Tyrosine Kinase Inhibitor Cessation Research Articles

Prolonged disease control despite ALK inhibitor discontinuation in advanced ALK-positive NSCLC

Introduction: EML4-ALK is an oncogenic driver, seen in around five per cent of advanced non-small-cell lung cancer (NSCLC) patients, which can be targeted with anaplastic lymphoma kinase tyrosine kinase inhibitors with great response rates. Disease flare refers to sudden rapid disease worsening on tyrosine kinase inhibitors (TKI) discontinuation, which is associated with shorter survival and worse outcomes. Here, we review cases previously published in the literature where patients developed disease flares, and contrast this with our patients who had prolonged survival despite TKI discontinuation. Case description: We report three different patients with advanced ALK-positive NSCLC seen at our institute, who had EML4-ALK translocation variant 1 oncogenic driver on next-generation sequencing. They received treatment with several different ALK inhibitors before opting to discontinue TKI. They were able to come off TKI safely without developing disease flare and had prolonged survival. Discussion: Shorter time to progression on TKI, presence of symptoms with disease progression or central nervous system/pleural metastasis have been previously linked with development of flare, although this was not seen in our case series. Tumour response at the time of treatment discontinuation, line of therapy, overall disease burden, fusion variant and co-alteration status can affect the prognosis of these patients after ALK TKI cessation. In particular, variant 1 and wild-type TP53 status may be a suitable patient population for dose optimisation strategies. Intermittent TKI dosing strategies may help to avoid acquiring resistance mutations and prevent long-term treatment toxicities. Conclusion: It is important for clinicians to identify patients at risk for developing disease flare on TKI discontinuation to improve outcomes. Intermittent TKI dosing strategies require further investigation.

European Stop Tyrosine Kinase Inhibitor Trial (EURO-SKI) in Chronic Myeloid Leukemia: Final Analysis and Novel Prognostic Factors for Treatment-Free Remission.

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.The European Stop Kinase Inhibitors (EURO-SKI) study is the largest clinical trial for investigating the cessation of tyrosine kinase inhibitors (TKIs) in patients with chronic myeloid leukemia in stable deep molecular remission (DMR). Among 728 patients, 434 patients (61%; 95% CI, 57 to 64) remained in major molecular response (MMR) at 6 months and 309 patients of 678 (46%; 95% CI, 42 to 49) at 36 months. Duration of TKI treatment and DMR before TKI stop were confirmed as significant factors for the prediction of MMR loss at 6 months. In addition, the type of BCR::ABL1 transcript was identified as a prognostic factor. For late MMR losses after 6 months, TKI treatment duration, percentage of blasts in peripheral blood, and platelet count at diagnosis were significant factors in multivariate analysis. For the entire study period of 36 months, multiple logistic regression models confirmed duration of treatment, blasts, and transcript type as independent factors for MMR maintenance. In addition to the duration of treatment, transcript type as well as blasts in peripheral blood at diagnosis should be considered as important factors to predict treatment-free remission.

The Mozart effect in chronic myeloid leukaemia.

Clinical research has not been able to establish whether the differences between first- and second-generation BCR-ABL 1 kinase inhibitors are clinically relevant with regard to outcome. In the study by Alcazer etal., a relevant difference seems to emerge-paradoxically in the absence of the drugs-as demonstrated by differences in the relapse kinetics after cessation of therapy. Commentary on: Alcazer etal. Kinetics of molecular recurrence after tyrosine kinase inhibitor cessation in chronic phase chronic myelogenous leukaemia patients. Br J Haematol 2024;204:1536-1539.

Treatment-free remission after a second TKI discontinuation attempt in patients with Chronic Myeloid Leukemia re-treated with dasatinib – interim results from the DAstop2 trial

Tyrosine kinase inhibitor (TKI) discontinuation in chronic myeloid leukemia (CML) has become part of routine care for patients with a sustained deep molecular response (DMR). Approximately 50% experience a molecular relapse upon TKI cessation. Most of them quickly regain DMR upon TKI resumption. Whether these patients can achieve a second treatment-free remission (TFR) remains unclear. DAstop2 (ClinicalTrials.gov ID: NCT03573596) is a prospective study including patients with a failed first TFR attempt re-treated with any TKI for ≥ one year. Upon entering the study, patients received the TKI dasatinib for additional two years. Patients with sustained DMR for ≥1 year qualified for a second TKI stop. Ninety-four patients were included between Oct 2017-Dec 2021. At the time of data analysis, 62 patients had attempted a 2nd stop. After a median follow-up of 27 months from 2nd stop, TFR rates were 61, 56 and 46% at 6, 12 and 24 months respectively. No progression to advanced stage disease was seen and 87% had re-achieved MR4 within a median of 3 months from TKI re-initiation. In summary, we show that a 2nd TFR attempt after dasatinib treatment is safe, feasible and TFR rates seem in the range of those reported in trials of a first TKI stop.

Age-Related Clonal Hematopoiesis Mutations Detected at the Time of Stopping Tyrosine Kinase Inhibitor Therapy Predict the Achievement of Treatment-Free Remission for Patients with CML

