Selective ABO immunoadsorption in hematopoietic stem cell transplantation with major ABO incompatibility.

OBJECTIVE: ABO mismatch between donor and recipient occurs in 40% of allogeneic hematopoietic stem cell transplantations (HCT). Different strategies have been described to reduce isohemagglutinins (IHA) before HCT. We describe the effect of selective ABO immunoadsorption (ABO IA) on erythrocyte transfusion rate and the development of post-transplant pure red cell aplasia (ptPRCA). METHODS: 63 patients with major ABO incompatibility were retrospectively analyzed. Nine patients with major ABO incompatibility and high-IHA titer were treated by ABO IA before HCT. We analyzed the need for transfusion and the occurrence of ptPRCA. We compared the outcome with patients treated by other methods to reduce IHA. RESULTS: In all nine patients treated by ABO IA, IHA decreased in a median four times. PtPRCA occurred in one patient. The median number of transfusions was 8 (range: 0-36) between d0 and d100. In 25 patients with high-IHA titer without treatment or treated by other methods to reduce IHA, the need for transfusions was comparable. No difference in the incidence of ptPRCA was observed. CONCLUSIONS: Selective ABO IA is a feasible, safe, and effective method to reduce IHA before HCT in major ABO incompatibility. No effect on transfusion rate or ptPRCA compared to other strategies could be observed.

Baseline and interim PET-based outcome prediction in peripheral T-cell lymphoma: A subgroup analysis of the PETAL trial.

The prospective randomized Positron Emission Tomography (PET)-Guided Therapy of Aggressive Non-Hodgkin Lymphomas (PETAL) trial was designed to test the ability of interim PET (iPET) to direct therapy. As reported previously, outcome remained unaffected by iPET-based treatment changes. In this subgroup analysis, we studied the prognostic value of baseline total metabolic tumor volume (TMTV) and iPET response in 76 patients with T-cell lymphoma. TMTV was measured using the 41% maximum standardized uptake value (SUV41max ) and SUV4 thresholding methods. Interim PET was performed after two treatment cycles and evaluated using the ΔSUVmax approach and the Deauville scale. Because of significant differences in outcome, patients with anaplastic lymphoma kinase (ALK)-positive lymphoma were analyzed separately from patients with ALK-negative lymphoma. In the latter, TMTV was statistically significantly correlated with progression-free survival, with thresholds best dichotomizing the population, of 232 cm3 using SUV41max and 460 cm3 using SUV4 . For iPET response, the respective thresholds were 46.9% SUVmax reduction and Deauville score 1-4 vs 5. The proportion of poor prognosis patients was 46% and 29% for TMTV by SUV41max and SUV4 , and 29% and 25% for iPET response by ΔSUVmax and Deauville, respectively. At diagnosis, the hazard ratio (95% confidence interval) for poor prognosis vs good prognosis patients according to TMTV was 2.291 (1.135-4.624) for SUV41max and 3.206 (1.524-6.743) for SUV4 . At iPET, it was 3.910 (1.891-8.087) for ΔSUVmax and 4.371 (2.079-9.187) for Deauville. On multivariable analysis, only TMTV and iPET response independently predicted survival. Patients with high baseline TMTV and poor iPET response (22% of the population) invariably progressed or died within the first year (hazard ratio, 9.031 [3.651-22.336]). Due to small numbers and events, PET did not predict survival in ALK-positive lymphoma. Baseline TMTV and iPET response are promising tools to select patients with ALK-negative T-cell lymphoma for early allogeneic transplantation or innovative therapies.

Six versus eight doses of rituximab in patients with aggressive B cell lymphoma receiving six cycles of CHOP: results from the "Positron Emission Tomography-Guided Therapy of Aggressive Non-Hodgkin Lymphomas" (PETAL) trial.

