Molecular and clinical advances in core binding factor primary acute myeloid leukemia: a paradigm for translational research in malignant hematology

Clonal chromosomal abnormalities are the most important prognostic indicators in acute myeloid leukemia (AML). Recent advances in molecular biology have allowed structural and functional characterization of many of these genomic rearrangements and have provided evidence for their primary role in leukemogenesis. Two of the most prevalent cytogenetic subtypes of adult primary or de novo AML, t(8;21)(q22;q22) and inv(16)(p13q22), are characterized by disruption of the AML1(CBF alpha 2) gene at 21q22 and the CBF beta gene at 16q22, respectively. Both genes encode a subunit of core binding factor (CBF), a regulator of normal hematopoiesis. At the molecular level, t(8;21)(q22;q22) and inv(16)(p13q22) result in the creation of novel fusion genes, AML1/ETO and CBF beta/MYH11, whose structures and functions are being successfully characterized by in vitro studies and transgenic animal models. Detection of t(8;21)(q22;q22) or inv(16)(p13q22) in adult patients with primary AML is a favorable independent prognostic indicator for achievement of cure after intensive chemotherapy or bone marrow transplantation and may serve as a paradigm for risk-adapted treatment in AML. The purpose of this review is to summarize the recent advances in the molecular biology and clinical management of t(8;21)(q22;q22) and inv(16)(p13q22) primary AML, collectively referred to here as CBF AML.     

Clinical significance of the most common chromosome translocations in adult acute myeloid leukemia

Acquired genetic alterations such as balanced and unbalanced chromosome aberrations and submicroscopic gene mutations and changes in gene expression strongly affect pretreatment features and prognosis of adults with acute myeloid leukemia (AML). The most frequent chromosome/molecular rearrangements, that is, t(8;21)(q22;q22)/RUNX1-RUNX1T1 and inv(16)(p13q22)/t(16;16)(p13;q22)/CBFB-MYH11 characteristic of core-binding factor (CBF) AML and t(15;17)(q22;q12-21)/PML-RARA characteristic of acute promyelocytic leukemia (APL), confer favorable clinical outcome when patients receive optimal treatment, that is, regimens that include high-dose cytarabine for CBF AML and all-trans-retinoic acid and/or arsenic trioxide for APL. Recently, mutations in such genes as KIT in CBF AML and FLT3 in APL have been correlated with clinical features and/or outcome of patients with these AML subtypes, and microarray gene expression profiling has been successfully used for diagnostic purposes and to provide biologic insights. These data underscore the value of genetic testing for common translocations for diagnosis, prognostication, and, increasingly, selecting therapy in acute leukemia.     

Cytogenetic Characteristics of de novo Acute Myeloid Leukemia in Southern Vietnam

Background: The cytogenetic characteristics are important factors for risk stratification at diagnosis of acute myeloid leukemia (AML); however, cytogenetic profile of Vietnamese patients with AML remains undetermined. In this study, we present the chromosomal data of de novo AML patients in Southern Vietnam. Methods: We performed cytogenetic testing for 336 AML patients using G banding. If the patients had suspected abnormalities, fluorescence in situ hybridization with probes of inv(3)(q21q26)/t(3;3)(q21;q26), 5q31, 7q31, t(8;21)(q21.3;q22), 11q23, t(15;17)(q24;q21), inv(16)(p13q22)/t(16;16)(p13;q22)were analyzed. Patients without above aberrations or with normal karyotype were tested by fluorescence in situ hybridization using probe 11q23. Results: We found that the median age was 39 years. According to French – American – British classification, AML-M2 is the most frequent type with 35.1%. Chromosomal abnormalities were detected in 208 cases, accounting for 61.9%. Among structural abnormalities, t(15;17) was the most common (19.6%), followed by t(8;21) and inv (16)/t(16;16) in 10.1% and 6.2%, respectively. In perspective of chromosomal numerical abnornmalities, loss of sex chromosomes are the most common (7.7%), followed by +8 in 6.8%, -7/del(7q) in 4.4%, +21 in 3.9% and -5/del (5q) in 2.1%. The prevalence of addditional cytogenetic aberrations accompanying with t(8;21) and inv(16)/t(16;16) were 82.4% and 52.4%, repectively. None of +8 cases was associated with t(8;21). Regarding cytogenetic risk assessment according to European Leukemia Net 2017, there were 121 (36%) patients in favorable-risk, 180 (53.6%) in intermediate-risk and 35 (10.4%) in adverse-risk group. Conclusion: In conclusion, this is the first comprehensive cytogenetic profile of Vietnamese patients diagnosed with de novo AML, which helps clinical doctors in prognostic classification for AML patients in Southern Vietnam.     

