Chromosomal rearrangement involving 11q23 locus in chronic myelogenous leukemia: a rare phenomenon frequently associated with disease progression and poor prognosis

The presence of additional cytogenetic aberrations in chronic myeloid leukemia cells at the time of diagnosis or their appearance on tyrosine kinase inhibitor therapy predicts the imatinib treatment failure

Currently used treatment of CML dramatically improved the prognosis of disease. However, additional chromosome aberrations (ACA/Ph+) are still one of the adverse prognostic factors.

OBJECTIVES

evaluation of the impact of ACA/Ph+ appearance during disease outcome on the response to treatment. THE STUDY GROUP: consisted of 203 patients. The median time of follow-up was 72 months. ACA/Ph+ was found in 53 patients.

RESULTS

patients were divided into four groups: standard risk, intermediate, high and very high risk. When ACA/Ph+ presence was documented at diagnosis time the optimal response was observed in 41.2%, 25%, and 0% of pts with intermediate, high and very high risk, respectively. If ACA/Ph+ were detected during imatinib treatment the optimal response was in 4.8% of patients. The risk of blastic transformation for patients with standard risk, intermediate, high and very high risk was 2.7%, 18.4%, 20% and 50%, respectively.

CONCLUSIONS

the presence of ACA/Ph+ at diagnosis time or their appearance on therapy seems to be clinically relevant not only in terms of the risk of blastic transformation but also in terms of the treatment failure. Gathering patients with various karyotypes and their responses to treatment would allow to set better guidelines and predictions.

Human T cell generation is restored in CD3δ severe combined immunodeficiency through adenine base editing

CD3δ SCID is a devastating inborn error of immunity caused by mutations in CD3D, encoding the invariant CD3δ chain of the CD3/TCR complex necessary for normal thymopoiesis. We demonstrate an adenine base editing (ABE) strategy to restore CD3δ in autologous hematopoietic stem and progenitor cells (HSPCs). Delivery of mRNA encoding a laboratory-evolved ABE and guide RNA into a CD3δ SCID patient's HSPCs resulted in a 71.2% ± 7.85% (n = 3) correction of the pathogenic mutation. Edited HSPCs differentiated in artificial thymic organoids produced mature T cells exhibiting diverse TCR repertoires and TCR-dependent functions. Edited human HSPCs transplanted into immunodeficient mice showed 88% reversion of the CD3D defect in human CD34+ cells isolated from mouse bone marrow after 16 weeks, indicating correction of long-term repopulating HSCs. These findings demonstrate the preclinical efficacy of ABE in HSPCs for the treatment of CD3δ SCID, providing a foundation for the development of a one-time treatment for CD3δ SCID patients.

Secondary fusion proteins as a mechanism of BCR::ABL1 kinase-independent resistance in chronic myeloid leukaemia

Drug resistance in chronic myeloid leukaemia (CML) may occur via mutations in the causative BCR::ABL1 fusion or BCR::ABL1-independent mechanisms. We analysed 48 patients with BCR::ABL1-independent resistance for the presence of secondary fusion genes by RNA sequencing. We identified 10 of the most frequently detected secondary fusions in 21 patients. Validation studies, cell line models, gene expression analysis and drug screening revealed differences with respect to proliferation rate, differentiation and drug sensitivity. Notably, expression of RUNX1::MECOM led to resistance to ABL1 tyrosine kinase inhibitors in vitro. These results suggest secondary fusions contribute to BCR::ABL1-independent resistance and may be amenable to combined therapies.