Background The gain of mutations with a competitive advantage in hematopoietic cells of healthy individuals is common with aging and termed clonal hematopoiesis of indeterminate potential (CHIP). Through sequencing studies we detected CHIP related mutants in chronic myeloid leukemia (CML) patients in deep molecular response. CHIP mutants may provide a selective growth advantage to non-leukemic cells, driving their clonal expansion in remission and potentially influencing treatment-free remission (TFR) if CHIP clones outcompete an emerging BCR:: ABL1 clone. Aim To determine if CHIP mutants detected at the time of stopping tyrosine kinase inhibitor (TKI) therapy could influence achievement of TFR. Methods An RNA-based sequencing method targeting 17 of the most frequently mutated CHIP genes was developed and applied to blood samples of 150 patients who attempted TFR. The median follow up of patients in TFR was 71 months. CHIP mutants met strict criteria for pathogenicity based on their potential to confer growth and survival advantages, i.e. the same criteria as cancer driver mutations. Variant allele frequency (VAF) of ≥0.4% was reproducibly detected. CHIP at the time of cessation, termed CHIP TOC, was defined as 1) ≥1 CHIP mutant with VAF ≥2.0% (n=30 patients) or 2) a novel criterion for patients with multiple CHIP mutants where the combined VAF was ≥2.0% (n=7). Overall, 25/37 patients (68%) with CHIP TOC had multiple mutations, range 2-7. Results CHIP TOC was detected in 37/150 patients (25%). The average age of patients with CHIP TOC was 66.3 years vs 58.0 for those without, P=.0004, which is consistent with the age related nature of CHIP. No patient aged <40 had CHIP TOC, whereas 44% of patients ≥70 had CHIP TOC. Twelve genes were mutated and the most frequent were TET2, DNMT3A, ASXL1 and PPM1D. The overall probability of TFR was 60.4% at 12 months and 53.0% at 84 months. CHIP TOC was associated with TFR. At 12 months, 83.6% of patients with CHIP TOC maintained TFR versus 52.9% of patients without CHIP TOC, P=.002. At 84 months, 62.9% of patients with CHIP TOC maintained TFR versus 49.6% of patients without CHIP TOC, P=.014. We previously demonstrated that e13a2 transcripts and a slow initial decline of BCR:: ABL1 after starting frontline TKI therapy, measured as the number of days over which BCR:: ABL1 halved, were our strongest predictors of relapse. Prognostic factors for the achievement of TFR at 12 and 84 months were examined in multivariable analysis. Candidate prognostic factors were CHIP TOC, BCR:: ABL1 halving time, BCR:: ABL1 transcript type, age at diagnosis, gender, duration of MR4.5 and time on TKI before TKI stop. The independent predictors of TFR at 12 and 84 months were the presence of CHIP TOC at TKI stop, a shorter BCR:: ABL1 halving time (indicating a more rapid initial BCR:: ABL1 decline) and the e14a2 (plus e14a2/e13a2) BCR:: ABL1 transcript type (Table 1). The rate of late relapse, defined as loss of MMR >12 months after cessation, was higher in patients with CHIP TOC. Overall, 85 patients had TFR at 12 months and late relapse occurred in 8. A landmark analysis demonstrated that the probability of maintaining TFR at 84 months for these 85 patients was 93.8% for those without CHIP TOC (n=57) and 75.2% for those with CHIP TOC (n=28), P=.007. The only variable associated with late relapse among the patients with CHIP TOC was fluctuation of BCR:: ABL1 within the first 12 months after cessation, defined as irregular rise and fall comprising 2 consecutive BCR:: ABL1 ratios with loss of MR4.5, or a single loss of MR4. Overall, 13 patients had fluctuation within the first 12 months and 5 of these had late relapse. All 5 had CHIP TOC. Patients with CHIP TOC and stable MR4.5 by 12 months had a 93.8% probability of TFR at 84 months (Table 2). Conclusion The presence of CHIP TOC at TKI cessation, a shorter BCR:: ABL1 halving time and e14a2 BCR:: ABL1 transcripts were independent predictors of TFR at 12 and 84 months. Delayed loss of MMR that occurred for a minority of patients with CHIP TOC may be associated with competition between CHIP clones and a residual leukemic clone. These patients had fluctuating BCR:: ABL1 over the first 12 months after cessation and prior to late relapse. Novel strategies may be warranted to reduce the risk of late relapse for these patients. Patients who sustained TFR by 12 months in stable MR4.5 had a reassuringly low risk of late relapse. CHIP status could be a key variable to guide TFR decision-making and monitoring.

Single Cell Analysis of Genes Involved in Asymmetric Hematopoietic Stem Cell (HSC) Division in Chronic Myeloid Leukemia (CML) : Evidence of the Regulation of Tetraspanin CD63 during Leukemia Progression

Tyrosine kinase inhibitor (TKI) therapies have profoundly changed the natural history and survival of CML patients. However, the majority of the patients remain on long-lasting therapies and switch one TKI to another, either because of intolerance or resistance. All TKI cessation trials showed approximately 50% of leukemia recurrence rates even after several years of TKI therapies, suggesting the persistence of residual leukemic stem cells in patients in deep molecular response (DMR). The resistance and persistence of CML HSC are related to intrinsic (BCR-ABL independent survival) or extrinsic (leukemic niche ) mechanisms some of which have been extensively studied. However, there has been no data with regard to the role of asymmetric cell division pathways in the persistence and progression of CML stem cell clone. Indeed, During asymmetric division process of hematopoietic stem cells, some proteins are differently segregated between daughter HSCs such as endosome associated tetraspanin proteins (CD53, CD63) and mitochondria-associated fission regulator Dynamin related protein-1(DRP1). Similarly, it has been shown that asymmetric organelle inheritance can influence HSC decisions towards differentiation versus self-renewal. Interestingly, the tetraspanin CD63 is known to be involved in the quiescence of human and murine HSC via activation of TGF-beta pathway, CD63 hi cells exhibiting increased self-renewal potential after the asymmetric division with reduced differentiation potential. Materials and Methods We have analyzed the transcriptome performed in a cohort of CML patients in chronic phase (CP) and blast phase (BP) (GSE4170) as well as in a validation cohort of RNA-sequencing (GSE100026). Similarly, single cell transcriptome analysis of Lin- CD34+ CD38- CML progenitors (GSE76312) were included in the study evaluating the expression of genes involved in asymmetric cell division. We have then generated an asymmetric hematopoietic stem cell risk score using a panel of genes involved in the asymmetric division of HSCs and correlated these results with the transcriptome of the CML cohorts above. A pseudotime analysis was performed to evaluate single cell trajectories of the genes identified. Results To determine the potential role of asymmetric cell division markers in the progression of CML, we have analyzed the expression of several of these genes during CML progression in two independent transcriptome cohorts. The regulation concordance between the two distinct cohorts was principally observed on asymmetric molecules which were found to be down-regulated during blast crisis as compared to chronic phase. The regulation concordance between the two distinct cohorts was principally observed on asymmetric molecules down regulated during blast crisis as compared to chronic phase suggesting less of asymmetric properties during advanced phase of the disease. The down regulation in patients in blast crisis was confirmed at single cell level for the expression of SELL, CD63, NUMB, HK2 and LAMP2. CD63 expression has also been found to be of interest in CML chronic phase. Indeed, single cell neural network and deep learning in CP samples showed that the CD63 expression was the best asymmetric gene marker predicting a poor prognosis and this appeared to be induced by opposite regulation of HK2 and NUMB. In patients in CP-CML, the single cell trajectory reconstitution revealed the major regulatory role of CD63 highlighting a trajectory cluster implicating HSPB1, PIM2, ANXA5, LAMTOR1, CFL1, CD52, RAD52, MEIS1, PDIA3, all genes known to be involved also in hematopoietic malignancies such as myelodysplasia, AML and ALL. Conclusion We show here for the first time the identification of the expression of genes involved in the asymmetric division of CML HSC. Among these genes we identified the tetraspanin CD63 as being down-regulated during CML progression. The expression of the genes involved in the asymmetric HSC division should require further studies in CML, either to predict persistence of CML or progressive disease. Figure 1 : Single cell transcriptome of Lin- CD34+ CD38- CML progenitors in CP links CD63 expression to progressive disease. A/ Piechart of counts for chronic phase cells analyzed according to prognosis; B/ pseudotime transformation of single cell transcriptome according patient prognosis; C/ Pseudotime expression heatmap; D/ Pseudotime expression of CD63 in CP.