Lymphoid blastic crisis of chronic myelogenous leukaemia with inv(16)(p13;q22)

We report a case of chronic myelogeneous leukaemia (CML) in B-lineage lymphoid blastic crisis (BC) having chromosome abnormality, inv(16)(p13;q22) in addition to Philadelphia chromosome, in 20/20 marrow metaphase. Inv(16)(p13;q22) was not observed in cells of chronic phase or accelerate phase. Abnormalities of chromosome 16, including inv(16)(p13;q22), del(16)(q22) and t(16;16)(p13;q22), have been reported mostly in acute myelomonocytic leukaemia (AML), (FAB M4-Eo), and some in CML-BC and myelodysplastic syndrome (MDS) cases. Most of the cases showed increase of myelomonocytic components and abnormal eosinophils with dysplastic granules in the bone marrow (BM). However, our case was diagnosed as lymphoid BC without increase of myelomonocytic components, although some abnormal eosinophilia was seen. To date, lymphoid BC of CML having inv(16)(p13;q22) abnormality has not been reported. The case presented here could be a clue to understand the pathophysiology of inv(16)(p13;q22) leukaemia.     

Stratification of pediatric acute myeloid leukemia through cancer cell gene-expression profiling

Treatment of children's acute lymphoblastic leukemia has been at the forefront of conventional chemotherapy development. Despite outstanding results in long-term survival of acute lymphoblastic leukemia, development of therapies for acute myeloid leukemia (AML) have lagged behind. AML in children demonstrate similar long-term survival compared with adults 18-65 years of age: 40-50% overall long-term survival. AML is a heterogeneous disease in both adults and children, but the presence of recurrent chromosome translocations and mutations in children are lower than in adult AML. In particular, patients without chromosome aberrancies have been examined for stratification through examination of gene expression. The paper from Baglobind and coauthors proposes a useful prognostication by gene-expression analysis of 75 gene pairs in 40% of patient cases, accurately discriminating mixed lineage leukemia (MLL) gene rearrangement, t(8;21)(q22;q22), inv(16)(p13q22), t(15;17)(q21;q22) and t(7;12)(q36;p13)-positive AML. Gene-expression analysis of AML has provided an important research tool for uncovering information about AML biology that can be used for the development of novel therapies.     

"Acute myelogenous leukemia like" translocations in CML blast crisis: two new cases of inv(16)/t(16;16) and a review of the literature

We describe two patients with CML blast crisis with clonal evolution affecting 16q22 (t(16;16)(p13;q22) and inv(16)(p13;q22), abnormalities of core binding factor, usually found in de novo acute myeloid leukemia (AML)). The bone marrow of both cases showed myelomonocytic (M4) differentiation and eosinophilia. Both patients had prominent extramedullary disease and had poor response to treatment. A literature search focused on patients with CML and additional chromosome changes more typical of AML, revealed that the morphology of the blasts correlated with the finding typical of the underlying "AML" cytogenetic abnormality and an overall very poor clinical outcome, even in the groups with "favorable" AML type translocations.     

Stratification of pediatric acute myeloid leukemia through cancer cell gene-expression profiling

Evaluation of: Balgobind BV, Marry M, van den Heuvel-Eibrink MM et al. Evaluation of gene expression signatures predictive for cytogenetic and molecular subtypes of pediatric acute myeloid leukemia. Haematologica 96(2), 221–230 (2010).

