Lymphoid Blast Crisis Research Articles

Asciminib plus dasatinib and prednisone for Philadelphia chromosome–positive acute leukemia

AbstractDasatinib is an effective treatment for Philadelphia chromosome–positive (Ph+) acute leukemia, but some patients develop resistance. Combination treatment with dasatinib and asciminib, an allosteric inhibitor of BCR::ABL1, may deepen responses and prevent the emergence of dasatinib-resistant clones. In this phase 1 study (NCT03595017), 24 adults with Ph+ acute lymphoblastic leukemia (ALL; ALL, n = 22; p190, n = 16; p210, n = 6) and chronic myeloid leukemia in lymphoid blast crisis (n = 2) were treated with escalating daily doses of asciminib in combination with dasatinib 140 mg daily plus prednisone 60 mg/m2 daily to determine the maximum tolerated dose. After a 28-day induction, dasatinib and asciminib were continued indefinitely or until hematopoietic stem cell transplant. The median age was 64.5 years (range, 33-85; 50% aged ≥65 years). The recommended phase 2 dose of asciminib was 80 mg daily in combination with dasatinib and prednisone. The dose limiting toxicity at 160 mg daily was asymptomatic grade 3 pancreatic enzyme elevation without symptomatic pancreatitis. There were no vaso-occlusive events. Among patients with de novo ALL, the complete hematologic remission rates at days 28 and 84 were 84% and 100%, respectively. At day 84, 100% of patients achieved complete cytogenetic remission, 89% achieved measurable residual disease negativity (<0.01%) by multicolor flow cytometry, and 74% and 26% achieved BCR::ABL1 reverse transcription polymerase chain reaction <0.1% and <0.01%, respectively. Dual BCR::ABL1 inhibition with dasatinib and asciminib is safe with encouraging activity in patients with de novo Ph+ ALL. This trial was registered at www.clinicaltrials.gov as #NCT02081378.

ALL-766 Asciminib as a Bridge to Allogenic Transplant in 3 Patients With Relapsed/Refractory Philadelphia Chromosome-positive ALL or CML Lymphoid Blast Crisis Refractory/Intolerant to Ponatinib

ALL-766 Asciminib as a Bridge to Allogenic Transplant in 3 Patients With Relapsed/Refractory Philadelphia Chromosome-positive ALL or CML Lymphoid Blast Crisis Refractory/Intolerant to Ponatinib

Asciminib as a Bridge to Allogenic Transplant in 3 Patients With Relapsed/Refractory Philadelphia Chromosome-Positive ALL or CML Lymphoid Blast Crisis Refractory/Intolerant to Ponatinib

Asciminib as a Bridge to Allogenic Transplant in 3 Patients With Relapsed/Refractory Philadelphia Chromosome-Positive ALL or CML Lymphoid Blast Crisis Refractory/Intolerant to Ponatinib

Asciminib monotherapy as frontline treatment of chronic-phase chronic myeloid leukemia: results from the ASCEND study

AbstractAsciminib is a myristoyl site BCR::ABL1 inhibitor approved for patients with chronic-phase chronic myeloid leukemia (CP-CML) failing ≥2 prior lines of therapy. The Australasian Leukaemia and Lymphoma Group conducted the Asciminib Evaluation in Newly Diagnosed CML study to assess efficacy of asciminib for newly diagnosed CP-CML. Patients commenced asciminib 40 mg twice daily. Patients with treatment failure, defined as BCR::ABL1 of >10% at 3 or 6 months, or >1% at 12 or 18 months, received either imatinib, nilotinib, or dasatinib in addition to asciminib. In patients with suboptimal response, defined as levels of 1% to 10% at 6 months, >0.1% to 1% at 12 months, or >0.01% to 1% at 18 months, the asciminib dose was increased to 80 mg twice daily. With a median follow-up of 21 months (range, 0-36), 82 of 101 patients continue asciminib. Most common reasons for treatment discontinuation were adverse events (6%), loss of response (4%), and withdrawn consent (5%). There were no deaths; 1 patient developed lymphoid blast crisis. The coprimary end points were early molecular response (BCR::ABL1 of ≤10% at 3 months), achieved in 93% (96% confidence interval [CI], 86-97%), and major molecular response by 12 months achieved in 79%; (95% CI, 70-87%), respectively. Cumulative incidence of molecular response 4.5 was 53% by 24 months. One patient had 2 cerebrovascular events; no other arterial occlusive events were reported. Asciminib as frontline CP-CML therapy leads to high rates of molecular response with excellent tolerance and a low rate of discontinuation for toxicity. This trial was registered at https://www.anzctr.org.au/ as #ACTRN12620000851965.

Asciminib antagonizes transplantable BCR::ABL1-positive lymphoid blast crisis in vivo by targeting malignant stem cells

Philadelphia chromosome-positive (Ph+) lymphoid blast crisis (BC), emanating from chronic myeloid leukemia (CML), is a fatal disease with limited treatment options. Asciminib (ABL001) is a novel selective allosteric inhibitor of the ABL kinase with high efficacy against TKI-resistant BCR::ABL1. In this study, we demonstrate significant suppression of an aggressive B-lymphoblastic disease and restoration of normal hematopoiesis in an inducible transgenic mouse model of p210-BCR::ABL1-positive CML-BC. Molecularly, asciminib treatment significantly reduced BCR::ABL1 transcripts to background levels, demonstrating its ability to suppress BCR::ABL1-induced disease. Furthermore, asciminib treatment normalized the long-term repopulating hematopoietic stem cell (LT-HSC) population in the BM, suggesting the selective targeting of malignant LT-HSCs. This was supported by secondary transplantation experiments, resulting in absence of BC in a proportion of mice. Importantly, none of the secondary transplanted mice that received further asciminib treatment developed leukemia. Sanger sequencing of the BCR::ABL1 myristoyl pocket region of both treatment-naïve and treated mice demonstrated a high mutational load. However, there was no indication of asciminib-specific mutations. These promising findings highlight the potential of asciminib as a drug that targets BC stem cells and as an alternative stand-alone or combinatorial therapy for first-line treatment of CML BC or Ph+ acute lymphoblastic leukemia.