Association of TIM-3 checkpoint receptor expression on T cells with treatment-free remission in chronic myeloid leukemia.

Dysregulation of immune-checkpoint receptors has been reported at diagnosis of chronic myeloid leukemia (CML), however, their role in the maintenance of remission after tyrosine kinase inhibitor (TKI) cessation is unclear. We assessed programmed cell death-1 (PD-1), T-cell immunoglobulin, and mucin-domain containing protein-3 (TIM-3), cytotoxic T-lymphocyte-associated protein-4 (CTLA-4), lymphocyte-activation gene-3 (LAG-3), andT-cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibitory motif (ITIM) domains (TIGIT) expression on T-cell subsets, regulatory T cells (T-regs), and natural killer (NK) cells at the time of TKI cessation in 44 patients (22 patients sustained treatment-free remission [TFR] and 22 experienced molecular relapse [MolR]). We confirmed our previous finding that absolute numbers of T-regs are increased in patients who experienced MolR compared with those who sustained TFR. The immune-checkpoint receptors PD-1, CTLA-4, LAG-3, and TIGIT on Tor NK cells were not differentially expressed between the MolR and TFR groups. However, TIM-3 was consistently upregulated on bulk T cells (CD3+) and T-cell subsets including, CD4+ T cells, CD8+ T cells, and T-regs, in patients who relapsed in comparison with those who maintained TFR after discontinuation. Furthermore, gene expression analysis from publicly available data sets showed increased TIM-3 expression on CML stem cells compared with normal hematopoietic stem cells. These findings suggest that among the targetable immune-checkpoint molecules, TIM-3 blockade may potentially improve effector immune response in patients with CML stopping TKI, while concomitantly targeting leukemic stem cells and could be a promising therapeutic strategy for preventing relapse after cessation of TKI in patients with CML.

A long-term follow-up of observation in treatment-free remission in patients with chronic myeloid leukemia

Introduction. The option of observation without therapy with tyrosine kinase inhibitors (TKIs) in chronic myeloid leukemia (CML) patients is already included in Russian and international clinical guidelines. Evaluation of long-term follow-up results of treatment free remission (TFR) in CML patients is relevant for the introduction of this approach into routine clinical practice. Aim — to demonstrate the outcomes in a long-term follow-up of CML patients who discontinued TKI therapy in the RU-SKI trial. Patients and methods. The prospective study included 98 CML patients with TKI therapy duration ≥ 3 years and a deep molecular response (DMR, BCR::ABL1 ≤ 0.01 %) duration ≥ 2 years. TKI therapy was resumed with the loss of a major MR (MMR, BCR::ABL1 > 0,1 %). Results. Median time of follow-up after TKI discontinuation was 64 months (range of 51–86 months). Survival without MMR loss at 3 and 5 years after TKI discontinuation was 51 % (CI 41–61 %) and 46 % (CI 36–57 %) respectively. From 3 to 5 years of follow-up without therapy, the loss of MMR occurred in 2 (4 %) patients. There was no MMR loss observed after 5 years of follow-up. In patients with first and second treatment discontinuation, survival without MMR loss was 50 % versus 12,5 %(р = 0,039). All 50 patients with molecular relapses regained MMR and MR4 after TKI therapy resumption. BCR::ABL1 level fluctuations 0,01–0,1 % were in 62 % (n = 29) patients, who were in TFR at the time of analysis. Loss of MR4 was observed in 38 (42 %) from 90 patients with first TKI discontinuation. Survival without MMR loss from MO4 loss was 24 % at 5 years after TKI discontinuation. Loss of MO4 in the first 3 months after TKI cessation was associated with a high probability of further MMR loss (8 % versus 54 % in patients with loss of MO4 for > 3 months, p = 0.00015). Conclusion. The low frequency of late relapses (4 % after 3 years of follow-up) and the possibility of long-term persistence of minimal residual disease (MRD) after discontinuation of therapy determine the need to optimize the timing of molecular monitoring, taking into account the MRD status of patients.

Cardiovascular risk in chronic myeloid leukaemia: A multidisciplinary consensus on screening and management.

Tyrosine kinase inhibitors (TKIs) have become the mainstay of treatment for chronic myeloid leukaemia (CML), but cardiovascular (CV) risk and exacerbation of underlying risk factors associated with TKIs have become widely debated. Real-world evidence reveals little application of CV risk factor screening or continued monitoring within UK CML management. This consensus paper presents practical recommendations to assist healthcare professionals in conducting CV screening/comorbidity management for patients receiving TKIs. We conducted a multidisciplinary panel meeting and two iterative surveys involving 10 CML specialists: five haematologists, two cardio-oncologists, one vascular surgeon, one haemato-oncology pharmacist and one specialist nurse practitioner. The panel recommended that patients commencing second-/third-generation TKIs undergo formal CV risk assessment at baseline, with additional investigations and involvement of cardiologists/vascular surgeons for those with high CV risk. During treatment, patients should undergo CV monitoring, with the nature and frequency of testing dependent on TKI and baseline CV risk. For patients who develop CV adverse events, decision-making around TKI interruption, cessation or change should be multidisciplinary and balance CV and haematological risk. The panel anticipates these recommendations will support healthcare professionals in implementing CV risk screening and monitoring, broadly and consistently, and thereby help optimise TKI treatment for CML.

