POPULARITY
In this episode of the Epigenetics Podcast, we caught up with Luciano Di Croce from the Center of Genomic Regulation in Barcelona to talk about his work on epigenetic landscapes in cancer. The Di Croce Lab focuses on the Polycomb Complex and its influence on diseases like cancer. Luciano Di Croce started out his research career investigating the oncogenic transcription factor PML-RAR. They could show that in leukemic cells knockdown of SUZ12, a key component of Polycomb repressive complex 2 (PRC2), reverts not only histone modification but also induces DNA de-methylation of PML-RAR target genes. More recently the team focused on two other Polycomb related proteins Zrf1 and PHF19 and were able to characterize some of their functions in gene targeting in different disease and developmental contexts. References Di Croce, L., Raker, V. A., Corsaro, M., Fazi, F., Fanelli, M., Faretta, M., Fuks, F., Lo Coco, F., Kouzarides, T., Nervi, C., Minucci, S., & Pelicci, P. G. (2002). Methyltransferase recruitment and DNA hypermethylation of target promoters by an oncogenic transcription factor. Science (New York, N.Y.), 295(5557), 1079–1082. https://doi.org/10.1126/science.1065173 Richly, H., Rocha-Viegas, L., Ribeiro, J. D., Demajo, S., Gundem, G., Lopez-Bigas, N., Nakagawa, T., Rospert, S., Ito, T., & Di Croce, L. (2010). Transcriptional activation of polycomb-repressed genes by ZRF1. Nature, 468(7327), 1124–1128. https://doi.org/10.1038/nature09574 Jain, P., Ballare, C., Blanco, E., Vizan, P., & Di Croce, L. (2020). PHF19 mediated regulation of proliferation and invasiveness in prostate cancer cells. eLife, 9, e51373. https://doi.org/10.7554/eLife.51373 Related Episodes Oncohistones as Drivers of Pediatric Brain Tumors (Nada Jabado) Transcription and Polycomb in Inheritance and Disease (Danny Reinberg) Targeting COMPASS to Cure Childhood Leukemia (Ali Shilatifard) Contact Epigenetics Podcast on Twitter Epigenetics Podcast on Instagram Epigenetics Podcast on Mastodon Active Motif on Twitter Active Motif on LinkedIn Email: podcast@activemotif.com
If you enjoyed this podcast, make sure to subscribe for more weekly education content from ASCO University. We truly value your feedback and suggestions, so please take a moment to leave a review. If you are an oncology professional and interested in contributing to the ASCO University Weekly Podcast, email ascou@asco.org for more information. TRANSCRIPT The purpose of this podcast is to educate and to inform. This is not a substitute for professional medical care and is not intended for use in the diagnosis or treatment of individual conditions. Guests on this podcast express their own opinions, experience, and conclusions. The mention of any product, service, organization, activity, or therapy should not be construed as an ASCO endorsement. [MUSIC PLAYING] Hello and welcome to the ASCO Guidelines podcast series. My name is Shannon McKernin and today I'm interviewing Dr. Valerie de Haas from Princess Máxima Center for Pediatric Oncology in the Netherlands, lead author on "Initial Diagnostic Workup of Acute Leukemia: ASCO Clinical Practice Guideline Endorsement of the CAP and ASH Guideline.” Thank you for being here today, Dr. de Haas. Thank you. So first, can you give us a general overview of what this guideline covers? Well, yes. The laboratory evaluation of patients who are suspected of having acute leukemia is very complex, and it has evolved significantly with the incorporation of advanced laboratory techniques. The traditional backbone of initial workup of AL, of acute leukemia, is composed of ctyomorphology, cytochemistry, immunophenotyping, and molecular cytogenetics. These techniques are the backbone of the initial diagnostic workup of acute leukemia. This is leading to risk stratification and fine tuning of the therapy by molecular signatures. The advanced molecular diagnostics, such as next-generation sequencing, has become more important in the diagnosis and in the risk stratification of acute leukemia. This guideline is meant for both pediatric and adult patients, and it was initially published in 2017. This year, we reviewed this guideline, and we have taken into account two important developments. First, since 2017, we've seen that there are major advances in molecular techniques and also that we can identify and validate new molecular markers. And those two events have contribute to a better risk stratification. And the second development is the effect that the WHO classification was revised in 2017 which also has led to new risk recoveries and refined subclassifications. So what are the key recommendations of this guideline? Well, in total, we have reviewed 27 guideline statements by the ASCO endorsement expert panelists. And discussion points are used to summarize issues that were identified from the updated literature. The ASCO expert panel determined that the recommendations from the guideline as published in 2016 are clear, thorough, and they are based upon the most relevant scientific evidences. We fully endorse the CAP-ASH guideline on initial diagnostic workup of acute leukemia. And we decided to include some discussion points according to clinical practice and according to the updated literature. In fact, we