Inotuzumab Use: A Single-Center Experience in B-Cell Acute Lymphoblastic Leukemia

Introduction: Inotuzumab Ozogamicin (InO) is a humanized anti-CD22 monoclonal antibody conjugated to calicheamicin, a cytotoxic antibiotic agent used in B-Acute Lymphoblastic Leukemia (B-ALL). The conjugate is internalized and produces DNA cleavage and subsequent apoptosis. InO has shown better results than conventional chemotherapy. Patients and methods: We present the results of a single-center experience with a small cohort of 13 patients diagnosed with ALL who received InO outside of clinical trials. Results: Of the 13 patients, 69% (9) were male. The median age was 38 years old (range 16-64). 10 patients younger than 55 years 9 patients had relapsed diseases, 3 refractory diseases and one patient was newly diagnosed. Regardless of relapsed disease, 7 patients used InO as a first line of salvage and 2 as a second line. In refractory disease, 1 patient used InO as the second salvage and 2 as third or more. White blood cells range from 1,500 to 285,000 mm3. Peripheral blood blast from 50-80%. Before InO administration, all the patients had bilirubin lower than 2 mg/DL (range 0.15-1.26 mg/dL), an ALT (alanine aminotransferase) medium value of 34 U/dl, and an AST (aspartate aminotransferase) medium value of 33 U/dL. The most common type of leukemia was CALLA in 8 patients: B-ALL Phi positive in 2, Lymphoid blast crisis in1, pre-B ALL 1, and t (8;22) 1 patient. 10 patients had CD-22 positivity in flow cytometry, and 3 had negative results. There was no relation between the intensity of CD 22 and the rate of response. 11 patients received InO as monotherapy, and 2 were associated with Mini-HyperCVAD-InO. 7 patients received 1 cycle and 6 patients received 2 cycles of InO; the average dose received was 2,7 mg/m2. 7 (53%) patients in complete response (CR) plus MDR (Minimal Residual disease) negative after treatment, 4 progressive diseases and 2 missing. Three patients received HCT (hematopoietic cell transplantation) post-InO, and two are waiting in complete remission. One patient relapsed while she was waiting for HCT and died. 4 patients received InO as a salvage after relapse post-HCT. All these patients had progressive diseases and died. In the patients that used InO as a bridge to HCT, the average time to transplant was 94 days. Regardless of Veno-Occlusive Disease (VOD), 1 patient developed it after InO treatment; no patients had VOD associated with HCT. Overall survival: 38 months; progression-free survival: 4.1 months. Mortality rate was 53% (7 patients). Causes were: 4 with progressive disease, 1 hemorrhagic stroke, 1 septic shock, and 1 suicide. Conclusion: We show our small local experience using this new drug in B-ALL patients. Patients who use InO as a bridge to HCT could have a good outcome. We had not found good results when InO was used in relapse post-HCT. There was no relation between the intensity of CD22 at flow cytometry and the rate of responses. The incidence of VOD was low. Rates of response are comparable to other real-world reports. This small experience could be the beginning of a multicenter Real-World study in Latin America.

The role of flow cytometry in the classification of myeloid disorders.

The World Health Organization classification (WHO-HAEM5) and the International Consensus Classification (ICC 2022) of myeloid neoplasms are based on the integration of clinical, morphologic, immunophenotypic, and genomic data. Flow cytometric immunophenotyping (FCIP) allows the identification, enumeration, and characterization of hematopoietic cells, and is therefore apowerful tool in the diagnosis, classification, and monitoring of hematological neoplasms. The vast majority of flow cytometry (FCM) studies in chronic myeloid neoplasms focus on its role in myelodysplastic neoplasms (MDS). FCM can also be helpful for the assessment of myeloproliferative neoplasms (MPN) and MDS/MPN, including the early detection of evolving myeloid or lymphoid blast crisis and the characterization of monocytic subsets. The classification of acute myeloid leukemia (AML) is primarily based on cytogenetic and molecular findings; however, FCIP is needed for subclassification of AML, not otherwise specified (NOS; ICC)/AML defined by differentiation (WHO-HAEM5). The main role of FCM in AML remains in making arapid diagnosis and as atool for measurable residual disease monitoring. Machine learning and artificial intelligence approaches can be used to analyze and classify FCM data. This article, based on an invited lecture at the 106th Annual Meeting of the German Society of Pathology in 2023, reviews the role of FCM in the classification of myeloid neoplasms, including recent publications on the application of artificial intelligence.

ABL001 (asciminib) Efficiently Targets Transplantable BCR::ABL1 Lymphoid Blast Crisis in the Scl-Tta-p210-BCR::ABL1 Mouse Model

Objectives: This study aimed at investigating the therapeutic efficacy of ABL001 in the ScltTA-p210-BCR::ABL1 transgenic mouse model. ABL001 (asciminib) is a novel allosteric inhibitor of ABL kinase demonstrating its particular efficacy against BCR::ABL1 mutations that emerge during treatment with traditional TKIs. However, the activity and tolerability of ABL001 in a primary mouse model of BCR::ABL1 disease remain unknown. In addition, resistance mutations against ABL001 were observed in the myristoyl pocket of BCR::ABL1, but their emergence has not been analyzed in BCR::ABL1+ murine hematopoietic cells. Importantly, leukemic stem cells (LSCs) expressing BCR::ABL1 have developed mechanisms to evade eradication by tyrosine kinase inhibitors, underscoring the necessity for alternative therapeutic approaches. Methods: 5-fluorouracil- (5-FU-) treated bone marrow (BM) cells harvested from FVB/N-tg(ScltTA)(tetO- p210-BCR::ABL1) double-transgenic (dtg) donor mice (CD45.1+) were transplanted into lethally irradiated recipient mice (CD45.2+). One week after transplantation, tetracycline (tet) was removed from the drinking water to induce Bcr-Abl1 expression. Following an additional week, mice were treated daily with ABL001 or vehicle control by oral gavage (30 mg/kg body weight). Therapeutic effects were assessed using flow cytometry (peripheral blood, spleen, and BM), histological examination, RNA analysis and DNA sequencing of the myristoyl pocket of BCR::ABL1. Secondary transplants using splenocytes were performed to analyze whether ABL001 treatment was able to suppress BCR::ABL1-positive repopulating malignant stem cells. Additionally, we assessed potential ABL001-resistant subclones after secondary transplantation by subjecting the mice to further ABL001 treatment, modeling clinically relevant mutations in BCR::ABL1-positive disease. Results: Within 3 weeks after tet withdrawal, the transplanted mice developed an aggressive B-lymphoblastic p210-BCR::ABL1-positive disease, mimicking lymphoid blast crisis, as described previously (Koschmieder et al., Blood, 2005). Interestingly, ABL001 treatment significantly reduced this BCR::ABL1-driven phenotype as indicated by suppression of malignant B cells and restoration of normal hematopoiesis. ABL001 also significantly improved survival compared to the vehicle control group (p=0.026). Histological analysis confirmed the alleviation of the BCR::ABL1-driven phenotype in spleen and BM. Furthermore, ABL001 treatment significantly reduced BCR::ABL1 transcripts to background levels, demonstrating its ability to suppress BCR::ABL1-induced disease in the BM. The efficacy of ABL001 in reducing the malignant clone correlated with normalization of spleen weight. Essentially, ABL001 treatment normalized the phenotypic long-term repopulating hematopoietic stem cell (LT-HSC) population in the BM, suggesting restoration of the stem cell pool and targeting malignant LT-HSCs. This was supported by secondary transplantation experiments, showing that several mice receiving ABL001-treated splenocytes failed to develop leukemia, while all mice who received vehicle-treated cells did. Moreover, none of the secondary transplanted mice who were treated with ABL001 developed leukemia. Interestingly, Sanger sequencing of the BCR::ABL1 myristoyl pocket region demonstrated wildtype sequences and the absence of resistance mutations. Conclusion: Our study demonstrates the efficacy of ABL001 in ameliorating p210-BCR::ABL1-induced lymphoid blast crisis by specifically targeting BCR::ABL1-positive malignant stem cells and restoring normal hematopoiesis in a transgenic mouse model. These promising findings highlight the potential of ABL001 as an alternative therapeutic strategy for first-line treatment of BCR::ABL1-driven leukemia, including B-lymphoblastic blast crisis. Furthermore, since TKI treatment alone has not proven successful in patients with lymphoid blast crisis, this now opens new avenues for the in vivo-testing of novel combination treatments of ABL001 with chemotherapy or other targeting agents.