Genetic landscape of chronic myeloid leukemia

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm caused by the BCR::ABL1 fusion gene, which aberrantly activates ABL1 kinase and promotes the overproduction of leukemic cells. CML typically develops in the chronic phase (CP) and progresses to a blast crisis (BC) after years without effective treatment. Although prognosis has substantially improved after the development of tyrosine kinase inhibitors (TKIs) targeting the BCR::ABL1 oncoprotein, some patients still experience TKI resistance and poor prognosis. One of the mechanisms of TKI resistance is ABL1 kinase domain mutations, which are found in approximately half of the cases, newly acquired during treatment. Moreover, genetic studies have revealed that CML patients carry additional mutations that are also observed in other myeloid neoplasms. ASXL1 mutations are often found in both CP and BC, whereas other mutations, such as those in RUNX1, IKZF1, and TP53, are preferentially found in BC. The presence of additional mutations, such as ASXL1 mutations, is a potential biomarker for predicting therapeutic efficacy. The mechanisms by which these additional mutations affect disease subtypes, drug resistance, and prognosis need to be elucidated. In this review, we have summarized and discussed the landscape and clinical impact of genetic abnormalities in CML.

Pediatric acute myeloid leukemia patients with i(17)(q10) mimicking acute promyelocytic leukemia: Two case reports

BACKGROUND

Chromosome i(17)(q10) abnormality is mainly associated with chronic myeloid leukemia (CML), myelodysplastic syndrome/myeloproliferative tumors (MDS/MPD), and acute myeloid leukemia (AML). The role of i(17)(q10) in AML is still unknown, the differences between AML and acute promyelocytic leukemia (APL)-like AML with i(17)(q10) need more research. This study aimed to investigate the clinical characteristics and laboratory evidence of 2 AML cases with i(17)(q10), similar to APL phenotype.

CASE SUMMARY

Both pediatric patients were males; case 1 had newly diagnosed AML, and case 2 showed relapsed tumor after 1 year of drug withdrawal. Bone marrow cell morphology, chromosome karyotype analysis, Fully-instrumented submersible housing test, immunological assays, molecular biological methods, and blood tumor panoramic gene test were performed. All-trans retinoic acid (ATRA) combined with arsenic acid (As2O3) were used in the first course of treatment. Bone marrow was dominated by abnormal promyelocytic granulocytes. Karyotype test revealed i(17)(q10) isochromosome. Immunological phenotype mainly included positive expressions of CD9, CD13, CD33, and CD38. Case 1 suffered intracranial hemorrhage after re-chemotherapy and died on D162. For case 2, on D145 and D265, bone marrow promyelocytic granulocytes accounted for 2%. Flow cytometric residual lesion detection showed no abnormal immunophenotype cells. The copy number of WT1 gene in two cases were 1087 and 1010, respectively, and the expression rates were 55.29% and 59.5%, respectively.

CONCLUSION

ATRA, As2O3, and chemotherapy may be ineffective in treating APL-like AML with i(17)(q10) but without t(15;17) and PML-RARA fusion gene.

Mutational landscape of chronic myeloid leukemia: more than a single oncogene leukemia

The BCR-ABL1 fusion gene, which causes aberrant kinase activity and uncontrolled cell proliferation, is the hallmark of chronic myeloid leukemia (CML). The development of tyrosine kinase inhibitors (TKI) that target the BCR-ABL oncoprotein has led to dramatic improvement in CML management. However, some challenges remain to be addressed in the TKI era, including patient stratification and the selection of frontline TKIs and CML progression. Additionally, with the emerging goal of treatment-free remission (TFR) in CML management, biomarkers that predict the outcomes of stopping TKI remain to be identified. Notably, recent reports have revealed the power of genome screening in understanding the role of genome aberrations other than BCR-ABL1 in CML pathogenesis. These studies have discovered the presence of disease-phase specific mutations and linked certain mutations to inferior responses to TKI treatment and CML progression. A personalized approach that incorporates genetic data in tailoring treatment strategies has been successfully implemented in acute leukemia, and it represents a promising approach for the management of high-risk CML patients. In this article, we will review current knowledge about the mutational profile in different phases of CML as well as patterns of mutational dynamics in patients having different outcomes. We highlight the effects of somatic mutations involving certain genes (e.g. epigenetic modifiers) on the outcomes of TKI treatment. We also discuss the potential value of incorporating genetic data in treatment decisions and the routine care of CML patients as a future direction for optimizing CML management.

