Prognosis of acute myeloid leukemia patients up to 60 years of age exhibiting trisomy 8 within a non-complex karyotype: individual patient data-based meta-analysis of the German Acute Myeloid Leukemia Intergroup

BACKGROUND AND OBJECTIVES

Trisomy 8 (+8) is among the commonest genetic aberrations seen in acute myeloid leukemia (AML). However, the prognostic significance of this aberration and the best consolidation strategy for patients with it are still not resolved. Additional prognostic indicators are needed to further classify these patients and determine their appropriate management.

DESIGN AND METHODS

Individual patient data-based meta-analysis was performed on 131 patients (median age 50 (18-60) years) with +8 as a sole aberration or +8 with one additional aberration treated between 1993 and 2002 in eight prospective German AML treatment trials. All patients received state-of-the-art treatment including high-dose cytarabine with the option for autologous or allogeneic hematopoietic stem cell transplantation (HSCT).

RESULTS

In total, the 131 patients had a 3-year overall survival (OS) of 29% and a 3-year relapse-free survival (RFS) of 32%. Independent prognostic factors contributing to shorter OS were age > or = 45 years, extramedullary disease, and a percentage of +8 positive metaphases >/=80%. Combining these three prognostic variables established a hierarchical model for OS. The 3-year OS was 13% for the high-risk group, 36% for the intermediate-risk group, and 55% for the low-risk group (p<0.0001). Age <45 years and allogeneic HSCT (as treated) were independent prognostic factors for longer RFS. Additional cytogenetic aberrations other than t(8;21), inv(16), t(16;16), t(15;17) or 11q23 had no influence on treatment outcome.

INTERPRETATION AND CONCLUSIONS

We provide a new prognostic model for risk stratification of AML patients with +8. The data indicate that allogeneic HSCT may prolong RFS compared to that achieved with other strategies of post-remission therapy.

Tyrosine kinase mutations of JAK2 are rare events in AML but influence prognosis of patients with CBF-leukemias

We investigated a large number of acute myeloid leukemia (AML) samples (n=959) for the presence of the JAK2 V617F mutation. We found a low incidence of the mutation in these AML samples (1%). JAK2 V617F mutations clustered in AML samples with an aberrant karyotype (p<0.05). The incidence of JAK2 V617F in patients with a core binding factor (CBF) leukemia was 3.6% (p<0.01). Moreover, JAK2 V617F mutations in CBF leukemias were associated with an aggressive clinical course with 80% of the patients relapsing.

Reduced intensity conditioning allows for up-front allogeneic hematopoietic stem cell transplantation after cytoreductive induction therapy in newly-diagnosed high-risk acute myeloid leukemia

There is substantial need to improve the outcome of patients with high-risk acute myeloid leukemia (AML). The clinical trial reported here investigated a new approach of up-front allogeneic hematopoietic stem cell transplantation (HSCT), provided a median of 40 days (range 22-74) after diagnosis, in twenty-six consecutive patients with newly-diagnosed high-risk AML characterized by poor-risk cytogenetics (n = 19) or inadequate blast clearance by induction chemotherapy (IC, n = 7). The median age was 49 years (range 17-68). During IC-induced aplasia after the 1st (n = 11) or 2nd (n = 15) cycle, patients received allogeneic peripheral blood stem cells (PBSC) from related (n = 11) or unrelated (n = 15) donors following a fludarabine-based reduced-intensity regimen. Seventeen patients were not in remission before HSCT with a median marrow blast count of 34% (range 6-70). All patients achieved rapid engraftment and went into remission with complete myeloid and lymphatic chimerism. Grades II to IV acute GvHD occurred in 14 (56%) and extensive chronic GvHD was documented in 8 (35%) patients. The probability of disease-free survival was 61% with only three patients relapsing 5, 6 and 7 months after transplantation, respectively. Up-front allogeneic HSCT as part of primary induction therapy seems to be an effective strategy in high-risk AML patients and warrants further investigation.

Efficacy of single-dose pegfilgrastim after chemotherapy for the mobilization of autologous peripheral blood stem cells in patients with malignant lymphoma or multiple myeloma

BACKGROUND

A single injection of pegfilgrastim has been shown to be equivalent to daily filgrastim in enhancing neutrophil recovery after chemotherapy, whereas the experiences with pegfilgrastim in mobilization of peripheral blood progenitor cells (PBPCs) are limited.

