Tomasz Sacha

Laboratory recommendations for scoring deep molecular responses following treatment for chronic myeloid leukemia

Treatment of chronic myeloid leukemia (CML) with tyrosine kinase inhibitors has advanced to a stage where many patients achieve very low or undetectable levels of disease. Remarkably, some of these patients remain in sustained remission when treatment is withdrawn, suggesting that they may be at least operationally cured of their disease. Accurate definition of deep molecular responses (MRs) is therefore increasingly important for optimal patient management and comparison of independent data sets. We previously published proposals for broad standardized definitions of MR at different levels of sensitivity. Here we present detailed laboratory recommendations, developed as part of the European Treatment and Outcome Study for CML (EUTOS), to enable testing laboratories to score MR in a reproducible manner for CML patients expressing the most common BCR-ABL1 variants.

The EUTOS population-based registry: incidence and clinical characteristics of 2904 CML patients in 20 European Countries

This population-based registry was designed to provide robust and updated information on the characteristics and the epidemiology of chronic myeloid leukemia (CML). All cases of newly diagnosed Philadelphia positive, BCR-ABL1+ CML that occurred in a sample of 92.5 million adults living in 20 European countries, were registered over a median period of 39 months. 94.3% of the 2904 CML patients were diagnosed in chronic phase (CP). Median age was 56 years. 55.5% of patients had comorbidities, mainly cardiovascular (41.9%). High-risk patients were 24.7% by Sokal, 10.8% by EURO, and 11.8% by EUTOS risk scores. The raw incidence increased with age from 0.39/100 000/year in people 20–29 years old to 1.52 in those >70 years old, and showed a maximum of 1.39 in Italy and a minimum of 0.69 in Poland (all countries together: 0.99). The proportion of Sokal and Euro score high-risk patients seen in many countries indicates that trial patients were not a positive selection. Thus from a clinical point of view the results of most trials can be generalized to most countries. The incidences observed among European countries did not differ substantially. The estimated number of new CML cases per year in Europe is about 6370.

Treatment and outcome of 2904 CML patients from the EUTOS population-based registry

The European Treatment and Outcome Study (EUTOS) population-based registry includes data of all adult patients newly diagnosed with Philadelphia chromosome-positive and/or BCR-ABL1+ chronic myeloid leukemia (CML) in 20 predefined countries and regions of Europe. Registration time ranged from 12 to 60 months between January 2008 and December 2013. Median age was 55 years and median observation time was 29 months. Eighty percent of patients were treated first line with imatinib, and 17% with a second-generation tyrosine kinase inhibitor, mostly according to European LeukemiaNet recommendations. After 12 months, complete cytogenetic remission (CCyR) and major molecular response (MMR) were achieved in 57% and 41% of patients, respectively. Patients with high EUTOS risk scores achieved CCyR and MMR significantly later than patients with low EUTOS risk. Probabilities of overall survival (OS) and progression-free survival for all patients at 12, 24 and 30 months was 97%, 94% and 92%, and 95%, 92% and 90%, respectively. The new EUTOS long-term survival score was validated: the OS of patients differed significantly between the three risk groups. The probability of dying in remission was 1% after 24 months. The current management of patients with tyrosine kinase inhibitors resulted in responses and outcomes in the range reported from clinical trials. These data from a large population-based, patient sample provide a solid benchmark for the evaluation of new treatment policies.

