New insights into the pathobiology and treatment of chronic myelogenous leukemia

Clinical Features and Outcomes of Patients With Chronic Myeloid Leukemia Presenting With Isolated Thrombocytosis: A Systematic Review and a Case From Our Institution

Chronic myeloid leukemia (CML) represents a common condition in the spectrum of myeloproliferative disorders (MPD). It classically exhibits leukocytosis, but rarely presents with isolated thrombocytosis. This paper is designed to review the clinicopathologic features, treatment, and outcomes of patients with CML who present with isolated thrombocytosis. We searched PubMed, MEDLINE®, ScienceDirect, and Scopus for English-language articles about case series and case reports for the period 2000-2020 with the terms "chronic myeloid leukemia" and "thrombocytosis" and pooled them with a case from our institution. Cases were also incorporated from the reference list and screened for inclusion. A total of 20 cases were included in the final cohort. The male-to-female ratio was 1:1.86. The mean age of the patients at the time of initial diagnosis was 40.5 years (range: 9-77 years). Out of 17 cases with available data, seven (41%) were asymptomatic and found to have thrombocytosis incidentally upon routine blood work. Five cases (29.4%) either had a history of thrombotic events or presented with severe thrombotic complications, including ischemic cerebrovascular accidents (CVA), myocardial infarction (MI), pulmonary embolism (PE), and/or miscarriages. Four cases (23.5%) had more than one symptom at presentation, including headache, syncope, and bruising. The average platelet count was 1,923 × 109/L (range: 584-8,688 × 109/L), and one case (5%) had anemia. The bone marrow (BM) examination showed normal cellularity and normal myeloid to erythroid (M/E) ratio in seven (50%) and 11 (84.6%) out of the 14 and 13 cases with reported data, respectively. Moreover, megakaryocytes in the BM were small in 10 cases (71.4%), pleomorphic in three cases (21.4%), and dysplastic in one case (7.1%). Accurate differentiation among MPD subtypes and the exclusion of CML is critical in reaching a proper diagnosis to decide on proper therapy and eventually modify outcomes. Prompt evaluation for the precise diagnosis of patients presenting with isolated marked thrombocytosis will help expedite their diagnosis and initiation of a specific tyrosine kinase inhibitor (TKI) therapy, thereby promptly inducing remission, preventing thrombotic complications, and avoiding adverse drug events, which would eventually improve outcomes.

Organic Nanoparticles as Drug Delivery Systems and Their Potential Role in the Treatment of Chronic Myeloid Leukemia

Chronic myeloid leukemia is a myeloproliferative neoplasm that occurs more prominently in the older population, with a peak incidence at ages 45 to 85 years and a median age at diagnosis of 65 years. This disease comprises roughly 15% of all leukemias in adults. It is a clonal stem cell disorder of myeloid cells characterized by the presence of t(9;22) chromosomal translocation, also known as the Philadelphia chromosome, or its byproducts BCR-ABL fusion protein/messenger RNA, leading to the expression of a protein with enhanced tyrosine kinase activity. This fusion protein has become the main therapeutic target in chronic myeloid leukemia therapy, with imatinib displaying superior antileukemic effects, placing it at the forefront of current treatment protocols and displaying great efficacy. Alternatively, nanomedicine and employing nanoparticles as drug delivery systems may represent new approaches in future anticancer therapy. This review focuses primarily on the use of organic nanoparticles aimed at chronic myeloid leukemia therapy in both in vitro and in vivo settings, by going through a thorough survey of published literature. After a brief introduction on the pathogenesis of chronic myeloid leukemia, a description of conventional, first- and second-line, treatment modalities of chronic myeloid leukemia is presented. Finally, some of the general applications of nanostrategies in medicine are presented, with a detailed focus on organic nanocarriers and their constituents used in chronic myeloid leukemia treatment from the literature.