STUDY DESIGN AND METHODS

Forty unselected patients with lymphoma or multiple myeloma were treated with different chemotherapy regimens followed by 6 mg of pegfilgrastim for mobilization of autologous PBPCs. Patients with an inadequate mobilization (blood CD34+ cells <or= 10/microL after nadir) were given additional daily doses of 10 microg per kg unconjugated filgrastim.

RESULTS

A median blood CD34+ peak concentration of 81 per microL (range, 10-565/microL) was found in 30 patients, who had only received pegfilgrastim, compared to 13 per microL (median, range 4-71/microL; p < 0.001) in 10 poor mobilizing patients with additional filgrastim. The median yield of CD34+ cells was 9.8 x 10(6) per kg (range, 1.5-88.1) after pegfilgrastim only versus 2.5 x 10(6) (range, 1.7-7.0) in poor mobilizers. Patients who needed additional cytokine administration were those with a more extensive previous antineoplastic treatment and mobilizing regimens containing PBPC toxic agents.

CONCLUSION

The results confirm the efficacy and feasibility of PBPC mobilization with chemotherapy and single-dose pegfilgrastim in patients with lymphoproliferative malignacies. In less heavily pretreated patients, 6 mg of pegfilgrastim after chemotherapy induced an adequate mobilization, whereas dose and schedule in patients after numerous cytotoxic regimens need further investigation.

Prevalence and prognostic impact of NPM1 mutations in 1485 adult patients with acute myeloid leukemia (AML)

Mutations of the nucleophosmin (NPM1) gene have recently been described in patients with acute myeloid leukemia (AML). To clarify the prevalence as well as the clinical impact of this mutation, we investigated 1485 patients with AML for NPM1 exon 12 mutations using fragment analysis. A 4 bp insert was detected in 408 of 1485 patients (27.5%). Sequence analysis revealed known mutations (type A, B, and D) as well as 13 novel alterations in 229 analyzed cases. NPM1 mutations were most prevalent in patients with normal karyotype (NK) (324 of 709; 45.7%) compared with 58 of 686 with karyotype abnormalities (8.5%; P < .001) and were significantly associated with several clinical parameters (high bone marrow [BM] blasts, high white blood cell [WBC] and platelet counts, female sex). NPM1 alterations were associated with FLT3-ITD mutations, even if restricted to patients with NK (NPM1-mut/FLT3-ITD: 43.8%; versus NPM1-wt/FLT3-ITD: 19.9%; P < .001). The analysis of the clinical impact in 4 groups (NPM1 and FLT3-ITD single mutants, double mutants, and wild-type [wt] for both) revealed that patients having only an NPM1 mutation had a significantly better overall and disease-free survival and a lower cumulative incidence of relapse. In conclusion, NPM1 mutations represent a common genetic abnormality in adult AML. If not associated with FLT3-ITD mutations, mutant NPM1 appears to identify patients with improved response toward treatment.

Fast appearance of donor dendritic cells in human skin: dynamics of skin and blood dendritic cells after allogeneic hematopoietic cell transplantation

BACKGROUND

Both number and origin (donor vs. host) of dendritic cells (DC) are associated with acute graft-versus-host disease (aGvHD), relapse and graft failure after human allogeneic hematopoietic cell transplantation (aHCT).

METHODS

We prospectively and simultaneously investigated skin and blood DC subtypes, their donor/recipient origin, and the correlation of DC reconstitution kinetics with treatment, clinical outcome, and incidence of aGvHD in patients undergoing aHCT.

RESULTS

A significant reduction of skin and a marked decrease of blood DC were observed in patients compared to healthy volunteers. A dominant donor chimerism of migratory Langerhans cells (LC) and dermal-dendritic-cells (DDC) was detected even early after transplantation, and developed independently from chemotherapy regimen, graft manipulation or time point after transplantation. Before start of the therapy patients showed significantly decreased numbers of peripheral blood CD123+ preDC2, whereas CD11c+ preDC1 numbers appeared to be diminished, but were statistically indistinguishable from controls. Host derived pB preDC were virtually absent following aHCT. After a further reduction in cell number around day 56 both preDC subtypes reconstituted and stabilized to pretransplant numbers by day 112. Occurrence of aGvHD and its treatment diminished numbers of both preDC subtypes. Furthermore conditioning therapy with Alemtuzumab apparently affected reconstitution of both preDC subsets negatively.

