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Ahmet H Elmaagacli

Publications and source records attributed to Ahmet H Elmaagacli.

14 recordsLinked to original sources
PubMed2006

Growth factor-independent 1B gene (GFI1B) is overexpressed in erythropoietic and megakaryocytic malignancies and increases their proliferation rate.

Growth factor-independent 1B (GFI1B) is a transcription factor essential for the development and differentiation of erythroid and megakaryocytic lineages. We evaluated the GFI1B expression in erythroleukaemia and megakaryocytic leukaemia, as well as in patients with other subtypes of acute myeloid leukaemia (AML), acute lymphoblastic leukaemia (ALL), chronic myeloid leukaemia (CML), myelodysplastic syndrome (MDS), severe aplastic anaemia (SAA), myelofibrosis with myeloid metaplasia (MMM) and in healthy volunteers. GFI1B expression was increased at least threefold in patients with erythroleukaemia (P < 0.01 compared with controls) and megakaryocytic leukaemia (P < 0.05) as well as in their corresponding leukaemic cell lines HEL, K562, CMK and M-07e. Patients with undifferentiated or monocytic AML, ALL, MMM, MDS and CML had no significantly altered GFI1B expression, whereas GFI1B expression was decreased 10-fold in patients with SAA (P < 0.0001 compared with controls). Silencing GFI1B by transfection with small interfering RNA (siRNA) markedly reduced the proliferation rate in the leukaemic cell lines HEL, K562 and NB4 (P < 0.01). Concomitantly, we observed a two- to threefold increase in the apoptosis rate in these cells after transfection with siRNA towards GFI1B. Our data indicate that GFI1B plays a major role in AML-M6 and AML-M7 and qualifies as a target for anti-leukaemic strategies in these malignancies.

Anemia, Aplastic↗
PubMed2006

Mutations in innate immune system NOD2/CARD 15 and TLR-4 (Thr399Ile) genes influence the risk for severe acute graft-versus-host disease in patients who underwent an allogeneic transplantation.

BACKGROUND: NOD2 and TLR-4 genes belong to the innate immune system that detects invading pathogens through several pattern-recognition receptors. Here we analyzed 403 patients for NOD2 gene mutations and 307 patients for TLR-4 gene mutations (Thr399Ile) with their respective donors and correlated the results with the incidence of acute graft-versus-host disease (aGVHD), severe acute GVHD (saGVHD), the risk for transplant-related mortality (TRM), overall survival (OS) and incidence of infectious complications. METHODS: We performed a retrospective single-center study. Genotyping of TLR-4 and NOD2 were evaluated by real-time polymerase chain reaction. RESULTS: Surprisingly, we found a significant reduced incidence of aGVHD, saGVHD, and intestinal GVHD for patients with NOD2 gene mutations on the donor side with 50%, 0% and 2% compared to patients with the wild-type NOD2 gene with 65%, 17%, and 26%, respectively (P<0.02). However, the incidence of saGVHD increased in patients with NOD2 mutations on the patient and donor (P/D) side with 44% versus 17% compared to patients with the wild-type gene (P<0.03). TLR-4 gene mutations at P/D side had an increased risk for saGVHD with 42% versus 15% of patients with wild-type gene (P<0.04). OS, TRM, and incidence of infectious complications were not influenced by the mutated genes. Multivariate analysis confirmed that NOD2 gene mutations on the donor side had a reduced risk for saGVHD (P<0.001), whereas mutations of the NOD2 gene on P/D side had an increased risk for saGVHD (P<0.01) in our analysis. CONCLUSIONS: These results suggest that NOD2 mutations have influence on the occurrence of acute GVHD after transplantation.

Acute Disease↗
PubMed2006

Quantitative analysis of chimerism after allogeneic stem cell transplantation by real-time polymerase chain reaction with single nucleotide polymorphisms, standard tandem repeats, and Y-chromosome-specific sequences.

