Clonal chromosomal abnormalities in Philadelphia-negative cells in chronic myeloid leukemia patients treated with nilotinib used in first-line therapy

Cytogenetics in the management of myeloproliferative neoplasms, mastocytosis and myelodysplastic/myeloproliferative neoplasms: Guidelines from the Group Francophone de Cytogénétique Hématologique (GFCH)

Myeloproliferative neoplasms, mastocytosis, myeloid/lymphoid neoplasms with hypereosinophilia and tyrosine kinase gene fusions, and myelodysplastic/myeloproliferative neoplasms are clonal hematopoietic cancers that, with the exception of certain entities, have an indolent course. In addition to their increasingly important role in the diagnosis of these entities, as shown by the recent classification of hematolymphoid tumors in the 5th edition of the World Health Organization and the International Consensus Classification of myeloid neoplasms and acute leukemias, identification of the profile of acquired genetic abnormalities is essential for adapting patient management and early detection of patients at high risk of progression. Alongside molecular abnormalities, cytogenetic abnormalities play an important role in the diagnosis, prognosis and follow-up of these diseases. Here, we review the recent literature on the impact of chromosomal abnormalities in these different entities and provide updated cytogenetic recommendations and guidelines for their management.

Development of Philadelphia chromosome-negative acute myeloid leukemia with IDH2 and NPM1 mutations in a patient with chronic myeloid leukemia who showed a major molecular response to tyrosine kinase inhibitor therapy

Tyrosine kinase inhibitors (TKIs) are standard therapies for chronic myeloid leukemia (CML) that can eradicate Ph-positive leukemic cells. However, disease control is not achievable in a minority of cases, most commonly due to evolution of TKI-resistant clones. There have also been rare cases of emergence of Ph-negative clones with other cytogenetic abnormalities, and, less commonly, development of Ph-negative acute myeloid leukemia (AML), whose molecular pathogenesis is largely unknown. Here we report molecular features of a patient with Ph + CML who developed Ph-negative AML after showing a major molecular response to dasatinib. A 55-year-old man was diagnosed with CML. He achieved a complete cytogenetic response three months after dasatinib therapy but developed AML with normal karyotype 1 year later. After receiving induction and consolidation chemotherapy for AML, the patient achieved complete remission with no evidence of CML under maintenance with bosutinib. Targeted sequencing of serial bone marrow samples identified mutations in IDH2 and NPM1 in the Ph-negative AML cells, which had not been detected in CML cells. These results suggest that Ph-negative AML in this patient originated from a preleukemic population, which might have expanded during or after the successful elimination of CML clones with TKI therapy.

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.

Poor prognosis of chromosome 7 clonal aberrations in Philadelphia-negative metaphases and relevance of potential underlying myelodysplastic features in chronic myeloid leukemia

Clonal chromosome abnormalities in Philadelphia-negative cells could concern chronic myeloid leukemia patients treated by tyrosine kinase inhibitors. The European LeukemiaNet distinguishes -7/del(7q) abnormalities as a “warning”. However, the impact of clonal chromosome abnormalities, and specifically those of -7/del(7q), in Philadelphia-negative cells on clinical outcomes is unclear and based on case-reports showing morphological dysplasia and increased risk of acute myeloid leukemia, suggesting the coexistence of chronic myeloid leukemia and high-risk myelodysplastic syndrome. The aim of this study was to determine whether the impact of -7/del(7q) clonal chromosome abnormalities in Philadelphia-negative cells on the clinical outcome is different from that of other types of abnormalities, and we argue for an underlying associated high-risk myelodysplastic syndrome. Among 102 chronic myeloid leukemia patients with clonal chromosome abnormalities in Philadelphia-negative cells with more than a median of 6 years of follow up, patients with -7/del(7q) more frequently had signs of dysplasia, a lower cumulative incidence of deep molecular response and often needed further treatment lines, with the consequent impact on event-free and progression-free survival. Morphological features of dysplasia are associated with myelodysplastic syndrome/acute myeloid leukemia mutations and compromise the optimal response to tyrosine kinase inhibitors, irrespectively of the type of clonal chromosome abnormalities in Philadelphia-negative cells. However, mutation patterns determined by next-generation sequencing could not clearly explain the underlying high-risk disease. We hereby confirm the pejorative prognostic value of -7/del(7q) clonal chromosome abnormalities in Philadelphia-negative cells and suggest that myelodysplastic features constitute a warning signal that response to tyrosine kinase inhibitors may be less than optimal.

Clonal chromosomal aberrations in Philadelphia negative cells such as monosomy 7 and trisomy 8 may persist for years with no impact on the long term outcome in patients with chronic myeloid leukemia

The appearance of clonal chromosomal aberrations in Philadelphia negative cells (CCA/Ph-) during the treatment of chronic myeloid leukemia (CML) was recently confirmed. Importance of these findings has not been clearly defined. We present data on the time of appearance, persistence, size of the CCA/Ph- clone in terms of drugs used and hematological, cytogenetic and molecular response rates. The focus was on the peripheral blood cytopenias and myelodysplastic changes in the bone marrow microscopic evaluation. In 5 out of 155 (3,2%) CML patients, the persistent presence (up to nine years) of CCA/Ph- was found (monosomy 7 and trisomy 8 in unrelated clones in two patients treated with tyrosine kinase inhibitors; trisomy 8 in two patients on imatinib; trisomy 21 in one patient on interferon alfa treatment). Aberrations were present in median 24% Ph- cells in 3-15 subsequent analyses at different cytogenetic and molecular response time points. No evident myelodysplastic changes nor transformation to MDS/AML occurred in patients with CCA/Ph-. All the patients achieved major molecular response (MMR). It seems that CCA/Ph- presence does not affect the long term outcome in patients with chronic myeloid leukemia. Further complex monitoring of the CML patients with CCA/Ph- is still needed.

