Monosomy 7 with severe myelodysplasia developing during imatinib treatment of Philadelphia-positive chronic myeloid leukemia: two cases with a different outcome

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.

Characterisation of clonal Philadelphia-negative cytogenetic abnormalities in a large cohort of chronic myeloid leukaemia

BACKGROUND

Clonal Philadelphia (Ph)-negative cytogenetic abnormalities (CPCA) have been reported in chronic myeloid leukaemia (CML) patients treated with either interferon or tyrosine kinase inhibitor (TKI). However, the incidences and types of these cytogenetic abnormalities after treatment vary due to the limited populations enroled.

METHODS

We analysed the frequency and types of CPCA in a cohort of 607 CML patients in the chronic phase after TKI treatment. We also followed up these CPCA with a median of 31.8 months (range from 11 to 63 months) from diagnosis and investigated their effects on disease progression.

RESULTS

We found 18 out of 607 CML patients had cytogenetic abnormality in the Ph-negative cells with an incidence of 3%. In total, six types of chromosomal abnormalities have been identified in these 18 patients with the majority of them aneuploidy abnormalities, especially the trisomy 8. Four of 18 patients (22.2%) were noted to have several abnormalities in the Ph-negative cells. Furthermore, follow-up studies of these CPCA showed that they could be either persistent or transient (15 vs 3 patients), and may not affect disease progression since none of them developed transformed myelodysplasia or transformed acute myeloid leukaemia.

CONCLUSION

Three percent of CML patients in the chronic phase were observed to have CPCA during TKI treatment. Our results suggest that the detection of CPCA in CML may not predict disease progression.

TKI rotation-induced persistent deep molecular response in multi-resistant blast crisis of Ph+ CML

In chronic myeloid leukemia (CML) resistance against one or more BCR-ABL1 tyrosine kinase inhibitors (TKI) remains a clinical challenge. Preclinical data suggest that TKI combinations may overcome resistance. We report on a heavily pre-treated 78 year-old female patient with CML who developed multi-resistant blast crisis with bone marrow fibrosis and a Ph- clone. Treatment with ponatinib resulted in blast cell clearance, decrease in fibrosis, and disappearance of BCR-ABL1, but also in severe thrombocytopenia with bleedings requiring platelet transfusions. We therefore switched from ponatinib to bosutinib. During bosutinib, platelet counts recovered. However, after 6 months, BCR-ABL1 mRNA levels increased to > 1%. Therefore, we ´switched back´ to ponatinib, and this was again followed by disappearance of BCR-ABL1 and a decrease in platelets. During the next 2 years, we applied ponatinib and bosutinib in continuous rotation-cycles and added hydroxyurea in order to suppress all sub-clones and to balance between efficacy and potential side effects following the principle of personalized medicine. With this approach the patient remained in complete molecular response and reached normal blood counts and a normal quality of life without vascular or other side effects. In conclusion, TKI rotation is a novel potent approach to suppress multiple resistant sub-clones and to balance between clinical efficacy and side effects in patients with advanced CML. Clinical trials are now warranted to show that TKI-rotation is in general safe and effective in these patients.

Dasatinib and Azacitidine Followed by Haploidentical Stem Cell Transplant for Chronic Myeloid Leukemia with Evolving Myelodysplasia: A Case Report and Review of Treatment Options

BACKGROUND CML presenting with a variant Philadelphia translocation, atypical BCR-ABL transcript, additional chromosomal aberrations, and evolving MDS is uncommon and therapeutically challenging. The prognostic significance of these genetic findings is uncertain, even as singular aberrations, with nearly no data on management and outcome when they coexist. MDS evolving during the course of CML may be either treatment-associated or an independently coexisting disease, and is generally considered to have an inferior prognosis. Tyrosine kinase inhibitors (TKI) directed against BCR-ABL are the mainstay of treatment for CML, whereas treatment modalities that may be utilized for MDS and CML include allogeneic stem cell transplant and - at least conceptually - hypomethylating agents. CASE REPORT Here, we describe the clinical course of such a patient, demonstrating that long-term combined treatment with dasatinib and azacitidine for coexisting CML and MDS is feasible and well tolerated, and may be capable of slowing disease progression. This combination therapy had no deleterious effect on subsequent potentially curative haploidentical bone marrow transplantation. CONCLUSIONS The different prognostic implications of this unusual case and new therapeutic options in CML are discussed, together with a review of the current literature on CML presenting with different types of genomic aberrations and the coincident development of MDS. Additionally, this case gives an example of long-term combined treatment of tyrosine kinase inhibitors and hypomethylating agents, which could be pioneering in CML treatment.

