Correlation Between KIT Expression and c-Kit Mutations in 2 Subtypes of Canine Oral Melanocytic Neoplasms

2021 ◽  
pp. 030098582110097
Author(s):  
Rebecca C. Smedley ◽  
Tuddow Thaiwong ◽  
Lorna E. Deeth ◽  
Matti Kiupel
Keyword(s):  
Tyrosine Kinase ◽  
Protein Function ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Surgical Removal ◽  
Kit Mutation ◽  
Mutation Status ◽  
Malignant Melanomas ◽  
Well Differentiated ◽  
Melanoma Subtypes

c-Kit mutations have been reported in 15% to 40% of certain human melanoma subtypes, including those histologically similar to canine oral malignant melanomas. Therapeutic response to tyrosine kinase inhibitors has been demonstrated in those human patients. As canine oral malignant melanomas tend to have a poor prognosis despite aggressive surgical removal, evaluation of KIT expression and identification of c-Kit mutations in canine oral melanocytic neoplasms was performed to determine if there is any indication that tyrosine kinase inhibitor drugs might effectively treat any of these cases. This study evaluated 27 canine oral malignant melanomas and 12 canine histologically well-differentiated oral melanocytic neoplasms for activating c-Kit mutations, determined differences in immunohistochemical expression of KIT and c-Kit mutation status, and determined if KIT expression could predict c-Kit mutation status. Among samples that contained intraepithelial nests of neoplastic melanocytes in the KIT-labeled sections, KIT was expressed within cells in these nests in 22/23 (96%) malignant melanomas and 5/7 histologically well-differentiated neoplasms. KIT was expressed in 10% to 30% of neoplastic melanocytes in the lamina propria in 3/24 (13%) malignant melanomas, but 0/9 (0%) histologically well-differentiated neoplasms. Next-generation sequencing identified 85 variants in c-Kit, including 9 nonsynonymous mutations that resulted in amino acid changes predicted to affect protein function. c-Kit mutations with predicted deleterious protein effects were more common in malignant melanomas (8/27 [30%] vs 1/12 [8%]). There was no apparent relationship between detected c-Kit mutations and KIT expression. These results do not support the use of therapies that target c-Kit.

scholarly journals Thrombotic microangiopathy in dasatinib-treated patients with chronic myeloid leukemia

2019 ◽  
Vol 4 (1-2) ◽  
pp. 41-45 ◽  
Author(s):  
Takeo Koshida ◽  
Sylvia Wu ◽  
Hitoshi Suzuki ◽  
Rimda Wanchoo ◽  
Vanesa Bijol ◽  
...  
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Tyrosine Kinase ◽  
Tyrosine Kinase Inhibitor ◽  
Tyrosine Kinase Inhibitors ◽  
Thrombotic Microangiopathy ◽  
Myeloid Leukemia ◽  
Kinase Inhibitors ◽  
Kidney Biopsy ◽  
Kinase Inhibitor ◽  
Target Effect

Dasatinib is the second-generation tyrosine kinase inhibitor used in the treatment of chronic myeloid leukemia. Proteinuria has been reported with this agent. We describe two kidney biopsy–proven cases of dasatinib-induced thrombotic microangiopathy that responded to stoppage of dasatinib and using an alternate tyrosine kinase inhibitor. Certain specific tyrosine kinase inhibitors lead to endothelial injury and renal-limited thrombotic microangiopathy. Hematologists and nephrologists need to be familiar with this off-target effect of dasatinib.

scholarly journals Targeting USP47 overcomes tyrosine kinase inhibitor resistance and eradicates leukemia stem/progenitor cells in chronic myelogenous leukemia

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Hu Lei ◽  
Han-Zhang Xu ◽  
Hui-Zhuang Shan ◽  
Meng Liu ◽  
Ying Lu ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Progenitor Cells ◽  
Chronic Myelogenous Leukemia ◽  
Drug Targets ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Myelogenous Leukemia ◽  
Tki Resistance

