Immunological monitoring of newly diagnosed CML patients treated with bosutinib or imatinib first-line

Single-cell analysis of immune recognition in chronic myeloid leukemia patients following tyrosine kinase inhibitor discontinuation

Immunological control of residual leukemia cells is thought to occur in patients with chronic myeloid leukemia (CML) that maintain treatment-free remission (TFR) following tyrosine kinase inhibitor (TKI) discontinuation. To study this, we analyzed 55 single-cell RNA and T cell receptor (TCR) sequenced samples (scRNA+TCRαβ-seq) from patients with CML (n = 13, N = 25), other cancers (n = 28), and healthy (n = 7). The high number and active phenotype of natural killer (NK) cells in CML separated them from healthy and other cancers. Most NK cells in CML belonged to the active CD56dim cluster with high expression of GZMA/B, PRF1, CCL3/4, and IFNG, with interactions with leukemic cells via inhibitory LGALS9-TIM3 and PVR-TIGIT interactions. Accordingly, upregulation of LGALS9 was observed in CML target cells and TIM3 in NK cells when co-cultured together. Additionally, we created a classifier to identify TCRs targeting leukemia-associated antigen PR1 and quantified anti-PR1 T cells in 90 CML and 786 healthy TCRβ-sequenced samples. Anti-PR1 T cells were more prevalent in CML, enriched in bone marrow samples, and enriched in the mature, cytotoxic CD8 + TEMRA cluster, especially in a patient maintaining TFR. Our results highlight the role of NK cells and anti-PR1 T cells in anti-leukemic immune responses in CML.

The Role of Mesenchymal Stem Cells and Imatinib in the Process of Liver Fibrosis Healing Through CCL2-CCR2 and CX3CL1-CX3CR1 Axes

Background

Persistent liver damage contributes to the development of liver fibrosis, marked by an accumulation of extracellular matrix. Macrophages play a pivotal role in this process, with the CCL2-CCR2 and CX3CR1-CX3CL1 axes serving as key regulators of macrophage recruitment, liver infiltration, and differentiation. In this study, utilizing a rat model of carbon tetrachloride (CCL4)-induced liver fibrosis, we aimed to investigate the impact of imatinib and bone marrow-derived mesenchymal stem cells (BM-MSCs) on the expression of these axis.

Methods

Sixteen Sprague-Dawley rats were divided into four groups: healthy, liver fibrosis, imatinib-recipient, and BM-MSC-recipient. Treatment effects were evaluated using histopathology and Sirus-red staining. Quantitative real-time PCR was employed to analyze changes in the expression of the genes CCL2, CCR2, CX3CL1, and CX3CR1.

Results

Histopathological assessments revealed the efficacy of imatinib and BM-MSCs in mitigating liver fibrosis. Our findings demonstrated a significant reduction in CCL2 and CCR2 expression in both imatinib and BM-MSCs treatment groups compared to the liver fibrosis group. Conversely, the gene expression of CX3CL1 and CX3CR1 increased in both therapeutic groups compared to the liver fibrosis groups.

Conclusions

The notable decrease in CCL2-CCR2 genes in both therapeutic groups suggests that BM-MSCs and imatinib may contribute to a decline in inflammatory macrophages within the liver. The lower CCL2-CCR2 expression in imatinib-recipient rats indicates better efficacy in modulating the recruitment of inflammatory macrophages. The elevated expression of CX3CL1 in BM-MSC-recipient rats suggests a greater impact on the polarization of LY6Chigh (inflammatory) to LY6Clow (anti-inflammatory) macrophages, warranting further investigation.

Switching from imatinib to nilotinib plus pegylated interferon-α2b in chronic phase CML failing to achieve deep molecular response: clinical and immunological effects

In order to improve molecular response for a discontinuation attempt in chronic myeloid leukemia (CML) patients in chronic phase, who had not achieved at least a molecular response <0.01% BCR-ABL1^IS (MR^4.0) after at least 2 years of imatinib therapy, we prospectively evaluated whether they could attain MR^4.0 after a switch to a combination of nilotinib and 9 months of pegylated interferon-α2b (PegIFN). The primary endpoint of confirmed MR^4.0 at month 12 (a BCR-ABL1^IS level ≤ 0.01% both at 12 and 15 months) was reached by 44% (7/16 patients, 95% confidence interval (CI): 23- 67%) of patients, with 81% (13/16 patients, 95% CI: 57-93%) of patients achieving an unconfirmed MR^4.0. The scheduled combination was completed by 56% of the patients, with premature discontinuations, mainly due to mood disturbances after the introduction of PegIFN, questioning the feasibility of the combination of nilotinib and PegIFN for this patient population and treatment goal. A comprehensive clinical substudy program was implemented to characterize the impact of the treatment changes on the immunological profile. This trial was registered at www.clinicaltrials.gov as #NCT01866553.

