The effects of combination treatments on drug resistance in chronic myeloid leukaemia: an evaluation of the tyrosine kinase inhibitors axitinib and asciminib

Hallmarks of cancer resistance

This review explores the hallmarks of cancer resistance, including drug efflux mediated by ATP-binding cassette (ABC) transporters, metabolic reprogramming characterized by the Warburg effect, and the dynamic interplay between cancer cells and mitochondria. The role of cancer stem cells (CSCs) in treatment resistance and the regulatory influence of non-coding RNAs, such as long non-coding RNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs), are studied. The chapter emphasizes future directions, encompassing advancements in immunotherapy, strategies to counter adaptive resistance, integration of artificial intelligence for predictive modeling, and the identification of biomarkers for personalized treatment. The comprehensive exploration of these hallmarks provides a foundation for innovative therapeutic approaches, aiming to navigate the complex landscape of cancer resistance and enhance patient outcomes.

Antileukemic potential of methylated indolequinone MAC681 through immunogenic necroptosis and PARP1 degradation

BACKGROUND

Despite advancements in chronic myeloid leukemia (CML) therapy with tyrosine kinase inhibitors (TKIs), resistance and intolerance remain significant challenges. Leukemia stem cells (LSCs) and TKI-resistant cells rely on altered mitochondrial metabolism and oxidative phosphorylation. Targeting rewired energy metabolism and inducing non-apoptotic cell death, along with the release of damage-associated molecular patterns (DAMPs), can enhance therapeutic strategies and immunogenic therapies against CML and prevent the emergence of TKI-resistant cells and LSC persistence.

METHODS

Transcriptomic analysis was conducted using datasets of CML patients' stem cells and healthy cells. DNA damage was evaluated by fluorescent microscopy and flow cytometry. Cell death was assessed by trypan blue exclusion test, fluorescent microscopy, flow cytometry, colony formation assay, and in vivo Zebrafish xenografts. Energy metabolism was determined by measuring NAD+ and NADH levels, ATP production rate by Seahorse analyzer, and intracellular ATP content. Mitochondrial fitness was estimated by measurements of mitochondrial membrane potential, ROS, and calcium accumulation by flow cytometry, and morphology was visualized by TEM. Bioinformatic analysis, real-time qPCR, western blotting, chemical reaction prediction, and molecular docking were utilized to identify the drug target. The immunogenic potential was assessed by high mobility group box (HMGB)1 ELISA assay, luciferase-based extracellular ATP assay, ectopic calreticulin expression by flow cytometry, and validated by phagocytosis assay, and in vivo vaccination assay using syngeneic C57BL/6 mice.

RESULTS

Transcriptomic analysis identified metabolic alterations and DNA repair deficiency signatures in CML patients. CML patients exhibited enrichment in immune system, DNA repair, and metabolic pathways. The gene signature associated with BRCA mutated tumors was enriched in CML datasets, suggesting a deficiency in double-strand break repair pathways. Additionally, poly(ADP-ribose) polymerase (PARP)1 was significantly upregulated in CML patients' stem cells compared to healthy counterparts. Consistent with the CML patient DNA repair signature, treatment with the methylated indolequinone MAC681 induced DNA damage, mitochondrial dysfunction, calcium homeostasis disruption, metabolic catastrophe, and necroptotic-like cell death. In parallel, MAC681 led to PARP1 degradation that was prevented by 3-aminobenzamide. MAC681-treated myeloid leukemia cells released DAMPs and demonstrated the potential to generate an immunogenic vaccine in C57BL/6 mice. MAC681 and asciminib exhibited synergistic effects in killing both imatinib-sensitive and -resistant CML, opening new therapeutic opportunities.

CONCLUSIONS

Overall, increasing the tumor mutational burden by PARP1 degradation and mitochondrial deregulation makes CML suitable for immunotherapy.