Abstract 2181: Treatment-free remission after discontinuation of ALK tyrosine kinase inhibitors (TKIs) in patients with ALK-positive anaplastic large cell lymphoma (ALCL)

Abstract Introduction: ALK-positive ALCL accounts for 0.8% of Korean lymphoma patients. ALK TKIs are effective and durable, but clinical outcomes after treatment discontinuation are unknown. We analyzed outcomes and minimal residual disease (MRD) in adult ALK-positive ALCL patients who discontinued ALK TKIs after achieving treatment-free remission. Methods: Six patients who achieved responses to crizotinib (N=5) and ceritinib (N=1) were analyzed. RNA extracted from the blood or tissues before TKI treatment were subjected to multiplex PCR-based next generation sequencing (NGS) using ARCHER® RNA Fusionplex® to detect NPM-ALK fusion. MRD was assessed by droplet digital PCR (ddPCR) of peripheral blood mononuclear cells (PBMCs) after the treatment discontinuation. Undetectable MRD was defined as less than one lymphocytic cell per 10,000 leukocytes (10-4) in peripheral blood. Results: Patients received ALK TKIs as second line (N=3) or third line and beyond (N=3). All achieved complete metabolic responses after median 28.5 months (range, 1.7-93.9) of treatments (Table 1). Before TKI, LY1 patient had no morphologic evidence of bone marrow involvement, but NPM1-ALK fusions were detected by NGS and ddPCR in blood, bone marrow, and tissue. LY1 patient remained in remission at 27.8 months after crizotinib discontinuation. In all patients, NPM1-ALK fusion were not detected in the PBMCs after discontinuing ALK TKIs for median 38.2 months (range, 0-61.9). No patient re-initiated anti-lymphoma therapies. Conclusion: Out data demonstrated that treatment-free remission was durable for more than two years in ALK-positive ALCL patients following the cessation of ALK TKIs. MRD-guided discontinuation decision may be considered for ALK-positive ALCL patients treated with ALK inhibitors who had undetectable MRD. Table 1. Summary of patient characteristics and outcomes of ALK TKI discontinuation No. Sex Age at diagnosis Ann Arbor stage ALK TKI Lines of prior therapy Treatment duration of ALK TKI (months) Reason for cessation Duration of ALK TKI cessation (months) Best response to ALK TKI Time of MRD assessment after TKI cessation MRD after TKI cessation 1 M 22 IIB Crizotinib 3 93.9 Fertility 27.8 CR 5.6 Negative 2 F 20 IVB Crizotinib 1 90.9 Fertility 25.9 CR 0.0 Negative 3 M 23 IV Ceritinib 1 42.7 Adverse event 61.9 CR 61.9 Negative 4 F 58 IV Crizotinib 3 1.7 Cost 86.6 CR 72.1 Negative 5 F 64 IVB Crizotinib 1 13.6 Cost 31.0 CR 14.4 Negative 6 M 75 IV Crizotinib 2 11.7 Cost 80.2 CR 62.0 Negative Citation Format: Jinyong Kim, Soyeon Kim, Tae Min Kim, Jeonghwan Youk, Miso Kim, Bhumsuk Keam, Dong-Wan Kim, Dae Seog Heo. Treatment-free remission after discontinuation of ALK tyrosine kinase inhibitors (TKIs) in patients with ALK-positive anaplastic large cell lymphoma (ALCL) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2181.

Successful delivery using interferon α for molecular relapse of chronic myeloid leukemia after interruption of tyrosine kinase inhibitor

A tyrosine kinase inhibitor (TKI) was used to treat the patient, a 35-year-old woman who was diagnosed with chronic myeloid leukemia at the age of 22 years. Since a four-year deep molecular response (DMR) was obtained, spontaneous pregnancy was planned under TKI withdrawal. Even though her disease had advanced to MR2.0 at the time of pregnancy confirmation, 2 months from TKI cessation, interferon α therapy was initiated in light of the patient's history. Later, the patient reached MR3.0, gave birth to a healthy baby, and maintained MR3.0-4.0. TKI was resumed after about 6 months of breastfeeding. Treatment-free remission (TFR) is required for natural conception despite the teratogenicity and miscarriage risks associated with BCR::ABL1 TKIs. When planning a pregnancy, it is also necessary to take the patients' backgrounds, disease states, and medical history into account.

Modelling of immune response in chronic myeloid leukemia patients suggests potential for treatment reduction prior to cessation.

Discontinuation of tyrosine kinase inhibitor (TKI) treatment is emerging as the main therapy goal for Chronic Myeloid Leukemia (CML) patients. The DESTINY trial showed that TKI dose reduction prior to cessation can lead to an increased number of patients achieving sustained treatment free remission (TFR). However, there has been no systematic investigation to evaluate how dose reduction regimens can further improve the success of TKI stop trials. Here, we apply an established mathematical model of CML therapy to investigate different TKI dose reduction schemes prior to therapy cessation and evaluate them with respect to the total amount of drug used and the expected TFR success. Our systematic analysis confirms clinical findings that the overall time of TKI treatment is a major determinant of TFR success, while highlighting that lower dose TKI treatment for the same duration is equally sufficient for many patients. Our results further suggest that a stepwise dose reduction prior to TKI cessation can increase the success rate of TFR, while substantially reducing the amount of administered TKI. Our findings illustrate the potential of dose reduction schemes prior to treatment cessation and suggest corresponding and clinically testable strategies that are applicable to many CML patients.

Tyrosine kinase inhibitor-associated ventricular arrhythmias: a case series and review of literature.

Tyrosine kinase inhibitors (TKIs) have been increasingly used as first-line therapy in hematologic and solid-organ malignancies. Multiple TKIs have been linked with the development of cardiovascular complications, especially atrial arrhythmias, but data on ventricular arrhythmias (VAs) is scarce. Herein we describe five detailed cases of VAs related to TKI use in patients with varied baseline cardiovascular risk factors between 2019 and 2022 at three centers. Individual chart review was conducted retrospectively. Patient ages ranged from 43 to 83years. Three patients were on Bruton's TKI (2 ibrutinib and 1 zanubrutinib) at the time of VAs; other TKIs involved were afatinib and dasatinib. Three patients had a high burden of non-sustained ventricular tachycardia (NSVT) requiring interventions, whereas two patients had sustained VAs. While all patients in our case series had significant improvement in VA burden after TKI cessation, two patients required new long-term antiarrhythmic drug therapy, and one had an implantable defibrillator cardioverter (ICD) placed due to persistent VAs after cessation of TKI therapy. One patient reinitiated TKI therapy after control of arrhythmia was achieved with antiarrhythmic drug therapy. Given the expanding long-term use of TKIs among a growing population of cancer patients, it is critical to acknowledge the association of TKIs with cardiovascular complications such as VAs, to characterize those at risk, and deploy preventive and therapeutic measures to avoid such complications and interference with oncologic therapy. Further efforts are warranted to develop monitoring protocols and optimal treatment strategies for TKI-induced VAs.