Multiplex proteomics using proximity extension assay for the identification of protein biomarkers predictive of acute graft-vs.-host disease in allogeneic hematopoietic cell transplantation

OBJECTIVES

Allogeneic hematopoietic cell transplantation (HCT) is associated with acute graft-vs.-host disease (aGVHD). The presented study applied a novel multiplex antibody-based proximity extension assay (PEA) proteomic platform that can detect thousands of serum proteins simultaneously for the identification of potential biomarkers of aGVHD.

METHODS

Serum samples from 28 patients who underwent allogeneic HCT for acute myeloid leukemia (AML) were analyzed; 17 were diagnosed with grade II-IV aGVHD while 11 patients were not. Samples collected on day -6, day 0, +14, +30, +60 and +90 post-HCT were analyzed for the relative concentrations of 552 proteins. The concentration of each protein from baseline to the closest time point before onset of aGVHD, or to the latest time point in control patients, was documented.

RESULTS

Individualized analysis identified 26 proteins demonstrating ≥3-fold increase at aGVHD onset compared to baseline, eliminating proteins with a similar increase in controls. Another approach used paired t-testing and logistic regression that identified a four-marker panel, including SLAMF7, IL-1ra, BTN3A2 and DAB2, where individual log-likelihood ratios ranged from 3.99 to 8.15 (logistic regression, p=0.004-0.046). When combined, the four-marker panel demonstrated an area under the curve (AUC) of 0.90 (95% CI: 0.78-1.00; p=0.0006) with high negative predictive value of 81.8% and positive predictive value of 86.7%. All four markers play a physiological role in immune regulation. Among these, three were also present in the individualized analysis (SLAMF7, IL-1ra and BTN3A2).

CONCLUSIONS

We conclude that serum proteins identified using multiplex proteomics, particularly SLAMF7, IL-1ra, BTN3A2 and DAB2, may potentially predict aGVHD.

Case report: Pleural effusion during tyrosine-kinase inhibitor treatment in chronic myeloid leukemia: Not only a dasatinib-related adverse event

The spectrum of TKI-related adverse events (AEs) is variable. Pleural effusion (PE) is a frequent AE attributable to dasatinib treatment, while it is only rarely associated with nilotinib. The pathogenetic mechanism leading to PE during nilotinib therapy is still unknown and its management has not yet been defined. To the best of our knowledge, only a limited number of similar case reports have already been reported in the literature so far. Here, we describe the case of a 41-year-old CML patient who developed PE during first-line nilotinib, successfully treated with steroids and nilotinib permanent discontinuation. We highlight the differences among our patient and the others, proposing therapeutic strategies to solve this rare but still possible AE, of which physicians should be aware.

IFN-α with dasatinib broadens the immune repertoire in patients with chronic-phase chronic myeloid leukemia

In chronic myeloid leukemia (CML), combination therapies with tyrosine kinase inhibitors (TKIs) aim to improve the achievement of deep molecular remission that would allow therapy discontinuation. IFN-α is one promising candidate, as it has long-lasting effects on both malignant and immune cells. In connection with a multicenter clinical trial combining dasatinib with IFN-α in 40 patients with chronic-phase CML (NordCML007, NCT01725204), we performed immune monitoring with single-cell RNA and T cell receptor (TCR) sequencing (n = 4, 12 samples), bulk TCRβ sequencing (n = 13, 26 samples), flow cytometry (n = 40, 106 samples), cytokine analyses (n = 17, 80 samples), and ex vivo functional studies (n = 39, 80 samples). Dasatinib drove the immune repertoire toward terminally differentiated NK and CD8⁺ T cells with dampened functional capabilities. Patients with dasatinib-associated pleural effusions had increased numbers of CD8⁺ recently activated effector memory T (Temra) cells. In vitro, dasatinib prevented CD3-induced cell death by blocking TCR signaling. The addition of IFN-α reversed the terminally differentiated phenotypes and increased the number of costimulatory intercellular interactions and the number of unique putative epitope-specific TCR clusters. In vitro IFN-α had costimulatory effects on TCR signaling. Our work supports the combination of IFN-α with TKI therapy, as IFN-α broadens the immune repertoire and restores immunological function.