AbstractIdentifying novel drug targets to overcome resistance to tyrosine kinase inhibitors (TKIs) and eradicating leukemia stem/progenitor cells are required for the treatment of chronic myelogenous leukemia (CML). Here, we show that ubiquitin-specific peptidase 47 (USP47) is a potential target to overcome TKI resistance. Functional analysis shows that USP47 knockdown represses proliferation of CML cells sensitive or resistant to imatinib in vitro and in vivo. The knockout of Usp47 significantly inhibits BCR-ABL and BCR-ABLT315I-induced CML in mice with the reduction of Lin−Sca1+c-Kit+ CML stem/progenitor cells. Mechanistic studies show that stabilizing Y-box binding protein 1 contributes to USP47-mediated DNA damage repair in CML cells. Inhibiting USP47 by P22077 exerts cytotoxicity to CML cells with or without TKI resistance in vitro and in vivo. Moreover, P22077 eliminates leukemia stem/progenitor cells in CML mice. Together, targeting USP47 is a promising strategy to overcome TKI resistance and eradicate leukemia stem/progenitor cells in CML.

Determinants of Choice of Front-Line Tyrosine Kinase Inhibitor for Chronic Phase CML: A Study from the "Registro Italiano LMC & Campus CML"

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 35-36
Author(s):  
Mario Tiribelli ◽  
Roberto Latagliata ◽  
Massimo Breccia ◽  
Isabella Capodanno ◽  
Maria Cristina Miggiano ◽  
...  
Keyword(s):  
High Risk ◽  
Tyrosine Kinase ◽  
Research Funding ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Multivariable Analysis ◽  
Chronic Phase ◽  
Front Line ◽  
Line Therapy ◽  
Concomitant Medications

Introduction : therapy of chronic phase (CP) chronic myeloid leukemia (CML) is based on tyrosine kinase inhibitors (TKIs) in virtually all patients. Three TKIs are approved for first-line therapy in Italy: imatinib and two second-generation (2G) TKIs, dasatinib and nilotinib. Choice of the front-line TKI is based on a combined evaluation of patient's and disease characteristics, age, risk, comorbidities and concomitant medications. Treating physician's preference and, in some cases, economic considerations, particularly after the advent of generic imatinib, may play a role in TKI selection. However, to date, few data are available on TKI use in a whole nation and on the possible drivers of treatment choice. Aim of the present work was to analyse the use of front-line TKI therapy in a large, unselected cohort of Italian CP-CML patients, correlating patient's features to drug choice. Methods: in the framework of the national Campus CML program, we retrospectively evaluated 1422 patients with CP-CML diagnosed from 2012 and 2019 in 21 haematologic Centres, mostly in academic and/or tertiary hospitals, widespread through the entire Italian territory and treated frontline with imatinib, dasatinib or nilotinib. Results: median age at diagnosis was 59.9 years [interquartile range (IQR) 47.1 - 71.7], with 317 (22.3%) patients under 45 years, 552 (38.8%) between 45 and 65 years and 553 (38.9%) older than 65 years; 821 (57.7%) patients were males. Among 1364 evaluable patients, CML risk according to Sokal score was low in 540 (39.6%), intermediate in 610 (44.7%) and high in 214 (15.7%) patients respectively; the number at low, intermediate or high risk according to the novel ELTS score among 1325 evaluable patients was 759 (57.3%), 402 (30.3%) and 164 (12.4%) respectively. Considering comorbidities, 1003 (70.6%) patients had at least one active disease at the time of CML diagnosis, the most common being hypertension (n=547, 38.5%), previous neoplasms (n=185, 13.0%), diabetes (n=150, 10.6%), chronic bronchopulmonary diseases (n=114, 8.0%), acute myocardial infarction (n=95, 6.7%), previous stroke (n=36, 2.5%) and other vascular diseases (n=98, 6.9%). Among 1335 evaluable patients, 813 (60.9%) were taking at least one concomitant medication, with 280 (21.0%) taking 3-5 drugs and 140 (10.5%) taking 6+ drugs at time of TKI start. As to the frontline therapy, 794 (55.8%) received imatinib and 628 (44.2%) were treated with 2G-TKIs, (226 dasatinib and 402 nilotinib) respectively. According to age, 2G-TKIs were chosen for majority of patients aged <45 (69.1%) while imatinib was used in 76.9% of patients over 65 (p<0.001). There was a predominance of imatinib use across all Sokal (51.1% in low, 61.3% in intermediate and 51.4% in high) and ELTS (50.3% in low, 60.4% in intermediate and 66.5%) risk categories. We observed a prevalent use of 2G-TKIs in patients presenting with higher WBC counts (55.1% if WBC >100,000/mm3 vs 38.2% if WBC <100,000/mm3; p<0.001), lower Hb (53.8% if Hb <10 g/dl vs 41.9 if Hb >10 g/dl; p=0.001) and bigger spleen (65.1% if spleen >5 cm vs 44.8% if spleen 1-5 cm vs 37.3% if spleen not palpable; p<0.001). There was a decreasing use of 2G-TKIs with higher number of concomitant drugs: 64.4% for 0, 47.7% for 1-2, 27.0% for 3-5 and 13.6% for >5 drugs, respectively (p<0.001). Concordantly, there was a significant higher use of imatinib in patients with hypertension (69.8%), diabetes (70.0%), COPD (73.7%), previous neoplasms (73.0%), AMI (86.3%) or stroke (97.2%) history (p<0.001 for all conditions). Lastly, we observed a wider use of imatinib (61.1%) in patients diagnosed in years 2018-19, compared to those of the period 2012-17 (53.7%; p=0.01). In multivariable analysis, factors correlated with imatinib use were age > 45 years, intermediate or high Sokal risk, presence of some comorbidities (2nd neoplasia and stroke) and number of concomitant medications. Conclusions: preliminary results of this observational study on almost 1500 patients show that around 55% of newly diagnosed Italian CP-CML patients receive imatinib as front-line therapy, and that the use of 2G-TKI is prevalent in the younger patients and in those with no concomitant clinical conditions. The counterintuitive finding of imatinib prevalence as frontline treatment in high risk patients might be explained by the older age of these patients. Introduction of the generic formulation in 2018 seems to have fostered the use of imatinib. Figure Disclosures Breccia: Novartis: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Incyte: Consultancy, Honoraria; Abbvie: Consultancy; Bristol-Myers Squibb/Celgene: Consultancy, Honoraria. Cavazzini:Pfize: Honoraria; Incyte: Honoraria; Novartis: Honoraria. Saglio:Bristol-Myers Squibb: Research Funding; Pfizer: Research Funding; Incyte: Research Funding; Novartis: Research Funding; Ariad: Research Funding; Roche: Research Funding.