Clinical Insights into Structure, Regulation, and Targeting of ABL Kinases in Human Leukemia

Chronic myeloid leukemia is a multistep, multi-lineage myeloproliferative disease that originates from a translocation event between chromosome 9 and chromosome 22 within the hematopoietic stem cell compartment. The resultant fusion protein BCR::ABL1 is a constitutively active tyrosine kinase that can phosphorylate multiple downstream signaling molecules to promote cellular survival and inhibit apoptosis. Currently, tyrosine kinase inhibitors (TKIs), which impair ABL1 kinase activity by preventing ATP entry, are widely used as a successful therapeutic in CML treatment. However, disease relapses and the emergence of resistant clones have become a critical issue for CML therapeutics. Two main reasons behind the persisting obstacles to treatment are the acquired mutations in the ABL1 kinase domain and the presence of quiescent CML leukemia stem cells (LSCs) in the bone marrow, both of which can confer resistance to TKI therapy. In this article, we systemically review the structural and molecular properties of the critical domains of BCR::ABL1 and how understanding the essential role of BCR::ABL1 kinase activity has provided a solid foundation for the successful development of molecularly targeted therapy in CML. Comparison of responses and resistance to multiple BCR::ABL1 TKIs in clinical studies and current combination treatment strategies are also extensively discussed in this article.

Synergy and antagonism between azacitidine and FLT3 inhibitors

Synergetic interactions between drugs can make a drug combination more effective. Alternatively, they may allow to use lower concentrations and thus avoid toxicities or side effects that not only cause discomfort but might also reduce the overall survival. Here, we studied whether synergy exists between agents that are used for treatment of acute myeloid leukaemia (AML). Azacitidine is a demethylation agent that is used in the treatment of AML patients that are unfit for aggressive chemotherapy. An activating mutation in the FLT3 gene is common in AML patients and in the absence of specific treatment makes prognosis worse. FLT3 inhibitors may be used in such cases. We sought to determine whether combination of azacitidine with a FLT3 inhibitor (gilteritinib, quizartinib, LT-850-166, FN-1501 or FF-10101) displayed synergy or antagonism. To this end, we calculated dose-response matrices of these drug combinations from experiments in human AML cells and subsequently analysed the data using a novel consensus scoring algorithm. The results show that combinations that involved non-covalent FLT3 inhibitors, including the two clinically approved drugs gilteritinib and quizartinib were antagonistic. On the other hand combinations with the covalent inhibitor FF-10101 had some range of concentrations where synergy was observed.

Asciminib in the Treatment of Philadelphia Chromosome-Positive Chronic Myeloid Leukemia: Focus on Patient Selection and Outcomes

Tyrosine kinase inhibitors (TKIs) have significantly changed the treatment of chronic myeloid leukemia (CML) and improved outcomes for patients with CML in chronic phase (CML-CP) and accelerated phase (AP). Now armed with numerous effective therapeutic options, clinicians must consider various patient- and disease-specific factors when selecting the most appropriate TKI across lines of therapy. While most patients with CML expected to have a near-normal life expectancy due to the success of TKIs, emphasis has expanded beyond response and survival to include factors like quality of life, tolerability, and long-term toxicity management. Importantly, a subset of patients can achieve sustained deep molecular response and can attain treatment-free remission. Despite these successes, unmet needs remain related to CML treatment, including the persistent challenge of treatment resistance and intolerance, broadening treatment options for patients with resistance mutations or serious comorbidities, and focus on specific populations such as children and young adults. In particular, the only previously available treatments for patients with CML-CP with the T315I mutation were ponatinib, olverembatinib (exclusively approved for use in China at the time of this writing), omacetaxine, and hematopoietic stem cell transplantation. Asciminib has entered the CML treatment landscape as a new option for adult patients with CML-CP who have received ≥2 prior TKIs or those with the T315I mutation. Asciminib's unique mechanism of action, Specifically Targeting the ABL Myristoyl Pocket, sets it apart from traditional adenosine triphosphate-competitive TKIs. While asciminib may overcome unmet needs for patients with CML-CP and continues to be studied in other novel settings, guidance on how to integrate asciminib in treatment algorithms is needed. This review focuses on clinical data and how asciminib can overcome current unmet needs, discusses how to individualize patient selection, and highlights future directions to investigate asciminib in earlier lines of therapy and in children and adolescents.

Combination strategies to overcome drug resistance in FLT+ acute myeloid leukaemia

BACKGROUND

Acute myeloid leukaemia (AML) remains difficult to treat despite the development of novel formulations and targeted therapies. Activating mutations in the FLT3 gene are common among patients and make the tumour susceptible to FLT3 inhibitors, but resistance to such inhibitors develops quickly.

METHODS

We examined combination therapies aimed at FLT3+-AML, and studied the development of resistance using a newly developed protocol. Combinations of FLT3, CDK4/6 and PI3K inhibitors were tested for synergism.