Trial Watch: combination of tyrosine kinase inhibitors (TKIs) and immunotherapy

The past decades witnessed the clinical employment of targeted therapies including but not limited to tyrosine kinase inhibitors (TKIs) that restrain a broad variety of pro-tumorigenic signals. TKIs can be categorized into (i) agents that directly target cancer cells, (ii) normalize angiogenesis or (iii) affect cells of the hematologic lineage. However, a clear distinction of TKIs based on this definition is limited by the fact that many TKIs designed to inhibit cancer cells have also effects on immune cells that are being discovered. Additionally, TKIs originally designed to target hematological cancers exhibit bioactivities on healthy cells of the same hematological lineage. TKIs have been described to improve immune recognition and cancer immunosurveillance, providing the scientific basis to combine TKIs with immunotherapy. Indeed, combination of TKIs with immunotherapy showed synergistic effects in preclinical models and clinical trials and some combinations of TKIs normalizing angiogenesis with immune checkpoint blocking antibodies have already been approved by the FDA for cancer therapy. However, the identification of appropriate drug combinations as well as optimal dosing and scheduling needs to be improved in order to obtain tangible progress in cancer care. This Trial Watch summarizes active clinical trials combining TKIs with various immunotherapeutic strategies to treat cancer patients.

Imatinib Mesylate Exerted Antitumor Effect by Promoting Infiltration of Effector T Cells in Tumor

Imatinib mesylate is a potent tyrosine kinase inhibitor that may induce immunological effects, such as inhibition of immune suppressive cells; but, how it modulates the immune system remains to be completely elucidated. In this study, we showed that cell proliferation of CT26 colon cancer and Lewis lung carcinoma (3LL) lung cancer cells was not inhibited by imatinib in vitro, although its administration significantly suppressed the growth of CT26, but not 3LL, subcutaneous tumors, and prolonged survival in CT26 tumor-bearing mice. Further, we examined the expression of immune cell-related molecules in the tumors to elucidate the differences in imatinib-mediated antitumor effects between CT26 and 3LL tumors. The nCounter assay showed that the expression of CD8 and CD8⁺ T cell-recruiting chemokine genes was significantly elevated in imatinib-treated CT26 tumors than that in control tumors; however, the gene expression remained unchanged in imatinib-treated or control 3LL tumors. Furthermore, frequency of interferon-γ⁺ (IFN-γ⁺) CD8⁺ T cells was increased in imatinib-treated CT26 tumors than control tumors, indicating induction of antitumor immunity by imatinib. The analysis indicates that imatinib promotes infiltration of effector T cells in tumors by upregulating expression of cytokines that recruit CD8⁺ T cells in the tumor microenvironment, which may lead to a strong antitumor effect.

Activated naïve γδ T cells accelerate deep molecular response to BCR-ABL inhibitors in patients with chronic myeloid leukemia

Tyrosine kinase inhibitors (TKIs) that target BCR-ABL are the frontline treatments in chronic myeloid leukemia (CML). Growing evidence has shown that TKIs also enhance immunity. Since gamma-delta T (γδT) cells possess the potent anticancer capability, here we investigated the potential involvement of γδT cells in TKI treatments for CML. We characterized γδT cells isolated from chronic-phase CML patients before and during TKI treatments. γδT expression increased significantly in CML patients who achieved major molecular response (MMR) and deep molecular response (DMR). Their Vδ2 subset of γδT also expanded, and increased expression of activating molecules, namely IFN-γ, perforin, and CD107a, as well as γδT cytotoxicity. Mechanistically, TKIs augmented the efflux of isopentenyl pyrophosphate (IPP) from CML cells, which stimulated IFN-γ production and γδT expansion. Notably, the size of the IFN-γ⁺ naïve γδT population in TKI-treated CML patients was strongly correlated with their rates to reach DMR and with the duration on DMR. Statistical analysis suggests that a cutoff of 7.5% IFN-γ⁺ naïve subpopulation of γδT in CML patients could serve as a determinant for MR^4.0 sustainability. Our results highlight γδT cells as a positive regulator for TKI responses in CML patients.