Risk of toxicity with immunotherapy–tyrosine kinase inhibitors for metastatic renal cell carcinoma: a meta-analysis of randomized controlled trials

2021 ◽  
Author(s):  
Alessandro Rizzo ◽  
Veronica Mollica ◽  
Matteo Santoni ◽  
Matteo Rosellini ◽  
Andrea Marchetti ◽  
...  
Keyword(s):  
Renal Cell Carcinoma ◽  
Adverse Events ◽  
Tyrosine Kinase ◽  
Cell Carcinoma ◽  
Metastatic Renal Cell Carcinoma ◽  
Renal Cell ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Meta Analysis ◽  
Relative Risks

Aim: Few data are available regarding the safety profile of immunotherapy–tyrosine kinase inhibitor (IO-TKI) combinations in metastatic renal cell carcinoma. The authors investigated all-grade and grade 3–4 (G3–4) adverse events in trials comparing IO-TKI combinations with sunitinib monotherapy. Methods: The relative risks of several all-grade and G3–4 adverse events were analyzed. Results: Relative risks were similar between patients receiving IO-TKI combinations versus sunitinib monotherapy. However, the use of IO-TKI combinations was associated with a higher risk of all-grade and G3–4 diarrhea, all-grade hypothyroidism, G3–4 decreased appetite, all-grade and G3–4 aspartate transaminase increase and all-grade and G3–4 alanine transaminase increase. Conclusion: The results of the authors' meta-analysis suggest that risks of treatment-related adverse events should be carefully considered when choosing IO-TKI combinations in metastatic renal cell carcinoma patients.

scholarly journals The importance of molecular biology in development, prognosis, treatment and resistance to targeted therapy in gastrointestinal stromal tumors

