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The existence of adult haemangioblasts with dual haematopoietic and endothelial developmental potential was confirmed after detection of Ph(+) vascular endothelial cells in chronic myeloid leukaemia (CML) patients. Blood outgrowth endothelial cells (OECs) from CML patients were found not to harbour the Philadelphia translocation and were thus not clonally related to BRC/ABL1(+) hematopoietic progenitors, but comprised a distinct subfraction of endothelial cells. Remarkably, the frequency of CML-derived OECs was 9-fold higher as compared to healthy donors (n = 19 and n = 300, respectively; P < 0.0001) and these cells showed increased proliferative potential, possibly reflecting the mobilisation of OEC progenitors by pro-angiogenic cytokines.

We analyzed the prognostic impact of the most frequent genetic abnormalities detected by fluorescence-in situ-hybridization combined with immunofluorescent cytoplasm immunoglobulin staining (cIg-FISH) in 101 patients with multiple myeloma, who underwent allogeneic stem cell transplantation after reduced melphalan/fludarabine-based conditioning from related (n=34) and unrelated (n=67) donors. The abnormalities were del(13q14) [62%], t(11;14)(q13;q32) [11%], t(4;14)(p16.3;q32) [16%], CMYC-gains (8q24) [17%], del(17p13.1) [16%], t(14;16)(q32;q23) [4%], whereas none of the patients had t(6;14)(p25;q32). Translocation t(4;14), CMYC-gains and del 17p were frequently associated with del(13q14): 64%, 80% and 92%, respectively. The complete remission (CR) rate was 45% for all patients. Patients with del(17p13) achieved fewer complete remission than others (7% vs. 56%; p=0.001), while no difference was seen for t(4;14) and other abnormalities. Univariate analysis revealed higher relapse rates for age > 50 years (p=0.002), del(13q14) (p=0.006) and del(17p13) (p=0.003). Patients with translocation t (4;14) had a similar four year event-free survival than others (50 vs 45%). In a multivariate analysis, only del(13q14) [HR: 2.34, p=0.03] and del(17p13) [HR: 2.24; p=0.04] influenced the risk of relapse, while for event-free survival, only age [HR 2.8; p=0.01] and del(17p13) [HR: 2.05; p=0.03] retained the prognostic value. These data seem to indicate that some adverse cytogenetic risk factors such as t(4;14) can be overcome by allogeneic stem cell transplantation, probably due to the graft versus myeloma effect. Del(17p13.1) is a significant factor for a lower chance of complete remissions and shorter event free survival following allogeneic stem cell transplantation. The presented data will have implications for risk-adapted strategies in the future.

Deletions of chromosome bands 13q14 and 17p13 (P53) as well as t(4;14)(p16;q32) or overrepresentation of CMYC are known to be adverse prognostic factors for time to progression (TTP) and overall survival (OS) in myeloma patients receiving conventional or high-dose chemotherapy followed by autologous stem cell transplantation. We investigated the impact of these chromosomal abnormalities as detected by fluorescence in situ hybridization combined with immunofluorescent cytoplasm immunoglobulin staining (cIg-FISH) on outcome after dose-reduced melphalan/fludarabin based allogeneic stem cell transplantation (SCT) in 64 patients (pts) with multiple myeloma (MM). Median age was 52 years (34 – 67 ys.), 38 patients were male, 26 female. 45 pts received stem cell graft from an unrelated donor and 19 pts from HLA-identical sibling. Deletion of 13q14 was found in 35 out of 64 pts (55%), P53 deletion in 7 out of 64 pts (11%), t(4;14)(p16;q32) in 11 out of 56 pts (20%) and trisomy of CMYC in 12 out of 55 pts (22%). The following strong correlations among the genetic changes have been seen: six out of seven pts with P53 deletion also showed deletion in chromosome band 13q14 (86%), which was also found in nine out of eleven pts with t(4;14) (82% del 13) and nine out of twelve pts with CMYC trisomy (75% del 13). The estimated event-free (EFS) and overall survival (OS) at four years for the entire study population was 48% and 57%, respectively. No significant difference of the estimated event-free survival at 3 years was seen for pts with del 13 (42% vs 54%, p=0,4), with P53 deletion (43% vs 49%, p=0,27) and for pts with t(4;14) (46% vs 62%, p=0,69) or CMYC overrepresentation (37% vs 50%, p=0,35). Comparison of pts showing both del 13 and P53 deletion, del 13 and t(4;14), del 13 and trisomy of CMYC or t(4;14) and CMYC trisomy with the rest of the study population did not show a significantly reduced EFS either. Even the comparison of pts with any chromosomal abnormalities and pts without any genetic changes detected by FISH did not show a significant difference in EFS (48% vs 50%, p=0,8). These preliminary data suggest that the negative prognostic impact of chromosomal abnormalities such as deletion of 13q14, P53 deletion, t(4;14) and overrepresentation of CMYC may be overcome by allogeneic SCT probably due to the graft versus myeloma effect.

Deletion of chromosome band 17p13 (P53) is known to be an adverse prognostic factor for time to progression (TTP) and overall survival (OS) in myeloma patients receiving conventional or high-dose chemotherapy. In this retrospective multicenter study, we investigated the impact of P53 deletion as detected by fluorescence in situ hybridization combined with immunofluorescent cytoplasm immunoglobulin staining (cIg-FISH) on outcome after allogeneic blood stem cell transplantation (SCT) in 50 patients (pts) with advanced or relapsed multiple myeloma (MM). Median age was 51 years (34 – 67 ys.), 32 patients were male, 18 female. Thirty pts received a stem cell graft from an unrelated donor, and 20 pts from a HLA-identical sibling. P53 gene deletion was found in 5 out of 49 pts (10,2 %). Deletion 13 detected by cIg-FISH was found in 20 out of 47 pts (42%). There was a strong correlation between P53 deletion and deletion 13: four out of the five patients with P53 deletion also showed deletion in chromosome band 13q14. The estimated event-free (EFS) and overall survival (OS) at three years for the entire study population was 43% and 65%, respectively. For patients with del 13 only a trend for a worse 3 year EFS was seen (38% vs 42%, p=0.2), while pts with P53 deletion had a significant reduced EFS (0% vs 46%, p=0.0001). Three out of five pts with P53 deletion relapsed very early after allogeneic SCT (day 81, 108 and 287 respectively). These data suggest that P53 is a risk factor for patients with MM treated with allogeneic SCT which can not be overcome by this treatment strategy.