Chip-Based Digital PCR Platform, Lab on an Array, the Newly Developed Highly Accurate and Sensitive Method for the Detection of BCR-ABL1 Transcripts in Chronic Myeloid Leukemia

Introduction: With the development of various BCR-ABL1 tyrosine kinase inhibitors (TKIs), chronic myeloid leukemia (CML) has become a manageable hematologic malignancy and current therapeutic goal is treatment free remission (TFR). To achieve a successful TFR in more patients, a precise assessment of minimal residual disease (MRD) has become one of the prerequisite requirements. Since undetectable BCR-ABL1 by conventional TaqmanTM-based quantitative polymerase chain reaction (qPCR) is not an indicator for complete eradication of CML clone, more precise methods should be developed. Currently, to overcome some limitations of conventional qPCR, such as rigorous standardization process and various sensitivity between laboratories, digital quantitative-PCR (dqPCR) methods such as nanofluidic or droplet dqPCR have been developed for accurate and precise detection of various genes and its use in the routine clinical practice is gradually expanding. However, current dqPCR methods may have limitations due to partition-based amplification and end-point interpretation. Therefore the establishment of clinical guideline is crucial for wide application on TFR in CML. Therefore, we have developed a novel technology, a chip-based real-time dqPCR platform (LOAA; Lab On An Array; so called Dr. PCR™) to achieve more stable, accurate and precise monitoring of BCR-ABL1 in a timely manner. Methods: To assess the equivalence between Dr. PCR and conventional qPCR, we evaluate the efficacy of BCR-ABL1 detection using cell lines and clinical specimens. For linearity assessment, we used BCR-ABL1 positive (e14a2) K562 cell line diluted to 9 points by 10-fold serial dilutions from 100 to 10-8 with BCR-ABL1 negative HL60 cells. With the results from cell lines, we also evaluated linearities for both e13a2 and e14a2 major BCR-ABL transcripts using 7 clinical specimens obtained from Leukemia Omics Research Institute of Eulji University. In detail, conventional qPCR was performed using Transcriptor First Strand cDNA Synthesis Kit (Roche, USA) for cDNA synthesis and Real-Q BCR-ABL Quantification Kit (Biosewoom, South Korea) for qPCR. Total 800ng of RNA per test was used for qPCR (QS5, Thermo Fisher, USA) with 8 replicates and duplicate for cell line and clinical specimens, respectively. For Dr. PCR (1-step reverse transcriptase PCR), 400ng (for cell lines) or 500ng (for clinical specimens) of RNA per test was applied to disposable cartridges of Dr. PCR™ BCR-ABL1 Major IS detection kit (Optolane Technologies, South Korea) with LOAA platform (Optolane Technologies, Korea). The copies of BCR-ABL1 and ABL1 were analyzed by LOAA analyzer S/W (Optolane Technologies, South Korea). Based on the results, correlation analysis between qPCR and Dr PCR was performed using correlation graphs and Blend-Altman plots. Results: Correlation analysis for cell line dilution assay showed that measured values from both qPCR and Dr. PCR were closely correlated with the R2 of 0.984. LOA95 (limit of agreement at 95% confidence interval) analyzed by Blend-Altman plot was -0.711 ~ 0.303 (mean = 0.02), indicating the two methods are closely correlated (Figure 1). The linearity assessment for e13a2 and e14a2 sub-genotypes using primary cells from 7 clinical specimens of CML patients again showed a close correlation with the R2 of 0.984 and 0.985, respectively. LOA95 values were -0.516 to 0.384 (mean = -0.066) and -0.407 to 0.361 (mean = -0.023), respectively. Interestingly, Dr PCR efficiently detected clinical specimens with low copy number of BCR-ABL1 compared to conventional qPCR, which is beneficial for the determination of MDR levels in patients especially those who are required to monitoring after cessation of TKIs. Comparison between conventional qPCR, droplet dqPCR and Dr PCR is listed (Table 1). Results with more specimens from CML patients and additional information will be updated at ASH presentation. Conclusion: Taken together, we believe our novel chip-based real-time dqPCR (Dr. PCR™) may minimize false positive results and maximize the analytical sensitivity of detecting BCR-ABL1 fusion transcripts and thus, would be useful for the selection of therapeutic option in routine clinical practice and TFR. We will include the result for further intensive study using more clinical specimens including samples of low copy number of BCR-ABL1. Study support: Funded by Korea Research FoundationFigure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Retrospective Study of Treatment Free Remission in Patients with Chronic Myeloid Leukaemia(CML) Treated at Tertiary Care Oncology Centre from India