2011 ◽  
pp. 69-79
Author(s):  
Alessandro Comandone ◽  
Elisa Berno ◽  
Simona Chiadò Cutin ◽  
Antonella Boglione
Keyword(s):  
Tyrosine Kinase ◽  
Gastrointestinal Stromal Tumors ◽  
Kinase Inhibitors ◽  
Growth Factor Receptor ◽  
Neoplastic Transformation ◽  
Response To Therapy ◽  
Mesenchymal Tumors ◽  
Kit Mutation ◽  
Stromal Tumors ◽  
Receive Treatment

Gastrointestinal stromal tumors (GISTs) are the commonest mesenchymal tumors of the gastroenteric tract, and are generally believed to originate from the neoplastic transformation of the interstitial cells of Cajal, the pacemaker structures of the stomach and intestine. Exon and genetic mutations (point/deletions) are fundamental for the development of GISTs: the constitutional characteristic of this neoplasm is the presence of the cell surface Kit receptor. Kit is the product of the proto-oncogene cKit, situated in chromosome 4. Ninety-eight percent of GISTs express mutated isoforms of Kit or of PDGFRA (Platelet growth factor receptor a). Kit mutation is the basic condition for autophosphorylation of tyrosine kinase residues in proteins. Autophosphorylation initiates pathogenetic processes in Cajal cells, toward a neoplastic transformation. Imatinib mesilate and, more recently, sunitinib are tyrosine kinase inhibitors, specific antagonists for Kit and PDGFRA, with good activity against GISTs. Most molecular and clinical data currently available concern imatinib. Exon mutations are strategic as prognostic and as predictive factors. In recent years, much evidence suggests that survival, response to therapy and resistance to imatinib are related to different mutations. In the near future, GIST patients will receive treatment differentiated by expressed Kit and PDGFRA mutations, thus truly individualized therapy.

Surgery of locally advanced and metastatic kidney cancer after tyrosine kinase inhibitors therapy: single institute experience

2018 ◽  
Vol 104 (5) ◽  
pp. 388-393
Author(s):  
Alberto De Gobbi ◽  
Davide Biasoni ◽  
Mario Catanzaro ◽  
Nicola Nicolai ◽  
Luigi Piva ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Target Therapy ◽  
Tnm Classification ◽  
Locally Advanced ◽  
Progression Free Survival ◽  
Metastatic Tumor ◽  
Grade Ii

Purpose: Renal cell carcinoma (RCC) is the most common tumor of the kidney. Considering the TNM classification of 2009, locally advanced and metastatic diseases are included in the groups stage III and IV. The surgical treatment of these tumors could be divided into 3 categories: (1) curative (nephrectomy and/or metastasectomy), (2) cytoreductive, and (3) palliative. Targeted agents showed impressive antitumor efficacy and prolongation of progression-free survival. The integration between target therapy and surgery in patients with locally advanced or metastatic RCC has sometimes facilitated surgery. We aimed to evaluate patients’ response to tyrosine kinase inhibitor (TKI) therapy and the feasibility of surgery after that and to observe complications related to surgery. Methods: From February 2007 to September 2014 in the Istituto Tumori of Milan, IRCCS, we selected patients with locally advanced or metastatic diseases, treated with target therapy before surgery (which comprised nephrectomy or partial nephrectomy, cytoreductive surgery, and metastasectomy) and cryoablation. Results: We selected 33 patients who underwent surgery after TKI therapy. As for response to TKIs, 20 patients (60%) had stable disease, 9 patients (28%) had a partial response, and 4 patients (12%) had progressive disease. A total of 17 patients (51%) presented complications directly or indirectly related to surgery and most of those were classified as grade II Clavien-Dindo score. Conclusions: The association between TKI and surgery seems to have no contraindications. Our dataset provides an example of how surgery after TKI is possible in locally advanced metastatic tumor and does not have an excessive rate of postoperative complications.

scholarly journals Nilotinib therapy in an imatinib intolerant chronic myeloid leukemia patient with pulmonary severe hypertension

2015 ◽  
Vol 4 (2S) ◽  
pp. 17-20
Author(s):  
Mario Annunziata
Keyword(s):  
Side Effects ◽  
Tyrosine Kinase ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Chronic Phase ◽  
Chronic Myeloid Leukemia Patient ◽  
Cytogenetic Response ◽  
Myelogenous Leukemia ◽  
Molecular Response ◽  
Cutaneous Rash