Chronic Myeloid Leukemia, Version 2.2021, NCCN Clinical Practice Guidelines in Oncology

Chronic myeloid leukemia (CML) is defined by the presence of Philadelphia chromosome (Ph) which results from a reciprocal translocation between chromosomes 9 and 22 [t(9;22] that gives rise to a BCR-ABL1 fusion gene. CML occurs in 3 different phases (chronic, accelerated, and blast phase) and is usually diagnosed in the chronic phase. Tyrosine kinase inhibitor therapy is a highly effective first-line treatment option for all patients with newly diagnosed chronic phase CML. This manuscript discusses the recommendations outlined in the NCCN Guidelines for the diagnosis and management of patients with chronic phase CML.

Coexistence of recurrent chromosomal abnormalities and the Philadelphia chromosome in acute and chronic myeloid leukemias: report of five cases and review of literature

Progression of chronic myelogenous leukemia (CML) is frequently accompanied by cytogenetic evolution. Additional genetic abnormalities are seen in 10–20% of CML cases at the time of diagnosis, and in 60–80% of cases of advanced disease. Unbalanced chromosomal changes such as an extra copy of the Philadelphia chromosome (Ph), trisomy 8, and i(17)(q10) are common. Balanced chromosomal translocations, such as t(3;3), t(8;21), t(15;17), and inv(16) are typically found in acute myeloid leukemia, but rarely occur in CML. Translocations involving 11q23, t(8;21), and inv(16) are relatively common genetic abnormalities in acute leukemia, but are extremely rare in CML. In the literature to date, there are at least 76 Ph+ cases with t(3;21), 47 Ph+ cases with inv(16), 16 Ph+ cases with t(8;21), and 9 Ph+ cases with t(9;11). But most of what has been published is now over 30 years old, without the benefit of modern immunophenotyping to confirm diagnosis, and before the introduction of treatment regimes such as TKI. In this study, we explored the rare concomitant occurrence of coexistence current chromosomal translocation and t(9;22) in CML or acute myeloid leukemia (AML).

High-risk additional chromosomal abnormalities at low blast counts herald death by CML

Blast crisis is one of the remaining challenges in chronic myeloid leukemia (CML). Whether additional chromosomal abnormalities (ACAs) enable an earlier recognition of imminent blastic proliferation and a timelier change of treatment is unknown. One thousand five hundred and ten imatinib-treated patients with Philadelphia-chromosome-positive (Ph+) CML randomized in CML-study IV were analyzed for ACA/Ph+ and blast increase. By impact on survival, ACAs were grouped into high risk (+8, +Ph, i(17q), +17, +19, +21, 3q26.2, 11q23, -7/7q abnormalities; complex) and low risk (all other). The presence of high- and low-risk ACAs was linked to six cohorts with different blast levels (1%, 5%, 10%, 15%, 20%, and 30%) in a Cox model. One hundred and twenty-three patients displayed ACA/Ph+ (8.1%), 91 were high risk. At low blast levels (1-15%), high-risk ACA showed an increased hazard to die compared to no ACA (ratios: 3.65 in blood; 6.12 in marrow) in contrast to low-risk ACA. No effect was observed at blast levels of 20-30%. Sixty-three patients with high-risk ACA (69%) died (n = 37) or were alive after progression or progression-related transplantation (n = 26). High-risk ACA at low blast counts identify end-phase CML earlier than current diagnostic systems. Mortality was lower with earlier treatment. Cytogenetic monitoring is indicated when signs of progression surface or response to therapy is unsatisfactory.