Clonal chromosomal abnormalities appearing in Philadelphia chromosome-negative metaphases during CML treatment

Clonal chromosomal abnormalities in Philadelphia chromosome-negative (CCA/Ph^-) metaphases emerge as patients with chronic phase chronic myeloid leukemia (CP-CML) are treated with tyrosine kinase inhibitors (TKIs). We assessed the characteristics and prognostic impact of 598 patients with CP-CML treated on clinical trials with various TKIs. CCA/Ph^- occurred in 58 patients (10%); the most common were -Y in 25 (43%) and trisomy 8 in 7 patients (12%). Response to TKI therapy was similar for patients with CCA/Ph^- and those without additional chromosomal abnormalities (ACAs). We further categorized CCA/Ph^- into those in which -Y was the only clonal abnormality, and all others. We found that patients with non -Y CCA/Ph^- had worse failure-free survival (FFS), event-free survival (EFS), transformation-free survival (TFS), and overall survival (OS) compared with those without ACAs with the following 5-year rates: FFS (52% vs 70%, P = .02), EFS (68% vs 86%, P = .02), TFS (76% vs 94%, P < .01), and OS (79% vs 94%, P = .03). In a multivariate analysis, non -Y CCA/Ph^- increased the risk of transformation or death when baseline characteristics were considered with a hazard ratio of 2.81 (95% confidence interval, 1.15-6.89; P = .02). However, this prognostic impact was not statistically significant when achieving BCR-ABL <10% at 3 months was included in the analysis. In conclusion, non -Y CCA/Ph^- are associated with decreased survival when emerging in patients with chronic-phase CML across various TKIs. This trial was registered at www.clinicaltrials.gov as #NCT00048672, #NCT00038649, and #NCT00050531 (imatinib); #NCT00254423 (dasatinib); #NCT00129740 (nilotinib); and NCT01570868 (ponatinib).

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.

Ataxia-Pancytopenia Syndrome Is Caused by Missense Mutations in SAMD9L

Ataxia-pancytopenia (AP) syndrome is characterized by cerebellar ataxia, variable hematologic cytopenias, and predisposition to marrow failure and myeloid leukemia, sometimes associated with monosomy 7. Here, in the four-generation family UW-AP, linkage analysis revealed four regions that provided the maximal LOD scores possible, one of which was in a commonly microdeleted chromosome 7q region. Exome sequencing identified a missense mutation (c.2640C>A, p.His880Gln) in the sterile alpha motif domain containing 9-like gene (SAMD9L) that completely cosegregated with disease. By targeted sequencing of SAMD9L, we subsequently identified a different missense mutation (c.3587G>C, p.Cys1196Ser) in affected members of the first described family with AP syndrome, Li-AP. Neither variant is reported in the public databases, both affect highly conserved amino acid residues, and both are predicted to be damaging. With time in culture, lymphoblastic cell lines (LCLs) from two affected individuals in family UW-AP exhibited copy-neutral loss of heterozygosity for large portions of the long arm of chromosome 7, resulting in retention of only the wild-type SAMD9L allele. Newly established LCLs from both individuals demonstrated the same phenomenon. In addition, targeted capture and sequencing of SAMD9L in uncultured blood DNA from both individuals showed bias toward the wild-type allele. These observations indicate in vivo hematopoietic mosaicism. The hematopoietic cytopenias that characterize AP syndrome and the selective advantage for clones that have lost the mutant allele support the postulated role of SAMD9L in the regulation of cell proliferation. Furthermore, we show that AP syndrome is distinct from the dyskeratoses congenita telomeropathies, with which it shares some clinical characteristics.