CONCLUSION

Given that induction of GvHD in humans is as host DC dependent as in mouse models, investigation of DC chimerism and number at different sites and especially in GvHD target organs might provide important insights into the pathogenesis of the main obstacle of aHCT.

Graft clonogenicity and intensity of pre-treatment: factors affecting outcome of autologous peripheral hematopoietic cell transplantation in patients with acute myeloid leukemia in first remission

A total of 22 patients with acute myeloid leukemia (AML) in first complete remission receiving autologous blood stem cell transplantation (ABSCT) were investigated in order to determine factors affecting outcome. All but two patients had a normal karyotype and received the same high-dose chemotherapy followed by G-CSF-mobilized peripheral blood stem cells after the second (n=5) or third (n=17) course of induction and post-remission chemotherapy, respectively. With a median follow-up of 30 months, the median disease-free survival is 24.1 months. Univariate analysis showed that three chemotherapy cycles before ABSCT were associated with a significant better disease-free survival (P=0.0018) and overall survival (P=0.0033), whereas the presence of an FLT3-mutation (n=6) showed no impact. The number of megakaryocytic progenitors (CFU-MK) infused tended to correlate with primary platelet engraftment (P=0.07) and were predictive for neutrophil (P=0.011) and platelet counts (P=0.009) 180 days after transplantation. Patients receiving a higher amount of CFU-MK had a better event-free survival (P=0.02). Our data suggest that the content of CFU-MK within the graft predicts the quality of hematological recovery and long-term disease control. Additionally, a minimum of three chemotherapy cycles before ABSCT seems to be associated with an improved outcome.

Activation of the RAS pathway is predictive for a chemosensitive phenotype of acute myelogenous leukemia blasts

PURPOSE

Activation of the RAS pathway plays a major role in cancer cells. In acute myeloid leukemia (AML), mutations of the RAS genes cause an intrinsic activation of this pathway. Until now, clinical studies could not find clear association of RAS mutations with the clinical outcome after AML therapy. This could be due to alternative initiating events for activation of the RAS pathway like constitutive tyrosine kinase activation or mutations in Ras-regulating genes.

EXPERIMENTAL DESIGN

In total, 191 AML patients (126 as training population and 65 as test population) were studied for Ras activity with a glutathione S-transferase pull-down assay using Raf binding of activated Ras.

RESULTS

AML samples showed a wide range of Ras activity values, which was in contrast to normal bone marrow donors who showed no or very limited Ras activity. Using a Ras binding score based on semiquantitative Western blotting, we defined patients with strong Ras activity and compared Ras activity with RAS mutation. Surprisingly, only a minority of RAS mutated AML samples (22.2%) showed strong Ras activity, whereas 25 patients presented strong Ras activity in the absence of RAS mutations. Clinical outcome did not show differences according to RAS mutations. In contrast, Ras activity predicted for a high response rate (P <0.05) and proved to be an independent factor for overall survival rate (P <0.05) in younger AML patients receiving high-dose 1-beta-D-arabinofuranosylcytosine as induction therapy.

CONCLUSION

The data highlight the role for alternative pathways of Ras activation without RAS mutations. Intrinsically activated Ras seems to increase sensitivity of the AML blast to high-dose 1-beta-D-arabinofuranosylcytosine therapy.

Telomere length and hTERT expression in patients with acute myeloid leukemia correlates with chromosomal abnormalities

BACKGROUND AND OBJECTIVES

Acute myeloid leukemia (AML) is a malignant, genetically heterogenous disorder characterized by uncontrolled growth of immature myeloid cells. The aim of this study was to analyze whether telomere length and/or hTERT expression are correlated with clonal chromosomal aberrations in AML.

DESIGN AND METHODS

Telomere length in mononuclear cells derived from 137 previously untreated patients with >or= 80% blasts was analyzed by flow fluorescent in situ hybridization. Results were expressed in telomere fluorescence Units (1 TFU=1 kb). The expression of hTERT, including its different splice variants was studied by reverse transcription-polymerase chain reaction.