identified four categories of key recommendations. The first one is the initial diagnostics focusing on basic diagnostics and determination of risk parameters. This concerns, in total, about 11 guideline recommendations, and they give an overview of the initial workup varying from the collection of the clinical history of the patient to initial basic diagnostics by cytomorphology, flow cytometry and molecular cytogenetic analysis of peripheral blood, bone marrow, and cerebrospinal fluids. Secondly, the second category were molecular markers and MRD detection, and they were addressed by 10 of the recommendations. And these recommendations give a structural overview of the molecular and cytogenetic workup for acute lymphoblastic leukemia versus acute myeloid leukemia identifying different prognostic markers. Also, the detection of MRD is taken into account in this recommendation. There is a major difference between children and adults, and this part is given most attention in the discussion part as the developments have been major during the past few years. The third one is the context of referral to another institution with expertise in the management of acute leukemia. This is addressed by four recommendations, emphasizing the point that referral to an institution with specific expertise is of major importance for the central workup of acute leukemia. And finally, the final reporting and report keeping is reflected in three recommendations, mainly supporting conclusions from 2017 which were describing the fact that the complete report with basic diagnostics in one central report should be available within 48 to 72 hours. And this should be followed by complete, final, comprehensive report in one or two weeks. So can you tell us about those discussion points that were made and why the panel decided to include these? The discussion points include mostly issues regarding diagnostics that involve flow cytometry and molecular techniques as addressed in part one and two of the guidelines. We think that the cytomorphologic assessment is essential for initial diagnosis of acute leukemia. Multicolor flow cytometry using 8 to 10 colors has led to a better distinction between myeloids, lymphoid, and mixed lineage blast origin. Even when the number of cells are limited, for instance in CNS involvement, fine needle aspirate of extramedullary leukemic infiltration, or skin biopsy for leukemic cutis. Also, it was suggested to better assess the central nervous system involved in leukemia. The expert panel recommends the immunophenotyping studies as an additional detection technique next to the cytomorphological examination of cytospins and particularly for those with a low level involvement of acute leukemia that cannot be well addressed by a morphologic examination only. The TDT immunohistochemistry staining of cytospins has alternatively been used for detection of CNS disease in AML and evaluation of CSF by multicolor flow cytometry has been recently adopted in some centers. Flow cytometry, using at least six, but we now use in some laboratories, even 8 to 10 colors has led to a much more specific in tentative diagnosis. And this has improved the detection of CNS involvement. The use of molecular tools, for instance, polymerase change reaction, PCR, NGS for low-level CSF involvement is still under study, and therefore, we did not recommend this in our discussion. Regarding the molecular markers and MRD detection, the discussion here was mainly based upon the results of translational research supported by better molecular detection techniques. And those molecular diagnoses have been developing in the past few years with the inclusion of many more molecular markers. And they included one of the key diagnostic criteria in the revised WHO classification, which was revised in 2017. And we made substantial changes that have been made in the ASH-CAP guidelines concerning molecular diagnostics. Those newly identified targets by advanced molecular techniques give possibilities for better risk stratification. Some examples of better molecular characterization of acute lymphoblastic leukemia are, for instance, additional testing for MLL translocations. Furthermore, we can look in patients with T-ALL for NOTCH1, and FBXW7 mutations. The Ikaros family zinc finger gene, the IKZF1 gene is frequently deleted in adults as well in children with B-ALL. And it was shown to have an independent prognostic significance and was also associated with poor clinical outcome. In the current text of the current risk that the protocols IKZF1 should be regularly included in the screening panels for all ALL patients. If we look for examples for better characterization of AML, acute myeloid leukemia, we have found an increasing number of additional cytogenetic aberrations, like for instance FLT3 ITD which is associated with poor outcome. Another example is appropriate mutational analysis for kids, which can be detected both in adult patient as pediatric patients with a confirmed core binding factor acute myeloid leukemia. So this is myeloid leukemia with a translocation A21, RUNX1, or inversion 16. This recommendation is very strong in adults, whereas in children, this prognostic fact impact remains unclear. So there have been