Standard first-line treatment of aggressive B cell lymphoma comprises six or eight cycles of cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) plus eight doses of rituximab (R). Whether adding two doses of rituximab to six cycles of R-CHOP is of therapeutic benefit has not been systematically investigated. The Positron Emission Tomography-Guided Therapy of Aggressive Non-Hodgkin Lymphomas (PETAL) trial investigated the ability of [18F]-fluorodesoxyglucose PET scanning to guide treatment in aggressive non-Hodgkin lymphomas. Patients with B cell lymphomas and a negative interim scan received six cycles of R-CHOP with or without two extra doses of rituximab. For reasons related to trial design, only about a third underwent randomization between the two options. Combining randomized and non-randomized patients enabled subgroup analyses for diffuse large B cell lymphoma (DLBCL; n = 544), primary mediastinal B cell lymphoma (PMBCL; n = 37), and follicular lymphoma (FL) grade 3 (n = 35). With a median follow-up of 52 months, increasing the number of rituximab administrations failed to improve outcome. A non-significant trend for improved event-free survival was seen in DLBCL high-risk patients, as defined by the International Prognostic Index, while inferior survival was observed in female patients below the age of 60 years. Long-term outcome in PMBCL was excellent. Differences between FL grade 3a and FL grade 3b were not apparent. The results were confirmed in a Cox proportional hazard regression model and a propensity score matching analysis. In conclusion, adding two doses of rituximab to six cycles of R-CHOP did not improve outcome in patients with aggressive B cell lymphomas and a fast metabolic treatment response.

Evidence for a pre-existing telomere deficit in non-clonal hematopoietic stem cells in patients with acute myeloid leukemia.

Telomere shortening represents an established mechanism connecting aging and cancer development. We sequentially analyzed telomere length (TL) of 49 acute myeloid leukemia (AML) patients at diagnosis (n = 24), once they achieved complete cytological remission (CCR) and/or during refractory disease or relapse and after 1-year follow-up, with all patients having at least two sequential samples. TL was analyzed by monochrome multiplex quantitative polymerase chain reaction. We have observed substantially shortened TL in the cells of patients at diagnosis compared to age-adjusted controls. In patients reaching CCR after chemotherapy, telomere shortening was less pronounced than in persistence or relapse but still significantly shortened compared to controls. We estimate patients harboring approximately 20 years of premature telomere loss compared to healthy aged-matched subjects at the time of AML onset. Our data indicate a pre-existing telomere deficit in non-clonal hematopoiesis of AML patients providing a link between age and AML development.

Accelerated telomere shortening in peripheral blood lymphocytes after occupational polychlorinated biphenyls exposure.

Polychlorinated biphenyls (PCBs) are organochlorine pollutants with a worldwide dissemination. We examined telomere length (TL) in peripheral blood cells of 207 individuals with a high body burden of PCBs due to occupational exposure in a transformer recycling company. Whereas TL in granulocytes was not affected, the age-adjusted TL in lymphocytes (∆TLLymph) of exposed individuals was significantly shorter than expected [-0.77 kb; 95 % confidence interval (CI) -0.9316; -0.6052; p = 0.0001]. PCB exposure did not affect lymphocyte numbers or T cell receptor excision circle (TREC) levels in T cells, suggesting that PCBs cause loss of telomeric DNA in T cells due to their metabolic activation and antigen-stimulated proliferation. In support of this hypothesis, blood plasma levels of PCB-exposed individuals inhibited expression of telomerase, the telomere elongating enzyme in vitro in antigen-specific T cell proliferation assays. 3-OH-CB28, a downstream metabolite of the lower chlorinated PCB-28 in PCB-exposed individuals (mean blood plasma concentration: 0.185 ± 0.68 ng/mL), inhibited telomerase gene expression within 48 h of incubation in lymphoproliferative assays starting at a concentration of 0.27-6.75 µg/mL and accelerated telomere shortening in long-term cell culture experiments. Accelerated telomere shortening due to PCB exposure may lead to limitations of cell renewal and clonal expansion of lymphocyte populations. As PCB-related immune dysfunctions have been linked to increased susceptibility to infectious diseases and increased risk of cancer, our data provide a possible explanation, for how PCBs could promote infections and cancer through limiting immune surveillance.