Nuclear export of chimeric mRNAs depends on an lncRNA-triggered autoregulatory loop in blood malignancies

Aberrant chromosomal translocations leading to tumorigenesis have been ascribed to the heterogeneously oncogenic functions. However, how fusion transcripts exporting remains to be declared. Here, we showed that the nuclear speckle-specific long noncoding RNA MALAT1 controls chimeric mRNA export processes and regulates myeloid progenitor cell differentiation in malignant hematopoiesis. We demonstrated that MALAT1 regulates chimeric mRNAs export in an m6A-dependent manner and thus controls hematopoietic cell differentiation. Specifically, reducing MALAT1 or m6A methyltransferases and the 'reader' YTHDC1 result in the universal retention of distinct oncogenic gene mRNAs in nucleus. Mechanically, MALAT1 hijacks both the chimeric mRNAs and fusion proteins in nuclear speckles during chromosomal translocations and mediates the colocalization of oncogenic fusion proteins with METTL14. MALAT1 and fusion protein complexes serve as a functional loading bridge for the interaction of chimeric mRNA and METTL14. This study demonstrated a universal mechanism of chimeric mRNA transport that involves lncRNA-fusion protein-m6A autoregulatory loop for controlling myeloid cell differentiation. Targeting the lncRNA-triggered autoregulatory loop to disrupt chimeric mRNA transport might represent a new common paradigm for treating blood malignancies.

Acute myeloid leukemia with t(11;19)(q23;p13.1) in a patient with a gastrointestinal stromal tumor undergoing imatinib therapy: A case report

BACKGROUND

Acute myeloid leukemia (AML) harboring 11q23 translocations is classified as therapy-related AML in patients who have undergone prior treatment with cytotoxic agents. There have been only a few reports of AML that subsequently developed during imatinib mesylate (IM) treatment for gastrointestinal stromal tumors (GISTs).

CASE SUMMARY

A 63-year-old woman was diagnosed with a hepatic GIST recurrence in April 2012; she was administered IM 400 mg/d. In November 2015, she developed dyspnea with pancytopenia while IM treatment was continued for 42 mo. A chromosome study using a bone marrow sample showed a 46, XX karyotype with t(11;19)(q23;p13.1) in 22 of 26 analyzed metaphase cells. Fluorescence in situ hybridization using the locus-specific indicator (11q23) gene break-apart probe showed positive rearrangement in 82% of interphase cells. Reverse-transcription polymerase chain reactions subsequently confirmed the KMT2A/ELL transcript. She achieved complete response with incomplete neutrophil recovery with two decitabine treatment cycles. After the third cycle of decitabine, the disease relapsed, and she refused further treatment. She died of hemorrhagic stroke 5 mo after diagnosis. To the best of our knowledge, this is the first report of AML with KMT2A gene rearrangements in a patient with a GIST receiving IM treatment.

CONCLUSION

Physicians should consider the potential risks of developing hematologic malignancies, including therapy-related AML, in patients with GISTs receiving IM treatment.

Genetic Testing in the Diagnosis and Biology of Acute Leukemia

OBJECTIVES

The 2017 Workshop of the Society for Hematopathology/European Association for Haematopathology examined the role of molecular genetics in the diagnosis and biology of acute leukemia.

METHODS

Acute leukemias were reviewed in two sessions: "Genetic Testing in Diagnosis of Acute Leukemias" (53 cases) and "Genetics Revealing the Biology of Acute Leukemias" (41 cases).

RESULTS

Cases included acute lymphoblastic leukemia, acute myeloid leukemia, and acute leukemia of ambiguous lineage. Many cases demonstrated genetic alterations of known diagnostic, prognostic, and/or therapeutic significance, while others exhibited alterations that illuminated disease biology. The workshop highlighted the complexity of acute leukemia diagnosis and follow-up, while illustrating advantages and pitfalls of molecular genetic testing.

CONCLUSIONS

Our understanding of the molecular genetics of acute leukemias continues to grow rapidly. Awareness of the potential complexity of genetic architecture and environment is critical and emphasizes the importance of integrating clinical information with morphologic, immunophenotypic, and molecular genetic evaluation.

