Chronic myeloid leukemia: sequencing of TKI therapies

Exploring treatment decision-making in chronic myeloid leukemia in chronic phase

The introduction of tyrosine kinase inhibitors (TKIs) has transformed the treatment of chronic myeloid leukemia (CML). Each approved TKI has its own risk-benefit profile, and patients have choices across lines of therapy. Identifying the initial and subsequent treatment that will lead to the best possible outcome for individual patients is challenging. In this review, we summarize data for each approved TKI across lines of therapy in patients with CML in chronic phase, highlighting elements of each agent's safety and efficacy profile that may impact patient selection, and provide insights into individualized treatment sequencing decision-making aimed at optimizing patient outcomes.

The impact of the BCR-ABL oncogene in the pathology and treatment of chronic myeloid leukemia

Chronic Myeloid Leukemia (CML) is characterized by chromosomal aberrations involving the fusion of the BCR and ABL genes on chromosome 22, resulting from a reciprocal translocation between chromosomes 9 and 22. This fusion gives rise to the oncogenic BCR-ABL, an aberrant tyrosine kinase identified as Abl protein. The Abl protein intricately regulates the cell cycle by phosphorylating protein tyrosine residues through diverse signaling pathways. In CML, the BCR-ABL fusion protein disrupts the first exon of Abl, leading to sustained activation of tyrosine kinase and resistance to deactivation mechanisms. Pharmacological interventions, such as imatinib, effectively target BCR-ABL's tyrosine kinase activity by binding near the active site, disrupting ATP binding, and inhibiting downstream protein phosphorylation. Nevertheless, the emergence of resistance, often attributed to cap structure mutations, poses a challenge to imatinib efficacy. Current research endeavours are directed towards overcoming resistance and investigating innovative therapeutic strategies. This article offers a comprehensive analysis of the structural attributes of BCR-ABL, emphasizing its pivotal role as a biomarker and therapeutic target in CML. It underscores the imperative for ongoing research to refine treatment modalities and enhance overall outcomes in managing CML.

Multidisciplinary management in chronic myeloid leukemia improves cardiovascular risk measured by SCORE

Introduction: Cardiovascular events are one of the main long-term complications in patients with chronic myeloid leukemia (CML) receiving treatment with tyrosine kinase inhibitors (TKIs). The proper choice of TKI and the adequate management of risk factors may reduce cardiovascular comorbidity in this population. Methods: This study evaluated the cardiovascular risk of a cohort of patients with CML at diagnosis and after follow-up in a specialized cardiovascular risk consultation. In order to do this, we performed data analysis from 35 patients who received TKIs and were referred to the aforementioned consultation between 2015 and 2018 at our center. Cardiovascular risk factors were analyzed separately, as well as integrated into the cardiovascular SCORE, both at diagnosis and at the last visit to the specialized consultation. Results: At the time of diagnosis, 60% had some type of risk factor, 20% had a high or very high risk SCORE, 40% had an intermediate risk, and 40% belonged to the low risk category. During follow-up, the main cardiovascular adverse event observed was hypertension (diagnosed in 8 patients, 23%). 66% of patients quit smoking, achieving control of blood pressure in 95%, diabetes in 50%, weight in 76%, and dyslipidemia in 92%. 5.7% of patients suffered a thrombotic event and a significant percentage of patients showed a reduction in their SCORE. Conclusion: Our study shows the benefit of controlling cardiovascular risk factors through follow-up in a specialized consultation for patients with CML treated with TKI.

Health-related quality of life of patients with resistant/intolerant chronic phase chronic myeloid leukemia treated with asciminib or bosutinib in the phase 3 ASCEMBL trial

In ASCEMBL, an open-label, randomized Phase 3 study, asciminib demonstrated superior efficacy and better safety profile compared with bosutinib in patients with chronic myeloid leukemia in chronic phase (CML-CP) previously treated with ≥2 tyrosine kinase inhibitors. Health-related quality of life (HRQOL) reported by patients is key to understanding the benefit and impact of treatment on patients' lives, and is becoming increasingly important as the life expectancy of CML-CP patients increases and patients require long-term treatment. In ASCEMBL, patients completed questionnaires to assess CML symptoms and interference with daily life (M.D. Anderson Symptom Inventory - CML [MDASI-CML]), general HRQOL (five-level EQ-5D [EQ-5D-5L], Patient Global Impression of Change - CML [PGIC-CML]), and impact of CML on working life and activity (Work Productivity and Activity Impairment questionnaire - CML [WPAI-CML]). Patients' CML symptoms and HRQOL remained stable during 48 weeks of treatment with asciminib, with a general trend for decreased CML symptom severity, particularly for fatigue, and improvement in HRQOL. A clinically meaningful increase in diarrhea severity was observed in patients treated with bosutinib compared to asciminib. These data provide better understanding of the patient perspective and treatment impact on HRQOL in a later-line setting, where little information has been published to date.