A high BMI is a risk factor in younger patients with de novo acute myelogenous leukemia.

Overweight and obese patients have an increased risk to develop several malignancies and, additionally, body mass index (BMI) impacts on outcome in several solid tumors. However, little is known for AML. We analyzed a cohort of 3526 patients with AML treated in three prospective multicenter trials within the German Study Alliance Leukemia. In multivariate analyses, we identified BMI as an independent risk factor for both DFS (HR 1.014, P = 0.0217) and OS (HR 1.015, P < 0.0036). Interestingly, overweight and obesity seemed to be a risk factor predominantly in patients with de novo AML younger than 65 yr with intermediate risk and adverse cytogenetics. Overweight with a BMI ≥25 kg/m² best discriminated the worse outcome and led to an absolute reduction in long-term survival of 5-7% in the group of all younger patients (3-yr OS 39.9% vs. 47.3%; 10-yr OS 28.7% vs. 33.8%, P = 0.0002). Additionally, response to induction therapy was significantly reduced in these patients (76.9% vs. 82.8%, P < 0.0001). Thus, in younger patients with de novo AML, overweight and obesity are risk factors for impaired response to induction therapy, DFS and OS. This effect is, in part but not fully, explained by dose reduction such as dose-capping at a body surface area of 2 m².

Tumor volume as a prognostic factor in resectable malignant melanoma.

BACKGROUND: Vertical tumor thickness according to Breslow and histological ulceration are still the most powerful predictors for the clinical outcome of resectable cutaneous malignant melanoma (MM) without lymph node infiltration. It has been proposed that tumor volume in MM may also be of prognostic relevance. METHODS: We retrospectively analyzed the prognostic impact of tumor volume and other established risk factors in 122 MM patients with a median follow-up period of 39.7 months. RESULTS: We found the logarithmic tumor volume to be a better prognostic factor compared to Breslow tumor thickness in multivariate analysis. MM with a tumor volume below a threshold of 140 mm(3) had a significantly higher relapse-free survival after 5 years of 98% compared to 47% in larger MMs (p < 0.0001). CONCLUSION: In some melanomas with a low tumor thickness, a higher tumor volume appeared to be linked to a higher risk of disease recurrence. Inclusion of tumor volume into the risk assessment of resectable MM may be of benefit in the future.

A phase I first-in-man study to investigate the pharmacokinetics and safety of liposomal dexamethasone in patients with progressive multiple myeloma.

Despite the introduction of multiple new drugs and combination therapies, conventional dexamethasone remains a cornerstone in the treatment of multiple myeloma (MM). Its application is, however, limited by frequent adverse effects of which the increased infection rate may have the strongest clinical impact. The efficacy-safety ratio of dexamethasone in MM may be increased by encapsulation in long-circulating PEG-liposomes, thereby both enhancing drug delivery to MM lesions and reducing systemic corticosteroid exposure. We evaluated the preliminary safety and feasibility of a single intravenous (i.v.) infusion of pegylated liposomal dexamethasone phosphate (Dex-PL) in heavily pretreated relapsing or progressive symptomatic MM patients within a phase I open-label non-comparative interventional trial at two dose levels. In the 7 patients that were enrolled (prior to having to close the study prematurely due to slow recruitment), Dex-PL was found to be well tolerated and, as compared to conventional dexamethasone, no new or unexpected adverse events were detected. Pharmacokinetic analysis showed high and persisting concentrations of dexamethasone in the circulation for over a week after i.v. administration, likely caused by the long-circulation half-life of the liposomes that retain dexamethasone as the inactive phosphate prodrug form, something which could significantly limit systemic exposure to the active parent drug. Thus, despite the limitations of this small first-in-man trial, Dex-PL seems safe and well tolerated without severe side effects. Follow-up studies are needed to confirm this in a larger patient cohort and to evaluate if i.v. Dex-PL can provide a safer and more efficacious dexamethasone treatment option for MM.