Impact of Additional Chromosomal Aberrations on the Disease Progression of Chronic Myelogenous Leukemia

The emergence of additional chromosomal abnormalities (ACAs) in Philadelphia chromosome/BCR-ABL1 positive chronic myeloid leukemia (CML), is considered to be a feature of disease evolution. However, their frequency of incidence, impact on prognosis and treatment response effect in CML is not conclusive. In the present study, we performed a chromosome analysis of 489 patients in different clinical stages of CML, using conventional GTG-banding, Fluorescent in situ Hybridization and Spectral Karyotyping. Among the de novo CP cases, ACAs were observed in 30 patients (10.20%) with lowest incidence, followed by IM resistant CP (16.66%) whereas in AP and BC, the occurrence of ACAs were higher, and was about 40.63 and 50.98%, respectively. The frequency of occurrence of ACAs were compared between the study groups and it was found that the incidence of ACAs was higher in BC compared to de novo and IM resistant CP cases. Likewise, it was higher in AP patients when compared between de novo and IM resistant CP cases, mirroring the fact of cytogenetic evolution with disease progression in CML. In addition, we observed 10 novel and 10 rare chromosomal aberrations among the study subjects. This study pinpoints the fact that the genome of advanced phase patients was highly unstable, and this environment of genomic instability is responsible for the high occurrence of ACAs. Treatment response analysis revealed that compared to initial phases, ACAs were associated with an adverse prognostic effect during the progressive stages of CML. This study further portrayed the cytogenetic mechanism of disease evolution in CML.

Efficacy of cytokine-induced killer cells targeting CD40 and GITR

Since the publication of a novel protocol in 1991, cytokine-induced killer (CIK) cells have shown promising results in the treatment against neoplastic diseases. Despite ongoing preclinical and clinical studies, CIK cell treatment in the context of human monoclonal antibodies targeting tumor-necrosis factor receptors remains overlooked. The present study investigated whether a combination of CIK cells with human monoclonal antibody anti-CD40 and anti-Glucocorticoid-induced TNF-related protein (GITR) would lead to further cytotoxicity against tumor cells expressing CD40 and GITR ligand (L). Therefore, in vitro experiments with human lymphoma cell lines SU-DHL-4 and Daudi (both CD40 positive) and human breast adenocarcinoma MCF-7 (GITRL positive) were performed and the secretion of interferon (IFN)-γ was measured. Three interesting results emerged: i) a combination of CIK cells and anti-CD40 mAb is more effective than CIK cell treatment alone; ii) the use of anti-GITR mAb and CIK cells significantly enhanced the cytotoxicity of CIK cells against MCF-7 compared with single CIK cell treatment and iii) the combination of both antibodies and CIK cells abrogates the anti tumoral effect of CIK cells on all three cell lines. By performing an ELISA for IFN-γ measurement, a lower secretion was observed when anti-CD40 or anti-GITR mAb was added. This outcome indicates that further studies in vitro and in vivo may aid in understanding the synergistic molecular mechanisms of CIK cells, and anti-CD40 and anti-GITR mAb.

Prognostic significance of additional chromosomal abnormalities at the time of diagnosis in patients with chronic myeloid leukemia treated with frontline tyrosine kinase inhibitors

Additional cytogenetic abnormalities (ACA) are considered a high risk feature in chronic myeloid leukemia (CML). However, its prognostic significance at the time of diagnosis in the setting of new tyrosine kinase inhibitors (TKIs) is less well understood. Patients with CML in CP with or without ACA at diagnosis treated with frontline TKIs in prospective clinical trials were analyzed for outcomes. Among 603 patients treated, 29 (5%) had ACA. Patients with ACA included 2 of 72 (2.8%) treated with imatinib 400 mg, 9 of 207 (4.3%) with imatinib 800 mg, 10 of 148 (6.7%) with dasatinib, 6 of 126 (4.7%) with nilotinib, and 2 of 50 (4%) with ponatinib. There was a significantly higher rate of complete cytogenetic response (CCyR) at 6 months in patients without ACA (P = .02). However cumulative CCyR and major molecular response (MMR) rates were not different. Similarly, MR4.0 and MR4.5 rates were similar for both groups; two CML-ACA patients maintained MR 4.5 for at least 2 years. At 5 years, ACA at diagnosis did not significantly impact transformation-free, failure-free, event-free, or overall survival expectations. Acknowledging small sample size estimates, response rates and survival outcomes were comparable in CP with ACA irrespective of whether chromosomal abnormalities were "major route" or other. The presence of ACA at diagnosis does not confer worse prognosis for patients with CML treated with TKI. Thus, the presence of ACA at diagnosis should not alter treatment strategies in these patients.