proven several publications which refer to a similar prognosis for children and others who refer to a poor prognosis in comparison to known mutated genes. So we suggest to test for this mutation in adults, especially, but also in children to learn from it. Finally, emerging evidence supports molecular studies as principle test for monitoring minimal residual disease of acute leukemia. And there are several key molecular markers that are included in the initial workup, which will be carried on for monitoring MRD, for instance, PML- RAR-alpha, RUNX1-RUNXT1, CBFB-MYH11, and NPM1, CEBP-alpha and others. Beside those aforementioned markers, it's very important to screen for other molecular markers that have predictive or prognostic value in the individual. And it is possible to use them for MRD. We have found a recent consensus from the European Leukemia Net MRD Working Group, who was proposing that for detection of molecular MRD, and they refer the RT PCR platform to NGS and digital PCR platforms. Although all those molecular techniques have been developed very quickly and it is very tempting to use them for initial diagnostics, currently, not all laboratories will have all those techniques available. So the expert panel strongly advises understanding to make distinction between diagnostic that are needed in the first phase to start treatment and subsequently, treatment stratification, in contrast to the usual dose findings in a broader research. For instance, available karyotyping, FISH, PCR techniques, if possible, NGS can be used in the initial start of treatment, whereas techniques like whole exome sequencing, whole genome sequencing, RNA sequencing, and epigenomic studies are meant for a broader research. And finally, how will these guideline recommendations affect patients? Well, in the end, the patients will receive better and especially, more personalized treatment. If we have results available within two weeks from diagnosis, it will be possible to better identify which basis will better benefit from more intensified and more personalized treatment, whereas others may need less intensive treatment with less toxicity. If you use traditional techniques to do this supported by molecular techniques like karyotyping, FISH, and PCR techniques, and in the end, following MRD to see which patients are responding to treatment, MRD detection will help to identify these patients and stratify them finally to the best treatment. Great. Thank you for your work on this important guideline, and thank you for your time today, Dr. de Haas. OK. Thanks a lot. And thank you to all of our listeners for tuning in to the ASCO Guidelines podcast series. If you've enjoyed what you've heard today, please rate and review the podcast and refer this show to a colleague.
The purpose of this podcast is to educate and to inform. This is not a substitute for professional medical care and is not intended for use in the diagnosis or treatment of individual conditions. Guests on this podcast express their own opinions, experience, and conclusions. The mention of any product, service, organization, activity, or therapy should not be construed as an ASCO endorsement. [MUSIC PLAYING] Hello and welcome to the ASCO Guidelines podcast series. My name is Shannon McKernin and today I'm interviewing Dr. Valerie de Haas from Princess Máxima Center for Pediatric Oncology in the Netherlands, lead author on "Initial Diagnostic Workup of Acute Leukemia: ASCO Clinical Practice Guideline Endorsement of the CAP and ASH Guideline.” Thank you for being here today, Dr. de Haas. Thank you. So first, can you give us a general overview of what this guideline covers? Well, yes. The laboratory evaluation of patients who are suspected of having acute leukemia is very complex, and it has evolved significantly with the incorporation of advanced laboratory techniques. The traditional backbone of initial workup of AL, of acute leukemia, is composed of ctyomorphology, cytochemistry, immunophenotyping, and molecular cytogenetics. These techniques are the backbone of the initial diagnostic workup of acute leukemia. This is leading to risk stratification and fine tuning of the therapy by molecular signatures. The advanced molecular diagnostics, such as next-generation sequencing, has become more important in the diagnosis and in the risk stratification of acute leukemia. This guideline is meant for both pediatric and adult patients, and it was initially published in 2017. This year, we reviewed this guideline, and we have taken into account two important developments. First, since 2017, we've seen that there are major advances in molecular techniques and also that we can identify and validate new molecular markers. And those two events have contribute to a better risk stratification. And the second development is the effect that the WHO classification was revised in 2017 which also has led to new risk recoveries and refined subclassifications. So what are the key recommendations of this guideline? Well, in total, we have reviewed 27 guideline statements by the ASCO endorsement expert panelists. And discussion points are used to summarize issues that were identified from the updated literature. The ASCO expert panel determined that the