Quantitative analyses of DAPK1 methylation in AML and MDS.

Aberrant DNA methylation and concomitant transcriptional silencing of death-associated protein kinase 1 (DAPK1) have been demonstrated to be key pathogenic events in chronic lymphocytic leukemia (CLL). In acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS), however, the presence of elevated DNA methylation levels has been a matter of continued controversy. Several studies demonstrated highly variable frequencies of DAPK1 promoter methylation by the use of methylation-specific PCR (MSP). By quantitative high-resolution assessment, we demonstrate that aberrant DNA methylation is an extremely rare event in this region. We observed elevated levels just in one out of 246 (0.4%) AML patients, all 42 MDS patients were unmethylated. In conclusion, we present a refined DAPK1 methylation analysis in a large representative patient cohort of AML and MDS patients proofing almost complete absence of elevated DNA methylation. Our results highlight the importance of quantitative measurements for translational research questions on primary patient specimens, particularly.

Telomere elongation and clinical response to androgen treatment in a patient with aplastic anemia and a heterozygous hTERT gene mutation.

Telomere length (TL) both reflects and limits the replicative life span of normal somatic cells. As a consequence, critically shortened telomeres are associated with a variety of disease states. Telomere attrition can be counteracted by a nucleoprotein complex containing telomerase. Mutations in subunits of telomerase, telomerase-binding proteins as well as in members of the shelterin complex have been described both in inherited and acquired bone marrow failure syndromes. Here, we report on a patient with acquired aplastic anemia and a nonsynonymous variation of codon 1062 of the hTERT gene (p.Ala1062Thr) whose substantial and maintained hematologic response to long-term androgen treatment (including complete transfusion independence) was paralleled by a significant and continued increase in TL in multilineage peripheral blood cells. To our knowledge, this represents the first case of sustained telomere elongation in hematopoietic stem cells induced by a pharmacological approach in vivo (141 words).

Array-based DNA methylation profiling in acute myeloid leukaemia.

Methylation in the promoter region of many genes is involved in regulating gene expression patterns. Using the Illumina GoldenGate© methylation assay, we examined the methylation status of 1505 CpG-sites from 807 genes in 32 samples from patients with acute myeloid leukaemia (AML) at diagnosis, nine at relapse and 15 normal controls and performed additional pyrosequencing and semiquantitative methylation specific polymerase chain reaction (MSP) of the GNMT promoter in 113 diagnostic AML samples. We found a gain of overall methylation in AML samples with a further increase at relapse. Regional hypermethylation as assessed by array analysis could be confirmed by both MSP and pyrosequencing. Additionally, large-scale methylation analysis identified interesting candidate genes. Cluster analysis indicated that cytogenetic subgroups seemed to be characterized by additional distinct epigenetic modifications and that basic DNA methylation patterns remain at relapse. Therefore, promoter hypermethylation is a frequent event in AML and is accentuated at relapse. Array-based methylation analysis determined distinct methylation profiles for non-malignant controls and AML samples with specific chromosomal aberrations and can identify target genes for further evaluation.

Sequence of administration and methylation of SOCS3 may govern response to gemtuzumab ozogamicin in combination with conventional chemotherapy in patients with refractory or relapsed acute myelogenous leukemia (AML).