Cytogenetics-based risk prediction of blastic transformation of chronic myeloid leukemia in the era of TKI therapy

The high fatality of patients with blast phase (BP) chronic myeloid leukemia (CML) necessitates identification of high-risk (HR) patients to prevent onset of BP. Here, we investigated the risk of BP based on additional chromosomal abnormality (ACA) profiles in a cohort of 2326 CML patients treated with tyrosine kinase inhibitors (TKIs). We examined the time intervals from initial diagnosis to ACA emergence (interval 1), from ACA emergence to onset of BP (interval 2), and survival after onset of BP (interval 3). Based on BP risk associated with each ACA, patients were stratified into intermediate-1, intermediate-2, and HR groups, with a median duration of interval 2 of unreached, 19.2 months, and 1.9 months, respectively. There was no difference in durations of intervals 1 or 3 among 3 groups. Including patients without ACAs who formed the standard-risk group, the overall 5-year cumulative probability of BP was 9.8%, 28.0%, 41.7%, and 67.4% for these 4 groups, respectively. The pre-BP disease course in those who developed BP was similar regardless of cytogenetic alterations, and 84.4% of BP patients developed BP within the first 5 years of diagnosis. In summary, interval 2 is the predominant determinant of BP risk and patient outcome. By prolonging the duration of interval 2, TKI therapy mitigates BP risk associated with low-risk ACAs or no ACAs but does not alter the natural course of CML with HR ACAs. Thus, we have identified a group of patients who have HR of BP and may benefit from timely alternative treatment to prevent onset of BP.

Myeloid neoplasms with concurrent BCR-ABL1 and CBFB rearrangements: A series of 10 cases of a clinically aggressive neoplasm

Chronic myeloid leukemia (CML) is defined by the presence of t(9;22)(q34;q11.2)/BCR-ABL1. Additional chromosomal abnormalities confer an adverse prognosis and are particularly common in the blast phase of CML (CML-BP). CBFB rearrangement, particularly CBFB-MYH11 fusion resulting from inv(16)(p13.1q22) or t(16;16)(p13.1;q22), is an acute myeloid leukemia (AML)-defining alteration that is associated with a favorable outcome. The co-occurrence of BCR-ABL1 and CBFB rearrangement is extremely rare, and the significance of this finding remains unclear. We identified 10 patients with myeloid neoplasms harboring BCR-ABL1 and CBFB rearrangement. The study group included six men and four women with a median age of 51 years (range, 20-71 years). The sequence of molecular alterations could be determined in nine cases: BCR-ABL1 preceded CBFB rearrangement in seven, CBFB rearrangement preceded BCR-ABL1 in one, and both alterations were discovered simultaneously in one patient. BCR-ABL1 encoded for p210 kD in all cases in which BCR-ABL1 preceded CBFB rearrangement; a p190 kD was identified in the other three cases. Two patients were treated with the FLAG-IDA regimen (fludarabine, cytarabine, idarubicin, and G-CSF) and tyrosine kinase inhibitors (TKI); seven with other cytarabine-based regimens and TKIs, and one with ponatinib alone. At last follow up (median, 16 months; range 2-85), 7 of 10 patients had died. The co-existence of BCR-ABL1 and CBFB rearrangement is associated with poor outcome and a clinical course similar to that of CML-BP, and unlike de novo AML with CBFB rearrangement, suggesting that high-intensity chemotherapy with TKI should be considered in these patients.