A Phase I Study of Asciminib (ABL001) in Combination with Dasatinib and Prednisone for BCR-ABL1-Positive ALL and Blast Phase CML in Adults

Introduction:Oral ABL1 kinase inhibitors rapidly produce deep remissions in BCR::ABL1+ acute lymphoblastic leukemia (ALL) and chronic myeloid leukemia in lymphoid blast crisis (CML-LBC). Second generation TKIs such as dasatinib (DAS) are more effective than imatinib (Foa et al. Blood 2011) but patients may develop resistance. Asciminib (ASC), previously ABL001, is a STAMP (Specifically Targeting the ABL Myristoyl Pocket) allosteric ABL1 inhibitor that binds to a site spatially distinct from ATP-competitive TKIs. Combination treatment with an allosteric and an ATP-competitive TKI may deepen clinical responses and limit mutational resistance as supported by a cell line xenograft model of CML (Wylie et al. Nature 2017) and patient-derived xenograft models of BCR::ABL1+ ALL. We hypothesized that dual ABL blockade with catalytic domain and allosteric inhibitors would be tolerable and active in BCR::ABL1+ ALL and CML-LBC. Methods: This investigator initiated, phase I study (NCT03595917) of asciminib (ASC) in combination with DAS plus prednisone (pred) for BCR::ABL1+ ALL studied ASC in escalating doses in a 3+3 design with the primary objective to determine the maximum tolerated dose (MTD)/recommended phase 2 dose (RP2D); a 10 patient (pt) expansion cohort was then accrued. Secondary objectives define the depth and durability of responses. Pts with BCR::ABL1+ ALL or CML-LBC newly diagnosed ≥ 50 years (yrs), or unfit; or relapsed/refractory (no prior DAS or ASC) were eligible in dose escalation; all pts ≥18 yrs were eligible in dose expansion. Pts received DAS 140 mg/day(d) and pred 60 mg/m 2/d 1-24 (max 120 mg/d, tapered d 25-32) with escalating daily doses of ASC (DL1: 40 mg; DL2: 80 mg; DL3: 160 mg). DAS and ASC were given in 28-d cycles indefinitely in setting of clinical benefit, with allogeneic stem cell transplant (SCT) consolidation after d85 per treating physician. Dose-limiting toxicity (DLT) was initially defined as CTCAEv4 non-heme toxicity grade (gr) 3+; the study was amended to assess DLT via CTCAEv5. Correlative science efforts seek to define biomarkers of response and resistance to dual ABL1 blockade. Results:The study enrolled 25 pts (48% female), with 14 in dose escalation (13 evaluable), and 11 in expansion (10 evaluable). Most (92%) had new ALL (p190: 15/23, p210: 8/23; 8% had CML-LBC. Median age was 65 yrs (range 33 - 85; 8 pts 70+). Median WBC was 15.1 K/μL (range 0.9 - 251.9 K/μL). No pt had CNS disease. DL1 and DL2 enrolled 3 pts each without DLT. Two of 3 pts at DL3 developed asymptomatic CTCAEv4 gr 3 amylase elevation during C1 meeting original DLT criteria. A 4 th pt enrolled on re-opened DL3 under an amendment defining asymptomatic CTCAEv4 gr 3 amylase/lipase elevations persisting ≤5d to not be a DLT. This pt experienced an asymptomatic CTCAEv4 gr 3 lipase elevation meeting DLT criteria. Thus, the study de-escalated to DL2, re-opening under an amendment assessing DLTs via CTCAEv5. Of note, all DLTs at DL3 would be gr &amp;lt;3 per CTCAEv5. Four more pts (3 evaluable) enrolled at DL2 without a DLT. Thus, ASC 80 mg/d was declared the RP2D, and 11 pts age ≥18 yrs enrolled in an expansion cohort, 10 of whom initiated study treatment. No pt had symptomatic pancreatitis. Rates of molecular response after 3 cycles among all evaluable patients were 58.3% (14/24) for MRD 3.0 and 25.0% (6/24) for MRD 4.0. Evaluable pts with new ALL treated at the RP2D achieved molecular response rates after 3 cycles of 78.6% (11/14) for MRD 3.0 and 42.9% (6/14) for MRD 4.0. Both patients with imatinib-refractory CML-LBC progressed (C9, C3). Of those with ALL, 8 bridged to SCT after 2-8 cycles; 2 elected local care (C5, C7); 1 transitioned to ponatinib for inadequate response plus recurrent DAS pulmonary toxicity (C4); 6 remained on study treatment until disease progression (C4 - MRD+, C45, C11, C11); 3 remain on study. Correlative science evaluation of serial pt biospecimens in pursuit of predictive biomarkers will be shared at the meeting. Conclusion: Dual ABL1 kinase inhibition with ASC and DAS plus pred in BCR::ABL1+ ALL and CML-LBC is feasible and tolerable in adults with BCR::ABL1+ ALL and CML-LBC. DLTs at ASC 160 mg/d were asymptomatic amylase and lipase elevation, without clinical sequelae. ASC 80 mg/day was declared the RP2D, and an expansion cohort of 10 pts was completed. High rates of molecular response and bridging to transplant highlight encouraging preliminary activity. A phase II expansion cohort incorporating blinatumomab is now open.

