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

Clinical implications of clonal chromosomal abnormalities in Philadelphia negative cells in CML patients after treated with tyrosine kinase inhibitors

Emergence of clonal chromosomal abnormalities in Philadelphia chromosome-negative (CCA/Ph-) cells in chronic myeloid leukemia (CML) patients during the treatment with tyrosine kinase inhibitors (TKIs) is an interesting phenomenon. Although previous studies revealed some potential impact of CCA/Ph- on CML patients' outcome, clinical significance of CCA/Ph- in CML patients remains to be further elucidated. We retrospectively reviewed the patients with CML evaluated at Genoptix Medical Laboratory in Carlsbad, California from 2005 to 2015. Twenty-four CML patients with CCA/Ph- cells were identified. These include 18 patients with single chromosomal abnormality, 4 patients with double chromosomal abnormalities, and two patients with complex cytogenetic abnormalities. In addition to trisomy 8 and monosomy 7, we identified that 20q- was also a common abnormality in CCA/Ph- cells. Most of the patients with CCA/Ph- cells demonstrated no significant dysplasia or increased blasts with two exceptions: one patient with persistent 7q- exhibiting mild dysmegakaryopoiesis, suggestive of an early evolving myelodysplastic syndrome, and another patient with complex cytogenetic abnormalities who developed acute myeloid leukemia after gained MLL amplification. One patient with complex cytogenetic abnormalities showed optimal response to TKI treatment, no overt dysplasia, and no disease progression during almost 4-years of follow-up. More interestingly, FISH tests could identify more cases with double chromosomal abnormalities and these cases showed suboptimal responses to TKI treatments. Our observation indicates that 20q- was also a common abnormality in CCA/Ph- cells, further FISH tests revealed additional CCA/Ph-, and the majority of CML patients with two or more chromosomal abnormalities in Ph- cells showed inferior response to TKI treatments. The results of our study suggest that CML cases with CCA/Ph- may represent a group of patients with heterogeneous genetic alterations.

Occurrence of chromosomal abnormalities in Philadelphia chromosome-negative metaphases in patients with chronic-phase chronic myeloid leukemia undergoing TKI treatments

Forty-three chromosomal abnormalities in Philadelphia-negative metaphases (Ph-CAs) appeared in 35 of 432 patients in chronic phase chronic myeloid leukemia (CP-CML) undergoing tyrosine kinase inhibitor (TKI) treatments. These CAs were mostly common in trisomy-8 (16 cases), trisomy-Y (five cases), and monosomy-7 (five cases). Furthermore, Ph- CAs were significantly associated with higher platelet count (494 × 10⁹/L vs. 326 × 10⁹/L, p = .006), and higher incidence of true clonal evolution in Ph-positive metaphase (22.9% vs. 9.1%, p = .017). Additionally, patients with Ph- CAs had worse rates of complete cytogenetic remission (76% vs. 86%, p = .0091), major molecular remission (55% vs. 76%, p = .001), progression-free survival (47% vs. 86%, p < .001), but a similar overall survival rates compared to those in patients without Ph- CAs. In conclusion, Ph- CAs may predict worse response to TKI therapies and survival in patients with CP-CML, thus requiring close cytogenetic monitoring.

Chronic Myeloid Leukemia: Beyond BCR-ABL1

PURPOSE OF REVIEW

In this review, we emphasize up-to-date practical cytogenetic and molecular aspects of chronic myeloid leukemia (CML) and summarize current knowledge on tyrosine kinase inhibitor (TKI) resistance and treatment response monitoring of CML.

RECENT FINDINGS

The introduction of TKIs has changed the natural course of CML and markedly improved patient survival. Over the past decades, many research efforts were devoted to elucidating the leukemogenic mechanisms of BCR-ABL1 and developing novel TKIs. More recent studies have attempted to answer new questions that have emerged in the TKI era, such as the cytogenetic and molecular bases of treatment failure and disease progression, the clinical impact of genetic aberrations in Philadelphia chromosome (Ph)-positive and Ph-negative cells, and the biological significance of Ph secondarily acquired during therapy of other hematological neoplasms. Recent progresses in the understanding of the cytogenetic and molecular mechanisms underlying therapeutic failure and disease progression have improved the risk stratification of CML and will be helpful in the design of novel therapeutic strategies.

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.

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 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.

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.

Transient presence of clonal chromosomal aberrations in Ph-negative cells in patients with chronic myeloid leukemia remaining in deep molecular response on tyrosine kinase inhibitor treatment

Advancements in treatment of chronic myeloid leukemia (CML) turned this formerly fatal neoplasm into a manageable chronic condition. Therapy with tyrosine kinase inhibitors (TKIs) often leads to significant reduction of disease burden, known as the deep molecular response (DMR). Herein, we decided to analyze the cohort of CML patients treated in our center with TKIs, who obtain and retain DMR for a period longer than 24 months. The aim of the study was to evaluate the frequency of clonal cytogenetic aberrations in Philadelphia-negative (Ph-) cells in patients with DMR during TKI treatment. The analyzed data was obtained during routine molecular and cytogenetic treatment monitoring, using G-banded trypsin and Giemsa stain (GTG) karyotyping and reverse transcription quantitative PCR. We noticed that approximately 50% of patients (28 of 55) in DMR had, at some follow-up point, transient changes in the karyotype of their Ph- bone marrow cells. In 9.1% of cases (5 of 55), the presence of the same aberrations was observed at different time points. The most frequently appearing aberrations were monosomies of chromosomes 19, 20, 21, and Y. Statistical analysis suggests that the occurrence of such abnormalities in CML patients correlates with the TKI treatment time.

-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-.