RESULTS

We show that AML cells express CDK4 and that the CDK4/6 inhibitors palbociclib and abemaciclib inhibit cellular growth. PI3K inhibitors were also effective in inhibiting the growth of AML cell lines that express FLT3-ITD. Whereas resistance to quizartinib develops quickly, the combinations overcome such resistance.

CONCLUSIONS

This study suggests that a multi-targeted intervention involving a CDK4/6 inhibitor with a FLT3 inhibitor or a pan-PI3K inhibitor might be a valuable therapeutic strategy for AML to overcome drug resistance. Moreover, many patients cannot tolerate high doses of the drugs that were studied (quizartinib, palbociclib and PI3K inhibitors) for longer periods, and it is therefore of high significance that the drugs act synergistically and lower doses can be used.

Higher-order interactions of Bcr-Abl can broaden chronic myeloid leukemia (CML) drug repertoire

Bcr-Abl, a nonreceptor tyrosine kinase, is associated with leukemias, especially chronic myeloid leukemia (CML). Deletion of Abl's N-terminal region, to which myristoyl is linked, renders the Bcr-Abl fusion oncoprotein constitutively active. The substitution of Abl's N-terminal region by Bcr enables Bcr-Abl oligomerization. Oligomerization is critical: it promotes clustering on the membrane, which is essential for potent MAPK signaling and cell proliferation. Here we decipher the Bcr-Abl specific, step-by-step oligomerization process, identify a specific packing surface, determine exactly how the process is structured and identify its key elements. Bcr's coiled coil (CC) domain at the N-terminal controls Bcr-Abl oligomerization. Crystallography validated oligomerization via Bcr-Abl dimerization between two Bcr CC domains, with tetramerization via tight packing between two binary assemblies. However, the structural principles guiding Bcr CC domain oligomerization are unknown, hindering mechanistic understanding and drugs exploiting it. Using molecular dynamics (MD) simulations, we determine that the binary complex of the Bcr CC domain serves as a basic unit in the quaternary complex providing a specific surface for dimer-dimer packing and higher-order oligomerization. We discover that the small α1-helix is the key. In the binary assembly, the helix forms interchain aromatic dimeric packing, and in the quaternary assembly, it contributes to the specific dimer-dimer packing. Our mechanism is supported by the experimental literature. It offers the key elements controlling this process which can expand the drug discovery strategy, including by Bcr CC-derived peptides, and candidate residues for small covalent drugs, toward quenching oligomerization, supplementing competitive and allosteric tyrosine kinase inhibitors.

Reply to Correspondence on "Synergy and Antagonism between Allosteric and Active-Site Inhibitors of Abl Tyrosine Kinase"

Manley and co-workers provide data demonstrating that, at super-pharmacological concentrations (300 μM), a ternary complex between Abl, asciminib, and ATP-competitive inhibitors is possible. The work in our manuscript concerns the interplay of asciminib (and GNF-2) with ATP-competitive inhibitors at pharmacologically relevant concentrations (Cmax =1.6-3.7 μM for asciminib). Manley and co-workers do not question any of the studies that we reported, nor do they provide explanations for how our work fits into their preferred model. Herein, we consider the data presented by Manley and co-workers. In addition, we provide new data supporting the findings in our Communication. Asciminib and ATP-competitive inhibitors do not simultaneously bind Abl at pharmacologically relevant concentrations unless the conformation selectivity for both ligands is matched.

Allosteric Enhancement of the BCR-Abl1 Kinase Inhibition Activity of Nilotinib by Co-Binding of Asciminib

Inhibitors that bind competitively to the ATP binding pocket in the kinase domain of the oncogenic fusion protein BCR–Abl1 are used successfully in targeted therapy of chronic myeloid leukemia (CML). Such inhibitors provided the first proof of concept that kinase inhibition can succeed in a clinical setting. However, emergence of drug resistance and dose-dependent toxicities limit the effectiveness of these drugs. Therefore, treatment with a combination of drugs without overlapping resistance mechanisms appears to be an appropriate strategy. In the present work, we explore the effectiveness of combination therapies of the recently developed allosteric inhibitor asciminib with the ATP-competitive inhibitors nilotinib and dasatinib in inhibiting the BCR–Abl1 kinase activity in CML cell lines. Through these experiments, we demonstrate that asciminib significantly enhances the inhibition activity of nilotinib, but not of dasatinib. Exploring molecular mechanisms for such allosteric enhancement via systematic computational investigation incorporating molecular dynamics, metadynamics simulations, and density functional theory calculations, we found two distinct contributions. First, binding of asciminib triggers conformational changes in the inactive state of the protein, thereby making the activation process less favorable by ∼4 kcal/mol. Second, the binding of asciminib decreases the binding free energies of nilotinib by ∼3 and ∼7 kcal/mol for the wildtype and T315I-mutated protein, respectively, suggesting the possibility of reducing nilotinib dosage and lowering risk of developing resistance in the treatment of CML.