Excellent Early and Major Molecular Responses Observed with Asciminib Treatment for CP-CML: Results from the ALLG CML13 Ascend-CML Study

ATP-competitive BCR::ABL1 inhibitors are effective in many patients with CP-CML patients. However, a significant minority experience treatment failure with currently available drugs due to resistance or toxicity. Asciminib, a first-in-class myristoyl site BCR::ABL1 inhibitor, is now indicated in many jurisdictions for CP-CML after ≥2 prior lines of treatment. The Australasian Leukaemia and Lymphoma Group (ALLG) CML13 ASCEND-CML trial assessed its tolerability and efficacy in the frontline setting, where data are scarce. ALLG CML13 is a prospective open-label phase II study that completed enrolment in Dec 2022 at 14 sites. Patients commenced asciminib 40mg twice a day (BID) at time of diagnosis, and were assessed according to optimal 2020 ELN targets ( BCR::ABL1 ≤10%, ≤1% &amp; ≤0.1% at 3, 6, 12 months respectively); and ≤0.01% at 18 months. Patients in Major Molecular Response (MMR; BCR::ABL1 ≤0.1%) at 12 months were switched to 80mg QD for ease of administration. Patients with treatment failure ( BCR::ABL1 &amp;gt;10% at 3 or 6 months; BCR::ABL1 &amp;gt;1% at 12 or 18 months) continued asciminib, with additional imatinib or dasatinib or nilotinib, according to physician preference. Patients with a suboptimal response at 6, 12, or 18 months, but without treatment failure, continued asciminib but with the dose doubled to 80mg BID. This is a pre-specified analysis of the co-primary end points: i) final analysis of Early Molecular Response (EMR, BCR::ABL1 ≤10% at 3 months) and ii) interim analysis of MMR by 12 months. By data cut-off in May 2023, 101 patients had median follow-up of 20 (0-29) months (including 1 patient who enrolled but never started therapy due to elevated lipase at baseline). Grade 3/4 adverse events (AEs) included neutropenia and thrombocytopenia, (reported in 6% and 5% of patients, respectively); increased lipase/amylase reported in 8% (clinical pancreatitis reported in 2%), anaemia (2%), infection (2%) and 1% each of increased AST/ALT, back, abdominal and chest pain from pulmonary embolism. The only treatment emergent vascular event was a stroke, reported in a male patient aged 73 with pre-existing diabetes and hypertension, after 20 months of asciminib. Fifteen patients discontinued asciminib: 6 due to AEs (2 with persistent cytopenia requiring an allograft, 3 with recurrent asymptomatic lipase elevation, 1 with pancreatitis); 3 lost to follow-up; and 6 due to resistant disease (1 confirmed loss of MMR at 9 months, without ABL1 mutation; 1 transformed to lymphoid blast crisis at 6 months with myristoyl site mutations A337T/V and P465S; 1 loss of MMR at 6 months with A337T mutation; 1 loss of MR2 with V506L; and 2 with failure to achieve EMR - below). No other transformation occurred. During the first 3 months of treatment, 85% of patients had an assigned dose density of &amp;gt;90%; 9% of patients dose reduced to &amp;lt;66%. EMR was achieved by 94/101 patients (93.1%; 96% CI 86-97%): 1 patient never started treatment, 1 patient missed this assessment, 3 patients had withdrawn by this timepoint, and 2 had BCR::ABL1 of 24% and 210%, respectively. Neither of the EMR failure patients had myristoyl site mutations; both were subsequently intolerant of combination TKI/asciminib therapy because of cytopenia and headaches, respectively and are now on dasatinib monotherapy. Six patients dose escalated and remain on asciminib 80mg BID: 3 after failing to achieve MMR by 12 months, &amp; 3 failing to achieve MR4 after 18 months; 2 have since achieved their targets. By 3 months, 48/101 (48%) patients achieved MMR and 12 (11.9%) achieved MR4. Considering only patients with &amp;gt;12 months of follow up, the interim rate of MMR by 12 months is 62/75 patients (82.7%; 98% CI 70-92%). With “off-protocol for any reason” as the competing risk, the cumulative incidences of MMR &amp; MR4.5 by 12 months were 81.1% &amp; 32.3% respectively (Figure). ASCEND is one of the first studies using frontline asciminib, with excellent achievement of EMR and MMR, and low transformation rate. Rates of MMR at 12 months are comparable to those reported with second generation TKIs, though achievement of deeper responses appears more rapid with asciminib. Treatment was well tolerated in general: majority of AEs were grade I/II events that did not result in treatment discontinuation, and only one vascular event was observed. Early achievement of MMR and MR4 may accelerate eligibility for, &amp; increased success of, treatment-free remission attempts.

A Peculiar Manifestation of Chronic Myelogenous Leukemia in Lymphoid Blast Crisis

A 61-year-old man with a history of factor V Leiden mutation, hypothyroidism, and transient ischemic attacks presented to his physician's office but could not recall the reason for his visit. Initial laboratory test results showed a slight leukocytosis with slight basophilia; neuro-immunologic, infectious, and metabolic work-up was unrevealing. Flow cytometry results showed atypical B lymphoblasts. Bone marrow biopsy results revealed a hypercellular bone marrow with CD10 staining lymphoblasts and Philadelphia chromosomal translocation. Hematologic malignancy fusion panel results revealed BCR/ABL1 fusion with p210 oncoprotein, establishing the diagnosis of chronic myelogenous leukemia in lymphoid blast crisis—a peculiar manifestation of a disease that usually manifests with significant leukocytosis.