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.

Bone marrow fibrosis may be an effective independent predictor of the 'TKI drug response level' in chronic myeloid leukemia

OBJECTIVES

The aim of this study was to assess bone marrow (BM) fibrosis and dysplasia in chronic myeloid leukemia (CML) patients receiving the first-generation tyrosine kinase inhibitor (TKI), imatinib, or second-generation TKIs, dasatinib, and nilotinib. We further investigated whether CML under TKI is associated with dysplastic BM changes during the clinicopathological course of the disease.

METHODS

In total, pre-treatment BM paraffin blocks of biopsy specimens were available for 41 adult patients diagnosed with chronic phase CML. Post-treatment BM aspirate clot and core biopsy samples were reviewed for fibrosis and dyshematopoiesis.

RESULTS

Overall, 13 (31.7%) patients achieved a complete cytogenetic response with imatinib treatment, with no events. In 25 patients, imatinib was discontinued owing to primary or secondary resistance. In patients with initial dysmyelopoiesis, the rate of BM fibrosis was 82.4 versus 47.6% for other patient groups (P = 0.02). Overall, 24 patients with newly diagnosed CML showed marrow fibrosis, among which 19 (79.1%) had imatinib resistance. However, only 5 out of 15 patients (33.5%) without marrow fibrosis had imatinib resistance (P = 0.08). Discussion Our findings indicate that BM fibrosis is an independent predictor of the 'TKI drug response level' in CML and support its inclusion as a critical pathobiological parameter for decision-making with regard to TKI drug selection de novo, calculation of prognosis at the onset of disease, and monitoring response to TKI in the long-term disease course of CML.

-7/7q- syndrome in myeloid-lineage hematopoietic malignancies: attempts to understand this complex disease entity

The recurrence of chromosomal abnormalities in a specific subtype of cancer strongly suggests that dysregulated gene expression in the corresponding region has a critical role in disease pathogenesis. -7/7q-, defined as the entire loss of chromosome 7 and partial deletion of its long arm, is among the most frequently observed chromosomal aberrations in myeloid-lineage hematopoietic malignancies such as myelodysplastic syndrome and acute myeloid leukemia, particularly in patients treated with cytotoxic agents and/or irradiation. Tremendous efforts have been made to clarify the molecular mechanisms underlying the disease development, and several possible candidate genes have been cloned. However, the study is still underway, and the entire nature of this syndrome is not completely understood. In this review, we focus on the attempts to identify commonly deleted regions in patients with -7/7q-; isolate the candidate genes responsible for disease development, cooperative genes and the factors affecting disease prognosis; and determine effective and potent therapeutic approaches. We also refer to the possibility that the accumulation of multiple gene haploinsufficiency, rather than the loss of a single tumor suppressor gene, may contribute to the development of diseases with large chromosomal deletions such as -7/7q-.

Clonal cytogenetic abnormalities after tyrosine kinase inhibitor therapy in Ph+ ALL resolution after decitabine therapy

Mixed chimerism and presence of minimal residual disease after stem cell transplantation (SCT) usually predict leukemia recurrence. In Philadelphia chromosome positive (Ph+) leukemia tyrosine kinase inhibitors can restore remission. These agents can induce clonal cytogenetic abnormalities in the Philadelphia negative cell population (CCA/Ph-), which may rarely progress to acute myeloid leukemia. A child with Ph+ acute lymphoblastic leukemia showed mixed donor chimerism and persistent bcr-abl transcripts after a matched sibling SCT. There was no response to tyrosine kinase inhibitor (TKI) therapy, but she has remained hematologically normal for more than 5 years. CCA/Ph- was detected but resolved with hypomethylating therapy.