We compared the results of chimerism analyses with real-time SNP-PCR to those obtained by the classical STR-PCR method in 135 hematopoietic stem cell transplantation recipients. Using 10 different SNP gene loci, the SNP-PCR method was able to discriminate patient from donor cells in 125 of 135 cases (93%), whereas the use of 11 different STR gene loci with the STR-PCR analysis using agarose or polyacrylamide gel resolution resulted in accurate donor-host discrimination in all patients. Of the 470 analyzed samples we found in 74% concordant results for both chimerism methods. In all 26% discordant cases the SNP-chimerism method showed mixed chimerism (MC), whereas the STR-method found complete chimerism (CC). As a consequence, the SNP-PCR chimerism analysis method detected a MC prior to the occurrence of relapse significantly earlier than the STR-PCR chimerism method (120 vs. 30 days, P < 0.007). The probability of relapses was significantly higher in patients with increasing MC (70%) compared to 30% in patients with CC (P < 0.00001) associated with a significantly shorter overall survival in patients with increasing MC. The multivariate Cox model showed that chimerism analsis with SNP-PCR was the only significant risk factor predicting relapse (RR 6.08, P < 0.0001).Furthermore, we analyzed the chimerism status in male recipients with a female donor in 580 samples of 134 patients using quantitative real-time PCR of Y-chromosome-specific sequences and compared the results with interphase XY-fluorescent in situ hybridization (FISH). MC without signs of relapse was detected in 35% of samples using quantitative real-time PCR of Y-chromosome-specific sequences. The detected Y-DNA amounts were low compared to the amounts detected in 104 samples of 42 patients with leukemic relapse at the time of analysis (P < 0.0001). Quantitative real-time PCR of Y-chromosome-specific sequences detected therefore an increasing MC with high residual host DNA amounts approximately 143 days (mean) prior to the occurrence of relapse. By comparing the results of Y-chromosome PCR with the XY-FISH analysis we found concordant results in 73% in patients with myeloablative regimens. The XY-FISH could detect 12 relapses, whereas the Y-chromosome PCR detect 36 relapses by MC (P < 0.005). Residual host cells gradually decreased during the posttransplant period from a mean of 5.4 ng (first months) to 0.5 ng (above 5 years) without evidence of relapses. The probability of relapses was significantly higher in patients with increasing MC (100%) compared to 8% in patients with CC (P < 0.00001) associated with a significantly shorter overall survival in patients with increasing MC. The multivariate Cox model showed that chimerism analysis of Y-chromosome-specific sequences is an important risk factor for relapse (RR 17.0, P < 0.0001). We conclude that the use of real-time SNP or Y-PCR may be superior to the STR-PCR or interphase XY-FISH methods in detecting patients who are at high risk for relapse after transplant.

Adolescent↗
PubMed2006

Donor cell reaction to OKT3 as predictor of chronic graft-vs-host disease in hematopoietic stem cell recipients.

OBJECTIVE: In the hematopoietic stem cell transplantation setting, granulocyte colony-stimulating factor (G-CSF) administration can reduce donor cell reactivity in vitro, but the clinical significance of this phenomenon was only sparsely defined. METHODS: We performed lymphocyte transformation tests in 28 related stem cell donors pre and 5 days post G-CSF treatment, respectively, and correlated proliferative responses of donor peripheral blood mononuclear cells with clinical parameters in the corresponding recipients. RESULTS: In vitro reactions towards 4 mitogens and 12 recall antigens at day 5 post G-CSF administration were predictive for the occurrence of chronic graft-vs-host disease (cGVHD). Here, proliferative responses towards the mitogen anti-CD3 monoclonal antibody (OKT3) above median were most informative; this threshold could be determined by discrimination and receiver operating curve (ROC) analyses. In the whole cohort (18 human leukocyte antigen [HLA]-identical and 10 partially mismatched donor-recipient pairs), OKT3 responses predicted cGVHD with an odds ratio of 33.0, a sensitivity of 79%, and a specificity of 90%. A subgroup analysis of HLA-identical pairs even yielded an odds ratio of 85.0. Furthermore, bivariate analysis defined HLA compatibility and responses towards OKT3 as independent risk factors for cGVHD (p = 0.02 and p = 0.0007, respectively). CONCLUSION: The proliferative capacity of G-CSF-mobilized donor cells appears as a graft factor that determines the future incidence of cGVHD in the corresponding recipient.

Adolescent↗
PubMed2005

Reduced risk for molecular disease in patients with chronic myeloid leukemia after transplantation from a KIR-mismatched donor.