Imatinib mesylate is a tyrosine kinase inhibitor that has significant efficacy in the treatment of chronic myelogenous leukemia. In general, hematologic and extrahematologic side effects of imatinib therapy are mild to moderate, with the large majority of patients tolerating prolonged periods of therapy. However, a minority of patients are completely intolerant of therapy, while others are able to remain on therapy despite significant side effects. Here, we describe a chronic phase CML patient with pulmonary arterial hypertension, mechanical hearth valve, who experienced extrahematologic adverse event (persistent grade III cutaneous rash, despite two discontinuations of imatinib and using of steroid). Necessitating switch to one of new tyrosine kinase inhibitors, nilotinib, has resulted in complete cytogenetic response and major molecular response, after 3 and 6 months, respectively. No cross-intolerance with imatinib was observed during nilotinib therapy. Besides, this clinical case suggests that warfarin and nilotinib can be used concurrently without the risk of increased anticoagulant effect.

Targeting Mcl-1 Enhances the Activity of Tyrosine Kinase Inhibitor Gilteritinib in FLT3 Mutated AML

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 30-31
Author(s):  
Bing Z Carter ◽  
Po Yee Mak ◽  
Vivian Ruvolo ◽  
Wenjing Tao ◽  
Paul Hughes ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Signaling Pathways ◽  
Progenitor Cells ◽  
Research Funding ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Mapk Signaling ◽  
Culture Conditions ◽  
Beta Catenin ◽  
Adaptive Resistance

Anti-apoptotic Bcl-2 proteins play critical roles in AML cell and AML stem/progenitor cell survival and drug resistance, hence are relevant therapeutic targets. Indeed, the combination of the selective Bcl-2 inhibitor venetoclax (VEN) with a hypomethylating agent elicits CR/CRi rates of > 65%, is well tolerated by elderly AML patients, and obtained FDA approval. However, despite of the major improvement in response rates, survival extension was limited and most patients ultimately relapsed largely due to the development of resistant disease. Molecular analysis of treated patients revealed that primary and adaptive resistance to VEN-based combinations was frequently characterized by acquisition or enrichment of clones activating signaling pathways such as FLT3 or RAS (DiNardo CD et al., Blood 2020). FLT3 is one of the most frequently mutated gene in AML, resulting in constitutive activation of FLT3 tyrosine kinase and its downstream signaling pathways such as RAS/MAPK, which can be targeted by FLT3 tyrosine kinase inhibitors (TKIs). However, patients treated with TKIs ultimately relapse and adapt to TKI therapy by reactivating the MAPK signaling pathway (Bruner JK et al., Cancer Res 2017), which is known to stabilize Mcl-1 levels. Furthermore, deregulated Mcl-1 expression was identified as a novel mechanism of primary TKI resistance in a subset of FLT3-ITD mutated AML patients (Breitenbuecher F et al., Blood 2009). Importantly, Mcl-1 expression can be induced by VEN treatment and is a major resistance factor to VEN (Pan R et al., Cancer Discover 2014; Carter BZ et al., ASH 2018). Hence, Mcl-1 inhibition may enhance the efficacy of TKIs in FLT3 mutated AML, targeting AML cells and stem/progenitor cells. To determine if targeting Mcl-1 enhances the activity of TKIs in FLT3 mutated AML, we treated MV4-11 and Molm13 cells with Mcl-1 inhibitor AMG176 and TKI gilteritinib (GIL) and observed synergism, as defined by combination index < 1 in both cells. Mechanistic studies demonstrated that GIL markedly decreased Mcl-1 and antagonized AMG176-induced Mcl-1 induction. GIL and its combination with AMG176 also decreased Bcl-xL. Although Bcl-2 protein levels were largely not changed in MV4-11 cells, we found both single treatment and the combination greatly decreased Bcl-2 associated athanogene (BAG) proteins BAG1, BAG3, and BAG4 at the RNA level, which needs to be confirmed at the protein level. The BAG proteins are a family of chaperone regulators and BAG1 was reported to bind and enhance the activity of multiple proteins known to support cells survival, including Bcl-2 (Takayama S et al., Cell 1995). Interestingly, GIL treatment greatly diminished the levels of beta-catenin and its target protein c-Myc, consistent with our previous report that FLT3 regulates beta-catenin signaling (Xiang et al., CCR, 2018). We have generated Mcl-1 overexpressing (OE) and VEN-resistance (VEN-R) MV4-11 and Molm13 cells. The Mcl-1 OE cells are highly resistant to VEN and the VEN-R cells expressed high levels of Mcl-1. Combined inhibition of AMG176 and GIL synergistically induced cell death in Mcl-1 OE and VEN-R resistant cells. Although the expression is low in AML cells we tested, BCL2A1 is also known as a resistant factor to VEN. We generated BCL2A1 OE MV4-11 and Molm13 cells and demonstrated that combined inhibition of FLT3 and Mcl-1 was highly effective in these cells as well. Western blot analysis revealed that GIL effectively decreased Mcl-1 in Mcl-1 OE and VEN-R and BCL2A1 in BCL2A1 OE MV4-11 cells. Next, we treated FLT3 mutated AML patient samples harboring both, ITD and D835 mutations, from 2 patients who had both failed VEN-based therapy and from 1 patient with ITD mutation, with AMG176 and GIL under MSC co-culture conditions. Synergy was observed in all samples in AML blasts and AML stem/progenitor cells. Collectively, our data demonstrate that targeting Mcl-1 enhances the activity of GIL in FLT3 mutated AML, including those resistant to/relapsed from VEN-based therapy, findings that may warrant clinical evaluation. Disclosures Carter: Syndax: Research Funding; Ascentage: Research Funding; AstraZeneca: Research Funding; Amgen: Research Funding. Hughes:Amgen: Current Employment. Chen:Amgen: Current Employment. Morrow:Amgen: Current Employment. Andreeff:Amgen: Research Funding; Centre for Drug Research & Development; Cancer UK; NCI-CTEP; German Research Council; Leukemia Lymphoma Foundation (LLS); NCI-RDCRN (Rare Disease Clin Network); CLL Founcdation; BioLineRx; SentiBio; Aptose Biosciences, Inc: Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo; Breast Cancer Research Foundation; CPRIT; NIH/NCI; Amgen; AstraZeneca: Research Funding; Daiichi-Sankyo; Jazz Pharmaceuticals; Celgene; Amgen; AstraZeneca; 6 Dimensions Capital: Consultancy.