Telomere loss in Philadelphia-negative hematopoiesis after successful treatment of chronic myeloid leukemia: evidence for premature aging of the myeloid compartment

Telomere shortening, a well-known marker of aging and cellular stress, occurs under several conditions in the hematopoietic compartment, including aplastic anemia and following iatrogenic noxae. We decided to verify whether pathological telomere erosion also arises in restored Philadelphia-negative (Ph-negative) hematopoiesis following successful treatment of chronic myeloid leukemia (CML). Eighty-one CML patients in complete cytogenetic remission were compared to 76 age-matched healthy subjects. Myeloid cells of CML patients had shorter telomeres than controls (6521 bp vs 7233 bp, p<0.001). This difference was specific for the myeloid compartment, since it was not observed in lymphoid cells (6774 bp vs 6909 bp, p=0.620). Acquired Ph-negative cytogenetic abnormalities (p=0.010), lack of complete molecular remission (p=0.016) and age (p=0.013) were independent predictors of telomere shortening. Telomere dynamics were assessed over a median follow-up period of 22 months. We documented accelerated non-physiological ongoing telomere shortening in 17/59 CML patients (28%). Patients experiencing grade 2-4 hematological toxicity, during CML remission possessed significantly shorter telomeres compared to those lacking toxicity (p=0.005 for any toxicity, p=0.007 for anemia). CML patients suffer from significant and often ongoing telomere stress resulting in premature and selective aging of the myeloid compartment which might have long-term consequences on function and integrity of Ph-negative hematopoiesis.

Factors influencing a second myeloid malignancy in patients with Philadelphia-negative -7 or del(7q) clones during tyrosine kinase inhibitor therapy for chronic myeloid leukemia

The detection of Philadelphia-negative (Ph(neg)) cells with non-random karyotypic abnormalities after tyrosine kinase inhibitor (TKI) therapy of chronic myeloid leukaemia (CML) can be associated with myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML). To our knowledge, however, there have been no studies on variables influencing the risk of MDS/AML in patients with specific Ph(neg) karyotypes. We systematically examined studies reporting -7 or del(7q) within Ph(neg) cells in TKI-treated CML patients, and abstracted clinical and cytogenetic data from individual reports into a standardized format for further analysis. Of 53 patients, 43 had Ph(neg) -7 clones [as the sole abnormality (-7(sole)) in 29, or with other clones (-7(dual)) in 14], and del(7q) was present in 10. A total of 16/51 evaluable patients, all with -7, transformed to MDS/AML. Transformation was more frequent (15/16 patients) within 6 months of Ph(neg) -7 detection rather than subsequently (P < 0.0001). At first detection after TKI therapy, Ph(neg) abnormal clones comprised ≥50% of Ph(neg) cells in a greater proportion of patients with -7 than del(7q) (P = 0.035). Upon comparing -7(sole) and -7(dual), the latter was likely to be transient (P = 0.004), and AML was frequently observed with persistent -7 clones (P = 0.03). By logistic regression analysis (n = 36), clone size (P = 0.017), time-to-detection longer than 15 months (P = 0.02), and CML response (P = 0.085) were associated with MDS/AML. Validation of these novel associations in registry-based studies will help develop predictive criteria that define the MDS/AML risk in individual patients.

Myelodysplastic syndrome with Ph negative monosomy 7 chromosome following transient bone marrow dysplasia during imatinib treatment for chronic myeloid leukemia

We describe a 60-year-old Japanese patient with chronic myeloid leukemia (CML) who developed myelodysplastic syndrome (MDS) with Ph negative monosomy 7 chromosome following transient bone marrow dysplasia during imatinib treatment. Most cases that developed chromosomal abnormality in Ph negative cells during imatinib therapy were reported to have less clinical implications, while rare cases developed MDS/AML. The present case suggested that metaphase karyotype analysis and bone marrow examination should be performed for the long term follow-up under imatinib treatment in cases showing cytopenia. The results also suggested that monosomy 7 in Ph negative cells may be an indicator of a poor prognosis.