BACKGROUND: To examine how killer-cell immunoglobulin-like receptor (KIR) ligand incompatibilities effect molecular relapse (MR), we compared the occurrence of bcr-abl-positive reverse-transcriptase polymerase chain reaction (RT-PCR) results in 236 CML patients (pts) after human leukocyte antigen (HLA)-identical (n=158) (group 1), HLA class I antigen mismatched and KIR-ligand compatible (n=49) (group 2), and HLA class I antigen mismatched and KIR-ligand incompatible (n=29) (group 3) hematopoietic stem-cell transplantation. METHODS: We performed a retrospective single-center study. MR was evaluated using the real-time RT-PCR method for the detection of bcr-abl transcripts. RESULTS: In the first group, 133 of 158 (84%) pts were in the first chronic phase of CML, and the corresponding figures were 33 of 49 (67%) pts in group 2 and 19 of 29 (64%) in group 3 (P<0.05). MR occurred in 1 of 29 (3%) pts in group 3 compared with 62 of 158 (39%) pts in group 1 and in 11 of 49 (22%) pts in group 2 (P<0.001). A hematologic relapse developed in 20 of 158 (13%) pts in group 1, 2 of 49 (4%) pts in group 2, and in 0 of 29 (0%) pts in group 3 (P<0.05). Multivariate analysis confirmed that KIR mismatches are a strong independent predictor for the occurrence of MR after transplantation (P<0.02). The 5-year overall survival rate did not vary greatly between the three groups (67% in group 1, 52% in group 2, and 66% in group 3). CONCLUSIONS: These results suggest that KIR-ligand incompatibility is an important prognostic factor in the occurrence of MR after transplantation for CML.

Adolescent↗
PubMed2005

WT1 and BCR-ABL specific small interfering RNA have additive effects in the induction of apoptosis in leukemic cells.

BACKGROUND AND OBJECTIVES: The Wilms' tumor gene (WT1) is aberrantly over-expressed in leukemic cells. Therefore, we wanted to study the effect of small interfering (siRNA) targeting WT1 in leukemic cells and normal CD34-positive cells with regard to proliferation, induction of apoptosis, and cell differentiation. Furthermore, we wanted to evaluate whether the additional use of BCR-ABL siRNA could increase the anti-leukemic effects of WT1 siRNA in chronic myeloid leukemia (CML) cells. DESIGN AND METHODS: We measured WT1 expression by reverse transcription polymerase chain reaction (RT-PCR) in various cell lines and in leukemic cells from patients, then transfected the cells with WT1-specific and BCR-ABL-specific siRNA before carrying out microarray analysis. We used the tunnel assay to measure apoptotic cells. RESULTS: We observed a reduction of WT1 gene expression, measured by real-time RT-PCR, in all studied cell lines: K-562, Kasumi-1, MV 4-11 and NB-4, as well as in cells of AML and CML patients. The results also demonstrated that WT1 siRNA significantly induced apoptosis and inhibited proliferation in MV4-11 cells, NB-4 cells, Kasumi-1 cells (p<0.01) and in K-562 cells (p<0.02) versus controls. In normal CD34-positive cells, the proliferation was only slightly inhibited (by about 20%) and no induction of apoptosis was found. Combined transfection with WT1 and BCR-ABL siRNA together in K-562 cells increased the inhibition of the rate of proliferation and the rate of induced apoptosis compared to transfection with BCR-ABL siRNA or WT1 siRNA alone (p<0.01). We found that most genes involved in cell signaling and protein metabolism were regulated by the WT1 gene in K-562 cells in a microarray analysis. INTERPRETATION AND CONCLUSIONS: In conclusion, WT1 might be a suitable target for new therapeutic strategies using siRNAs in leukemic cells.

Apoptosis↗
PubMed2004

Genotypic inhibitory killer immunoglobulin-like receptor ligand incompatibility enhances the long-term antileukemic effect of unmodified allogeneic hematopoietic stem cell transplantation in patients with myeloid leukemias.

It remains controversial whether alloreactive donor-derived natural killer (NK) cells display graft-versus-leukemia reactions after unmodified allogeneic hematopoietic stem cell transplantation (HSCT). The present study evaluated the role of inhibitory killer immunoglobulin-like receptor (KIR) ligand incompatibility using a well-defined and uniform setting of unmodified allogeneic HSCT in 374 patients with myeloid leukemias. The most striking finding was a significant heterogeneity in the 5-year estimates of hematologic leukemic relapse after human leukocyte antigen (HLA)-identical (n = 237; 22%), HLA class I-disparate (n = 89; 18%), and KIR ligand-incompatible transplantations (n = 48; 5%) (P < .04). Multivariate analysis confirmed that the relative relapse risk (RR) was influenced by HLA class I disparity alone (RR 0.49), but was lowest after HLA class I-disparate, KIR ligand-incompatible transplantations (RR 0.24) (P < .008). The primary graft failure rates, however, increased from 0.4% after HLA class I-identical to 2.3% after HLA class I-disparate, and to 6.3% after KIR ligand-incompatible transplantations, respectively (P < .02). Unlike some other reports, no beneficial effect of KIR ligand incompatibility on other major endpoints of allogeneic HSCT (transplantation-related mortality, and overall and event-free survival) was detectable in the present study. In conclusion, unmodified allogeneic HSCT from KIR ligand-incompatible donors provides a superior long-term antileukemic efficacy in patients with myeloid malignancies.