Treatment of children^’s acute lymphoblastic leukemia has been at the forefront of conventional chemotherapy development. Despite outstanding results in long-term survival of acute lymphoblastic leukemia, development of therapies for acute myeloid leukemia (AML) have lagged behind. AML in children demonstrate similar long-term survival compared with adults 18–65 years of age: 40–50% overall long-term survival. AML is a heterogeneous disease in both adults and children, but the presence of recurrent chromosome translocations and mutations in children are lower than in adult AML. In particular, patients without chromosome aberrancies have been examined for stratification through examination of gene expression. The paper from Baglobind and coauthors proposes a useful prognostication by gene-expression analysis of 75 gene pairs in 40% of patient cases, accurately discriminating mixed lineage leukemia (MLL) gene rearrangement, t(8;21)(q22;q22), inv(16)(p13q22), t(15;17)(q21;q22) and t(7;12)(q36;p13)-positive AML. Gene-expression analysis of AML has provided an important research tool for uncovering information about AML biology that can be used for the development of novel therapies.     

Prognostic of Core Binding Factor (CBF) Acute Myeloid Leukemia With Complex Karyotype

BackgroundCore-binding factor acute myeloid leukemia (CBF AML) with recurrent genetic abnormalities inv(16)(p13.1q22) or t(16;16)(p13.1;q22)/ CBFB-MYH11 are usually prognostically favorable but heterogeneous group and additional abnormalities change their prognosis.Materials and MethodsTo evaluate the impact of a complex karyotype on CBF AML prognosis, we included 24 patients with a median age of 56.4 years (23.2-83.3) and a median number of abnormalities of 5 (4-13).ResultsMedian follow-up was 110.4 months. Among patients with a primary clone, complete remission (CR) was reached in 66.7% of patients. 31.3% of patients experienced AML relapse with a median of 8.5 months. Median OS for transplanted patients was 80.7 versus 40.5 months for non-transplanted patients, excluding the 4 patients with early death. Among patients harboring AML with clonal evolution, CR was reached in 62.5% of patients. 50% of patients underwent allogeneic stem cell transplantation (ASCT). In these, median RFS was 19.3 versus 0 months in non-transplanted patients. Median OS seemed also longer in transplanted patients with 23.5 versus 2.95 months in non-transplanted.ConclusionUse of new treatment and tailored strategy based on measurable residual disease monitoring may now improve these results. However, these data allow us to reconsider the good prognosis historically associated with CBF patients despite of karyotype and the place of ASCT in the strategy.     

Cytogenetic, molecular genetic, and clinical characteristics of acute myeloid leukemia with a complex karyotype

Patients with acute myeloid leukemia (AML) harboring three or more acquired chromosome aberrations in the absence of the prognostically favorable t(8;21)(q22;q22), inv(16)(p13q22)/t(6;16)(p13;q22), and t(15;17)(q22;q21) aberrations form a separate category - AML with a complex karyotype. They constitute 10% to 12% of all AML patents, with the incidence of complex karyotypes increasing with the more advanced age. Recent studies using molecular-cytogenetic techniques (spectral karyotyping [SKY], multiplex fluorescence in situ hybridization [M-FISH]) and array comparative genomic hybridization (a-CGH) considerably improved characterization of previously unidentified, partially identified, or cryptic chromosome aberrations, and allowed precise delineation of genomic imbalances. The emerging nonrandom pattern of abnormalities includes relative paucity, but not absence, of balanced rearrangements (translocations, insertions, or inversions), predominance of aberrations leading to loss of chromosome material (monosomies, deletions, and unbalanced translocations) that involve, in decreasing order, chromosome arms 5q, 17p, 7q, 18q, 16q, 17q, 12p, 20q, 18p, and 3p, and the presence of recurrent, albeit less frequent and often hidden (in marker chromosomes and unbalanced translocations) aberrations leading to overrepresentation of segments from 8q, 11q, 21q, 22q, 1p, 9p, and 13q. Several candidate genes have been identified as targets of genomic losses, for example, TP53, CTNNA1, NF1, ETV6, and TCF4, and amplifications, for example, ERG, ETS2, APP, ETS1, FLI1, MLL, DDX6, GAB2, MYC, TRIB1, and CDX2. Treatment outcomes of complex karyotype patients receiving chemotherapy are very poor. They can be improved to some extent by allogeneic stem cell transplantation in younger patients. It is hoped that better understanding of genomic alterations will result in identification of novel therapeutic targets and improved prognosis in patients with complex karyotypes.     