Background Tyrosine kinase inhibitors (TKI) have dramatically improved outcomes in Chronic Myeloid Leukemia(CML) patients, but lifelong TKI therapy can negatively impact patients' quality of life due to chronic adverse events. Treatment free remission(TFR) is now the new goal of CML therapy. Studies have shown this is feasible in developed countries. Literature on discontinuation of TKI therapy in resource limited countries such as India is scarce. The purpose of this study was to investigate whether some chronic myeloid leukemia patients with excellent and sustained molecular responses to tyrosine kinase inhibitor treatment can gradually de-escalate TKI therapy and stop therapy in Indian setting. Methods We included all patients above the age of 18years with diagnosis of CML in first Chronic Phase (CP) on TKI therapy of minimum 3 years duration with major molecular response (MMR i.e., <0.1% BCR-ABL1 transcript) of minimum of 2 years duration, enrolled for treatment free remission between January 2018 to December 2021. Starting dose of imatinib was 400mg once daily, dasatinib 100mg once daily and nilotinib 300mg twice a day. In this study the dose of these drugs was reduced by 25% every 6 months . This dose reduction was done with 2 monthly outpatient clinic visits and 2 monthly BCR-ABL1 quantitative PCR monitoring. Patients who maintained MMR during 6 months of dose de-escalation qualified for next level of dose de-escalation. Eventually treatment was stopped completely and monitoring continued. This was retrospective medical record based study done at a tertiary care centre in North India. Results Between Jan 2018 to Dec 2021, 29 patients were enrolled for dose de-escalation and treatment cessation. Among these 29 patients, 19 were on imatinib, 2 on dasatinib and 8 patients on nilotinib. Median age was 39 years( range 21 years to 67 years). Twelve patients were male and 17 female. Median duration of TKI therapy prior to de-escalation was 8 years (range 4years-14 years). Median duration of major molecular response prior to dose reduction was 6 years( range 3years-12 years). In our study 17 of 29 patients had an outcome, while 12 patients are still on de-escalation phase with maintained MMR and are not included in the outcome analysis. Eight patient had loss of MMR(47.05%), 6 while on dose de-escalation and 2 after cessation of TKI. All eight patients achieved MMR after re-initiation of the prior dose, out of these 6 patients had sustained MMR(>6months) at reduced TKI dosing compared to conventional dose. Nine patients (52.9%) have successfully stopped TKI for median duration of 11months (range 6 to 19 months). Conclusion TKI de-escalation was safe for most patients with excellent prior response to TKI therapy. This way of dose reduction , ensured motivation and commitment of patients by doing regular OPD follow ups and BCR-ABL1 PCR testing. In our study 52.9% patient could successfully maintain TFR at a median follow up of 11 months of stopping the drug. We also identified that a subgroup of patients(35.29%) who were unsuccessful in complete cessation of therapy but maintained their molecular response at reduce dose of TKI . These findings show that lower TKI doses might maintain molecular responses in these patients, implying that such patients could be overtreated with routine dosing. More studies of dose de-escalation are warranted.

Duration of ≥MR4 Is the Best Predictor for a Successful 1st Treatment-Free Remission (TRF1) Attempt in CML Patients Treated with Tyrosine Kinase Inhibitors (TKI); Long-Term Follow-up of a Large Cohort of Patients Including a Cohort Undergoing a 2nd Tfr (TFR2) Attempt

Background: Prior to TKIs, CML was uniformly fatal unless the patient underwent allogeneic-HSCT. With TKIs, some patients achieve deep molecular responses with bcr-abl <0.01% (MR4); a portion of such patients can achieve long-term TFR, possibly cure, after TKI cessation. This approach is now considered the goal for every newly diagnosed CML patient. We present a single centre experience, with long-term follow up, of a cohort of CML patients undergoing TFR1 and TFR2 attempts. Method: Our database of 173 patients diagnosed with CML from 1994 to 2022 was searched for patients who had the potential to be eligible for a TFR attempt (pending adequate response to TKI): CML diagnosed in 1st chronic phase (CP1); no allogeneic HSCT in CP1; >3 yrs treatment with TKI; adequate follow-up. 120 patients fulfilled these criteria. Results: 70/120 (58%) achieved accepted criteria to attempt TFR: >3 years of TKI treatment; a deep molecular response (≥MR4) and underwent TFR attempt. Median age at diagnosis was 49.5 (20-81) yrs; 42% were female. Sokal score was low in 38%; intermediate in 29%; high in 33%. 66% of patients received multiple TKIs; 23% had received interferon. TKI at time of TFR1 attempt was imatinib (40%), nilotinib (30%), dasatinib (27%), and ponatinib (3%). Median time from diagnosis to TFR was 8.5 (4-23) yrs and median time on TKI was 7.5 (3.4-17.9) yrs. 36/70 (51%) remain in TFR with median follow-up of 46 (1-180) mths including; 16 patients now >5 yrs and 2 now >10 yrs in ongoing TFR; the cohort includes 2 patients with historically acquired bcr-abl mutations and 1 with a historically acquired additional cytogenetic abnormalities (no longer present at TFR1 attempt). All 3 are long-term TFR successes. Median time to relapse was 5 (2-36) mths, 25/34 (73.5%) relapsed within 6 mths of TKI withdrawal and 28/34 (82.4%) within 12 mths. Time of relapse for 1 patient is unknown. The remaining 5 patients relapsed at 13, 14, 18, 20, and 36 mths. All patients with CML recurrence (bcr-abl >0.1%) restarted TKI with a rapid return to major molecular response (MMR) or better (2 are too early for assessment) with median time to MMR of 3 (1-12) mths. No patient developed CML with high-risk features or blast phase. The strongest predictors for TFR success were duration of MR4 prior to attempting TFR1 (Table 1) - 60% (25/42) of patients with >5 yrs of ≥MR4 prior to cessation remain in TFR, compared to 55% (11/20) with 3-5 yrs and 0% (0/7) of patients with <3 yrs (p<0.03 for <3 vs 3-5 yrs and <3 vs >5 yrs, p=0.79 for 3-5 vs >5 yrs) ; prior treatment with interferon (81% - 13/16 - of patients who received interferon remain in TFR compared to 37% - 20/54 - who had not received interferon, p=0.0035), and a Sokal score <0.8 (64% of patients with low Sokal score remain in TFR compared to 45% with a score 0.8-1.2 and 45% with a score >1.2, p=0.35 for <0.8 vs 0.8-1.2, p=0.16 for <0.8 vs >1.2, p=1 for 0.8-1.2 vs >1.2). 6 patients had transient rises in their bcr-abl (>0.01%), ranging from 0.012 - 0.033, but these 6 returned to MR4 or better and remain in TFR for 8-77 mths. 13 (38%) of the 34 failed TFR1 patients attempted TFR2. Median time on TKI between 1st and 2nd attempts was 5.7 (4.8-8.9) yrs and had a median time ≥MR4 of 5.4 (4.6-8.8) yrs. Median follow up was 12 (1-27) mths. Currently, 9 (69%) patients remain in TFR2. Of the 4 patients who relapsed, all did so in the first 6 months after TKI withdrawal. 17 patients (25%) developed a withdrawal syndrome. Symptoms included fatigue, myalgias, and arthralgias. All but 4 patients had resolution over a median of 11 (1-25) mths. 3 patients benefited from a course of prednisolone. 4 patients have had persistent symptoms for median 12.5 (10-19) mths. Conclusion: Of 120 patients with adequate duration of TKI, 58% were eligible for TFR1 attempt which, to date, is successful in 51%. Prior interferon treatment, longer period in ≥MR4 and a Sokal score <0.8 predicted a successful TFR. For those that fail TFR1, TFR2 appears safe, and with short follow-up, currently 9/13 (69%) patients remain off treatment. In our cohort, overall 64% (45/70; 36 TFR1 + 9 TFR2) of patients eligible for TFR attempts remain off TKI giving an actual or functional cure rate of 38% (45/120). Historically acquired bcr-abl mutations or additional cytogenetic abnormalities are not necessarily contraindications to a TFR attempt - with 3 long-term TFR successes in our cohort. TFR is safe with no cases of disease progression, and all patients with TFR failure and adequate duration of follow-up regaining MMR. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Long-Term Follow-up of Tyrosine Kinase Inhibitors Discontinuation in Chronic Myeloid Leukemia: A Single-Center Experience