Human BCR/ABL1 induces chronic myeloid leukemia-like disease in zebrafish

Chronic myeloid leukemia (CML) is induced by the BCR/ABL1 oncogene, which encodes a protein tyrosine kinase. We examined the effect of direct overexpression of the human p210 BCR/ABL1 oncoprotein in zebrafish. Humanized p210 BCR/ABL1 protein was detectable in Tg(hsp70: p210BCR/ABL1 ) transgenic zebrafish embryos and adult kidney marrow. Transgenic zebrafish developed CML, which could be induced via cells transplanted into recipients. The expression of human BCR/ABL1 promoted myeloid lineages in Tg(hsp70:p210BCR/ABL1) transgenic embryos. A total of 77 of 101 (76.24%) Tg(hsp70:p210BCR/ABL1) adult transgenic zebrafish (age 6 months-1 year) developed CML. CML in zebrafish showed a triphasic phenotype, similar to that in humans, involving a chronic phase predominantly characterized by neutrophils in various degrees of maturation, an accelerated phase with an increase in blasts and immature myeloid elements, and a blast phase with >90% blasts in both the peripheral blood and kidney marrow. Tyrosine kinase inhibitors, as the standard drug treatment for human CML, effectively reduced the expanded myeloid population in Tg(hsp70:p210BCR/ABL1) transgenic embryos. Moreover, we screened a library of 171 compounds and identified ten new drugs against BCR/ABL1 kinase-dependent or -independent pathways that could also reduce lcp1+ myeloid cell numbers in Tg(hsp70:p210BCR/ABL1) transgenic embryos. In summary, we generated the first humanized zebrafish CML model that recapitulates many characteristics of human CML. This novel in vivo model will help to elucidate the mechanisms of CML disease progression and allow high-throughput drug screening of possible treatments for this disease.

Inorganic Nanoparticles as Drug Delivery Systems and Their Potential Role in the Treatment of Chronic Myelogenous Leukaemia

Chronic myeloid leukemia is a myeloproliferative disease where cells of myeloid linage display a t(9;22) chromosomal translocation leading to the formation of the BCR/ABL fusion gene and the continuous activation of tyrosine kinases. This malignancy has a peak incidence at 45 to 85 years, accounting for 15% of all leukemias in adults. Controlling the activity of tyrosine kinase became the main strategy in chronic myeloid leukemia treatment, with imatinib being placed at the forefront of current treatment protocols. New approaches in future anticancer therapy are emerging with nanomedicine being gradually implemented. Setting through a thorough survey of published literature, this review discusses the use of inorganic nanoparticles in chronic myeloid leukemia therapy. After an introduction on the basics of chronic myeloid leukemia, a description of the current treatment modalities of chronic myeloid leukemia and drug-resistance mechanisms is presented. This is followed by a general view on the applications of nanostrategies in medicine and then a detailed breakdown of inorganic nanocarriers and their uses in chronic myeloid leukemia treatment.

A study on stability and medical implications for a complex delay model for CML with cell competition and treatment

We study a mathematical model describing the dynamics of leukemic and normal cell populations (stem-like and differentiated) in chronic myeloid leukemia (CML). This model is a system of four delay differential equations incorporating three types of cell division. The competition between normal and leukemic stem cell populations for the common microenvironment is taken into consideration. The stability of one steady state is investigated. The results are discussed via their medical interpretation.

Myeloid sarcoma as the presenting symptom of chronic myelogenous leukemia blast crisis

Myeloid sarcoma is an extramedullary tumor composed of immature myeloid cells that efface the underlying tissue architecture. It is usually associated with acute myelogenous leukemia, but can be associated with myeloproliferative neoplasms, myelodysplastic disorders, or myeloproliferative/ myelodysplastic syndromes. If it is unrecognized, appropriate chemotherapy may be delayed and survival jeopardized. We present a case of a myeloid sarcoma presenting in an otherwise asymptomatic patient who ultimately was found to have chronic myelogenous leukemia, presenting in blast crisis. We also review the distinct clinical and pathologic features of myeloid sarcoma, as well as treatment of the disease.

Extramedullary blast crisis of chronic myelogenous leukemia as an initial presentation

Extramedullary blast crisis of chronic myelogenous leukemia (CML) is defined as the development of extramedullary disease caused by the infiltration of blasts regardless of proliferation of blasts in the bone marrow. The onset of extramedullary blast crisis in the newly diagnosed patients is known to be extremely rare. Here, we present a case of extramedullary blast crisis of CML as an initial presentation in a 17-year-old female presenting with pain in the left femur tumor. This case was treated successfully with dasatinib and allogeneic hematopoietic stem cell transplantation, with achievement of long-term remission.