In older patients suffering from acute myelogenous leukemia (AML), aggressive chemotherapy is accompanied with high treatment-related morbidity and mortality. Gemtuzumab ozogamicin (GO), a humanized monoclonal anti-CD33 antibody, represents a well tolerated treatment option, but optimal treatment schedules are still unknown. Additionally, Suppressor of cytokine signaling 3 (SOCS3) inhibits the CD33-induced block on cytokine-induced proliferation. Consequently, a variable response of AML cells to anti-CD33-targeted therapy may be caused by modulation of SOCS3 expression. Twenty-four patients with refractory or relapsed CD33-positive AML received GO as a single agent before or after conventional chemotherapy. The methylation status of the SOCS3 CpG island was assessed by methylation-specific polymerase chain reaction. Response (RR) and overall survival (OS) were significantly higher in 16 patients receiving chemotherapy before GO (RR 81%, OS 14.8 months) compared to three patients who received GO single agent therapy (RR 33%, OS 7.2 months) or 16 with GO before chemotherapy (RR 0% OS 2.2 months, P = 0.01 for RR and P < 0.001 for OS). Methylation of the SOCS3 CpG island was found in 8/24 patients. There was a trend towards a higher RR and longer OS in patients with SOCS3 hypermethylation (RR 86%, OS 25.1 months) compared to unmethylated SOCS3 (RR 56%, OS 10.3 months, P = 0.09). Administration of GO a few days after chemotherapy seems to provide better response and survival compared to administration of GO directly before chemotherapy. The potential role of SOCS3 hypermethylation as a biomarker should be further investigated in patients undergoing GO containing therapies.

Antineoplastic chemotherapy in cancer patients with methicillin-resistant Staphylococcus aureus (MRSA).

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen causing serious morbidity and mortality in immunosuppressed patients. Antineoplastic chemotherapy causes immunosuppression, and thus there is concern whether such patients should proceed to therapy without delay or dose reduction. There are presently no guidelines with appropriate provisions for antineoplastic chemotherapy in cancer patients with MRSA colonization or infection. PATIENTS AND METHODS: We retrospectively analyzed the clinical outcome of all 27 patients with known MRSA infection or colonization undergoing antineoplastic chemotherapy for solid or hematological malignancies in our institution. RESULTS: In our patients, MRSA was detected at multiple sites. 11 patients were found to be colonized with MRSA, whereas 16 patients had colonization and/or infection. MRSA sepsis occurred in 12 cases. Interestingly, at the time of MRSA sepsis, neutrophil counts were less than 500/µl in 42% of our patients. However, fatal complications due to MRSA occurred in only 2 patients. Among patients with MRSA sepsis, the mortality rate was 14%. CONCLUSIONS: Our results with a limited number of patients support the contention that antineoplastic chemotherapy may well be administered to patients with MRSA and should not necessarily lead to dose reduction or treatment delay, especially in cases with curative intent.

Comparison of flow-FISH and MM-qPCR telomere length assessment techniques for the screening of telomeropathies.

Assessment of telomere length (TL) in peripheral blood leukocytes is part of the diagnostic algorithm applied to patients with acquired bone marrow failure syndromes (BMFSs) and dyskeratosis congenita (DKC). Monochrome multiplex-quantitative polymerase chain reaction (MM-qPCR) and fluorescence in situ hybridization (flow-FISH) are methodologies available for TL screening. Dependent on TL expressed in relation to percentiles of healthy controls, further genetic testing for inherited mutations in telomere maintenance genes is recommended. However, the correct threshold to trigger this genetic workup is still under debate. Here, we prospectively compared MM-qPCR and flow-FISH regarding their capacity for accurate identification of DKC patients. All patients (n = 105) underwent genetic testing by next-generation sequencing and in 16 patients, mutations in DKC-relevant genes were identified. Whole leukocyte TL of patients measured by MM-qPCR was found to be moderately correlated with lymphocyte TL measured by flow-FISH (r² = 0.34; P < 0.0001). The sensitivity of both methods was high, but the specificity of MM-qPCR (29%) was significantly lower compared with flow-FISH (58%). These results suggest that MM-qPCR of peripheral blood cells is inferior to flow-FISH for clinical routine screening for suspected DKC in adult patients with BMFS due to lower specificity and a higher rate of false-positive results.

Impact of complete surgical resection on outcome in aggressive non-Hodgkin lymphoma treated with immunochemotherapy.