recommendations from the guideline as published in 2016 are clear, thorough, and they are based upon the most relevant scientific evidences. We fully endorse the CAP-ASH guideline on initial diagnostic workup of acute leukemia. And we decided to include some discussion points according to clinical practice and according to the updated literature. In fact, we identified four categories of key recommendations. The first one is the initial diagnostics focusing on basic diagnostics and determination of risk parameters. This concerns, in total, about 11 guideline recommendations, and they give an overview of the initial workup varying from the collection of the clinical history of the patient to initial basic diagnostics by cytomorphology, flow cytometry and molecular cytogenetic analysis of peripheral blood, bone marrow, and cerebrospinal fluids. Secondly, the second category were molecular markers and MRD detection, and they were addressed by 10 of the recommendations. And these recommendations give a structural overview of the molecular and cytogenetic workup for acute lymphoblastic leukemia versus acute myeloid leukemia identifying different prognostic markers. Also, the detection of MRD is taken into account in this recommendation. There is a major difference between children and adults, and this part is given most attention in the discussion part as the developments have been major during the past few years. The third one is the context of referral to another institution with expertise in the management of acute leukemia. This is addressed by four recommendations, emphasizing the point that referral to an institution with specific expertise is of major importance for the central workup of acute leukemia. And finally, the final reporting and report keeping is reflected in three recommendations, mainly supporting conclusions from 2017 which were describing the fact that the complete report with basic diagnostics in one central report should be available within 48 to 72 hours. And this should be followed by complete, final, comprehensive report in one or two weeks. So can you tell us about those discussion points that were made and why the panel decided to include these? The discussion points include mostly issues regarding diagnostics that involve flow cytometry and molecular techniques as addressed in part one and two of the guidelines. We think that the cytomorphologic assessment is essential for initial diagnosis of acute leukemia. Multicolor flow cytometry using 8 to 10 colors has led to a better distinction between myeloids, lymphoid, and mixed lineage blast origin. Even when the number of cells are limited, for instance in CNS involvement, fine needle aspirate of extramedullary leukemic infiltration, or skin biopsy for leukemic cutis. Also, it was suggested to better assess the central nervous system involved in leukemia. The expert panel recommends the immunophenotyping studies as an additional detection technique next to the cytomorphological examination of cytospins and particularly for those with a low level involvement of acute leukemia that cannot be well addressed by a morphologic examination only. The TDT immunohistochemistry staining of cytospins has alternatively been used for detection of CNS disease in AML and evaluation of CSF by multicolor flow cytometry has been recently adopted in some centers. Flow cytometry, using at least six, but we now use in some laboratories, even 8 to 10 colors has led to a much more specific in tentative diagnosis. And this has improved the detection of CNS involvement. The use of molecular tools, for instance, polymerase change reaction, PCR, NGS for low-level CSF involvement is still under study, and therefore, we did not recommend this in our discussion. Regarding the molecular markers and MRD detection, the discussion here was mainly based upon the results of translational research supported by better molecular detection techniques. And those molecular diagnoses have been developing in the past few years with the inclusion of many more molecular markers. And they included one of the key diagnostic criteria in the revised WHO classification, which was revised in 2017. And we made substantial changes that have been made in the ASH-CAP guidelines concerning molecular diagnostics. Those newly identified targets by advanced molecular techniques give possibilities for better risk stratification. Some examples of better molecular characterization of acute lymphoblastic leukemia are, for instance, additional testing for MLL translocations. Furthermore, we can look in patients with T-ALL for NOTCH1, and FBXW7 mutations. The Ikaros family zinc finger gene, the IKZF1 gene is frequently deleted in adults as well in children with B-ALL. And it was shown to have an independent prognostic significance and was also associated with poor clinical outcome. In the current text of the current risk that the protocols IKZF1 should be regularly included in the screening panels for all ALL patients. If we look for examples for better characterization of AML, acute myeloid leukemia, we have found an increasing number of additional cytogenetic aberrations, like for instance FLT3 ITD which is associated with poor outcome. Another example is appropriate mutational