Novel Treatment Strategies Utilizing Immune Reactions against Chronic Myelogenous Leukemia Stem Cells

Simple Summary

Although tyrosine kinase inhibitors (TKIs) are highly effective in the treatment of patients with chronic myelogenous leukemia (CML), leukemic stem cells (LSCs) are known to be resistant to TKIs. As a result, the application of immunotherapies against LSCs may cure CML.

Abstract

Introduction of tyrosine kinase inhibitors (TKIs) has improved the prognosis of patients with chronic myelogenous leukemia (CML), and treatment-free remission (TFR) is now a treatment goal. However, about half of the patients experience molecular relapse after cessation of TKIs, suggesting that leukemic stem cells (LSCs) are resistant to TKIs. Eradication of the remaining LSCs using immunotherapies including interferon-alpha, vaccinations, CAR-T cells, and other drugs would be a key strategy to achieve TFR.

Patterns of Immune Activation in HIV and Non HIV Subjects and Its Relation to Cardiovascular Disease Risk

Introduction

Insight into inflammation patterns is needed to understand the pathophysiology of HIV and related cardiovascular disease (CVD). We assessed patterns of inflammation related to HIV infection and CVD risk assessed with carotid intima media thickness (CIMT).

Methods

A cross-sectional study was performed in Johannesburg, South Africa, including participants with HIV who were virally suppressed on anti-retroviral therapy (ART) as well as HIV-negative participants who were family members or friends to the HIV-positive participants. Information was collected on CVD risk factors and CIMT. Inflammation was measured with the Olink panel ‘inflammation’, allowing to simultaneously assess 92 inflammation markers. Differences in inflammation patterns between HIV-positive and HIV-negative participants were explored using a principal component analysis (PCA) and ANCOVA. The impact of differentiating immune markers, as identified by ANCOVA, on CIMT was assessed using linear regression while adjusting for classic CVD risk factors.

Results

In total, 185 HIV-positive and 104 HIV negative participants, 63% females, median age 40.7 years (IQR 35.4 – 47.7) were included. HIV-positive individuals were older (+6 years, p <0.01) and had a higher CIMT (p <0.01). No clear patterns of inflammation were identified by use of PCA. Following ANCOVA, nine immune markers differed significantly between HIV-positive and HIV-negative participants, including PDL1. PDL1 was independently associated with CIMT, but upon stratification this effect remained for HIV-negative individuals only.

Conclusion

HIV positive patients on stable ART and HIV negative controls had similar immune activation patterns. CVD risk in HIV-positive participants was mediated by inflammation markers included in this study.

Understanding and Monitoring Chronic Myeloid Leukemia Blast Crisis: How to Better Manage Patients

Chronic myeloid leukemia (CML) is triggered primarily by the t(9;22) (q34.13; q11.23) translocation. This reciprocal chromosomal translocation leads to the formation of the BCR-ABL fusion gene. Patients in the chronic phase (CP) experience a good curative effect with tyrosine kinase inhibitors. However, cases are treatment refractory, with a dismal prognosis, when the disease has progressed to the accelerated phase (AP) or blast phase (BP). Until now, few reports have provided a comprehensive description of the mechanisms involved at different molecular levels. Indeed, the underlying pathogenesis of CML evolution comprises genetic aberrations, chromosomal translocations (except for the Philadelphia chromosome), telomere biology, and epigenetic anomalies. Herein, we provide knowledge of the biology responsible for blast transformation of CML at several levels, such as genetics, telomere biology, and epigenetic anomalies. Because of the limited treatment options available and poor outcomes, only the therapeutic response is monitored regularly, which involves BCR-ABL transcript level assessment and immunologic surveillance, with the optimal treatment strategy for patients in CP adapted to evaluate disease recurrence or progression. Overall, selecting optimal treatment endpoints to predict survival and successful TFR improves the quality of life of patients. Thus, identifying risk factors and developing risk-adapted therapeutic options may contribute to a better outcome for advanced-phase patients.