The Gain-of-Function JAK2 V617F Mutation Shifts the Phenotype of Essential Thrombocythemia and Chronic Idiopathic Myelofibrosis to More “Erythremic” and Less “Thrombocythemic”: A Molecular, Histologic, and Clinical Study

We investigated the prevalence of the JAK2 V617F gain-of-function mutation in patients with Philadelphia chromosome-negative chronic myeloproliferative disorders (Ph- MPD) and explored the links between JAK2 mutational status and the clinicopathologic picture of essential thrombocythemia (ET), chronic idiopathic myelofibrosis (CIMF), and polycythemia vera (PV). Allele-specific polymerase chain reaction results for 59 ET, 18 CIMF, and 9 PV cases were compared with values for clinical variables at presentation and last follow-up and with the diagnostic trephine bone marrow biopsy pictures. JAK2 V617F was found in 38 (64%) of ET cases, 7 (39%) of CIMF cases, and 9 (100%) of PV cases. The ET patients with the mutant JAK2 showed significantly higher (although not overtly polycythemic) red blood cell parameter values, lower platelet counts, and higher white blood cell counts. Similar trends were found in CIMF. Megakaryocyte clustering was much less pronounced in the CIMF cases with mutant JAK2, with an analogous trend occurring in the ET cases. Bone marrow cellularity values and the numbers of CD34+ and CD117+ blasts in the ET and CIMF groups did not differ. Fibrosis was slightly less marked in the ET cases with mutant JAK2. The mutation did not significantly influence the clinical course during the follow-up in either disease in the short term (median follow-up, 22 months). The JAK2 V617F mutation is prevalent in all Ph- MPD and may skew their presenting phenotype, including bone marrow histology, toward a more “erythremic” and less “thrombocythemic” phenotype.

Quantitative Analysis of Mutant Subclones in Chronic Myeloid Leukemia: Comparison of Different Methodological Approaches

Identification and quantitative monitoring of mutant BCR-ABL1 subclones displaying resistance to tyrosine kinase inhibitors (TKIs) have become important tasks in patients with Ph-positive leukemias. Different technologies have been established for patient screening. Various next-generation sequencing (NGS) platforms facilitating sensitive detection and quantitative monitoring of mutations in the ABL1-kinase domain (KD) have been introduced recently, and are expected to become the preferred technology in the future. However, broad clinical implementation of NGS methods has been hampered by the limited accessibility at different centers and the current costs of analysis which may not be regarded as readily affordable for routine diagnostic monitoring. It is therefore of interest to determine whether NGS platforms can be adequately substituted by other methodological approaches. We have tested three different techniques including pyrosequencing, LD (ligation-dependent)-PCR and NGS in a series of peripheral blood specimens from chronic myeloid leukemia (CML) patients carrying single or multiple mutations in the BCR-ABL1 KD. The proliferation kinetics of mutant subclones in serial specimens obtained during the course of TKI-treatment revealed similar profiles via all technical approaches, but individual specimens showed statistically significant differences between NGS and the other methods tested. The observations indicate that different approaches to detection and quantification of mutant subclones may be applicable for the monitoring of clonal kinetics, but careful calibration of each method is required for accurate size assessment of mutant subclones at individual time points.

The JAK2 V617F mutation in Philadelphia-negative chronic myeloproliferative disorders

Buccal epithelial cells are occasionally used as a source of supposedly non-neoplastic DNA in patients suffering from haematological malignancies. Formerly, Kralovics et al found the JAK2 V617F mutation in DNA derived from buccal swabs in only 2.2% of patients with Philadelphia-negative chronic myeloproliferative disorders (Ph− CMPD).1 We compared the JAK2 V617F mutational status in DNA derived from buccal swabs to that in DNA extracted from either bone marrow or peripheral blood in 35 Ph− CMPD patients, including five cases of polycythaemia vera (PV), five cases of chronic idiopathic myelofibrosis (CIMF) and 25 cases of essential thrombocythaemia (ET). Genomic DNA was isolated from buccal swabs immediately on collection and …

Imatinib in the treatment of chronic myeloid leukemia: current perspectives on optimal dose

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Monitorowanie kinetyki zmian wczesnego chimeryzmu hematopoetycznego i charakterystyka wszczepienia molekularnego za pomocą metody STR-PCR u pacjentów poddanych alloHSCT☆☆☆