Specific chromosomal aberrations in de novo acute myeloid leukemia: a comparative analysis of results with a report of three novel chromosomal rearrangements t(7;14)(q35;q13), t(8;18)(p11.2;q12), t(13;15) in Indian population

Background: Acute myeloid leukemia (AML) is a heterogeneous disease with regard to morphology, immunophenotype, and genetic rearrangements. Multiple recurrent chromosomal aberrations have been identified by conventional cytogenetic analysis, which is now widely recognized as one of the most important diagnostic and prognostic determinants in AML. Method: Conventional cytogenetic analysis was done on 200 de novo AML subjects. Results: Of these, 176 (88%) were successfully karyotyped and 24 (12%) showed culture failure. Among the176 subjects, 101 (57.4%) were abnormal and 75 (42.6%) showed an apparently normal karyotype. The various aberrations observed were t(8;21)(q22;q22) (5.2%); t(15;17) (q22;q11-21) (9%); t(9;22)(q34;q11)(1.7%); t(14;17)(q32;q11.2)(0.5%); inv(16)(p13;q22)(1.7%); 11q23 rearrangements (4%); monosomy 7 (2.2%) and 22 (1.1%); deletion of 9q (q22q34) (5.1%), 5q (q13q33) (0.5%) and 13q (q13q31) (0.5%); common trisomies like +8 (5.6%), +16 (1.7%), +22 (1.1%), +21 (0.5%), +13 (0.5%), +11 (0.5%), +3 (0.5%); hyperdiploidy (3.4%); hypodiploidy (1.1%); complex karyotype (4%); and other structural abnormalities (4.5%). Apart from these, three novel chromosomal abnormalities viz. t(8;18), t(7;14), t(13;15) were observed in the current study population. Conclusion: This study confirms that the incidence of chromosomal abnormalities varies considerably. Comparatively, the incidence t(15;17), and del9q is higher, while that of −5/del5q, −7/del7q and inv (16) were lower in our population. Similarly, the frequency of other recurrent FAB associated abnormalities viz. 11qabn was comparable to previous reports. Furthermore, ongoing cytogenetic studies are warranted in larger groups of AML cases to identify newly acquired chromosomal aberrations that may aid in cloning novel genes involved in the neoplastic process, ultimately helping in the development of targeted therapeutic drugs.     

Specific chromosomal aberrations in de novo acute myeloid leukemia: A comparative analysis of results with a report of three novel chromosomal rearrangements t(7;14)(q35;q13), t(8;18)(p11.2;q12), t(13;15) in Indian population

Background: Acute myeloid leukemia (AML) is a heterogeneous disease with regard to morphology, immunophenotype, and genetic rearrangements. Multiple recurrent chromosomal aberrations have been identified by conventional cytogenetic analysis, which is now widely recognized as one of the most important diagnostic and prognostic determinants in AML. Method: Conventional cytogenetic analysis was done on 200 de novo AML subjects. Results: Of these, 176 (88%) were successfully karyotyped and 24 (12%) showed culture failure. Among the176 subjects, 101 (57.4%) were abnormal and 75 (42.6%) showed an apparently normal karyotype. The various aberrations observed were t(8;21)(q22;q22) (5.2%); t(15;17) (q22;q11-21) (9%); t(9;22)(q34;q11)(1.7%); t(14;17)(q32;q11.2)(0.5%); inv(16)(p13;q22)(1.7%); 11q23 rearrangements (4%); monosomy 7 (2.2%) and 22 (1.1%); deletion of 9q (q22q34) (5.1%), 5q (q13q33) (0.5%) and 13q (q13q31) (0.5%); common trisomies like +8 (5.6%), +16 (1.7%), +22 (1.1%), +21 (0.5%), +13 (0.5%), +11 (0.5%), +3 (0.5%); hyperdiploidy (3.4%); hypodiploidy (1.1%); complex karyotype (4%); and other structural abnormalities (4.5%). Apart from these, three novel chromosomal abnormalities viz. t(8;18), t(7;14), t(13;15) were observed in the current study population. Conclusion: This study confirms that the incidence of chromosomal abnormalities varies considerably. Comparatively, the incidence t(15;17), and del9q is higher, while that of −5/del5q, −7/del7q and inv (16) were lower in our population. Similarly, the frequency of other recurrent FAB associated abnormalities viz. 11qabn was comparable to previous reports. Furthermore, ongoing cytogenetic studies are warranted in larger groups of AML cases to identify newly acquired chromosomal aberrations that may aid in cloning novel genes involved in the neoplastic process, ultimately helping in the development of targeted therapeutic drugs.     