Efficacy and safety of bosutinib versus imatinib for newly diagnosed chronic myeloid leukemia in the Asian subpopulation of the phase 3 BFORE trial

Bosutinib is approved in the United States, Europe, Japan, and other countries for treatment of newly diagnosed chronic phase (CP) chronic myeloid leukemia (CML), and CML resistant/intolerant to prior therapy. In the phase 3 BFORE trial (Clinicaltrials.gov, NCT02130557), patients were randomized 1:1 to first-line bosutinib or imatinib 400 mg once daily. We examined efficacy, safety, and patient-reported outcomes of bosutinib vs imatinib and pharmacokinetics of bosutinib in the Asian (n = 33 vs 34) and non-Asian (n = 235 vs 234) subpopulations of BFORE followed for at least 24 months. At the data cutoff date, 72.7 vs 66.7% of Asian and 70.6 vs 66.4% of non-Asian patients remained on treatment. The major molecular response rate at 24 months favored bosutinib vs imatinib among Asian (63.6 vs 38.2%) and non-Asian (60.9 vs 52.6%) patients, as did the complete cytogenetic response rate by 24 months (86.7 vs 76.7%, 81.5 vs 76.3%). Treatment-emergent adverse events in both subpopulations were consistent with the primary BFORE results. Trough bosutinib concentration levels tended to be higher in Asian patients. Health-related quality of life was maintained after 12 months of bosutinib in both subpopulations. These results support bosutinib as a first-line treatment option in Asian patients with CP CML.

Long-term cardiac, vascular, hypertension, and effusion safety of bosutinib in patients with Philadelphia chromosome-positive leukemia resistant or intolerant to prior therapy

INTRODUCTION

Long-term follow-up (≥4 years) demonstrated a low incidence of cardiac and vascular treatment-emergent adverse events (TEAEs) with bosutinib treatment. We evaluated cardiac, vascular, hypertension, and effusion TEAEs after ≥ 7 years of follow-up in patients with Philadelphia chromosome-positive (Ph+) leukemia.

METHODS

This retrospective analysis of a phase I/II study and its ongoing extension study included data from patients with chronic phase chronic myeloid leukemia (CML) treated with bosutinib after resistance/intolerance to imatinib (CP2L) or to imatinib plus dasatinib and/or nilotinib (CP3L), and those with accelerated/blast phase CML or acute lymphoblastic leukemia after treatment with, at a minimum, imatinib (ADV).

RESULTS

In all, 570 patients were treated with bosutinib; median treatment duration was 11.1 months (range: 0.03-133.1). The incidence of cardiac, vascular, hypertension, and effusion-related TEAEs was 10.9%, 8.8%, 9.1%, and 13.3%, respectively. Few patients had maximum grade 3-4 TEAEs (cardiac, 3.9%; vascular, 4.0%; hypertension, 3.0%; effusion, 4.6%). Grade 5 TEAEs occurred in the cardiac (0.7%) and vascular (1.8%) clusters only. In years 5-7, fewer than 5% of patients each year had newly occurring cardiac, vascular, hypertension, or effusion TEAEs. The exposure-adjusted TEAE rates (patients with TEAEs/total patient-year) pooled across CP2L, CP3L, and ADV cohorts were as follows: cardiac, 0.044; vascular, 0.035; hypertension, 0.038; and effusion, 0.056, of which, correspondingly, 0.9%, 1.2%, 0%, and 2.1% required treatment discontinuation.

CONCLUSIONS

The incidence of cardiac, hypertension, vascular, and effusion events was low in patients with Ph+ CML resistant or intolerant to prior therapy who were treated with bosutinib.

Treatment-free remission and immunity in chronic myeloid leukemia

Chronic myeloid leukemia (CML) is caused by the reciprocal translocation t(9;22)(q34;q11), resulting in the BCR-ABL1 fusion gene. BCR-ABL1 tyrosine kinase inhibitors (TKIs) improve overall survival in patients with chronic phase CML (CML-CP). Approximately half of the patients who achieve a durable deep molecular response can achieve sustained treatment-free remission (TFR) after TKI discontinuation; thus TFR is now a therapeutic goal for most patients with CML-CP. Sensitive BCL-ABL1 transcript detection methods reveal that evidence of residual CML cells remains in patients who achieve sustained TFR, indicating that the host immune system protects against CML relapse. The human immune system is composed of innate and adaptive arms. Natural killer cells are major components of the innate immune system, while T cells are major components of the adaptive immune system. Myeloid-derived suppressor cells and regulatory T cells, both suppressors of the immune response, have important roles in the regulation of CML. Here, we review the current understanding of the immune response in CML, especially in TFR.