The structural basis of BCR-ABL recruitment of GRB2 in chronic myelogenous leukemia

BCR-ABL drives chronic myeloid leukemia (CML). BCR binding to GRB2 transduces signaling via the Ras/MAPK pathway. Despite considerable data confirming the binding, molecular-level understanding of exactly how the two proteins interact, and especially, what are the determinants of the specificity of the SH2^GRB2 domain-pBCR recognition are still open questions. Yet, this is vastly important for understanding binding selectivity, and for predicting the phosphorylated receptors, or peptides, that are likely to bind. Here, we uncover these determinants and ascertain to what extent they relate to the affinity of the interaction. Toward this end, we modeled the complexes of the phosphorylated BCR (pBCR) and SH2^GRB2 and other pY/Y-peptide-SH2 complexes and compared their specificity and affinity. We observed that pBCR's ₁₇₆FpYVNV₁₈₀ motif is favorable and specific to SH2^GRB2, similar to pEGFR, but not other complexes. SH2^GRB2 contains two binding pockets: pY-binding recognition pocket triggers binding, and the specificity pocket whose interaction is governed by N179 in pBCR and W121 in SH2^GRB2. Our proposed motif with optimal affinity to SH2^GRB2 is E/D-pY-E/V-N-I/L. Collectively, we provide the structural basis of BCR-ABL recruitment of GRB2, outline its specificity hallmarks, and delineate a blueprint for prediction of BCR-binding scaffolds and for therapeutic peptide design.

Novel Naturally Occurring Dipeptides and Single-Stranded Oligonucleotide Act as Entry Inhibitors and Exhibit a Strong Synergistic Anti-HIV-1 Profile

Introduction

The availability of new classes of antiretroviral drugs is critical for treatment-experienced patients due to drug resistance to and unwanted side effects from current drugs. Our aim was therefore to evaluate the anti-HIV-1 activity of a new set of antivirals, dipeptides (WG-am or VQ-am) combined with a single-stranded oligonucleotide (ssON). The dipeptides were identified as naturally occurring and enriched in feces and systemic circulation in HIV-1-infected elite controllers and were proposed to act as entry inhibitors by binding to HIV-1 gp120. The ssON is DNA 35-mer, stabilized by phosphorothioate modifications, which acts on the endocytic step by binding to cell host receptors and inhibiting viruses through interference with binding to nucleolin.

Methods

Chou–Talalay’s Combination Index method for quantifying synergism was used to evaluate the drug combinations. Patient-derived chimeric viruses encoding the gp120 (env region) were produced by transient transfection and used to evaluate the antiviral profile of the combinations by drug susceptibility assays.

Results

We found that the combination WG-am:ssON or VQ-am:ssON had low combination index values, suggesting strong antiviral synergism. Of the two combinations, WG-am:ssON (1 mM:1 μM) had high efficacy against all prototype or patient-derived HIV-1 isolates tested, independent of subtype including the HIV-1-A6 sub-subtype. In addition, the antiviral effect was independent of co-receptor usage in patient-derived strains.

Conclusion

WG-am and ssON alone significantly inhibited HIV-1 replication regardless of viral subtype and co-receptor usage, and the combination WG-am:ssON (1 mM:1 μM) was even more effective due to synergism.

Rotating between ponatinib and imatinib temporarily increases the efficacy of imatinib as shown in a chronic myeloid leukaemia model

Targeted therapies for chronic myeloid leukaemia (CML) are effective, but rarely curative. Patients typically require treatment indefinitely, which gives ample time for drug resistance to evolve. Drug resistance issues are one of the main causes of death owing to CML, thus any means of preventing resistance are of importance. Drug rotations, wherein treatment is switched periodically between different drugs are one such option, and have been theorized to delay the onset of resistance. In vitro testing of drug rotation therapy is a first step towards applying it in animal or human trials. We developed a method for testing drug rotation protocols in CML cell lines based around culturing cells with a moderate amount of inhibitors interspersed with washing procedures and drug swaps. Drug rotations of imatinib and ponatinib were evaluated in a CML specific cell line, KCL-22. The growth of KCL-22 cells was initially reduced by a drug rotation, but the cells eventually adapted to the protocol. Our results show that ponatinib in a drug rotation temporarily sensitizes the cells to imatinib, but the effect is short-lived and is eventually lost after a few treatment cycles. Possible explanations for this observation are discussed.