Introduction: Ever since the availability of BCR-ABL1 tyrosine kinase inhibitors (TKIs) as treatment for chronic myeloid leukemia (CML), life expectancy of patients has dramatically improved, approaching that of the overall population. Several clinical trials have demonstrated the possibility of discontinuing TKI. However, the information on the safety of long-term TKI cessation is still limited. Methods: We carried out a descriptive, retrospective and single-center study, including 56 patients with CML who discontinued TKI treatment between January 2006 and July 2022. We defined strict molecular relapse as loss of MR4 (BCR-ABL1 International Scale (IS) ≤ 0,01% or undetectable BCR-ABL1 in samples with ≥10.000 transcripts), loose molecular relapse as loss of major molecular response (MMR) (BCR-ABL1 IS ≤ 0,1% in samples with ≥10.000 transcripts) and deep molecular response (DMR) as response greater than or equal to MR4. Progression-free survival (PFS) was estimated by the method of Kaplan-Meier and defined as the time from TKI discontinuation to the date of first event (loss of DMR or death). Results: We included 56 patients (table 1). Median age at time of stopping TKI treatment was 60,3 (50,7-75,8) years and 35 (62,5%) were male. 44 patients had received 1 line of TKI treatment, 7 two lines, 2 three lines and 3 four lines. The previous TKI treatment consisted of imatinib (n=34), nilotinib (n=6), dasatinib (n=34), two lines of imatinib because of pregnancy (n=1), imatinib dasatinib (n=3), imatinib nilotinib (n=1), dasatinib imatinib (n=1), dasatinib ponatinib (n=1), imatinib dasatinib nilotinib (n=1), nilotinib dasatinib nilotinib (n=1), imatinib dasatinib imatinib dasatinib (n=1), imatinib nilotinib dasatinib dasatinib+asciminib (n=1), imatinib nilotinib dasatinib nilotinib (n=1). Duration of imatinib treatment was 121,5 (100-172,8) months, dasatinib 74,4 (29-86,1), nilotinib 34,3 (19,1-45,6), ponatinib 49 and asciminib 20,7. The reasons for switching from first to second line were intolerance (n=7, 58,3%), resistance to any TKI (n=4, 33,3%) and pregnancy (n=1, 8,3%). From second to third line was intolerance (n=5, 100%). Duration of DMR before TKI discontinuation was 87,6 (49,2-116,4) months. The last molecular responses before TKI cessation were RM5 (n=18, 32,1%), RM4.5 (n=28, 50%), RM4 (n=9, 16%) y MMR (n=1, 1,8%). Reasons for TKI discontinuation were the presence of side effects (n=28, 50%), an attempt to achieve a treatment-free remission (TFR) in patients with a DMR (n=16, 28,6%), patient preference (n=10, 17,8%) and pregnancy (n=2, 3,6%). After TKI discontinuation, 34 (60,7%) patients have maintained DMR for a median of 4,22 (2,12-7,14) years, of which six more than 8 years being the maximum follow-up of 12,6 years. 5 patients had died while DMR due to CML-unrelated causes. The probability of PFS at 1 year and 12,6 years was 65,3% (95% CI: 58,6%-71,7%) and 34,8% (95% CI: 25%-44,1%) respectively (Figure 1). 22 (39,28%) patients had strict molecular relapse with a median of 3,9 (3,2-7,8) months, of which 12 (21,4%) were loose molecular relapses. Loss of DMR occurred most frequently in the first 6 months after TKI discontinuation (n=15, 68,1%). The last CMR loss was at 95 months. 18 patients restarted treatment, 2 died due to CML-unrelated causes, 1 maintained RMM without treatment due to intolerance and 1 stopped treatment due to personal preference. At the time of restarting treatment, the BCR-ABL1 IS was ≤10% (n=3), ≤1% (n=7), ≤0,1% (n=7) and ≤0,01% (n=1). After restarting treatment, 18 (100%) patients had MMR, of whom 16 (80%) had DMR. Median time to regaining DMR after resuming TKI therapy was 3 (0,9-3,05) months. A second attempt at TFR was made in 5 patients. The median duration of TKI therapy after restarting the treatment and the second discontinuation was 60,2 (40,2-63) months. 4 patients maintained CMR with a follow-up of 11 (7,2-24,4) months, and one patient died while DMR for reasons unrelated to CML. Adverse effects improved in most patients. TKI withdrawal syndrome was noticed in 12 (21,4%) patients. Conclusion: In our study, the PFS at 12,6 years was 34,8%. Including the patients who have had a second discontinuation of TKI, 39 (69,6%) patients remain in DMR off-treatment, with a median follow-up of 49,1 (26,7-85,7) months. 6 patients had a follow-up of more than 8 years without treatment, which is still ongoing. These data confirm the applicability and safety of TKI discontinuation. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

A Real-World Study to End Tyrosine Kinase Inhibitor in Chronic Myeloid Leukaemia (EnTIC) in Malaysia: One Year Follow-up of Multicenter Study in Malaysia