RESULTS

Age-adjusted telomere length in AML patients was significantly reduced as compared to in matched controls, consisting of peripheral blood granulocytes from healthy individuals (0-90 years) (median: -2.5 TFU; p<0.001). Patients with an aberrant karyotype had significantly shorter telomeres than patients with a normal karyotype (median -3.0 vs. -2.3 TFU; p=0.03). The shortest telomeres were found in patients with multiple aberrations (median -3.7 TFU; p=0.03). hTERT expression was found to be correlated with chromosomal abnormalities as well as with the detection of functional hTERT splicing variants.

INTERPRETATION AND CONCLUSIONS

These findings suggest an important role of intense telomere loss in the development of genetic instability during the pathogenesis of AML. It is assumed that critical telomere shortening in AML blasts could lead to telomerase activation and therefore prevent blasts from replicative senescence, one possible mechanism for clonal selection and disease progression. Therefore, telomere length might serve as a prognostic marker for AML patients. These findings would have to be confirmed in large, prospective studies.

MDR1 and MRP1 gene expression are independent predictors for treatment outcome in adult acute myeloid leukaemia

Multi drug resistance (MDR) is a major obstacle for cancer therapy. The three major candidates accounting for the development of MDR in acute myeloid leukaemia (AML) are multi drug resistance gene (MDR1), multi drug resistance-related protein gene (MRP1) and lung resistance protein gene (LRP). So far, the differential impact of resistance gene expression on treatment outcome in AML is not clear. Therefore, we examined MDR1, MRP1 and LRP gene expression at diagnosis in 331 adult AML patients in the context of other known prognostic factors, such as age, disease status, cytogenetics and FMS-like tyrosine kinase 3 (FLT3)-internal tandem duplication mutational status. Median observation time was longer than 5 years [64.1 months (40.0-87.6)]. MDR1 expression proved to be an independent prognostic factor for outcome of induction therapy (P <0.001) and overall survival (P=0.02), whereas MRP1 expression was an independent predictor for disease-free survival (P=0.01) in the multivariate analysis. This prognostic impact of both resistance genes was also found in patients with intermediate risk cytogenetics. LRP expression, however, had no impact on treatment outcome in AML. Our study shows that resistance gene expression should be considered together with age, cytogenetics and FLT3 mutational status for risk-adapted treatment strategies in AML in the future.

Prognostic significance of N-RAS and K-RAS mutations in 232 patients with acute myeloid leukemia

Reports on the prognostic impact of mutations in the RAS proto-oncogenes in patients with acute myeloid leukemia (AML) are conflicting. A peptide nucleic acid (PNA)-based technique was used on 232 AML samples to detect point mutations of the hotspots in N-RAS and K-RAS. No significant correlations between RAS mutations and clinical features, karyotype or FLT3 were found.

Individual Patient Data–Based Meta-Analysis of Patients Aged 16 to 60 Years With Core Binding Factor Acute Myeloid Leukemia: A Survey of the German Acute Myeloid Leukemia Intergroup

Purpose

To evaluate prognostic factors for relapse-free survival (RFS) and overall survival (OS) and to assess the impact of different postremission therapies in adult patients with core binding factor (CBF) acute myeloid leukemias (AML).

Patients and Methods

Individual patient data–based meta-analysis was performed on 392 adults (median age, 42 years; range, 16 to 60 years) with CBF AML (t(8;21), n = 191; inv(16), n = 201) treated between 1993 and 2002 in prospective German AML treatment trials.

Results

RFS was 60% and 58% and OS was 65% and 74% in the t(8;21) and inv(16) groups after 3 years, respectively. For postremission therapy, intention-to-treat analysis revealed no difference between intensive chemotherapy and autologous transplantation in the t(8;21) group and between chemotherapy, autologous, and allogeneic transplantation in the inv(16) group. In the t(8;21) group, significant prognostic variables for longer RFS and OS were lower WBC and higher platelet counts; loss of the Y chromosome in male patients was prognostic for shorter OS. In the inv(16) group, trisomy 22 was a significant prognostic variable for longer RFS. For patients who experienced relapse, second complete remission rate was significantly lower in patients with t(8;21), resulting in a significantly inferior survival duration after relapse compared with patients with inv(16).

Conclusion

We provide novel prognostic factors for CBF AML and show that patients with t(8;21) who experience relapse have an inferior survival duration.