Evaluation of anti-tumor effect of the exopolysaccharide from new cold-adapted yeast, Rhodotorula mucilaginosa sp. GUMS16 on chronic myeloid leukemia K562 cell line

Recently, the development and application of fungal exopolysaccharides (EPS) as natural biopolymers are on the rise. The present study is based on the investigation of possible antiproliferative and antioxidant activities of EPS from the Rhodotorula mucilaginosa sp. GUMS16 on BCR-ABL positive cells (K562). The cytotoxicity, colony formation assays lactate and dehydrogenase (LDH) activity were performed to assess the possible cancer cell death. To elucidate the underlying antiproliferative mechanism of the EPS, cell cycle analysis following real-time PCR (gene expression assessment) were evaluated. The results indicated that, the EPS with an IC50 dose of 1500 μg/ml, reduced the viability of K562 cells without having toxic effects on normal cells as well as decrease in size and number of colonies in EPS-treated group (p < 0.0001). The increase of LDH was 2.75 times more than the control (p < 0.0001). Gene expression revealed up- and down-regulation of apoptotic and anti-apoptotic genes in EPS group compared with the control. Moreover, the DPPH scavenging activity of the EPS in treated cells was significantly higher than the control group (p < 0.0001). Taken together, we concluded that the EPS from GUMS16 strain is able to inhibit the growth of K562 cells besides having antioxidant activities.

Genomic Mechanisms Influencing Outcome in Chronic Myeloid Leukemia

Chronic myeloid leukemia (CML) represents the disease prototype of genetically based diagnosis and management. Tyrosine kinase inhibitors (TKIs), that target the causal BCR::ABL1 fusion protein, exemplify the success of molecularly based therapy. Most patients now have long-term survival; however, TKI resistance is a persistent clinical problem. TKIs are effective in the BCR::ABL1-driven chronic phase of CML but are relatively ineffective for clinically defined advanced phases. Genomic investigation of drug resistance using next-generation sequencing for CML has lagged behind other hematological malignancies. However, emerging data show that genomic abnormalities are likely associated with suboptimal response and drug resistance. This has already been supported by the presence of BCR::ABL1 kinase domain mutations in drug resistance, which led to the development of more potent TKIs. Next-generation sequencing studies are revealing additional mutations associated with resistance. In this review, we discuss the initiating chromosomal translocation that may not always be a straightforward reciprocal event between chromosomes 9 and 22 but can sometimes be accompanied by sequence deletion, inversion, and rearrangement. These events may biologically reflect a more genomically unstable disease prone to acquire mutations. We also discuss the future role of cancer-related gene mutation analysis for risk stratification in CML.

Computational Identification of BCR-ABL Oncogenic Signaling as a Candidate Target of Withaferin A and Withanone

Withaferin-A (Wi-A), a secondary metabolite extracted from Ashwagandha (Withania somnifera), has been shown to possess anticancer activity. However, the molecular mechanism of its action and the signaling pathways have not yet been fully explored. We performed an inverse virtual screening to investigate its binding potential to the catalytic site of protein kinases and identified ABL as a strong candidate. Molecular docking and molecular dynamics simulations were undertaken to investigate the effects on BCR-ABL oncogenic signaling that is constitutively activated yielding uncontrolled proliferation and inhibition of apoptosis in Chronic Myeloid Leukemia (CML). We found that Wi-A and its closely related withanolide, Withanone (Wi-N), interact at both catalytic and allosteric sites of the ABL. The calculated binding energies were higher in the case of Wi-A at catalytic site (−82.19 ± 5.48) and allosteric site (−67.00 ± 4.96) as compared to the clinically used drugs Imatinib (−78.11 ± 5.21) and Asciminib (−54.00 ± 6.45) respectively. Wi-N had a lesser binding energy (−42.11 ± 10.57) compared to Asciminib at the allosteric site. The interaction and conformational changes, subjected to ligand interaction, were found to be similar to the drugs Imatinib and Asciminib. The data suggested that Ashwagandha extracts containing withanolides, Wi-A and Wi-N may serve as natural drugs for the treatment of CML. Inhibition of ABL is suggested as one of the contributing factors of anti-cancer activity of Wi-A and Wi-N, warranting further in vitro and in vivo experiments.