Clonal evolution analyses of a chronic myeloid leukemia patient with hematopoietic stem cell transplantation based on deep sequencing

BackgroundThe Philadelphia (Ph) chromosome is the hallmark chromosome aberration in chronic myeloid leukemia (CML), which confers the cancer phenotype of the disease. However, how the Ph chromosome forms and the genetic clonal evolution structure after targeted Ph treatment are still unclear.MethodsIn this study, we performed genome sequencing and clonal evolution analyses in a series of bone marrow specimens and skin biopsy from a CML patient who had received hematopoietic stem cell transplantation from her sister, then relapsed (lymphoid blast crisis), and received Ph-targeted therapy.ResultsThe Ph chromosome was the “driver” clonal change in the original CML and the relapse. Both the patient and her sister had micro-deletions in the BCR gene region; however, the patient had a frameshift BRIP1 mutation that may account for the malfunctioning homologous recombination DNA repair of the BCR gene region and formation of the Ph chromosome.ConclusionWe found that the BCR-ABL1 translocation was the driving force of the patient’s CML and relapse. The malfunctioning double-strand DNA break repair caused by the BRIP1 mutation could be the cause of Ph chromosome formation in the patient.

Classification of Acute Leukaemia based on Blast Morphology, Cytochemistry and Flow Cytometry

Introduction: Acute leukaemias are a heterogeneous group of malignancies due to the abnormal proliferation of immature cells. The classification of acute leukaemia has been transformed over a period. French American British’s (FAB) classification of acute leukaemia is based on morphology and cytochemistry. Later, the World Health Organization (WHO) classification stressed immunophenotyping to be done in the classification of acute leukaemia. Immunophenotyping is a powerful tool for classification and also for treatment and prognosis. Aim: To study the morphology of blasts in the peripheral smear and bone marrow cytochemistry and to compare with immunophenotyping in the classification of acute leukaemia. Materials and Methods: A cross-sectional study was undertaken in the Department of Transfusion Medicine and Immunohematology, at St. Johns National Academy of Health Sciences a Tertiary Care Hospital in Bengaluru over a period of one year from November 2018 to October 2019. The morphology of the blast was studied in peripheral blood and bone marrow aspirate stained by Leishman stain. Cytochemistry in peripheral smear and bone marrow with Sudan Black B and Periodic Acid-Schiff (PAS) stain was done in all acute leukaemia. The flow cytometry samples were processed within 24 hours of collection of the samples with a panel of markers including myeloid and lymphoid lineage and precursor markers. The results of morphology were confirmed with flow cytometry and final reports were released. Results: A total of 112 cases of acute leukaemia were studied and classified based on morphology, cytochemistry, and immunophenotyping of blasts. A total of 46 cases of Acute Myeloid Leukaemia (AML) and 63 cases of Acute Lymphoblastic Leukaemia (ALL). Two cases were found with Chronic Myeloid Leukaemia (CML) in blast crisis, one with myeloid and another with lymphoid blast crisis. One biphenotypic leukaemia was noted. Sudan Black was positive in 35 (76%) of AML and PAS was positive in 28 (44%) of ALL. The most common AML subtype was AML-M2 and the most common ALL subtype was B cell ALL. The most common symptom was fever and the sign was pallor. Conclusion: The present study showed that morphological diagnosis is important, based on which the cytochemistry and flow cytometry is performed for diagnosis. In cases of the diagnostic dilemma of acute leukaemia with morphology and cytochemistry, immunophenotyping supports diagnosing and classifying acute leukaemia.

BCR::ABL1-Positive Acute Lymphoblastic Leukemia: Different Clinical Behavior and Relevance of Prognostic Features in Typical ALL and in CML-like Disease

Recently we showed that in 20-30% of children diagnosed as BCR::ABL1-positive (Ph+) acute lymphoblastic leukemia (ALL) the BCR::ABL1 fusion is present in a wider clone, involving myeloid cells, non-ALL B-cells and T-cells. This leads to discordant minimal residual disease (MRD) levels assessed by the quantification of two available MRD targets - immunoglobulin (IG)/T-cell receptor (TR) genes rearrangements and BCR::ABL1 fusion. As the cases with multilineage BCR::ABL1 involvement resemble lymphoid blast crisis (LBC) of chronic myeloid leukemia (CML) we named these leukemias "CML-like", as distinct from "typical Ph+ ALL". To reveal biological and clinical differences between the two subtypes, we retrospectively analyzed prognostic relevance of MRD and other features in 147 children with BCR::ABL1-positive ALL treated according to EsPhALL (n = 133) or other (n = 14) protocols. MRD was assessed by DNA-based monitoring of BCR::ABL1 genomic breakpoint and of clonal IG/TR rearrangements. Although overall prognosis of CML-like (n = 48) and typical Ph+ ALL (n = 99) was similar (5-year EFS 60% and 49%; 5-year OS 75% and 73%, respectively), typical Ph+ ALL presented more relapses (12/48 vs. 42/99; p = 0.046) while CML-like patients more often died in the first remission (6/48 vs. 3/99; p = 0.059 for CR1 deaths in total and p = 0.01 for CR1 deaths out of the total deaths). Prognostic role of MRD measured at standard treatment timepoints (TP1 - end of induction IA, day 33; TP2 - end of consolidation IB, week 12) was highly significant in the typical Ph+ ALL (p = 0.0005 for EFS). In contrast, in CML-like patients prognostic impact of MRD was not significant and thus inapplicable for therapy adjustment. Similarly, although diagnostic white blood cell counts were similar in the two subgroups, impact of the hyperleukocytosis ≥ 50 x 109/l on outcome was highly significant in the typical Ph+ ALL (and remained significant in multivariate analyses, being apparent even in patients with fast MRD response), but no prognostic impact was found in CML-like patients. While in the typical Ph+ ALL the NCI risk tended to impact 5-year OS (89% vs. 67%; p = 0.03), there was no impact on prognosis in the CML-like patients. The BCR::ABL1 transcript type (minor/p190 vs. Major/p210), IKZF1 deletion, sex, or the age at diagnosis (< 10 vs. ≥ 10 years) did not show any prognostic relevance. Earlier start of continuous tyrosine kinase inhibitors (TKI) treatment (day 15 vs. day 33) was associated with lower MRD levels in the typical Ph+ ALL but not in CML-like patients. However, earlier TKI start tended to result in better 5-year OS in both subtypes (78% vs. 67%; p = 0.082 and 83% vs. 60%; p = 0.066 for typical Ph+ ALL and CML-like, respectively). To shed more light on the nature of the two subtypes, we now collect additional data (including transcriptome profiles, single cell characteristics, genomic breakpoint features) in order to reveal biological background, cell of origin and further potential differences between the subtypes. Such data could help to find optimal treatment strategies, and also to answer the attractive question whether CML-like disease is in fact a regular CML in LBC or whether there is a wider spectrum of BCR::ABL1-positive leukemias. If these studies lead to a conclusion that CML-like is indeed indistinguishable from LBC-CML, it will be necessary to re-define CML as a disease manifesting - at least in childhood - very often in LBC and with the minor-BCR::ABL1/p190 fusion variant. In conclusion, our data unequivocally confirm that although clinically presenting at diagnosis as one entity, there are two biologically distinct subtypes of BCR::ABL1-positive ALL - typical Ph+ ALL and CML-like disease. The different biology is reflected in treatment response and although the overall survival rates of both subtypes are similar on current protocol, the key reasons of treatment failure are different - toxicity of intensive ALL treatment in CML-like patients and relapses in typical Ph+ ALL. Thus, early distinguishing of the two subtypes is essential to enable optimal treatment approach and therapy adjustments in upcoming trials. For the typical Ph+ ALL, TKI and concurrent chemotherapy with risk-directed intensity should be recommended; in the CML-like disease, representing one-fourth to one-third of childhood patients diagnosed as BCR::ABL1-positive ALL, no relevant risk factor applicable for therapy tailoring was found so far.

