Long Term Survival of Chronic Myeloid Leukemia Patients with Chromosomal Aberrations in Philadelphia Negative Metaphases During Treatment with Tyrosine Kinase Inhibitors

Research Article

Austin J Clin Med. 2022; 8(1): 1043.

Long Term Survival of Chronic Myeloid Leukemia Patients with Chromosomal Aberrations in Philadelphia Negative Metaphases During Treatment with Tyrosine Kinase Inhibitors

Varelas C, Papaioannou G, Gavriilaki E*, Gkaitatzi M, Touloumenidou T, Vadikoliou C, Lalayanni C, Stavroyianni N, Papalexandri A, Batsis I, Sakellari I, Anagnostopoulos A and Athanasiadou A

Hematology & HCT Unit, General Hospital “George Papanikolaou”, Thessaloniki, Greece

*Corresponding author: Eleni Gavriilaki, Department of Hematology - BMT Unit, G. Papanicolaou Hospital, Exochi, 57010, Thessaloniki, Greece

Received: February 02, 2022; Accepted: February 28, 2022; Published: March 07, 2022


Additional clonal aberrations (ACAs) in Philadelphia negative metaphases of Chronic Myeloid Leukemia (CML) patients treated with tyrosine kinase inhibitors (TKIs) were an early noticed event in the course of the treatment plan. However, their biological and clinical implications are not conclusive. In the present study, we investigated their incidence and impact on the prognosis and treatment response. Among 200 CML patients treated in our Department from 2002 to 2019, ACAs in Ph- cells were found in 21 (10.5%), with a median time from initiation of TKIs at 58 months. In addition to monosomy 7, trisomy 8 and loss of chromosome Y, we also identified other numerical and structural abnormalities including add(6)(q27), t(4;15)(q31;q26) t(2;10)(q23;q24), which have never been reported before. We noticed that the number of ACAs developed in Phcells is associated to the number of treatments before the initiation of TKIs. Probability of long-term overall survival at 15 years was 87.1%. Persistent clones were revealed in eight patients. As a result, our study indicates that Ph- ACAs do not impact the outcomes of CML. Aberrations such as monosomy 7 need close monitoring due to their association with increased risk of evolution to myelodysplastic syndrome or acute leukemia.

Keywords: Ph(-) clone, Chronic myeloid leukemia; Tyrosine kinase inhibitors


Chronic Myeloid Leukemia (CML) is a hematopoietic disorder of multipotential stem cells, hallmarked by the cytogenetic event t(9;22)(q34;q11). It results in the generation of the Philadelphia (Ph) chromosome carrying the BCR-ABL1 fusion gene, which plays a central role in the pathogenesis of CML [1,2]. The initiation of tyrosine kinase inhibitors (TKIs) targeting the BCR-ABL oncoprotein as a first line treatment, has significantly improved the prognosis of this disease. As a result, the survival of CML patients is almost identical to that of the general population [3]. Early during the course of treatment with TKIs, it was found that some patients developed additional clonal aberrations (ACAs) in the Ph+ and Ph- cells [4,5]. Although the development of these ACAs in Ph+ is considered a sign of clonal evolution, suggesting disease progression [4], the clinical and biological significance of their emergence in Ph- cells remains unclear [6,7]. The incidence of ACAs in Ph- cells of various treatment groups is estimated to be 2-17% [8,9]. The most common reported ACAs include monosomy 7, trisomy 8 and loss of chromosome Y [10]. In the present study, we report 21 patients who developed ACAs in Ph- cells. In addition to the common reported aberrations, we also identify other structural and numerical abnormalities, some of which are described for the first time. The results from this investigation may be able to provide further information in the effort to understand the pathogenic and prognostic implications of the clonal chromosomal aberrations in CML.

Materials and Methods


We conducted a retrospective analysis of patients diagnosed with CML in our Department (Hematology & HCT Unit, General Hospital “George Papanikolaou” Thessaloniki, Greece) from 2002 to 2019. Imatinib, Dasatinib and Nilotinib were the TKIs used in the treatment plan according to our Department’s protocols. We systematically recorded data of patients identified carrying ACAs in Ph- cells at some point of their course of treatment with TKIs. The study was conducted according to the Declaration of Helsinki and patients provided written informed consent.

Cytogenetic analysis

Conventional cytogenetic analysis was performed on G-banded metaphase cells prepared from unstimulated 24hr and 48hr bone marrow aspirates cultured using standard techniques. At least 20 metaphases were evaluated for each case when satisfactory cell cultures were available. A clonal cytogenetic abnormality was defined as the same numerical gain or structural abnormalities in at least 2 metaphases or the same numerical loss in at least 3 metaphases. The karyotype was documented according to the International System for Human Cytogenomic Nomenclature (ISCN 2016) [11].


BCR-ABL t(9;22) quantitative assay was performed in the Molecular Biology Laboratory in our Department. Briefly, patient RNA was isolated and reverse transcribed to complementary DNA (cDNA). The BCR/ABL and ABL reference gene sequences were amplified in duplicate using multiplexed quantitative real-time PCR. This assay can detect the major, minor, and micro BCR/ABL breakpoints and has an analytical sensitivity of better than 0.002%. Next Generation Sequencing (NGS) was not performed, due to the fact that most patients were diagnosed before it was available.

Statistical analysis

Data were analyzed using the statistical program SPSS 23.0 (IBM SPSS Statistics for Windows, Version 23.0. Armonk, NY: IBM Corp). Descriptive statistics were performed using median (range) for continuous variables, and frequency for categorical variables. Continuous variables were compared using t-test or Mann-Whitney, according to normality. Categorical variables were compared using the chi-square test. Correlation between continuous variables was assessed with the Pearson’s or Spearman’s correlation coefficient. Binary or linear logistic regression was used when appropriate. Kaplan-Meier estimates were used to calculate the probability of overall survival (OS). The level of statistical significance was defined at 0.05.


Chromosomal abnormalities

Twenty one out of 200 CML patients (10.5%) were identified carrying ACAs in Ph- cells at some point of their course of treatment with TKIs. The patients’ characteristics are summarized in Table 1. Median time from diagnosis to their last follow up was 156 months (range 20-240), and a median time from the beginning of treatment with TKIs, 58months (range 3-204). These ACAs were identified in patients receiving the following TKIs: Imatinib, Dasatinib and/or Nilotinib. Sixteen out of 21 patients were male, suggestive of male predominance, while median age at diagnosis was 49 years (range 20-77). Sixteen patients were diagnosed in chronic phase (CP), 3 in accelerating phase (AP) and 2 in blast crisis (BC).

Citation: Varelas C, Papaioannou G, Gavriilaki E, Gkaitatzi M, Touloumenidou T, Vadikoliou C, et al. Long Term Survival of Chronic Myeloid Leukemia Patients with Chromosomal Aberrations in Philadelphia Negative Metaphases During Treatment with Tyrosine Kinase Inhibitors. Austin J Clin Med. 2022; 8(1): 1043.