Adolescent↗
PubMed2004

Quantitative TP73 transcript analysis in hepatocellular carcinomas.

PURPOSE: The p53 family member p73 displays significant homology to p53, but data from primary tumors demonstrating increased expression levels of p73 in the absence of any gene mutations argue against a classical tumor suppressor function. A detailed analysis of the p73 protein in tumor tissues has revealed expression of two classes of p73 isoforms. Whereas the proapoptotic, full-length, transactivation-competent p73 protein (TA-p73) has a putative tumor suppressor activity similar to p53, the antiapoptotic, NH(2)-terminally truncated, transactivation-deficient p73 protein (DeltaTA-p73) has been shown to possess oncogenic activity. The oncogenic proteins can be generated by the following two different mechanisms: (a) aberrant splicing (p73Deltaex2, p73Deltaex2/3, DeltaN'-p73) and (b) alternative promoter usage of a second intronic promoter (DeltaN-p73). The purpose of our study was to elucidate the origin of DeltaTA-p73 isoforms in hepatocellular carcinomas. EXPERIMENTAL DESIGN: We analyzed the underlying mechanisms of p73 overexpression in cancer cells by quantification of p73 transcripts from 10 hepatocellular carcinoma patients using isoform-specific real-time reverse transcription-PCR. RESULTS: Our data demonstrate that only aberrantly spliced DeltaTA-p73 transcripts from the TA promoter show significantly increased expression levels in the tumor whereas the DeltaN-p73 transcript generated from the second promoter is not significantly up-regulated. CONCLUSIONS: Although we only analyzed 10 patient samples the results strongly suggest that the elevated activity of the first promoter (TA promoter) accounts for high-level expression of both full-length TA-p73 and aberrantly spliced DeltaTA-p73 isoforms in hepatocellular carcinoma tissues.

Aged↗
PubMed2003

Improvement of inflammatory bowel disease after allogeneic stem-cell transplantation.

Because causes of inflammatory bowel disease (IBD) remain obscure and a curative therapy is still lacking, the influence of stem-cell transplantation (SCT) on IBD is of major interest. We retrospectively analyzed the course of seven patients with Crohn's disease and four patients with idiopathic ulcerative colitis who underwent allogeneic SCT between July 1994 and August 2002 for acute and chronic myeloid leukemia and myelodysplastic syndrome. After a median follow-up of 34 months posttransplantation, 10 patients are alive. None of the patients showed IBD activity after SCT, except one patient with mild persistent symptoms of Crohn's disease early after transplant. Colonoscopy after complete discontinuation of prophylactic posttransplant immunosuppression revealed no pathologic findings. These observations imply that host immune dysregulation plays a central role in the perpetuation of IBD. It may be influenced by the implementation of a new allogeneic immune system resulting from the transplantation of hematopoietic stem cells.

Acute Disease↗
PubMed2002

Outcome of transplantation of highly purified peripheral blood CD34+ cells with T-cell add-back compared with unmanipulated bone marrow or peripheral blood stem cells from HLA-identical sibling donors in patients with first chronic phase chronic myeloid leukemia.

Outcomes of highly purified CD34(+) peripheral blood stem cell transplantation (PBSCT) for chronic phase chronic myeloid leukemia (CML) (n = 32) were compared with those of PBSCT (n = 19) and of bone marrow transplantation (BMT) (n = 22) in the HLA-compatible sibling donor setting. Median follow-up was 18 months after CD34(+)-PBSCT and unmanipulated PBSCT and 20 months after BMT. CD34(+)-PBSCT was associated with delayed T-cell immune reconstitution at 3 months and 12 months after transplantation compared with PBSCT (P <.001) or BMT (not significant [NS]). The estimated probability of grades II to IV acute graft-versus-host disease (GVHD) was 60% +/- 13% for the PBSCT group, 37% +/- 13% for the BMT group, and only 14% +/- 8% for the CD34(+)-PBSCT group (CD34-PBSCT versus BMT, P <.01; and CD34-PBSCT versus PBSCT, P <.001). The probabilities for molecular relapse were 88% for CD34(+)-PBSCT, 55% after BMT, and 37% after PBSCT (CD34(+)-PBSCT versus PBSCT, P <.03). Cytogenetic relapse probability was 58% after CD34(+)-PBSCT, 42% after BMT, and 28% after PBSCT (NS). After CD34(+)-PBSCT, 26 of 32 patients received a T-cell add-back. Hematologic relapse occurred in 4 of 22 patients after BMT, in 3 of 19 patients after PBSCT, and in only 1 of 32 patients after CD34(+)-PBSCT. The occurrence of a hematologic relapse in patients receiving CD34(+)-PBSC transplants was prevented by donor leukocyte infusions, which were applied at a median of 4 times (range, 1-7 times) with a median T-cell dose of 3.3 x 10(6) x kg/body weight [at a median] beginning at day 120 (range, 60-690 days). The estimated probability of 3-year survival after transplantation was 90% in the CD34(+)-PBSCT group, 68% in the PBSCT group, and 63% in the BMT group (CD34-PBSCT versus BMT, P <.01; and CD34-PBSCT versus PBSCT, P <.03). Transplantation of CD34(+)-PBSCs with T-cell add-back for patients with CML in first chronic phase seems to be safe and is an encouraging alternative transplant procedure to BMT or PBSCT.