analysis for kids, which can be detected both in adult patient as pediatric patients with a confirmed core binding factor acute myeloid leukemia. So this is myeloid leukemia with a translocation A21, RUNX1, or inversion 16. This recommendation is very strong in adults, whereas in children, this prognostic fact impact remains unclear. So there have been proven several publications which refer to a similar prognosis for children and others who refer to a poor prognosis in comparison to known mutated genes. So we suggest to test for this mutation in adults, especially, but also in children to learn from it. Finally, emerging evidence supports molecular studies as principle test for monitoring minimal residual disease of acute leukemia. And there are several key molecular markers that are included in the initial workup, which will be carried on for monitoring MRD, for instance, PML- RAR-alpha, RUNX1-RUNXT1, CBFB-MYH11, and NPM1, CEBP-alpha and others. Beside those aforementioned markers, it's very important to screen for other molecular markers that have predictive or prognostic value in the individual. And it is possible to use them for MRD. We have found a recent consensus from the European Leukemia Net MRD Working Group, who was proposing that for detection of molecular MRD, and they refer the RT PCR platform to NGS and digital PCR platforms. Although all those molecular techniques have been developed very quickly and it is very tempting to use them for initial diagnostics, currently, not all laboratories will have all those techniques available. So the expert panel strongly advises understanding to make distinction between diagnostic that are needed in the first phase to start treatment and subsequently, treatment stratification, in contrast to the usual dose findings in a broader research. For instance, available karyotyping, FISH, PCR techniques, if possible, NGS can be used in the initial start of treatment, whereas techniques like whole exome sequencing, whole genome sequencing, RNA sequencing, and epigenomic studies are meant for a broader research. And finally, how will these guideline recommendations affect patients? Well, in the end, the patients will receive better and especially, more personalized treatment. If we have results available within two weeks from diagnosis, it will be possible to better identify which basis will better benefit from more intensified and more personalized treatment, whereas others may need less intensive treatment with less toxicity. If you use traditional techniques to do this supported by molecular techniques like karyotyping, FISH, and PCR techniques, and in the end, following MRD to see which patients are responding to treatment, MRD detection will help to identify these patients and stratify them finally to the best treatment. Great. Thank you for your work on this important guideline, and thank you for your time today, Dr. de Haas. OK. Thanks a lot. And thank you to all of our listeners for tuning in to the ASCO Guidelines podcast series. If you've enjoyed what you've heard today, please rate and review the podcast and refer this show to a colleague.
Medizinische Fakultät - Digitale Hochschulschriften der LMU - Teil 07/19
Bei etwa 30 % der Patienten mit akuter myeloischer Leukämie (AML) können aktivierende Mutationen der Rezeptortyrosinkinase FLT3 gefunden werden. Damit ist FLT3 eines der am häufigsten mutierten Gene in der AML. Die Mutationen treten in zwei Regionen des FLT3-Rezeptors auf: Längenmutationen (FLT3-LM) in der juxtamembranösen Region (24 %) und Punktmutationen der Aktivationsschleife der zweiten Tyrosinkinasedomäne (FLT3-TKD-Mutationen; 7 %). FLT3-Mutationen verleihen Ba/F3-Zellen Unabhängigkeit von Interleukin-3. In einem Knochenmarktransplantationsmodell der Maus erzeugen FLT3-LM ein myeloproliferatives Syndrom und in Zusammenwirken mit PML-RARα eine akute Promyelozytenleukämie. Darüber hinaus scheint das Auftreten von FLT3-LM bei Patienten mit einer schlechteren Prognose assoziiert zu sein. In dieser Arbeit wurden AML-Zelllinien und durch FLT3-Mutationen transformierte Ba/F3-Zellen mit dem kleinmolekularen PTK-Inhibitor SU5614 behandelt. SU5614 induziert selektiv Wachstumsarrest, Zellzyklusarrest und Apoptose in Ba/F3-Zellen und leukämischen Zelllinien, die FLT3-Mutationen tragen. Darüber hinaus hebt SU5614 die antiapoptotische und wachstumsfördernde Wirkung von FLT3-Ligand (FL) in FL-abhängigen Zellen auf. In Zelllinien, die keinen aktivierten FLT3-Rezeptor tragen, zeigte die Substanz keine zytotoxische Wirkung. Auf biochemischer Ebene hemmt SU5614 die Hyperphosphorylierung des FLT3-Rezeptors und seiner Downstream-Targets STAT3, STAT5 und MAPK, sowie die Expression der STAT5-Zielgene BCL-XL und p21. Es konnte somit demonstriert werden, dass das Indolinonderivat SU5614 ein potenter Hemmstoff von mutiertem FLT3 und Wildtyp-FLT3 ist. Des Weiteren konnte gezeigt werden, dass Zelllinien leukämischen Ursprungs, die endogen FLT3-Mutationen exprimieren, selektiv empfindlich gegenüber SU5614 sind. Diese selektive und potente Zytotoxizität von FLT3-Inhibitoren impliziert den klinischen Einsatz solcher Inhibitoren als zusätzliche molekulare Therapiemöglichkeit bei Patienten mit akuter myeloischer Leukämie und FLT3-Mutationen.
