and bone marrow of patients with APL (AML, FAB:M3). Therapy aims to achieve repeated negative results in these patients thus confirming clinical complete remission. We report a case of APL in second complete remission in which no leukemic cells had been detected in BM and PB for 20 months, and in which PBPC-pheresis was carried out for future transplantation. In two of five pheresis PML-RAR alpha fusion transcripts were detected. This shows that the residual leukemic population may only reach detection level after enrichment by PBPC-pheresis.

B lymphocytes with latent EBV infection appearing in long-term bone marrow cultures (HLTBMCs) from haematological patients induce lysis of stromal microenvironment.

Human long-term bone marrow cultures (HLTBMCs) are a valuable in vitro model for studying the role of the haemopoietic microenvironment. Here we report the spontaneous appearance of EBV-positive B cells in 6/40 HLTBMCs from patients with various haematological diseases after 3-5 months of culture. After subcultivation of these cells, a novel type of cell line could be characterized, which displayed surface markers and morphological features typical for EBV transformed B-cell lines. As the deproteinized and ultrafiltrated culture supernatants of these cell lines were found to contain an agent with stroma toxic properties, they were termed SSB lines (stroma-toxic-agent-secreting B-cell lines). This agent also exhibited a colony-inhibitory activity on in vitro myelopoiesis and erythropoiesis. These properties are typical for the two polyamines spermine and spermidine which were detected at elevated levels in the culture supernatants of SSB lines. The hypothesis that latent presence of EBV in bone marrow may induce an increased synthesis of spermine and spermidine, which are known to be associated with malignant haematological diseases and bone marrow aplasia, is discussed.