Natural Killer Cells and Anti-Cancer Therapies: Reciprocal Effects on Immune Function and Therapeutic Response

Simple Summary

Natural Killer (NK) cells are innate lymphocytes that play an important role in the immune response against cancer. Their activity is controlled by a balance of inhibitory and activating receptors, which in cancer can be skewed to favor their suppression in support of immune escape. It is therefore imperative to find ways to optimize their antitumor functionality. In this review, we explore and discuss how their activity influences, or even mediates, the efficacy of various anti-cancer therapies and, vice versa, how their activity can be affected by these therapies. Knowledge of the mechanisms underlying these observations could provide rationales for combining anti-cancer treatments with strategies enhancing NK cell function in order to improve their therapeutic efficacy.

Abstract

Natural Killer (NK) cells are innate immune cells with the unique ability to recognize and kill virus-infected and cancer cells without prior immune sensitization. Due to their expression of the Fc receptor CD16, effector NK cells can kill tumor cells through antibody-dependent cytotoxicity, making them relevant players in antibody-based cancer therapies. The role of NK cells in other approved and experimental anti-cancer therapies is more elusive. Here, we review the possible role of NK cells in the efficacy of various anti-tumor therapies, including radiotherapy, chemotherapy, and immunotherapy, as well as the impact of these therapies on NK cell function.

Improving outcomes in chronic myeloid leukemia through harnessing the immunological landscape

The quest for treatment-free remission (TFR) and deep molecular response (DMR) in chronic myeloid leukemia (CML) has been profoundly impacted by tyrosine kinase inhibitors (TKIs). Immunologic surveillance of residual leukemic cells is hypothesized to be one of the critical factors in successful TFR, with self-renewing leukemic stem cells implicated in relapse. Immunological characterization in CML may help to develop novel immunotherapies that specifically target residual leukemic cells upon TKI discontinuation to improve TFR rates. This review focuses on immune dysfunction in newly diagnosed CML patients, and the role that TKIs and other therapies have in restoring immune surveillance. Immune dysfunction and immunosurveillance in CML points towards several emerging areas in the key goals of DMR and TFR, including: (1) Aspects of innate immune system, in particular natural killer cells and the newly emerging target plasmacytoid dendritic cells. (2) The adaptive immune system, with promise shown in regard to leukemia-associated antigen vaccine-induced CD8 cytotoxic T-cells (CTL) responses, increased CTL expansion, and immune checkpoint inhibitors. (3) Immune suppressive myeloid-derived suppressor cells and T regulatory cells that are reduced in DMR and TFR. (4) Immunomodulator mesenchymal stromal cells that critically contribute to leukomogenesis through immunosuppressive properties and TKI- resistance. Therapeutic strategies that leverage existing immunological approaches include donor lymphocyte infusions, that continue to be used, often in combination with TKIs, in patients relapsing following allogeneic stem cell transplant. Furthermore, previous standards-of-care, including interferon-α, hold promise in attaining TFR in the post-TKI era. A deeper understanding of the immunological landscape in CML is therefore vital for both the development of novel and the repurposing of older therapies to improve TFR outcomes.

Role of cancer immunology in chronic myelogenous leukemia

Chronic myelogenous leukemia (CML) is caused by the BCR-ABL chimeric tyrosine kinase, which is derived from the reciprocal translocation, t(9;22)(q34;q11). BCR-ABL tyrosine kinase inhibitors (TKIs) can provide prolonged overall survival in CML patients, resulting in life expectancy nearly to general population, and now approximately half of patients who achieved deep molecular response (DMR) can sustain durable molecular remission after discontinuation TKIs. However, residual leukemic cells still detected in the patients who sustained in molecular remission after discontinuation TKIs with the sensitive BCL-ABL1 transcript detection method. Given the fact that residual leukemic cells can exist in these patients, host immune systems can protect the patients to develop CML progression derived from residual leukemic cells. The human immune system is generally composed by innate and adaptive immune systems, corresponding to their functional diversities. Natural killer (NK) cells are major components of the innate immune system, while T lymphocytes (T cells) are major components of the adaptive immune system, and both NK cell and T cell mediate immune responses have an important role in CML. Myeloid-derived suppressor cells (MDSCs) that promote expansion of regulatory T cells (Tregs), leading to host immune suppression, are also important. Although regulation mechanism of these immune system has not been fully elucidated, tumor antigen (e.g. Wilms tumor-1), and surface receptors (e.g. killer immunoglobulin-like receptor and natural killer group 2) on NK cells, are pivotal role in these immune system regulations. Hence, we reviewed the current the immunological analysis, especially T cell and NK cell immunity in CML.