Introduction The practice of indefinite tyrosine kinase inhibitor (TKI) provision for Chronic Myeloid Leukaemia (CML) has remained unchallenged and the ability of TKIs to eradicate the CML clone is still largely unknown. Hence, a multicentre observational study involving major hospitals in Malaysia to observe the clinical practice to End TKI In CML (EnTIC) was performed. This study aims to determine the molecular response to TKI cessation in CML patients by close monitoring of BCR-ABL1. Materials and Methods A total of 88 adult patients diagnosed with CML in chronic phase and receiving first line TKI (imatinib, nilotinib or dasatinib) for at least four years with sustained MR4 (IS: 0.01%) for at least 2 years were recruited from January 2021 till July 2022. Close clinical review, and monthly BCR-ABL1 quantification analysis using real-time polymerase chain reaction for molecular monitoring were carried out. Results Eighty-eight patients with equal gender distribution (44 male and 44 female) and a median age of 41 years old (range, 31.5-53.5 years old) were included in the analysis. Chinese (60.2%, n =53) were the most prevalent ethnic group, followed by Malay (33%, n =29), and Indian (5.7%, n=5). 82.8% (n=64) of the patients had high presenting white blood cell count (>30x10⁹/L), with a median presenting white blood cell count of 102x109/L. Of the 64 patients, 38 of them (59.3%) had thrombocytosis (>450x10⁹/L). Majority of these patients (71.2%, n=37) presented with low Sokal score. First-line TKIs were administered to all patients throughout the course of treatment, with a median duration of 9 years (range: 7-13 years) and a median of 4 years for sustained deep molecular response (DMR) (range 3-6 years) was achieved. With a median follow-up of 14 months (range, 1-18 months) after stopping TKI, 57 patients (64.8%) remain in treatment-free remission (TFR). Thirty-one patients failed TFR, with a median duration of 2 months (range 1-5 months). Patients who remained in TFR at 166 days (5.5 months) and beyond were likely to achieve long term TFR in the following months (Fig 1). Conclusion The preliminary findings of EnTIC study demonstrate that a clinically significant percentage of patients were able to remain in MMR after stopping TKI. We observed the likelihood of breakthrough MMR during TFR trial is most often within the first 6 months of stopping TKI. Nonetheless, a longer follow-up duration and analyses of TFR data in EnTIC will be important to further evaluate the patients, and identifying clinically significant characteristics to predict disease relapse before stopping treatment. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Clinical characteristics and outcomes of tyrosine kinase inhibitor-related lower GI adverse effects.

A variety of tyrosine kinase inhibitors (TKIs) are currently approved for the treatment of solid tumors and hematological cancers. However, TKIs are often associated with gastrointestinal (GI) adverse effects (AEs), especially diarrhea. Therefore, in the present study, we aimed to describe the clinical features and outcomes of TKI-associated lower GI AEs. This was a retrospective single-center cohort study of patients with cancer treated with TKIs from March 2016 to September 2020 who experienced diarrhea without other identifiable causes. Basic and GI AE-related characteristics and outcomes were compared using χ2 and Mann-Whitney U tests. Of 2172 patients who received TKIs over the study period, we included 228 in the final analysis. Of these, 166 (72.8%) had hematological cancers. Besides diarrhea, GI symptoms included nausea (36.4%), vomiting (21.9%), abdominal pain (15.4%), and bleeding (3.1%). Symptoms were typically mild, with 209 patients (91.7%) presenting with Common Terminology Criteria for Adverse Events grade 1-2 diarrhea. Only 5 patients (2.2%) received immunosuppressants for diarrhea treatment, 83 (36.4%) received no treatment, 29 (12.7%) received antibiotics, 101 (44.3%) received supportive antidiarrheal medications, and 17 patients (7.5%) needed TKI dose reduction or cessation of TKI use. When compared with patients with hematological cancers, those with solid tumors had a higher rate of hospitalization (29.0% vs. 7.2%; p < 0.001) and mortality (75.8% vs. 43.4%; p < 0.001) but a lower rate of recurrence of GI AEs (21.0% vs. 42.8%; p = 0.003. Only 15 patients (6.6%) underwent colonoscopy, with normal endoscopic findings in 8 patients (53.3%) and nonulcerative inflammation in 5 patients (33.3%). The inflammation universally involved the left colon. Twelve of the 15 patients who underwent colonoscopy had active colitis. In the hematological cancer group, patients with acute myeloid leukemia had a lower GI AE recurrence rate than did patients with other hematological cancers (7.2% vs. 30.1%; p = 0.001). Ten percent of cancer patients receiving TKIs experienced lower GI AEs, which were usually mild. Symptoms TKI-related GI adverse effects were nonspecific, often overlapping those of other cancer therapy-related GI AEs. Treatment of GI AEs was largely supportive, with limited roles for antibiotics and immunosuppressants.

Withdrawal syndrome after tyrosine kinase inhibitors discontinuation in patients with chronic myeloid leukemia

Withdrawal syndrome (WS) a musculoskeletal pain after discontinuation of tyrosine kinase inhibitors (TKI) in patients with chronic myeloid leukemia (CML) has been described in the treatment-free remission (TFR) studies. The pathophysiological mechanisms and predisposing factors of WS have not been well established. Our aim was to evaluate clinical features and factors associated with WS in the Russian cohort of CML patients who discontinued TKI therapy. WS was evaluated in total of 183 CML patients with chronic phase and sustained deep molecular response (DMR). WS was defined as a musculoskeletal pain newly observed after TKI cessation or as a worsening of previously observed symptoms. DMR loss free survival at 36 months was 49% and 43% in prospective and retrospective groups respectively (p=0.96) with mеdian (Me) time of observation 33 months (range 1136). WS was observed in 49 (27%) patients: grade 12 was in 45 (92%) patients, grade 3 in 4 (8%) patients. Me time to WS occurrence was 2 months (range 17), Ме duration of WS was 5 months (range 135). WS was resolved in 14 of 15 patients with molecular relapse after 13 months of TKI re-initiation and was decreased in 1 patient. WS was completely resolved in 31 of 34 patients who continued remained in TFR and decreased in 3 patients. WS was resolved spontaneously or with nonsteroidal anti-inflammatory drugs in 14 (45%) and 17 (55%) patients accordingly. Older age (p0.0001), longer duration of TKI therapy (p0.0001) and presence of locomotion system diseases (p=0.022) were observed in patients with WS. No WS was observed in pregnant patients (р0.001). Survival without DMR loss at 12 months after TKI stop was 66 and 42% in patients with and without WS accordingly (р=0.095). The rate of WS was 27% that is in a good concordance with the data of the other TFR studies. A longer period of TKI exposure, older age and the history of locomotion system diseases were associated with the development of the WS. We found for the first time that WS was not observed in patients with pregnancy. There was no association of WS development and the rate of molecular relapses.