A sensitive model for prediction of relapse in adult acute myeloid leukaemia with t(8;21) using white blood cell count, CD56 and MDR1 gene expression at diagnosis

Acute myeloid leukaemia (AML) carrying t(8;21) has an overall favourable prognosis. However, relapse occurs and the impact of multidrug resistance gene (MDR1) expression on recurring disease in this group of patients is not known. We determined quantifiable MDR1 expression in the bone marrow of 28 AML patients with t(8;21) by a validated real-time polymerase chain reaction assay. Using MDR1 expression, white blood cell count and CD56 expression at diagnosis we observed complete concordance of predicted and observed relapses. A calculated logit out of these three variables was a strong independent prognostic factor for overall (P = 0.007) and disease-free survival (P = 0.002).

P-glycoprotein-mediated drug efflux is a resistance mechanism of chronic myelogenous leukemia cells to treatment with imatinib mesylate

Imatinib (Glivec), STI571) is an intracellular acting drug that demonstrates high activity against BCR-ABL-positive chronic myelogenous leukemia (CML) or acute lymphoblastic leukemia (ALL). However, many patients, especially with advanced disease, develop drug resistance. Here, we show by a novel high-performance liquid chromatography-based method that intracellular levels of imatinib decrease in P-glycoprotein (Pgp)-positive leukemic cells. In a model of K562 cells with gradually increasing Pgp expression, a Pgp-dependent decline of intracellular imatinib levels was observed. Decreased imatinib levels were associated with a retained phosphorylation pattern of the Bcr-Abl target Crkl and loss of effect of imatinib on cellular proliferation and apoptosis. The modulation of Pgp by cyclosporin A (CSA) readily restored imatinib cytotoxicity in these cells. Finally, we provide first data showing a biological effect of Pgp modulation in the imatinib treatment of a patient with BCR-ABL-positive ALL. MDR1 overexpression must therefore be considered as an important clinical mechanism in the diversity of resistance development to imatinib treatment.

Increased myelotoxicity of idarubicin: is there a pharmacological basis? Results of a pharmacokinetic and an in vitro cytotoxicity study

BACKGROUND

Clinical trials evaluating idarubicin (IDA) in acute myeloid leukemia, multiple myeloma and non-Hodgkin's lymphoma (NHL) have provided some evidence for an increased myelotoxicity of IDA compared to other anthracyclines. IDA is known to be less sensitive towards multidrug resistance mediated by P-glycoprotein (P-gp). This phenotype is a major impediment to successful antineoplastic treatment, but P-gp is also expressed on hematopoietic stem cells (HSC).

METHODS

We investigated the pharmacokinetics of IDA and etoposide (ETO) in seven previously untreated patients with aggressive NHL. The patients received a CHOP-derived protocol (CIVEP) in which doxorubicin (DOX) was substituted by IDA 11-16 mg/m(2) and ETO 3 x 100 mg/m(2) was added. Furthermore, we evaluated in vitro the impact of P-gp expression on the cytotoxicity of DOX and IDA in cells from three parental chemosensitive leukemia and lymphoma cell lines (HL60, U937, CCRF) and their resistant sublines, as well as in CD34-positive HSC.

RESULTS

The peak plasma levels (C(max)), terminal elimination half-life (t(1/2)) and area under the concentration curve (AUC) both for IDA and for ETO did not differ from published data. In cell line models the numbers of viable cells in a P-gp-expressing resistant CCRF-VCR100 subline were significantly more reduced by IDA ( P<0.001), but there was no difference in the cytotoxicities of IDA and DOX in chemosensitive CCRF cells and in the (non-P-gp-expressing) resistant U937 and HL60 sublines. Cytotoxicity against HSC was more pronounced after incubation with IDA than after treatment with DOX ( P=0.014), even when a tenfold higher concentration of DOX than of IDA was used. The addition of cyclosporin A increased the cytotoxic effect of DOX but not that of IDA in HSC.

CONCLUSIONS

The pharmacokinetics of IDA and its main metabolite idarubicinol in CHOP-derived protocols were not different from data obtained with other combinations or monotherapy. The increased myelotoxicity of IDA may be a consequence of P-gp expression in CD34-positive HSC.