Medizinische Fakultät - Digitale Hochschulschriften der LMU - Teil 06/19
We applied mass spectrometry based approach to explore the proteins differentially regulated by PML-RARalpha a translocation characteristic of acute promyelocytic leukemia (APL). Differentialy expressed proteins, a number of which are related to cell cycle function, including OP18, HSP70, GRP75 and Pin1 were identified by mass spectrometry. Further analysis of the OP18 pathway indicated that mRNA expression of OP18 was higher in APL patients and the increased OP18 protein expression upon PML-RAR induction was overcome by retinoic acid treatment. PML-RARalpha induced cell cycle progression and led to mitotic exit. RNA interference experiments revealed that siRNA against OP18 overcomes PML-RARalpha effects on cell cycle progression. In addition to increased OP18 expression by PML-RARalpha, 2D gel electrophoresis revealed an isomer of OP18, subsequently confirmed as Ser63 phosphomer to be downregulated by PML-RARalpha. Based on these findings, point mutation experiments indicated that decreased phosphorylation of Ser63 in OP18 is important for PML-RARalpha mediated cell cycle and mitotic index effects since constitutive phosphorylated mutant (Ser63-asp) of OP18 overcame the PML-RARalpha effects in U937-PR cells, NB4 and APL patients. In summary, our results demonstrate that the effect of PML-RAR on cell cycle progression and mitotic exit is via two mechanisms: increasing the expression of OP18 and decreasing the phosphorylation of OP18 at Ser63.
Tierärztliche Fakultät - Digitale Hochschulschriften der LMU - Teil 02/07
Die meisten genetischen Abweichungen, die bei humanen akuten Leukämien gefunden werden können, lassen sich in zwei Klassen einteilen: Klasse I Mutationen, wie z.B. aktivierende Mutationen in Rezeptortyrosinkinasen (z.B. FLT3 oder c-KIT), die einen Proliferations- und/oder Überlebensvorteil für hämatopoetische Vorläuferzellen bieten und Klasse II Mutationen (wie z.B. AML1-ETO oder PML/RARα), die hämatopoetische Transkriptionsfaktoren betreffen und primär die Reifung der Zellen und die Apoptose unterbinden. Im Zusammenspiel entstehen hämatopoetische Vorläuferzellen, deren Proliferation und Differenzierung empfindlich gestört ist (Gilliland, 2002), was die Ursache für Leukämien sein kann. In dieser Arbeit wurden zwei genetische Alterationen untersucht, die den zwei verschiedenen Klassen entstammen: eine Längenmutation der Rezeptortyrosinkinase FLT3 und das Fusionsgen aus AML1 und ETO, AML1-ETO. Es wurde die Frage gestellt, ob diese Mutationen, die auch gemeinsam in humanen AML Patienten gefunden werden (Care et al., 2003), im Zusammenspiel Leukämie auslösen können. Ein murines Knochenmarktransplantationsmodell wurde etabliert, bei dem Knochenmarkzellen, die entweder AML1-ETO, FLT3-LM, beide Mutationen zusammen, oder GFP alleine exprimierten, in Mäuse injiziert wurden. Die Kontrollmäuse entwickelten keine Erkrankung, wohingegen die Mäuse, die AML1-ETO und FLT3-LM zusammen exprimierten, an aggressiver Leukämie erkrankten. Interessanterweise gab es unterschiedliche Phänotypen: es entstanden sowohl myeloische als auch lymphatische (B- und T-Zell) Leukämien. Alle Leukämien wurden durch FACS und Zytologie, teilweise auch durch Histopathologie bestätigt. Es kann durch die vorliegenden Daten bestätigt werden, dass weder AML1-ETO noch FLT3-LM alleine in der Lage sind Leukämie auszulösen. FLT3-LM stellt aber einen sehr potenten Kooperationspartner dar, um gemeinsam mit AML1-ETO eine Leukämie zu induzieren. Diese Arbeit kann zum Verständnis der Pathophysiologie von akuten Leukämien beitragen, was die Grundvorausetzung zur Entwicklung von Heilmethoden ist. Der nächste Schritt sollte sein, verschiedene Substanzen, wie zum Beispiel Tyrosinkinaseinhibitoren zu testen, um bei entsprechender Wirkung die Prognose für Patienten mit AML1-ETO positiven Leukämien zu verbessern.