Acute leukaemia and myelodysplastic syndromes with chromosomal rearrangement involving 11q23 locus, but not MLL gene

AIMS

Chromosome 11q23 translocations, resulting in MLL (KMT2A) rearrangement, have been well characterised in acute myeloid leukaemia (AML) and acute lymphoblastic leukaemia (ALL). However, little is known of haematopoietic neoplasms associated with 11q23 translocation but without MLL rearrangement (11q23+/MLL-). The aim of this study is to characterise such cases with 11q23+/MLL-.

METHODS AND RESULTS

We retrospectively searched our database for cases with haematopoietic malignancies with 11q23+/MLL-. We identified nine patients, two with AML, two with B-lymphoblastic leukaemia (B-ALL); two with T-lymphoblastic leukaemia (T-ALL), two with myelodysplastic syndrome (MDS) and one with chronic myelomonocytic leukaemia (CMML). The translocations included t(X;11)(p11.2;q23), t(2;11)(p21;q23), t(6;11)(q27;q23), t(8;9;11)(q13;q13;q23), t(11;11)(p15;q23), t(11;14)(q23;q24) and t(11;15)(q23;q14). Five of six patients with acute leukaemia had received chemotherapy and detection of 11q23 translocation occurred at time of disease relapse. Both patients with MDS and the patient with CMML had 11q23 translocation detected at time of initial diagnosis, all three patients progressed to AML after >1 year on hypomethylating agent therapy. All patients received risk-adapted therapies, including stem cell transplant in five patients. At the last follow-up, eight patients died with a median overall survival of 14 months.

CONCLUSIONS

11q23+/MLL- occurs rarely, involving different partner chromosomes and showing clinical and pathological features and disease subtypes different from those cases with MLL rearrangement. 11q23+/MLL- appears to be associated with clonal evolution/disease progression in acute leukaemia, a high risk for AML progression in MDS/CMML and a high incidence of disease relapse.

Risk stratification of chromosomal abnormalities in chronic myelogenous leukemia in the era of tyrosine kinase inhibitor therapy

Clonal cytogenetic evolution with additional chromosomal abnormalities (ACAs) in chronic myelogenous leukemia (CML) is generally associated with decreased response to tyrosine kinase inhibitor (TKI) therapy and adverse survival. Although ACAs are considered as a sign of disease progression and have been used as one of the criteria for accelerated phase, the differential prognostic impact of individual ACAs in CML is unknown, and a classification system to reflect such prognostic impact is lacking. In this study, we aimed to address these questions using a large cohort of CML patients treated in the era of TKIs. We focused on cases with single chromosomal changes at the time of ACA emergence and stratified the 6 most common ACAs into 2 groups: group 1 with a relatively good prognosis including trisomy 8, -Y, and an extra copy of Philadelphia chromosome; and group 2 with a relatively poor prognosis including i(17)(q10), -7/del7q, and 3q26.2 rearrangements. Patients in group 1 showed much better treatment response and survival than patients in group 2. When compared with cases with no ACAs, ACAs in group 2 conferred a worse survival irrelevant to the emergence phase and time. In contrast, ACAs in group 1 had no adverse impact on survival when they emerged from chronic phase or at the time of CML diagnosis. The concurrent presence of 2 or more ACAs conferred an inferior survival and can be categorized into the poor prognostic group.

Pharmacological inhibition of LSD1 for the treatment of MLL-rearranged leukemia

BACKGROUND

Mixed lineage leukemia (MLL) gene translocations are found in ~75% infant and 10% adult acute leukemia, showing a poor prognosis. Lysine-specific demethylase 1 (LSD1) has recently been implicated to be a drug target for this subtype of leukemia. More studies using potent LSD1 inhibitors against MLL-rearranged leukemia are needed.