Effect of circular RNAs and N6-methyladenosine (m6A) modification on cancer biology

N6-methyladenosine (m6A), as the most abundant and well-known RNA modification, has been found to play an important role in cancer. Circular RNAs (circRNAs) are a class of single-stranded covalently closed RNA molecules generated by the reverse splicing process. Recent studies have revealed the vital roles of circRNAs in many diseases, including tumorigenesis. Accumulating evidence also shows an association between m6A modification and circRNAs. This study aimed to review the interactions between m6A modification and circRNAs and illustrate their roles in tumorigenesis. m6A modification can modulate the biogenesis, translation, cytoplasmic export, degradation, and other functions of circRNAs in different tumors. circRNAs can also modulate m6A modification by affecting writers, erasers, and readers. We focused on the potential regulatory mechanisms and the biological consequences of m6A modification of circRNAs, as well as the interactions in tumors of different systems. Finally, we listed the possible development directions of m6A modification and circRNAs, which might facilitate the clinical application of tumor therapy. AVAILABILITY OF DATA AND MATERIALS: Not applicable. Keywords.

Contemporary practice patterns of tyrosine kinase inhibitor use among older patients with chronic myeloid leukemia in the United States

Introduction:

The choice of BCR-ABL1 tyrosine kinase inhibitors (TKI) for the first line of therapy (LOT) for chronic-phase chronic myeloid leukemia (CML) is tailored to disease risk and patient characteristics like comorbidities, which become more prevalent with age. However, contemporary evaluations of frontline TKI choice and the factors associated with TKI switching in this specific patient population are lacking.

Methods:

We sought to describe TKI use in older patients (age: 66–99 years) with CML in the United States. Using the Surveillance, Epidemiology, and End Results–Medicare-linked database, we identified 810 older (median age: 75 years, interquartile range: 70–80 years) patients diagnosed during 2007–2015.

Results:

Imatinib was the most common frontline TKI (63.1%) throughout the study period, but its utilization as such decreased from 76% in 2010 to 47% in 2015. Most patients (65.3%) used only one TKI, but 12.5% of the 281 patients who switched from frontline TKI received ⩾4 LOT. Among the 167 patients switching from frontline imatinib, 18.6% eventually returned to imatinib with nearly all as the third LOT, supporting its favorable safety profile and indicating that the initial switch from imatinib might have been premature. Older patients within our cohort, white patients and those with greater comorbidity were less likely to switch from frontline TKI. Diagnosis year, geographic region, and surrogates for socioeconomic status and healthcare access had no impact on TKI switching.

Conclusion:

As expected, our findings highlight the frequent use of imatinib as the treatment option for older CML patients despite the availability of second-generation TKIs.

Genetic Biomarkers in Chronic Myeloid Leukemia: What Have We Learned So Far?

Chronic Myeloid Leukemia (CML) is a rare malignant proliferative disease of the hematopoietic system, whose molecular hallmark is the Philadelphia chromosome (Ph). The Ph chromosome originates an aberrant fusion gene with abnormal kinase activity, leading to the buildup of reactive oxygen species and genetic instability of relevance in disease progression. Several genetic abnormalities have been correlated with CML in the blast phase, including chromosomal aberrations and common altered genes. Some of these genes are involved in the regulation of cell apoptosis and proliferation, such as the epidermal growth factor receptor (EGFR), tumor protein p53 (TP53), or Schmidt-Ruppin A-2 proto-oncogene (SRC); cell adhesion, e.g., catenin beta 1 (CTNNB1); or genes associated to TGF-β, such as SKI like proto-oncogene (SKIL), transforming growth factor beta 1 (TGFB1) or transforming growth factor beta 2 (TGFB2); and TNF-α pathways, such as Tumor necrosis factor (TNFA) or Nuclear factor kappa B subunit 1 (NFKB1). The involvement of miRNAs in CML is also gaining momentum, where dysregulation of some critical miRNAs, such as miRNA-451 and miRNA-21, which have been associated to the molecular modulation of pathogenesis, progression of disease states, and response to therapeutics. In this review, the most relevant genomic alterations found in CML will be addressed.

Long-term results of frontline dasatinib in chronic myeloid leukemia

BACKGROUND

Dasatinib is a second-generation tyrosine kinase inhibitor that, when used as frontline therapy, produces more and faster cytogenetic and molecular responses compared with imatinib. The authors report the long-term follow-up from the first study using dasatinib as initial therapy for chronic-phase chronic myeloid leukemia.

METHODS

Between November 2005 and August 2014, patients were randomly assigned to receive 100 mg daily or 50 mg twice daily. After June 2009, all patients started with 100 mg daily.

