Response to blinatumomab or inotuzumab ozogamicin for isolated extramedullary relapse of adult acute lymphoblastic leukemia after allogeneic hematopoietic cell transplantation: a case study

Isolated extramedullary relapse (EMR) without bone marrow relapse (BMR) after allogeneic hematopoietic cell transplantation (allo-HCT) is a rare condition in patients with acute lymphoblastic leukemia (ALL), and the role of immunotherapeutic agents for these patients remains unclear. We analyzed treatment outcomes of blinatumomab or inotuzumab ozogamicin (INO) as first- or second-line salvage therapy in nine patients with Philadelphia chromosome-negative B-cell precursor ALL presenting with isolated EMR after previous allo-HCT. In seven patients receiving blinatumomab as first-line salvage therapy, 4 (57.1%) achieved complete remission (CR). Among the three patients without remission after blinatumomab, two switched to INO and subsequently showed responses {one CR and one partial response [PR]}, and one switched to multiagent chemotherapy that led to CR. In the two patients receiving first-line salvage therapy with INO, one showed PR and the other achieved CR. Overall, 6 (66.7%) of nine patients achieved CR, and five of them proceeded to allo-HCT in CR. The median overall survival after relapse was 27.8 months. In conclusion, both blinatumomab and INO showed good response rates and a safe bridging role to second allo-HCT in patients with isolated EMR. However, clinical differences between isolated EMR and EMR with BMR remain to be elucidated.

Bone marrow CD34+progenitor cells in Philadelphia chromosome-negative chronic myeloproliferative disorders – A clinicopathological study on 575 patients

Contrasting the circulating CD34+ hematopoietic progenitor cells (HPCs) in chronic myeloproliferative disorders (CMPDs), scant knowledge is available regarding their quantity in the bone marrow (BM). Therefore, a clinicopathological study was performed on trephine biopsies in 575 patients with CMPDs focused on chronic idiopathic myelofibrosis (CIMF). A comparison with 25 healthy subjects revealed no significant differences in the numbers of HPCs (6 +/- 3/mm2) in polycythemia vera, essential thrombocythemia and advanced fibro-osteosclerotic stages of CIMF. Pre-fibrotic and early-stage CIMF displayed 16 +/- 11 precursors per mm2 BM. Sequential biopsies in this disorder showed a decline in HPCs (10 +/- 6/mm2) with evolving myelofibrosis-myeloid metaplasia (MMM), while in terminal stages acceleration generated an increase (24 +/- 25/mm2). A significant association between the quantity of HPCs and the development of myelofibrosis, splenomegaly, and anemia as well as an increase in peripheral blasts was recognizable in CIMF. Moreover, in all subtypes of CMPDs, a favorable prognosis was significantly associated with a higher number of HPCs in the BM. In conclusion, enhanced inflow of precursors from the BM with subsequent trapping, self-renewal and mobilization by the spleen is assumed to indicate a progressive generalization and worsening of the outcome. This putative pathomechanism is significantly associated with the evolution of MMM.

[The distribution feature of TCR Vbeta repertoire in peripheral blood T cells from patients with Ph(+) and Ph(-) CML]

To investigate the T cell distribution characters of TCR Vbeta repertoire in Ph(+) and Ph(-) CML. The 24 subfamilies of the TCR Vbeta genes were amplified in peripheral blood T cells from 13 patients with CML (Ph+ b3a2, 5 cases; Ph+ b2a2, 5 cases; Ph(-), 3 cases) by RT-PCR, to analyze the usage of Vbeta subfamilies in different CML patients. The results showed that the expression pattern of Vbeta repertoire was different in normal individuals and in patients with CML which only have part of Vbeta subfamily T cells. 4 - 16 (mean 10.2) Vbeta subfamily T cells were detected in the Ph+ b3a2 CML, 8 - 11 (mean 8.8) Vbeta subfamily T cells in the Ph(+) b2a2 CML and 5 - 6 (mean 5.7) in Ph(-) CML. Moreover, the expression of Vbeta subfamily T cells was different among these three types CML.Vbeta10 and Vbeta16 were detected in the all cases with Ph(+) b3a2 and Ph(+) b2a2 CML, whereas Vbeta9 and Vbeta22 could be found in the most cases with Ph(+) b3a2 CML or Vbeta24 and Vbeta8 in Ph(+) b2a2 CML. In patients with Ph(-) CML, Vbeta24 were detected in all samples, and Vbeta9, Vbeta10, Vbeta13 and Vbeta22 were found in the most cases. The results suggest that skew distribution of TCR Vbeta subfamily T cells was existed in peripheral blood of Ph(+) and Ph(-) CML patients. The selected usage of TCR Vbeta is different in various types of CML patients. It may relate to difference of CML cells associated antigen and individual special immunity reaction.