BACKGROUND: Surgical resection is considered to be of purely diagnostic value in aggressive lymphoma. Evidence for an impact on outcome is scant and restricted to retrospective observations. METHODS: In the "Positron Emission Tomography-guided Therapy of Aggressive non-Hodgkin Lymphomas" (PETAL) trial, patients with a negative baseline positron emission tomography (PET) scan were documented in a prospective observational substudy. Baseline PET-negative patients with the absence of lymph node enlargement on computed tomography and a negative bone marrow biopsy were considered to have undergone complete lymphoma resection. RESULTS: Eighty-two of 1,041 patients (7.9%) had a negative baseline PET scan, and 67 were included in this analysis. All were treated with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP), plus rituximab for CD20-positive lymphomas. Among 52 patients with diffuse large B-cell lymphoma (DLBCL), 48 had completely resected disease. Their outcome tended to be better than that of 115 baseline PET-positive stage I DLBCL patients treated in the main part of the PETAL trial (2-year progression-free survival 92.7% [95% confidence interval 84.7-100] versus 88.4% [82.5-94.3], P = .056; 2-year overall survival 92.7% [84.7-100] versus 93.7% [89.2-98.2], P = .176), but this was restricted to patients below the age of 60 years (2-year progression-free survival 100% versus 92.2% [84.8-99.6], P = .031; 2-year overall survival 100% versus 95.9% [90.2-100], P = .075). In peripheral T-cell lymphoma, eight of 11 patients had completely resected disease. In contrast to DLBCL, complete resection was not associated with improved outcome compared to the control. CONCLUSION: Young patients with early stage DLBCL may benefit from complete lymphoma resection prior to immunochemotherapy.

Successful treatment of hepatic encephalopathy in a patient with acute lymphoblastic leukemia.

Infiltration of the liver with consecutive severe dysfunction is rarely seen in adult acute lymphoblastic leukemia (ALL). We describe a case of a 32-year-old woman with severe icterus, thrombocytopenia, neutropenia and hepatosplenomegaly. ALL was diagnosed. One day after admission, she developed hepatic encephalopathy with ammonia concentrations in plasma >100 micromol/l. Hepatic infiltration was presumed and chemotherapy was initiated immediately which led to resolution of hepatic encephalopathy and complete hematological remission. Clinicians should be aware of unusual presentations of ALL and difficulties for the application of chemotherapy in patients with liver failure.

Cisplatin as single-agent chemotherapy in patients with liver dysfunction due to metastases.

BACKGROUND: Chemotherapeutic options are often limited for patients with hepatic dysfunction induced by advanced metastases. The toxicity and efficacy of cytotoxic drugs are often unpredictable due to altered drug activation or inactivation and excretion. Therefore, numerous chemotherapeutic agents should not be administered to patients with liver failure. PATIENTS AND METHODS: We retrospectively analysed 14 patients with solid tumours presenting with liver dysfunction induced by metastasis who were treated with cisplatin single-agent chemotherapy. RESULTS: Tolerance of therapy was acceptable with 1 grade I and 1 grade II renal toxicity. 6 patients experienced grade III haematological toxicity. Partial remission of the disease was observed in 6 cases, and 6 patients could receive combination chemotherapy after improvement of liver function. The median overall survival of the patient cohort was 4.8 months. CONCLUSION: Cisplatin monotherapy may thus be considered as a treatment option for patients with liver dysfunction induced by different solid tumours.

Correlation of C-reactive protein with survival and radiographic response to first-line platinum-based chemotherapy in advanced non-small cell lung cancer.