The Role of Adult Cancer Predisposition Genes in Hematological Malignancies of Childhood

Background: Increasing evidence suggests that adult cancer genes (ACGs) contribute substantially to the development of several malignancies in childhood, although with reduced penetrance. The association of BRCA1 and BRCA2 with breast and ovarian cancer is sufficiently described, as well as the presence of heterozygous mutations in one of the mismatch repair genes (MSH2, MSH6, MLH1, PMS2) in hereditary colon carcinoma. Moreover, there is a plethora of genes, mainly regulating DNA repair mechanisms and cell cycle arrest as BRIP1, CHEK2, ATM, PALB2, HOXB13, RAD51C, RAD51D, which predispose to a variety of adult type cancers. The recurrent presence of pathogenic variants in one of the ACGs is observed in several pediatric cancer cohorts and gaining recognition in the field of pediatric cancer susceptibility. However, the incidence and impact of ACGs in childhood cancer and especially in pediatric hematological malignancies is not fully explored yet. Aims: Our aim is to understand the frequency and the impact of germline variants in adult cancer predisposition genes in the etiology of hematological malignancies in children. Methods: We analyzed parent-child whole exome sequencing (WES) data of 162 children (<18yrs) with hematological malignancies (N=117 leukemia, N=43 lymphoma, N=2 myelodysplastic syndrome) for the presence of pathogenic variants in adult onset cancer predisposition genes. For part of the detected variants, we performed further functional analysis to investigate the effect of the alteration on protein function. Results: We diagnosed a classical cancer predisposition syndrome associated with the respective hematological malignancy in 5/162 patients (3%): Li-Fraumeni (N=1), Constitutional mismatch repair deficiency (CMMRD) (N=1), Nijmegen-Breakage syndrome (NBS) (N=1) and Noonan syndrome (N=2). Additionally we identified in 19/162 patients a pathogenic / likely pathogenic variant (P/LP) in one of the ACGs, including BRIP1, CHEK2, HOXB13, BRCA1, MSH2 and STK11. Strikingly, we observed a high frequency of CHEK2 germline variants in our cohort (15/162) (Figure 1A). The majority of those patients had a leukemia (N=11 BCP-ALL, N=1 T-ALL, N=1 CML) and two patients were diagnosed with a Hodgkin lymphoma. Interestingly, eight different CHEK2 variants including three truncating variants were detected in our cohort. Three variants were recurrent (p.Ile157Thr N=5, p.Ile160Met N=3, p.Thr367Metfs*15 N=2). According to the classification of the American College of Medical Genetics and Genomics 7/8 variants identified in 14 patients were predicted to be pathogenic or likely pathogenic. For two of these variants an impaired function had been already described in the literature. To test the functional consequences of the five remaining variants, we overexpressed these, in comparison to two control CHEK2 variants, in U2OS cells. Four out of seven variants (N=1 truncating, N=1 in-frame deletion, N=2 missense) led to loss of protein expression (Figure 1B) and loss of CHEK2-Thr68 phosphorylation upon irradiation induced DNA damage. Hence, according to the functional analysis, five out of fifteen patients carried a CHEK2 variant impairing its function. Interestingly, 4/5 patients with a pathogenic variant had a BCP-ALL and 1/5 had a BCR-ABL CML that rapidly progressed to lymphoid blast crisis while under imatinib therapy (400 mg/m2). Conclusion/Summary: We identified heterozygous pathogenic variants in ACGs in the germline of 11.7% of children with hematological malignancies by WES-based screening of 162 cases. Strikingly 14/162 patients (8,6%) harbored a P/LP variant in the CHEK2 gene. Functional studies revealed that five patients carried a germline variant leading to loss of CHEK2 expression and/or loss of Thr68 phosphorylation upon irradiation. We conclude that impaired CHEK2 function may be an important germline-encoded host factor predisposing to the development of hematological malignancies in children. Figure 1 (A): Schematic representation of the CHEK2 protein indicating the localization of the identified variants. The length of the bars correlates to the number of patients with the respective CHEK2 variant and the color of the bars to the variant type (green: missense, red: frameshift indels, orange: splicing). (B): Western blot analysis of HA-tagged CHEK2 protein variants ectopically expressed in U2OS cells. GAPDH was used as a loading control. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

A Phase I Clinical Trial of Point-of-Care Manufactured Fresh Anti-CD19/20/22 Chimeric Antigen Receptor T Cells for Treatment of Relapsed or Refractory Lymphoid Malignancies (Non-Hodgkin Lymphoma, Acute Lymphoblastic Leukemia, Chronic Lymphocytic Leukemia, B Prolymphocytic Leukemia)