A case of Philadelphia chromosome positive myeloproliferative neoplasm in a pregnant woman with unusual primary myelofibrosis features

Myeloproliferative neoplasms (MPNs) are traditionally separated into BCR-ABL-positive chronic myeloid leukemia (CML), and BCR-ABL-negative MPNs including primary myelofibrosis (PMF), essential thrombocythemia (ET), and so forth. One of the diagnostic requirements for PMF and ET is the absence of the Philadelphia chromosome, while its presence is almost universally indicative of CML. However, a diagnostic dilemma arises when Philadelphia chromosome-positive MPNs lack the majority of the typical features seen in CML. Some of these classic CML features include basophilIa, marked leukocytosis, neutrophils left-shift with myelocytes bulge, and "dwarf" megakaryocytes. Presented here is a case of a 32-year-old pregnant patient who did not have typical morphologic findings for CML, and yet the Philadelphia chromosome was positive. The patient demonstrated some pathologic features that are commonly presented in PMF that included bone marrow reticulin fibrosis, leukoerythroblastosis, splenomegaly, and increased serum lactate dehydrogenase.

C/EBPβ promotes BCR-ABL-mediated myeloid expansion and leukemic stem cell exhaustion

The BCR-ABL fusion oncoprotein accelerates differentiation and proliferation of myeloid cells during the chronic phase of chronic myeloid leukemia (CP-CML). Here, the role of CCAAT/enhancer binding protein β (C/EBPβ), a regulator for 'emergency granulopoiesis,' in the pathogenesis of CP-CML was examined. C/EBPβ expression was upregulated in Lineage(-) CD34(+) CD38(-) hematopoietic stem cells (HSCs) and myeloid progenitors isolated from bone marrow of patients with CP-CML. In EML cells, a mouse HSC line, BCR-ABL upregulated C/EBPβ, at least in part, through the activation of STAT5. Myeloid differentiation and proliferation induced by BCR-ABL was significantly impaired in C/EBPβ-deficient bone marrow cells in vitro. Mice that were transplanted with BCR-ABL-transduced C/EBPβ knockout bone marrow cells survived longer than mice that received BCR-ABL-transduced wild-type (WT) bone marrow cells. Significantly higher levels of leukemic stem cells were maintained in BCR-ABL-transduced C/EBPβ-deficient cells than in BCR-ABL-transduced WT cells. These results suggest that C/EBPβ is involved in BCR-ABL-mediated myeloid expansion. Further elucidation of the molecular mechanisms underlying the C/EBPβ-mediated stem cell loss might reveal a novel therapeutic strategy for eradication of CML stem cells.

Global dynamics of hematopoietic stem cells and differentiated cells in a chronic myeloid leukemia model

We consider a mathematical model describing evolution of normal and leukemic hematopoietic stem cells (HSC) and differentiated cells in bone marrow. We focus on chronic myeloid leukemia (CML), a cancer of blood cells resulting from a malignant transformation of hematopoietic stem cells. The dynamics are given by a system of ordinary differential equations for normal and leukemic cells. Homeostasis regulates the proliferation of normal HSC and leads the dynamics to an equilibrium. This mechanism is partially efficient for leukemic cells. We define homeostasis by a functional of either hematopoietic stem cells, differentiated cells or both cell lines. We determine the number of hematopoietic stem cells and differentiated cells at equilibrium. Conditions for regeneration of hematopoiesis and persistence of CML are obtained from the global asymptotic stability of equilibrium states. We prove that normal and leukemic cells can not coexist for a long time. Numerical simulations illustrate our analytical results. The study may be helpful in understanding the dynamics of normal and leukemic hematopoietic cells.

Chronic myelogenous leukemia, BCR-ABL1+

Session 1 of the 2007 Workshop of the Society for Hematopathology/European Association for Haematopathology focused on chronic myelogenous leukemia, BCR-ABL1+ (CML). CML is a myeloproliferative neoplasm arising at the level of a pluripotent stem cell and consistently associated with the BCR-ABL1 fusion gene. CML most commonly manifests in a chronic phase of the disease with neutrophilic leukocytosis, and the demonstration of the Philadelphia chromosome is the ultimate confirmation of the diagnosis. However, in select cases, the initial diagnosis remains challenging, and a number of issues pertaining to the manifestations and disease evolution remain unresolved. These issues have been illustrated by the cases submitted to our workshop and include unusual manifestations of CML, including manifestation in the accelerated and/or blast phase, and patterns of disease progression and therapy resistance in the era of protein tyrosine kinase inhibitor therapy.