OBJECTIVE: This study was conducted to assess the prognostic role of regular measurements of C-reactive protein (CRP) in patients with advanced-stage non-small cell lung cancer (NSCLC) during platinum-based first-line therapy. METHODS: A total of 210 patients were retrospectively analyzed regarding CRP values, infections, histological type, stage, performance status, gender, age, body mass index and survival. Additionally, in 88 of these patients, changes of CRP values were correlated with response to chemotherapy by radiographic imaging. RESULTS: Elevation of CRP prior to the first cycle was an adverse prognostic factor for overall survival. Comparing CRP values before and after 2 cycles correlated with response and identified patient groups with a remarkable difference of overall survival (18.8 vs. 7.5 months). Normalization of CRP was associated with a low risk for progression, whereas patients with an increase of CRP values of more than 25% showed a progressive disease in most cases. Besides performance status, no correlation of CRP with other clinical data was found. CONCLUSIONS: Measurement of CRP before initiation and during a platinum-based chemotherapy can provide prognostic information for the individual patient with advanced NSCLC and is able to support or even replace assessment of response by radiographic imaging in defined situations.

Antineoplastic chemotherapy in Jehovah's Witness patients with acute myelogenous leukemia refusing blood products - a matched pair analysis.

BACKGROUND: Acute myelogenous leukemia (AML) may be cured in a substantial number of patients using intensive chemotherapeutic regimens leading to temporary severe myelosuppression. Patients belonging to the denomination of Jehovah's Witnesses (JW), however, are bound by their religious convictions not to accept blood products and are therefore at higher risk for life-threatening events. Reports how to handle this challenge are mainly anecdotal. MATERIAL AND METHODS: We here report in much more detail about our experience with nine patients belonging to the denomination of JW who were treated for AML in our department from 1998 to 2007 and who explicitly wished to receive chemotherapy without blood transfusions. RESULTS: Reduced dose induction chemotherapy administered by several treatment cycles to prevent sustained myelosuppression still led to complete remissions in three out of nine of JW patients but was associated with a high rate of relapse. No durable remission was achieved. The overall hazard ratio for death was 12.1 compared to a matched control group treated with full transfusion support. The predominant cause of non-AML mortality was severe anemia (four out of five early deaths) and uncontrollable bleeding (n = 1). CONCLUSION: Reduced dose chemotherapy without transfusion support in JW suffering from AML is associated with a lower rate of remission, high mortality by severe anemia and very low chances for long-term remissions. Less hematotoxic treatment options including hypomethylating agents or molecular targeted therapies with intensive consolidation after improvement of bone marrow function are promising for these patients but need further investigation.

Telomere shortening correlates with leukemic stem cell burden at diagnosis of chronic myeloid leukemia.

Telomere length (TL) in peripheral blood (PB) cells of patients with chronic myeloid leukemia (CML) has been shown to correlate with disease stage, prognostic scores, response to therapy, and disease progression. However, due to considerable genetic interindividual variability, TL varies substantially between individuals, limiting its use as a robust prognostic marker in individual patients. Here, we compared TL of BCR-ABL-, nonleukemic CD34+CD38- hematopoietic stem cells (HSC) in the bone marrow of CML patients at diagnosis to their individual BCR-ABL+ leukemic stem cell (LSC) counterparts. We observed significantly accelerated telomere shortening in LSC compared with nonleukemic HSC. Interestingly, the degree of LSC telomere shortening was found to correlate significantly with the leukemic clone size. To validate the diagnostic value of nonleukemic cells as internal controls and to rule out effects of tyrosine kinase inhibitor (TKI) treatment on these nontarget cells, we prospectively assessed TL in 134 PB samples collected in deep molecular remission after TKI treatment within the EURO-SKI study (NCT01596114). Here, no significant telomere shortening was observed in granulocytes compared with an age-adjusted control cohort. In conclusion, this study provides proof of principle for accelerated telomere shortening in LSC as opposed to HSC in CML patients at diagnosis. The fact that the degree of telomere shortening correlates with leukemic clone's size supports the use of TL in leukemic cells as a prognostic parameter pending prospective validation. TL in nonleukemic myeloid cells seems unaffected even by long-term TKI treatment arguing against a reduction of telomere-mediated replicative reserve in normal hematopoiesis under TKI treatment.