Background: CD19-targeted CAR-T cells have transformed the treatment of relapsed/refractory B-cell malignancies. However, relapse occurs in over 50% of patients treated with commercial CD19 directed CAR-T due to antigen escape from selective immune pressure either on the target antigen or due to exhaustion and lack of persistence of CAR-T cells. Hence there is an unmet need for next-generation CAR-Ts that have broad antigen recognition and novel costimulatory domains to promote survival and decrease exhaustion of CAR-Ts. Targeting three B-cell antigens simultaneously is a novel approach to prevent antigen-negative relapse while inclusion of the OX40 domain will promote CAR-Ts persistence and expansion. Whether targeting three commonly expressed antigens is feasible or safe and will result in durable remissions is not known. We hypothesize that this trispecific targeting of CD19/20/22 CAR-T construct will be safe and effective in patients with relapsed, refractory B-cell malignancies. Study Design and Methods: This parallel group phase 1 study follows a 3+3 phase 1 design to determine the safety of the infusion of point-of-care manufactured fresh CAR-T cells targeting CD19/20/22 and to find the recommended phase II dose for this cellular therapy. CAR-T cells will be manufactured over 6 days. Patients will be enrolled in one of the two cohorts: Cohort A (single infusion): Non-Hodgkin's Lymphoma (NHL) with lesions <= 5 cm; Indolent lymphomas; B-PLL (B-Pro lymphocytic leukemia); Chronic Lymphocytic Leukemia -CLL (without Richter's transformation), Cohort B (split infusion): B-ALL (B-Acute lymphoblastic leukemia); Lymphoid blast crisis of Chronic myeloid leukemia; CLL (with Richter's transformation); NHL with lesions > 5 cm and/or lymphoblastic lymphoma, or NHL with circulating lymphoma cells. Patients who are CAR-naïve will be enrolled in this study. The study involves infusion of anti-CD19/20/22 CAR-T cells administered after an immunosuppressive conditioning regimen of fludarabine and cyclophosphamide. Cyclophosphamide 60 mg/kg will be infused intravenously over 60 minutes on day -6. Fludarabine 25 mg/m2 will be infused intravenously daily over 30 minutes on days -5 to -3. In each group, patients will be enrolled sequentially to each dose level, starting with dose level 1. Three CAR-T dose-levels: 5x105, 1x106 & 2x106 cells/kg/dose will be explored to determine MTD. For cohort B patients, the total CAR-T cell dose infused, will be divided in two doses, dose 1 (day 0) is 40% of the total dose and dose 2 (day 7) is 60% of total dose. The minimum number of subjects enrolled in the complete study will be 18 (9 per cohort) and the maximum number in dose escalation will be 36 (18 per cohort). Patients in each cohort will be monitored for 30 days before enrollment of next patientTwo patients have been enrolled in the trial and received fresh infusion of Anti CD19/20/22 CAR-T cells and accrual is ongoing. Updates on the initial cohort of patients will be presented at the meeting. ClinicalTrials.gov NCT: NCT05418088 Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Multicenter Phase I Study of Post-Transplant Low-Dose Inotuzumab Ozogamicin to Prevent Relapse of Acute Lymphoblastic Leukemia

Background: The curative potential of allogeneic transplant (alloHCT) in patients with acute lymphoblastic leukemia (ALL) is hampered by relapse, the major cause of treatment failure. Risk factors for relapse include measurable residual disease (MRD) before or after alloHCT, transplantation in second complete remission (CR) or beyond, and reduced intensity conditioning (RIC) regimens. In ALL patients, relapse rates range from 30% to 50%, with most relapses occurring within the first year after alloHCT. After relapse, options for disease control are limited, and consequently overall survival (OS) is poor. Post-alloHCT maintenance may reduce MRD, provide time for a graft-versus-leukemia effect to develop, and ultimately decrease relapse rates and prolong progression-free-survival (PFS) and overall survival (OS). Inotuzumab ozogamicin (INO) is an anti-CD22 monoclonal antibody bound to calicheamicin and approved to treat relapsed ALL. With the hypothesis that low-dose INO would be safe and reduce relapse rates, we conducted a phase I study to define INO dose in this setting. Herein we present the results of this multicenter study. Methods: Eligibility included patients aged 16-75 who underwent alloHCT for CD22+ALL and were in CR after transplant, had a high risk for relapse after alloHCT (MRD before or after alloHCT, transplantation,in second CR or beyond, RIC regimen, lymphoid blast crisis of chronic myeloid leukemia, or Ph-like ALL), had adequate graft and organ function after transplant (platelets > 50 ANC > 1000), did not have active grade III/IV aGVHD or any active liver GVHD, and had no history of hepatic VOD. Patients were consented after transplant. The primary objective was to define a post-alloHCT maximum tolerated dose (MTD) of INO. Secondary objectives included describing the safety profile of INO, determining the rate of hepatic veno-occlusive disease (VOD) in this setting, evaluating non-relapse mortality (NRM), PFS and OS at 1-year post-alloHCT, and determining if INO at these doses is effective at eradicating MRD. Pre-treatment tests included a bone marrow biopsy and aspirate to assess disease state and MRD. The trial design was a 3+3 model. The study treatment consisted of 28-day cycles (initially planned for 4 cycles, increased up to 12 cycles) of INO starting at dose level 0 (0.3mg/m2; n= 4), then 0.4 mg/m2 (n= 3), 0.5 mg/m2 (n= 6) and 0.6 mg/m2 (n= 5) given on cycle day 1. The first cycle was initiated between day 40 and 100 post-alloHCT. Pre-defined dose limiting toxicities (DLT) included VOD, prolonged cytopenia (more than 28 days), severe toxicities ascribed to INO, and death. If there were no DLTs experienced in first two cycles of a cohort, subsequent patients were enrolled in the next highest dose level. Results: We have enrolled 19 patients (18 treated, Table 1) with a median follow up of 18.1 months and a median number of 3 doses (range, 1-9). Only treated patients are included in analyses. The median time to first INO dose was 84 days (range, 47-100) after alloHCT. There was one DLT (prolonged thrombocytopenia) and the study reached the final pre-defined dose of 0.6mg/m2. No VOD was observed. The most common toxicity was thrombocytopenia (42.1% of patients; 31.6% experienced grade 3 or 4 thrombocytopenia), neutropenia (31.6% of patients, 15.8% experienced grade 3 or 4 neutropenia), and nausea/vomiting (42% of patients, all grade 1 or 2). 68% of patients received reduced intensity or non-myeloablative conditioning. OS at 1-year post-alloHCT was 94.4% and PFS was 88.9%. One-year NRM was 5.5%. One patient died of aGVHD on 0.6mg/m2 and one patient relapsed on 0.5mg/m2 at 7 months post-alloHCT. Another patient relapsed from Ph-like ALL 23 months post-alloHCT. Seven of the patients enrolled either had MRD before (n = 4) or after alloHCT (n = 3) as measured by flow cytometry, PCR, or NGS. For patients with MRD before or after alloHCT, 1-year OS and PFS are 100% (Figure 1). The 1-year PFS and OS of recipients of RIC transplants was 83.3% and 91.7%. Conclusions: We have determined that INO at doses of 0.3, 0.4, 0.5 and 0.6mg/m2 was well tolerated and that 0.6 mg/m2 is the MTD. Thrombocytopenia may be the DLT. The low observed relapse rate and favorable safety profile justify investigating low-dose INO as maintenance therapy after alloHCT in a phase II trial. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Early and Deep Molecular Responses Achieved with Frontline Asciminib in Chronic Phase CML - Interim Results from ALLG CML13 Ascend-CML