Streszczenie Allogeniczna transplantacja komorek hematopoetycznych jest jednym ze sposobow leczenia nowotworowych i nienowotworowych schorzen hematologicznych. Po przeszczepieniu komorki hematopoetyczne dawcy osiedlają sie w niszach szpikowych biorcy, co skutkuje powstaniem prawidlowego ukladu krwiotworczego i immunologicznego o genotypie dawcy - calkowity chimeryzm dawcy. Wszczepienie molekularne (ME) poprzedza wystąpienie wszczepienia hematologicznego. Wczesna ocena chimeryzmu moze miec istotne znaczenie dla dalszego przebiegu procesu przyjmowania sie przeszczepienia i warunkuje mozliwośc podjecia wczesnej interwencji leczniczej. Do badania wlączono 38 pacjentow, u ktorych wykonano 43 allogeniczne transplantacje (alloHSCT). Przyjmowanie sie przeszczepu śledzono we krwi obwodowej od 2. do 14. doby po transplantacji, nastepnie w 21. i 28. dobie. W 30. dobie poziom chimeryzmu oznaczano we krwi obwodowej i w szpiku kostnym. Chimeryzm hematopoetyczny oceniano przy zastosowaniu metody molekularnej STR-PCR. Wykazano, ze zmiany poziomu chimeryzmu we wczesnym okresie po transplantacji w grupie pacjentow poddanych alloSCT (alloHSCT po-przedzona kondycjonowaniem mieloablacyjnym) przebiegają zgodnie z zaleznością liniową (R2=0,996), natomiast w grupie pacjentow poddanych alloNMSCT (alloHSCT poprzedzona kondycjonowaniem niemie-loablacyjnym) są zgodne z zaleznością logarytmiczną (R2=0,959). Poziom chimeryzmu hematopoetycznego jest wyzszy w grupie pacjentow poddanych alloSCT, w 2. dobie roznice te cechuje znamiennośc statystyczna (p=0,0048). Wszczepienie molekularne poprzedza wystąpienie wszczepienia hematologicznego (pacjenci poddani alloSCT p=1,44×10−12, pacjenci pod-dani alloNMSCT p=2,12×10−6). W grupach pacjentow poddanych alloSCT i alloHSCT, ktorzy otrzymali wiecej niz 3×106 komorek CD34+/kg masy data roznica w czasie wystąpienia ME w porownaniu z grupą chorych, ktorzy otrzymali mniej niz 3×106 komorek CD34+/kg, byla znamienna statystycznie (alloSCT p=0,0013, alloHSCT p = 0,021).

Insulin resistance is an underlying mechanism of impaired glucose metabolism during nilotinib therapy: Correspondence

Impaired glucose metabolism (IGM) with hyperglycemia represents one of the most frequently observed adverse events (AE) during nilotinib therapy of chronic myeloid leukemia (CML). The exact mechanism of IGM remains controversial. Although a case report has shown a decrease in insulin secretion1 , our previous pilot data suggested development of insulin resistance as a possible mechanism.2 In this prospective study we aimed to confirm results from our pilot study using a larger cohort of CML patients treated with nilotinib and to compare results with data obtained on control groups receiving imatinib and dasatinib.

Molecular Biology of Chronic Myeloid Leukemia

Chronic myeloid leukemia (CML) is a clonal myeloproliferative disorder resulting from an acquired genetic aberration t(9;22)(q34;q11) (Philadelphia chromosome) in stem cells. As a result the BCR/ABL fusion gene is formed which encodes a specific mRNA, translated into BCR/ABL proteins with an abnormally high tyrosine kinase activity, playing a crucial role in leukemic transformation and neoplastic proliferation of hematopoietic stem cells. BCR/ABL protein activates a number of transcription factors and gene promoters; however, its expression does not explain all the biological mechanisms of the origin of CML and its progression. Trisomy of chromosome 8, 19, isochromosome 17, and an additional Ph chromosome are the most frequent additional chromosomal abnormalities detected in course of CML progression. Suppressor genes dysfunction may play a role in the progression of CML. There is a considerable heterogeneity of the molecular mechanism and the genes involved in the development and progression of CML.