Adolescent↗
PubMed2002

Improved disease-free-survival after transplantation of peripheral blood stem cells as compared with bone marrow from HLA-identical unrelated donors in patients with first chronic phase chronic myeloid leukemia.

Outcomes after peripheral blood stem cell transplantation (PBSCT) for chronic phase chronic myeloid leukemia (n = 37) were compared with outcomes after bone marrow transplantation (BMT) (n = 54) in the HLA-compatible unrelated donor setting. Median follow-up was 17 months after PBSCT and 29 months after BMT. Both neutrophil and platelet recovery were faster after PBSCT (P <.05). PBSCT was associated with improved immune reconstitution, with higher peripheral blood naive (CD4(+)CD45RA(+)) and memory (CD4(+) CD45RO(+)) helper T cells at 3 months and 12 months after transplantation (P <.03). The cumulative incidence of acute (grades II-IV) and chronic graft-versus-host disease (GVHD) were similar, but BMT was associated with a higher cumulative incidence of severe, acute (grade III-IV) GVHD at 24% as compared with 8% with PBSCT (P <.05). Molecular relapse, defined by 2 consecutive positive polymerase chain reaction assays for bcr-abl within a 4-week interval, occurred in 12 of 45 evaluable patients (27%) after BMT and in 4 of 37 (11%) after PBSCT (not significant). Cytogenetic relapse occurred in 5 of 54 patients after BMT (9%) and in 1 of the 37 (3%) patients after PBSCT (not significant). Seventeen of the 54 patients died after BMT (31%), as compared with 2 of 37 patients after PBSCT (5%). Deaths in the BMT group were associated mainly with infections and severe, acute GVHD. The estimated probability of transplant-related mortality (TRM) and disease-free survival at 1000 days after receiving the transplant were 30% and 64% in the BMT group and 5% and 91% in the PBSCT group (P <.03). Overall survival 1000 days after receiving the transplant was 66% after BMT and 94% after PBSCT (P <.02). In the multivariate analysis, only acute GVHD significantly influenced TRM (P <.01).

Adolescent↗
PubMed2002

Real-time PCR for monitoring minimal residual disease and chimerism in patients after allogeneic transplantation.

Real-time PCR is a new fluorometric method for cycle-to-cycle quantification of PCR product growth rates. The real-time PCR method is fast and associated with a high reproducibility rate. It is used more often for monitoring MRD and chimerism in patients after allogeneic stem cell transplantation (SCT). There are real-time PCR methods for patients with CML, AML and ALL patients with inv(16), t(8;21), t(15;17); t(1;19) and other chromosomal aberrations. For patients with AML monitoring MRD is useful to identify patients who were at high risk for relapse after receiving chemotherapy. In patients with CML monitoring MRD might be helpful to assess success of after allogeneic SCT, or response to therapies with interferon alfa or STI 571. We found, that it is possible to estimate the relapse stage in CML after SCT by the amount of bcr-abl fusion transcript detected using a real-time PCR method. The median measured bcr-abl amount differ significantly (P<0.001) between the various stages, which has relevant clinical implications because it enables early therapeutic decisions in relapsing patients after transplant as e.g. the application of DLI to induce graft-versus-leukemia effects. Using real-time PCR it is possible to detect differences at alleles between recipient and donor at a single nucleotide basis (SNP) for chimerism analysis. The real-time PCR method enables to achieve a high a sensitivity of up to 1x10(-4), which is much more sensitive than all other chimerism methods including VNTR-PCR, STR-PCR. Furthermore, chimerism in male recipients with a female donor can be monitored also by detecting y-chromosome specific sequences by real-time PCR after transplant, which might be the most sensitive method to detect host type gene sequences. All in all, new real-time PCR methods offer a fast, reliable and very sensitive method to evaluate MRD and chimerism in patients after allogeneic SCT and therefore, to help to identify patients who are at high risk for leukemic relapse.

Hematopoietic Stem Cell Transplantation↗