ATP-competitive BCR::ABL1 inhibitors are effective as frontline treatment for many Chronic Phase (CP) CML patients. However, a significant minority of patients experience treatment failure with currently available drugs, due to resistance or toxicities. Asciminib, a first-in-class drug that inhibits BCR::ABL1 by binding to its myristoyl site, is efficacious in patients who have failed 2 or more lines of treatment (Rea et al, Blood 2021). The Australasian Leukaemia Lymphoma Group (ALLG) CML13 ASCEND-CML trial aims to assess its tolerability and efficacy in the frontline setting. ALLG CML13 is a prospective open-label phase II study, enrolling 100 patients over 15 Australian and New Zealand sites. Patients commence treatment with asciminib 40mg twice a day (BID), and are assessed thereafter according to optimal 2020 ELN targets (BCR::ABL1 ≤10%, ≤1% & ≤0.1% at 3, 6, 12 months respectively); and ≤0.01% at 18 months. Patients with treatment failure (BCR::ABL1 >10% at 3 or 6 months; BCR::ABL1 >1% at 12 or 18 months) continue asciminib and add either imatinib, dasatinib or nilotinib, according to physician preference. Patients who have not failed, but have not achieved optimal response at 6, 12, or 18 months, have their asciminib dose doubled to 80mg BID. Co-primary end points are achievement of early molecular response (EMR, BCR::ABL1 ≤10% at 3 months) and major molecular response (BCR::ABL1 ≤0.1%) by 12 months. We report a protocol-specified interim analysis of EMR that allows for reporting of repeated confidence intervals. This trial received funding support from Novartis. By data cut-off at July 15, 2022, the trial remains open to recruitment with 79/100 patients registered, with a median follow-up of 10 (0-19) months. The most commonly reported grade 3/4 adverse events thus far were neutropenia, and thrombocytopenia (n=5 and 4, 5.5% and 5.2%, respectively); as well as increased lipase and amylase without clinical pancreatitis (n=6 & 2; 7.8% & 2.6%, respectively). Grade 3 increased AST/ALT, anaemia, back pain, abdominal pain and infection were each reported once. Nine patients have discontinued asciminib: 1 with persistent grade 4 cytopenia requiring HSCT, 4 with recurrent asymptomatic lipase elevations (including 1 patient who registered but had not started therapy), 1 withdrawn consent and 1 lost to follow-up. Two patients had resistance: 1 had confirmed loss of MMR at 9 months after reaching a nadir of 0.067% at 6 months, without evidence of a kinase domain or myristoyl site mutation; 1 transformed to lymphoid blast crisis at 6 months with myristoyl site mutations A337T (40%), A337V (10%) and P465S (10%), having previously achieved BCR::ABL1 of 0.37% at 3 months. The molecular analysis for EMR includes all registered patients with at least 3 months of follow-up (n=63); 1 patient missed this assessment, and 3/63 patients had withdrawn by this timepoint (all 4 scored as non-responders). EMR was achieved by 59/63 (93.7%; 99.1% CI 81.1-98.9%). By 3 months, 11 patients have already achieved MR4 or better; 29/63 patients achieved MMR (Fig 1 & 2). Three patients had asciminib dose escalation on protocol: 1 patient with BCR::ABL1 of 1.1% at 6 months, and 2 with BCR::ABL1 of 0.34% and 0.43% at 12 months; subsequent molecular results are pending. Trial interim analysis suggest asciminib to have favorable tolerability and efficacy as frontline treatment for CP-CML. The EMR rate is particularly encouraging, and is likely to translate to improved long term outcomes, with higher achievement of deep molecular responses and potentially treatment-free survival. Equally encouraging is the safety profile and early discontinuation rate. Cytopenia and lipase elevations were the most common adverse events, and appear to be ABL1 inhibitor class effects, though clinically relevant pancreatitis has not occurred. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

B-Lymphoid Blast Phase–Chronic Myeloid Leukemia: Current Therapeutics

Blast crisis (BC) is one of the most dreaded complications of chronic myeloid leukemia (CML). Fortunately, the incidence of BC has diminished markedly in the BCR-ABL tyrosine kinase inhibitor (TKI) era. The primary objective of initial treatment in BC is to achieve a second chronic phase (CP) and to proceed to an allogeneic stem cell transplantation (SCT) in eligible patients. The clinical outcome of patients with CML BC remains unsatisfactory, even with highly potent TKIs, as remissions are short lived and there is an unmet need for novel therapies. We provide a comprehensive summary reviewing the current management of Lymphoid BC.

Minimal residual disease in BCR::ABL1-positive acute lymphoblastic leukemia: different significance in typical ALL and in CML-like disease.

Recently, we defined "CML-like" subtype of BCR::ABL1-positive acute lymphoblastic leukemia (ALL), resembling lymphoid blast crisis of chronic myeloid leukemia (CML). Here we retrospectively analyzed prognostic relevance of minimal residual disease (MRD)and other features in 147 children with BCR::ABL1-positive ALL (diagnosed I/2000-IV/2021, treated according to EsPhALL (n = 133) or other (n = 14) protocols), using DNA-based monitoring of BCR::ABL1 genomic breakpoint and clonal immunoglobulin/T-cell receptor gene rearrangements. Although overall prognosis of CML-like (n = 48) and typical ALL (n = 99) was similar (5-year-EFS 60% and 49%, respectively; 5-year-OS 75% and 73%, respectively), typical ALL presented more relapses while CML-like patients more often died in the first remission. Prognostic role of MRD was significant in the typical ALL (p = 0.0005 in multivariate analysis for EFS). In contrast, in CML-like patients MRD was not significant (p values > 0.2) and inapplicable for therapy adjustment. Moreover, in the typical ALL, risk-prediction could be further improved by considering initial hyperleukocytosis. Early distinguishing typical BCR::ABL1-positive ALL and CML-like patients is essential to enable optimal treatment approach in upcoming protocols. For the typical ALL, tyrosine-kinase inhibitors and concurrent chemotherapy with risk-directed intensity should be recommended; in the CML-like disease, no relevant prognostic feature applicable for therapy tailoring was found so far.