Comparative analysis of MLL partial tandem duplication and FLT3 internal tandem duplication mutations in 956 adult patients with acute myeloid leukemia

Partial tandem duplication (PTD) of the MLL gene and internal tandem duplication (ITD) of the juxtamembrane region of the FLT3 receptor tyrosine kinase gene have been described in acute myeloid leukemia (AML) patients, preferentially in those with normal cytogenetics. These alterations have been associated with a poor prognosis. In our study, we analyzed the prevalence and the potential prognostic impact of these aberrations in a large unselected and well-defined cohort of 956 patients with AML. Results were correlated with cytogenetic data and clinical outcome. MLL PTD was detected by RT-PCR, subsequent nucleotide sequencing, and Southern blotting. The overall incidence was found to be 5.0% (48/956), whereas FLT3 ITD was detected in 19.2% (184/956). Sixteen cases were positive for both alterations. The rate of MLL PTD in FLT3 ITD positive patients was significantly higher than that in FLT3 ITD negative patients [16/184 (8.7%); 32/772 (4.1%); P = 0.025]. However, both aberrations were highly increased in patients with normal karyotype (MLL PTD 35/431, P = 0.004; FLT3 ITD 132/334, P < 0.001). When restricted to this subgroup, the rate of MLL PTD in patients with FLT3 mutations was not significantly increased. No statistically significant differences were detected between patients positive for MLL PTD and patients negative for MLL PTD in the rate of complete remissions or the overall survival, although we did see a significantly shorter disease-free survival in patients age 60 or younger. In conclusion, although there is an overlap in the mutational spectrum in AML with FLT3 ITD and MLL PTD mutations, our data do not support a common mechanistic basis. Although associated with inferior disease-free survival, the results of this study do not unequivocally support the notion that MLL PTD mutations represent an independent prognostic factor.

Severe epidermal necrolysis after treatment with imatinib and consecutive allogeneic hematopoietic stem cell transplantation

Imatinib is a new promising therapeutic option for chronic myeloid leukemia (CML) with efficacy even in the blast phase of the disease. However, most patients treated with imatinib in the blast phase develop progressive disease rapidly. Thus, treatment with imatinib has to be followed by other treatment strategies. The normally mild to moderate side effects of imatinib including skin rashes might therefore be aggravated. Here, we describe a patient with severe epidermal necrolysis after treatment with imatinib and consecutive allogeneic hematopoietic stem cell transplantation. Prolonged inhibition of platelet-derived growth factor by imatinib may be an explanation for this observed skin toxicity.

MDR1 gene polymorphisms affect therapy outcome in acute myeloid leukemia patients

Allelic variants of the MDR-1 gene have been shown recently to influence protein expression and P-glycoprotein (P-gp) function in healthy volunteers. Therefore, 405 acute myeloid leukemia patients were investigated for somatic genotypes of the three most frequent single nucleotide polymorphisms (SNPs) in exons 12, 21, and 26. In all three loci, homozygous wild-type alleles were classified as genotype A, heterozygous as B, and homozygous mutant (alternative) allele as C. Patients with the C genotype in exons 12 and 26 showed a lower median age (both P < 0.05). Additionally, the C genotype in exons 12 and 26 was associated with cytogenetic poor risk aberrations (both P < 0.05). A possible regulatory impact of the SNPs on MDR1 mRNA expression was investigated by a Real time-PCR assay. MDR1 expression was strongly correlated with a decreased complete remission rate (P = 0.01) but failed to predict decreased overall survival (OS). There was a significant association of the A genotype in exons 21 (P = 0.05) and 26 (P < 0.05) with lower MDR1 expression, whereas the B variants showed highest MDR1 values at all three investigated gene loci. The A genotype in exon 26 was associated with lower OS (P < 0,01). In these patients, worse OS is likely attributable to an increased risk of relapse (P < 0.001). We were able to detect a linkage disequilibrium of the investigated SNPs, indicating combined polymorphisms that could affect the regulation of MDR1 expression. The A genotype of all SNPs demonstrated both lowest MDR1 values and significantly decreased OS (P < 0.05) with a high probability of relapses (P < 0.01). These observations indicate that allelic variants of the MDR1 gene may influence therapy outcome by additional mechanisms, different from P-gp expression on acute myeloid leukemia blasts, possibly involving pharmacokinetic effects of P-gp.