scholarly journals Mechanisms of Disease Progression and Resistance to Tyrosine Kinase Inhibitor Therapy in Chronic Myeloid Leukemia: An Update

2019 ◽  
Vol 20 (24) ◽  
pp. 6141 ◽  
Author(s):  
Luana Bavaro ◽  
Margherita Martelli ◽  
Michele Cavo ◽  
Simona Soverini
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Tyrosine Kinase ◽  
Disease Progression ◽  
Myeloid Leukemia ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Fusion Gene ◽  
Primary Resistance ◽  
Secondary Resistance ◽  
Dismal Prognosis

Chronic myeloid leukemia (CML) is characterized by the presence of the BCR-ABL1 fusion gene, which encodes a constitutive active tyrosine kinase considered to be the pathogenic driver capable of initiating and maintaining the disease. Despite the remarkable efficacy of tyrosine kinase inhibitors (TKIs) targeting BCR-ABL1, some patients may not respond (primary resistance) or may relapse after an initial response (secondary resistance). In a small proportion of cases, development of resistance is accompanied or shortly followed by progression from chronic to blastic phase (BP), characterized by a dismal prognosis. Evolution from CP into BP is a multifactorial and probably multistep phenomenon. Increase in BCR-ABL1 transcript levels is thought to promote the onset of secondary chromosomal or genetic defects, induce differentiation arrest, perturb RNA transcription, editing and translation that together with epigenetic and metabolic changes may ultimately lead to the expansion of highly proliferating, differentiation-arrested malignant cells. A multitude of studies over the past two decades have investigated the mechanisms underlying the closely intertwined phenomena of drug resistance and disease progression. Here, we provide an update on what is currently known on the mechanisms underlying progression and present the latest acquisitions on BCR-ABL1-independent resistance and leukemia stem cell persistence.

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