Autoantibodies to Abl and Bcr proteins

Formation of an aberrant, chimeric Bcr-Abl protein is the hallmark of Philadelphia (Ph) chromosome-positive leukemias. The Bcr-Abl protein, as well as its normal cellular counterparts--Abl and Bcr--are intracellular molecules with postulated roles in a variety of critical biologic functions. In this study, we demonstrate the existence of autoantibodies against these proteins. Plasma from 18 of 31 individuals (58%), including 14 of 20 Ph-positive CML patients (70%), two of four normal volunteers (50%), and two of seven patients with Ph-negative leukemia (29%) recognized p210Bcr-Abl when used in immunoprecipitation followed by immunoblotting experiments. In all 18 patients, plasma was able to recognize baculovirus-expressed Abl protein; in four patients, recognition of baculovirus-expressed Bcr protein was also demonstrated. These observations suggest that a humoral immune response to p210Bcr-Abl is discernible in both Ph-positive and -negative leukemias and in healthy individuals, and is most likely due to autoantibodies which recognize normal Abl and, to a lesser extent, normal Bcr proteins.

Chronic myeloid leukemia from basics to bedside

The discovery of the Philadelphia chromosome and its consistent involvement in chronic myeloid leukemia (CML) was the first time that a relationship between a cytogenetic abnormality and malignancy was demonstrated. This review will try to provide an insight into the molecular mechanisms underlying this disease and outline the therapeutical options for patients with CML.

Molecular status of individual CFU-GM colonies derived from chemotherapy-mobilised peripheral blood stem cells in chronic myeloid leukaemia

Following chemotherapy in chronic myeloid leukaemia (CML), some peripheral blood (PB) cells may be Philadelphia (Ph) chromosome negative. The BCR-ABL mRNA status of residual Ph+ progenitors is not known. We examined the BCR-ABL mRNA status of individual colony-forming-unit granulocyte-macrophage (CFU-GM) colonies derived from PB harvested following chemotherapy. Seven patients were treated with 200 mg/m2/day cytarabine and 20 mg/m2/day Idarubicin and followed by Lenograstim. PB collections commenced daily when the white blood cell count reached 0.6 x 10(9)/l and continued until at least 5 x 10(8)/kg nucleated cells were obtained. CD34+ cells, Ph status, and CFU-GM were estimated at each harvest. For each patient, up to 24 individual CFU-GM colonies were analysed for BCR-ABL status. Two cases were BCR-ABL negative on all colonies and completely Ph-, and another case was BCR-ABL positive in all colonies and completely Ph+. In contrast, in two patients all colonies were BCR-ABL negative, despite virtually complete Ph+ metaphases. The final assessible case had five of nine BCR-ABL negative colonies, despite 94% Ph+ metaphases. After chemotherapy priming, the PB may contain Ph+ CFU-GM that do not express BCR-ABL.

Phenotypic characterization of normal and CML CD34-positive cells: only the most primitive CML progenitors include Ph-neg cells

We studied the sequence of acquisition of CD33, CD38 and HLA-DR antigens on CD34+ cells from marrow and blood of Ph-chromosome positive CML patients and normal marrow. We examined the Ph status of the various CML cell populations. The mean proportions of normal and CML CD34+ cells expressing CD33 and CD38 were not significantly different. However, a significantly greater proportion of CML CD34+ cells expressed HLA-DR antigens compared with normal CD34+ cells and the level of HLA-DR expression per CML cell was abnormally high. When the sequence of acquisition of these antigens on normal and CML CD34+ cells was evaluated using 3-colour fluorescence analysis, the results suggested that HLA-DR was expressed earlier than CD38 or CD33 and these findings were confirmed by following the acquisition of CD38 and CD34+/DR+/CD38-subpopulation during liquid culture. We performed cytogenetic studies on CD34+ subpopulations in 6 cases. In 4 cases there were some Ph-negative metaphases detectable in the CD34+/DR-subpopulation (range 12.5 to 60%). In the CD34+/DR+ fractions, however, all 6 patients had only Ph-positive metaphases and only 1/5 patients had detectable Ph-negative metaphases in the CD34+/CD38-subpopulation. We conclude that expression of HLA-DR antigens may precede the expression of CD38 on CD34+ cells during normal stem cell differentiation. In CML DR may be expressed aberrantly and Ph-negative cells are found predominantly in the DR negative subpopulation.