Combating drug resistance in acute myeloid leukaemia by drug rotations: the effects of quizartinib and pexidartinib

BACKGROUND

Acute myeloid leukaemia (AML) is an aggressive blood cancer. In approximately 30% of the cases, driver mutations in the FLT3 gene are identified. FLT3 inhibitors are used in treatment of such patients together with cytotoxic drugs or (in refractory AML) as single agents. Unfortunately, resistance to FLT3 inhibitors limits their efficacy. Resistance is often due to secondary mutations in the gene encoding the molecular target. The gatekeeper mutation F691L confers resistance to specific FLT3 inhibitors such as quizartinib, but pexidartinib is much less resistance to this mutation. Pexidartinib alone is however sensitive to many other resistance mutations. In chronic myeloid leukaemia (CML), it has been suggested that rotation between drugs with a different landscape of resistance mutations might postpone the emergence of resistance.

METHODS

We studied the effect of quizartinib and pexidartinib in AML cell lines that express FLT3 (MOLM-14 and MV4-11). Using a rotation protocol, we further examined whether the emergence of resistance could be postponed. Computational modelling was used to analyse the onset of resistance and suggest which mutations are most likely to occur in a quantitative fashion.

RESULTS

The cells were sensitive to both inhibitors but quickly developed resistance that could be inherited, suggesting a genetic origin. Rotation protocols were not useful to postpone the emergence of resistance, which implies that such protocols, or changing from pexidartinib to quizartinib (or vice-versa) should not be used in patients. The computational modelling led to similar conclusions and suggested that F691L is the most common mutation to occur with quizartinib, and also when both drugs are used in rotation.

CONCLUSIONS

AML patients are not likely to benefit from a quizartinib/pexidartinib rotation protocol. A combination of tyrosine kinase inhibitors (with different molecular targets) might be more useful in the future. Development of specific FLT3 inhibitors that are less sensitive to resistance mutations might also lead to a better outcome.

Target spectrum of the BCR-ABL tyrosine kinase inhibitors in chronic myeloid leukemia

BCR-ABL1 plays a key role in the pathogenesis of chronic myeloid leukemia (CML), and it has been investigated as a druggable target of tyrosine kinase inhibitors (TKIs) over two decades. Since imatinib, the first TKI for anti-cancer therapy, was successfully applied in CML therapy, further generation TKIs and a novel allosteric inhibitor targeting the myristate binding site have been developed as alternative options for CML management. However, significant concerns regarding toxicity profiles, especially in long-term treatment, have emerged from TKI clinical data. Efforts to reduce adverse events and serious complications are warranted not only for survival, but also quality of life in CML patients. A better understanding of the mechanism of action will help to identify on- and off-target effects of TKIs, and guide personalized TKI drug selection in each individual CML patient. Herein, this review summarizes the biologic mechanism of BCR-ABL1 inhibition and differential target spectra, and related off-target effects of each TKI.

Chronic myeloid leukemia-from the Philadelphia chromosome to specific target drugs: A literature review

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm and was the first neoplastic disease associated with a well-defined genotypic anomaly - the presence of the Philadelphia chromosome. The advances in cytogenetic and molecular assays are of great importance to the diagnosis, prognosis, treatment, and monitoring of CML. The discovery of the breakpoint cluster region (BCR)-Abelson murine leukemia (ABL) 1 fusion oncogene has revolutionized the treatment of CML patients by allowing the development of targeted drugs that inhibit the tyrosine kinase activity of the BCR-ABL oncoprotein. Tyrosine kinase inhibitors (known as TKIs) are the standard therapy for CML and greatly increase the survival rates, despite adverse effects and the odds of residual disease after discontinuation of treatment. As therapeutic alternatives, the subsequent TKIs lead to faster and deeper molecular remissions; however, with the emergence of resistance to these drugs, immunotherapy appears as an alternative, which may have a cure potential in these patients. Against this background, this article aims at providing an overview on CML clinical management and a summary on the main targeted drugs available in that context.