Atypical chronic myeloid leukaemia: A case of an orphan disease-A multicenter report by the Polish Adult Leukemia Group

Characteristics, primary treatment, and survival of MDS/MPN with neutrophilia: a population-based study

Myelodysplastic and myeloproliferative neoplasms (MDS/MPN) with neutrophilia, until recently called atypical chronic myeloid leukemia (aCML), being part of the MDS/MPN is a very rare disease with poor prognosis. Although emerging data reveal its cytogenetic and molecular profile, integrated survival and treatment data remain scarce. We analyzed a cohort of 347 adult patients diagnosed with MDS/MPN with neutrophilia, registered in the Netherlands Cancer Registry between 2001 and 2019. Our demographic baseline data align with other cohorts. We observed cytogenetic aberrations exclusively in patients aged >65 years, with trisomy 8 being the most common abnormality. We identified 16 distinct molecular mutations, with some patients (16/101) harboring up to 3 different mutations; ASXL1 being the most frequent one (22%). In a multivariable Cox regression analysis, only age, hemoglobin level and allogeneic hematopoietic stem cell transplant (alloHSCT) were associated with overall survival (aged >65 years; hazard ratio [HR] 1.85; P = .001 and alloHSCT HR, 0.51; P = .039). Because no other treatment modality seemed to affect survival and might cause toxicity, we propose that all patients eligible for alloHSCT should, whenever possible, receive an allogeneic transplant. It is imperative that we strive to improve outcomes for patients who are not eligible for alloHSCT. Tackling this challenge requires international collaborative efforts to conduct prospective intervention studies.

Atypical CML: diagnosis and treatment

Atypical chronic myeloid leukemia (aCML) is included in the group of myelodysplastic/myeloproliferative neoplasms by the International Consensus Classification and has been renamed as MDS/MPN with neutrophilia by the fifth edition of World Health Organization classification. It is always characterized by morphologic identification of granulocytic dysplasia with >10% circulating immature myeloid cells, 2 distinguished features that differentiate this disease among the others. Somatic mutations may help to diagnose but are not specifically pathognomonic of the disease, with the most detected including ASXL1, SETBP1, NRAS, KRAS, SRSF2, and TET2 and with low-frequency CBL, CSF3R, JAK2, and ETNK1. The genomic landscape of aCML has been recently unravelling, revealing that SETBP1 and ETNK1 are usually not ancestral but secondary events associated with disease progression. Unfortunately, until now, no consensus on risk stratification and treatment has been developed: Mayo Clinic prognostic score identified as adverse events age >67 years, hemoglobin level <10  g/dL, and TET2 mutations. Although some possible genetic markers have been identified, allogeneic transplant remains the only curative strategy.

Molecular Pathogenesis of BCR-ABL-Negative Atypical Chronic Myeloid Leukemia

Atypical chronic myeloid leukemia is a rare disease whose pathogenesis has long been debated. It currently belongs to the group of myelodysplastic/myeloproliferative disorders. In this review, an overview on the current knowledge about diagnosis, prognosis, and genetics is presented, with a major focus on the recent molecular findings. We describe here the molecular pathogenesis of the disease, focusing on the mechanisms of action of the main mutations as well as on gene expression profiling. We also present the treatment options focusing on emerging targeted therapies.

Atypical Chronic Myeloid Leukemia: New Developments from Molecular Diagnosis to Treatment

Atypical Chronic Myeloid Leukemia, BCR-ABL1 negative (aCML) is a rare hematological entity, included in the group of myelodysplastic (MDS)/myeloproliferative (MPN) overlap syndromes. It is characterized by an aggressive course, a high rate of acute myeloid leukemia (AML) transformation, and a dismal outcome. The clinical presentation includes splenomegaly and leukocytosis with neutrophilia and left-shifted granulocytosis accompanied by granulocytic dysplasia and sometimes multilineage dysplasia. In past years, the disease incidence was likely underestimated, as diagnosis was only based on morphological features. Recently, the improving knowledge in the molecular biology of MDS/MPN neoplasms has made it possible to distinguish aCML from other overlapping syndromes, basing on next generation sequencing. Among the most commonly mutated genes, several involve the Jak-STAT, MAPK, and ROCK signaling pathways, which could be actionable with targeted therapies that are already used in clinical practice, opening the way to tailored treatment in aCML. However, currently, there are few data available for small samples, and allogeneic transplant remains the only curative option for eligible patients.

Atypical Chronic Myeloid Leukemia: Where Are We Now?

Atypical chronic myeloid leukemia, BCR-ABL1 negative (aCML) is a rare myelodysplastic syndrome (MDS)/myeloproliferative neoplasm (MPN) with a high rate of transformation to acute myeloid leukemia, and poor survival. Until now, the diagnosis has been based on morphological grounds only, possibly making the real frequency of the disease underestimated. Only recently, new insights in the molecular biology of MDS/MPN syndromes have deepened our knowledge of aCML, enabling us to have a better molecular profile of the disease. The knowledge gleaned from next generation sequencing has complemented morphologic and laboratory WHO criteria for myeloid neoplasms and can provide greater specificity in distinguishing aCML from alternative MDS/MPN or MPNs. The most commonly mutated genes (>20%) in aCML are SETBP1, ASXL1, N/K-RAS, SRSF2, and TET2, and less frequently (< 10%) CBL, CSFR3, JAK2, EZH2, and ETNK1. Several of these mutations affect the JAK-STAT, MAPK, and ROCK signaling pathways, which are targetable by inhibitors that are already in clinical use and may lead to a personalized treatment of aCML patients unfit for allogeneic transplant, which is currently the only curative option for fit patients. In this review, we present two emblematic clinical cases and address the new molecular findings in aCML and the available treatment options.

Atypical CML- the role of morphology and precision genomics

Atypical chronic myeloid leukemia is an esoteric myeloid malignancy with features of both myeloproliferative and myelodysplastic syndromes. This disease is characterized primarily by morphologic-based criteria, and has clinical and molecular features overlapping with other myeloid malignancies. No one molecular abnormality is specific, and multiple mutations are often present in various combinations, due to the malignant multi-step clonal evolution of myeloid malignancies. In this review, we will address what we know about atypical chronic myeloid leukemia; evaluate how the molecular landscape in myeloid malignancies overlaps, and discuss what we can learn by incorporating individualized precision genomic strategies.

Atypical chronic myeloid leukaemia - a rare subtype of myelodysplastic/myeloproliferative neoplasm

Atypical chronic myeloid leukaemia (aCML) belongs to the group of myelodysplastic/myeloproliferative neoplasms. Changing diagnostic criteria and the rarity of the disease, with incidence approximately 100-times lower than the incidence of BCR-ABL1-positive chronic myeloid leukaemia, result in limited knowledge on aCML. At present the diagnosis is made based on the presence of granulocytic lineage dysplasia and precisely defined quantitative peripheral blood criteria, after exclusion of other molecularly defined myeloid neoplasms. Distinctive cytogenetic and molecular changes for aCML are missing, although recently SETBP1 mutations were described in a significant proportion of patients. The majority of patients are male and elderly. The prognosis of aCML patients is very bad, with median overall survival ranging between 10.8 and 25 months, and acute myeloid leukaemia-free survival amounting to approximately 11 months. No treatment recommendations can be made based upon current evidence, although allogeneic haematopoietic stem cell transplantation seems to be able to induce long-term remission in eligible patients.