Genetic analysis of dasatinib-treated chronic myeloid leukemia rapidly developing into acute myeloid leukemia with monosomy 7 in Philadelphia-negative cells

Despite the recent success of tyrosine kinase inhibitors (TKIs) in the treatment of chronic myeloid leukemia (CML), approximately 2-17% of patients develop clonal cytogenetic changes in the Philadelphia-negative (Ph(-)) cell population. A fraction of these patients, in particular those displaying trisomy 8 or monosomy 7, are at risk of developing a myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML). Consequently, there is a need to characterize the clinical features of such cases and to increase our understanding of the pathogenetic mechanisms underlying the emergence of clonal cytogenetic changes in Ph(-) cells. To date, most cases reported have received treatment with imatinib. Here we describe the case of a patient with CML who developed monosomy 7 in Ph(-) cells during dasatinib therapy. At 20 months after dasatinib initiation, the patient developed MDS, which rapidly progressed into AML. Genome-wide 500K SNP array analysis of the monosomy 7 clone revealed no acquired submicroscopic copy number changes. Given the strong association between monosomy 7 and mutation of genes involved in the RAS pathway in juvenile myelomonocytic leukemia, we also screened for pathogenetic variants in KRAS, NRAS, and PTPN11, but did not detect any changes.

Chronic myelogenous leukemia, BCR-ABL1+

Session 1 of the 2007 Workshop of the Society for Hematopathology/European Association for Haematopathology focused on chronic myelogenous leukemia, BCR-ABL1+ (CML). CML is a myeloproliferative neoplasm arising at the level of a pluripotent stem cell and consistently associated with the BCR-ABL1 fusion gene. CML most commonly manifests in a chronic phase of the disease with neutrophilic leukocytosis, and the demonstration of the Philadelphia chromosome is the ultimate confirmation of the diagnosis. However, in select cases, the initial diagnosis remains challenging, and a number of issues pertaining to the manifestations and disease evolution remain unresolved. These issues have been illustrated by the cases submitted to our workshop and include unusual manifestations of CML, including manifestation in the accelerated and/or blast phase, and patterns of disease progression and therapy resistance in the era of protein tyrosine kinase inhibitor therapy.

Emerging stem cell concepts for imatinib-resistant chronic myeloid leukaemia: implications for the biology, management, and therapy of the disease

Chronic myeloid leukaemia (CML) is a myeloid neoplasm defined by the BCR/ABL oncoprotein that is considered essential for leukaemogenesis and accumulation of neoplastic cells. The BCR/ABL kinase inhibitor imatinib is an effective agent in most patients and can now be regarded as front-line therapy. Hence, intrinsic and acquired resistance to imatinib has been described and is an emerging challenge in clinical practice. While CML stem cells display primary resistance, stem cell subclones may, in addition, acquire imatinib-resistant mutants of BCR/ABL. Other factors that are considered to contribute to stem cell resistance include the genetic background, clonal evolution, additional biological features of subclones, gene amplifications, silencing of tumour suppressor genes and specific pharmacological aspects. In this article, mechanisms of resistance of CML (stem) cells against imatinib and other BCR/ABL inhibitors are discussed, together with strategies to overcome and/or to prevent resistance with available drugs or novel anti-leukaemic approaches.

Secondary myelodysplastic syndrome in a patient with Philadelphia-positive acute lymphoblastic leukemia after achieving a major molecular response with hyperCVAD plus imatinib mesylate

The addition of imatinib to high-intensity chemotherapy has improved the outcome of patients with Philadelphia chromosome (Ph)-positive acute lymphoblastic leukemia (ALL). However, the possible long-term side effects of this combination are not yet known. Development of new clonal abnormalities in complete cytogenetic remission after treatment with imatinib has been reported in patients with chronic myeloid leukemia but not in patients with Ph-positive ALL. Here, we present a patient with Ph-positive ALL who received hyperCVAD plus imatinib and achieved hematologic, cytogenetic, and major molecular responses. The patient then developed myelodysplastic syndrome and solitary central nervous system relapse of ALL.