Repetitive cycles of high-dose cytarabine benefit patients with acute myeloid leukemia and inv(16)(p13q22) or t(16;16)(p13;q22): results from CALGB 8461.

PURPOSE: To study the impact of repetitive (three to four courses) versus a single course of high-dose cytarabine (HDAC) consolidation therapy on outcome of patients with acute myeloid leukemia (AML) and inv(16)(p13q22) or t(16;16)(p13;q22). PATIENTS AND METHODS: We examined the cumulative incidence of relapse (CIR), relapse-free survival (RFS), and overall survival (OS) for 48 adults younger than 60 years with inv(16)/t(16;16) who had attained a complete remission on one of four consecutive clinical trials and were assigned to receive HDAC consolidation therapy. Twenty-eight patients were assigned to either three or four courses of HDAC, and 20 patients were assigned to one course of HDAC followed by alternative intensive consolidation therapy. RESULTS: Pretreatment features were similar for the two groups. The CIR was significantly decreased in patients assigned to receive three to four cycles of HDAC compared with patients assigned to one course (P=.03; 5-year CIR, 43% v 70%, respectively). The difference in RFS also approached statistical significance (P=.06). In a multivariable analysis that adjusted for potential confounding covariates, only treatment assignment (three to four cycles of HDAC) predicted for superior RFS (P=.02). The OS of both groups was similar (P=.93; 5-year OS, 75% for the three to four cycles of HDAC group v 70% for the one cycle of HDAC group), reflecting a high success rate with stem-cell transplantation salvage treatment administered among patients in both treatment groups. CONCLUSION: We conclude that, in AML patients with inv(16)/t(16;16), repetitive HDAC therapy decreases the likelihood of relapse compared with consolidation regimens including less HDAC.     

Acute myeloid leukemia with inv(8)(p11q13)

A patient with acute monoblastic leukemia (AML M5a) and the pericentric inversion inv(8)(p11q13) as well as additional chromosome abnormalities in her bone marrow cells is described. This is the fourth known case of inv(8)(p11q13)-positive acute leukemia, and the second such case in which gain of 1q material occurred during clonal evolution. All patients with acute leukemia and inv(8)(p11q13) have been females, most have been young, and there has been a tendency for the disease to run an aggressive course. Both hematologically and cytogenetically, therefore, inv(8)(p11q13)-positive leukemia may be viewed as a variant of AML with t(8;16)(p11;p13). This similarity is also apparent at the molecular genetic level, in-as-much as the MOZ gene in 8p11 is rearranged in both the translocation and the inversion; in t(8;16)-positive leukemia, a MOZ-CBP chimeric gene is generated, whereas inv(8) has been shown to generate a MOZ-TIF2 fusion gene. Southern blot analysis of the present case after MOZ0.8 hybridization of Bam HI digested DNA gave an 11 kb aberrant band in addition to the germline band, corresponding to a breakpoint immediately upstream of the 4 kb long MOZ exon that begins at position 3746. Also previously investigated inv(8)-positive leukemias have shown breaks in this intron indicating that it contains sequence motifs predisposing to illegitimate recombination.     

11例t(16;21)(p11;q22)急性髓系白血病病例报告并文献复习

目的:探讨11例伴t(16;21)(p11;q22)染色体易位的急性髓系白血病（acute myeloid leukemia,AML)患者的临床和实验室特点。方法:回顾性分析2007年07月至2022年03月我院收治的11例t((16;21)(p11;q22)染色体易位的AML患者临床及实验室特征并复习相关文献。结果:11例t(16;21)(p11;q22)染色体易位的白血病均为AML,FAB分型:M2型4例,M4型1例,M5型3例,AML(非M3)型3例;其中男5例,女6例。染色体R显带分析11例均可见到t(16;21)(p11;q22)染色体易位,其中9例伴有附加染色体异常。融合基因TLS/FUS-ERG检测了9例均为阳性。免疫表型除表达髓系CD34、CD117、CD33、CD13、CD38外,均表达CD56。化疗1个周期后完全缓解7例。结论:t(16;21)(p11;q22)染色体易位是一种少见的重现性染色体异常,该易位产生TLS/FUS-ERG融合基因,免疫学检测多伴CD56阳性,以AML中M2/M5型多见,化疗1个周期大部分可完全缓解,但短期内易复发,预后不良。     

Abnormalities of chromosome 16q in myeloid malignancy: 14 new cases and a review of the literature.