METHODS

LSD1 inhibitors were examined for their biochemical and biological activities against LSD1 and MLL-rearranged leukemia as well as other cancer cells.

RESULTS

Potent LSD1 inhibitors with biochemical IC50 values of 9.8-77 nM were found to strongly inhibit proliferation of MLL-rearranged leukemia cells with EC50 of 10-320 nM, while these compounds are generally non-cytotoxic to several other tumor cells. LSD1 inhibition increased histone H3 lysine 4 (H3K4) methylation, downregulated expression of several leukemia-relevant genes, induced apoptosis and differentiation, and inhibited self-renewal of stem-like leukemia cells. Moreover, LSD1 inhibitors worked synergistically with inhibition of DOT1L, a histone H3 lysine 79 (H3K79) methyltransferase, against MLL-rearranged leukemia. The most potent LSD1 inhibitor showed significant in vivo activity in a systemic mouse model of MLL-rearranged leukemia without overt toxicities. Mechanistically, LSD1 inhibitors caused significant upregulation of several pathways that promote hematopoietic differentiation and apoptosis.

CONCLUSIONS

LSD1 is a drug target for MLL-rearranged leukemia, and LSD1 inhibitors are potential therapeutics for the malignancy.

Clinical and prognostic significance of 3q26.2 and other chromosome 3 abnormalities in CML in the era of tyrosine kinase inhibitors

Chromosome 3q26.2 abnormalities in acute myeloid leukemia, including inv(3)/t(3;3) and t(3;21), have been studied and are associated with a poor prognosis. Their prevalence, response to tyrosine kinase inhibitor (TKI) treatment, and prognostic significance in chronic myelogenous leukemia (CML) are largely unknown. In this study, we explored these aspects using a cohort of 2013 patients with CML diagnosed in the era of TKI therapy. Chromosome 3 abnormalities were observed in 116 (5.8%) of 2013 cases. These cases were divided into 5 distinct groups: A, inv(3)(q21q26.2)/t(3;3)(q21;q26.2), 26%; B, t(3;21)(q26.2;q22), 17%; C, other 3q26.2 rearrangements, 7%; D, rearrangements involving chromosome 3 other than 3q26.2 locus, 32%; and E, gain or loss of partial or whole chromosome 3, 18%. In all, 3q26.2 rearrangements were the most common chromosome 3 abnormalities (50%, groups A-C). 3q26.2 rearrangements emerged at different leukemic phases. For cases with 3q26.2 rearrangements that initially emerged in chronic or accelerated phase, they had a high rate of transformation to blast phase. Patients with 3q26.2 abnormalities showed a marginal response to TKI treatment, and no patients achieved a long-term sustainable response at a cytogenetic or molecular level. Compared with other chromosomal abnormalities in CML, patients with 3q26.2 rearrangements had poorer overall survival. The presence or absence of other concurrent chromosomal abnormalities did not affect survival in these patients, reflecting the predominant role of 3q26.2 rearrangements in determining prognosis. Interestingly, although heterogeneous, chromosome 3 abnormalities involving non-3q26.2 loci (groups D, E) also conferred a worse prognosis compared with changes involving other chromosomes in this cohort.

Philadelphia chromosome-negative acute myeloid leukemia with 11q23/MLL translocation in a patient with chronic myelogenous leukemia

Although defined by the presence of t(9;22), chronic myelogenous leukemia (CML) can have other concurrent additional cytogenetic changes, especially during disease progression. Additional chromosomal changes (ACAs) in CML often occur in Philadelphia chromosome (Ph)-positive cells and are associated with disease acceleration and treatment resistance. Occasionally chromosomal changes occur in Ph-negative cells and this phenomenon is often transient and does not correlate with disease progression. Very rarely myelodysplastic syndrome or acute leukemia can develop in Ph-negative cells. In this study, we report an unusual case of acute myeloid leukemia (AML) with 11q23/MLL translocation emerging from Ph-negative cells in a patient with CML.