[Clinical observation of chromosomal abnormalities in Ph negative cells of chronic myeloid leukemia patients treated with tyrosine kinase inhibitors]

OBJECTIVE

To observe the clinical features, characteristics and outcomes of chromosomal abnormalities in Philadelphia negative cells (Ph(-)CA) of chronic myeloid leukemia (CML) patients treated with tyrosine kinase inhibitor (TKI), and provide the evidence for clinical treatment.

METHODS

We collected and analyzed the clinical and laboratory data of 8 CML patients treated in the affiliated Tumor Hospital of Zhengzhou University from September 2011 to July 2015 and Ph(-)CA occurred after TKI therapy. Karyotypes and BCR-ABL fusion genes were analyzed by R-banding and real-time quantitative polymerase chain reaction (RT-PCR), respectively.

RESULTS

6 cases were male and 2 cases were female, with a median age of 51 (31-75) years old. 6 patients had low Sokal risk scores and 2 had intermediate scores. 4 cases of Ph(-) CA occurred with imatinib, 1 case with dasatinib and 3 cases with nilotinib. The median duration of Ph(-) CA appearance was 12.0 (1.7-34.5) months since taking TKI. Chromosomal abnormality +8 was the most common type in Ph(-)CA, which accounted for 50.0%, followed by -7 (25.0%). When found Ph(-)CA, all patients had complete hematologic response (CHR), but none got main molecular response (MMR). The Ph(-)CA had gone in 7 cases at the end of follow-up and the median duration was 6.2 (2.5-31.5) months. After Ph(-) CA disappeared, 1 patient obtained MMR and 2 cases achieved complete molecular response (CMR), but Ph(+) clone recurred in 1 case.

CONCLUSION

Ph(-)CA can be found in CML patients treated with imatinib, dasatinib and nilotinib, and +8 is the most common Ph(-)CA. So detection of karyotype is significant during treatment. Although most Ph(-)CA can disappear, -7/7q- or other complex karyotypes should be monitored closely.

Transient monosomy 7 in a chronic myelogenous leukemia patient during nilotinib therapy: a case report

Tyrosine kinase inhibitor treated chronic myelogenous leukemia patients with monosomy 7 arising in Philadelphia chromosome negative (Ph−) cells tend to evolve into MDS/AML. However, monosomy 7 in Ph− cells can be a transient finding, and it is not an absolute indication of the emergence of a new myeloid malignancy.

Dasatinib-related Follicular Hyperplasia: An Underrecognized Entity With Characteristic Morphology

Dasatinib, a second-generation tyrosine kinase inhibitor with activity against BCR-ABL1 and other Src family tyrosine kinases, is approved as a first-line treatment option for Philadelphia chromosome-positive chronic myelogenous leukemia (CML) in the chronic phase. Recently, lymphadenopathy with morphologic features of reactive follicular hyperplasia was described in a cohort of patients with CML on long-term dasatinib therapy. However, the complete morphologic and immunophenotypic features of this previously underappreciated adverse effect have not been fully described. Herein, we report 3 cases of unexplained lymphadenopathy resulting in multiple diagnostic procedures in patients with CML and a history of long-term dasatinib therapy. Morphologic examination demonstrated preserved nodal architecture showing hybrid features of progressive transformation of germinal centers and Castleman-type changes in a background of florid follicular hyperplasia. Large germinal centers were disrupted by complex infolding of IgD+ mantle zones arranged as cuffs surrounding perforating capillaries. Other abnormalities variably present included decreased CD20 expression among polytypic B cells and increased Epstein-Barr virus reactivity in scattered paracortical cells and/or individual germinal centers. B-cell clonality studies showed no predominant clonal rearrangements. Consideration of dasatinib-related lymphadenopathy may pre-empt unnecessary repeat diagnostic procedures in patients with CML or other dasatinib-susceptible malignancies and persistent lymphadenopathy.

Clinically silent clonal cytogenetic abnormalities arising in patients treated for lymphoid neoplasms

Newly emerged clonal cytogenetic abnormalities (CCA) in patients with prior cytotoxic therapy are highly concerning for therapy-related myeloid neoplasms (t-MN). In some patients, however, CCA appeared to be clinically "silent". In this study, we describe 25 patients who developed CCA after they received cytotoxic therapies for lymphoid neoplasms but never developed t-MN. These clinically "silent" CCA were always present as single abnormalities, often detected in a small subset of cells, and tended to disappear over time. We conclude that the occurrence of CCA is not always associated with t-MN. Clinical correlation is essential to guide a proper management of these patients.