Fourteen patients with abnormalities of chromosome 16q, 13 with acute myelogenous leukaemia (AML), and one with refractory anaemia with excess of blasts (RAEB), are described. Seven patients had inv(16)(p13q22), two had del(16)(q22), and five had other abnormalities of 16q. Six of the seven patients with inv(16) had AML M4Eo and, following treatment with adriamycin, cytosine arabinoside, and 6-thioguanine, all achieved complete remission (CR). Neither patient with del(16)(q22) had typical M4Eo morphology at diagnosis; CR was achieved in one and one had resistant leukaemia. Patients with other abnormalities of 16q had blasts of diverse morphology and, although morphologically abnormal eosinophils were seen in three patients, this was not as marked as in the patients with inv(16). CR was achieved in two of the four patients with other abnormalities of 16q but duration of remission was short in both cases. These results suggest that most patients with del(16)(q22) and other abnormalities of 16q22 do not have typical AML M4Eo. Such patients tend to have a worse prognosis, and are more likely to have complex karyotypes typical of secondary leukaemia.     

Chromosome change at 16q22 in nonlymphocytic leukemia: clinical implication on leukemia patients with inv(16) versus del(16)

Nineteen patients with inv(16)(p13q22) or del(16) in myeloid leukemia are described. Eight showed inv(16)(p13q22), including one with de novo acute myeloid leukemia (AML-M2) and seven with de novo acute myelomonocytic leukemia (AMML-M4). Additional chromosome changes were detected in five of the cases; the most common change was trisomy 22. All but one of the de novo M2 and M4 leukemia patients with inv(16)(p13q22) showed initial bone marrow eosinophilia (greater than 5%) with basophilic granules. The remaining 11 showed deletion of the long arm of a chromosome no. 16 [del(16)(q22 or q23)]. Eight of the 11 were diagnosed as having chronic myelomonocytic leukemia, three transformed into an acute phase with M4 morphology; none of them gained complete remission. Two of the remaining three patients with del(16) were diagnosed as having M4 leukemia without marrow eosinophilia. The remaining one was a case of M4 leukemia following a myelodysplastic syndrome. The findings indicate that del(16) might be related to chronic myelomonocytic leukemia or leukemia with a prior history of myelodysplastic syndrome without evidence of marrow eosinophilia. On the other hand, inv(16)(p13q22) is highly associated with de novo AML especially AMML-M4 with bone marrow eosinophilia and a favorable prognosis.     

Chromosome abnormalities and MLL rearrangements in acute myeloid leukemia of infants.

Of 29 infants with acute myeloid leukemia (AML), 14 (48%) had various 11q23 translocations. MLL rearrangements were examined in 21 of the 29 patients, and 11 (52%) showed the rearrangements. 11q23 translocations and/or MLL rearrangements were found in 17 (58%) of the 29 patients. While all but one of the 17 patients with 11q23/MLL rearrangements had M4 or M5 type of the FAB classification, the 12 patients without such rearrangements had various FAB types, including M2, M4, M4EO, M6 and M7. Of the 12 patients with other chromosome abnormalities or normal karyotypes, two had inv(16) ort(16;16), one had t(1;22)(p13;q13), and two had a novel translocation, t(7;12)(q32;p13). The breakpoint on 12p of the t(7;12) was assigned to intron 1 or the region just upstream of exon 1 of the TEL/ETV6 gene by fluorescence in situ hybridization. The event-free survival at 5 years for the 17 patients with 11q23/MLL rearrangements was 42.2%, and that for the 12 patients without such rearrangements was 31.3% (P = 0.5544). 11q231MLL rearrangements have been frequently reported and a poor prognosis in infant acute lymphoblastic leukemia implied. Our study showed that while 11q23/MLL rearrangements were also common in infant AML, AML infants with such rearrangements had a clinical outcome similar to that of AML infants without such rearrangements.