RESULTS

With a median follow-up of 6.5 years, 94 of 149 treated patients (63%) were still receiving dasatinib on study. The median patient age was 48 years (interquartile range, 37-55 years), and 9% of patients had a high risk Sokal risk score. The cumulative complete cytogenetic response rate at 11 years was 92.6%, the major molecular response (MR) rate was 88.2%, and the MR4.5 rate (indicating a ≥4.5-log reduction in BCR-ABL1 transcripts) was 79.5%. The median time to a major MR and MR4.5 was 6 and 23 months, respectively. A sustained MR4.5 (≥2 years) was achieved in 82 patients (55%). The 10-year overall survival, transformation-free survival, event-free survival, and failure-free survival rates were 89%, 95%, 86%, and 65%, respectively. Univariate analysis showed that the achievement of a complete MR was associated with improved overall survival. The most common reasons for treatment discontinuation were toxicity and elective discontinuation. The most common treatment-emergent grade 3 and 4 adverse events were fatigue, thrombocytopenia, and infections.

CONCLUSIONS

After this long-term follow-up, dasatinib continues to show an excellent safety profile and produces rapid cytogenetic responses and MRs, durable deep MRs, and excellent long-term survival outcomes in patients with chronic-phase chronic myeloid leukemia.

Liquid biopsies in myeloid malignancies

Hematologic malignancies are the most common type of cancer affecting children and young adults, and encompass diseases, such as leukemia, lymphoma, and myeloma, all of which impact blood associated tissues such as the bone marrow, lymphatic system, and blood cells. Clinical diagnostics of these malignancies relies heavily on the use of bone marrow samples, which is painful, debilitating, and not free from risks for leukemia patients. Liquid biopsies are based on minimally invasive assessment of markers in the blood (and other fluids) and have the potential to improve the efficacy of diagnostic/therapeutic strategies in leukemia patients, providing a useful tool for the real time molecular profiling of patients. The most promising noninvasive biomarkers are circulating tumor cells, circulating tumor DNA, microRNAs, and exosomes. Herein, we discuss the role of assessing these circulating biomarkers for the understanding of tumor progression and metastasis, tumor progression dynamics through treatment and for follow-up.

Circular RNAs in Cancer: emerging functions in hallmarks, stemness, resistance and roles as potential biomarkers

Circular RNAs (circRNAs) are a class of RNA molecules with closed loops and high stability. CircRNAs are abundantly expressed in eukaryotic organisms and exhibit both location- and step-specificity. In recent years, circRNAs are attracting considerable research attention attributed to their possible contributions to gene regulation through a variety of actions, including sponging microRNAs, interacting with RNA-binding proteins, regulating transcription and splicing, and protein translation. Growing evidence has revealed that circRNAs play critical roles in the development and progression of diseases, especially in cancers. Without doubt, expanding our understanding of circRNAs will enrich knowledge of cancer and provide new opportunities for cancer therapy. In this review, we provide an overview of the characteristics, functions and functional mechanisms of circRNAs. In particular, we summarize current knowledge regarding the functions of circRNAs in the hallmarks, stemness, resistance of cancer, as well as the possibility of circRNAs as biomarkers in cancer.

How to treat chronic myeloid leukemia (CML) in older adults

Chronic myeloid leukemia (CML), a myeloproliferative neoplasm defined by the t(9;22)(q34;q11) chromosomal translocation, primarily affects older adults. Historically, effective treatment options were not available for older CML patients ineligible for curative allogeneic stem cell transplant, and the disease was therefore usually fatal within several years of diagnosis. The development of tyrosine kinase inhibitors (TKIs) that effectively target the constitutively active mutant tyrosine kinase in CML has dramatically improved outcomes for all patients with CML, including older patients. While older patients were underrepresented in prospective trials, TKI therapy can be successfully administered to older adults with CML with excellent efficacy and proven tolerability. TKI selection and monitoring for adverse events should be tailored based on co-morbidities. As with younger patients, life expectancy of older adults with CML now approaches that of age-matched controls. Here we review guidelines for management of older adults with CML.

Dasatinib cessation after deep molecular response exceeding 2 years and natural killer cell transition during dasatinib consolidation

Tyrosine kinase inhibitors (TKI) improve the prognosis of patients with chronic myelogenous leukemia (CML) by inducing substantial deep molecular responses (DMR); some patients have successfully discontinued TKI therapy after maintaining DMR for ≥1 year. In this cessation study, we investigated the optimal conditions for dasatinib discontinuation in patients who maintained DMR for ≥2 years. This study included 54 patients with CML who were enrolled in a D‐STOP multicenter prospective trial, had achieved DMR, and had discontinued dasatinib after 2‐year consolidation. Peripheral lymphocyte profiles were analyzed by flow cytometry. The estimated 12‐month treatment‐free survival (TFS) was 62.9% (95% confidence interval: 48.5%‐74.2%). During dasatinib consolidation, the percentage of total lymphocytes and numbers of CD3⁻ CD56⁺ natural killer (NK) cells, CD16⁺ CD56⁺ NK cells and CD56⁺ CD57⁺ NK‐large granular lymphocytes (LGL) were significantly higher in patients with molecular relapse after discontinuation but remained unchanged in patients without molecular relapse for >7 months. At the end of consolidation, patients whose total lymphocytes comprised <41% CD3⁻ CD56⁺ NK cells, <35% CD16⁺ CD56⁺ NK cells, or <27% CD56⁺ CD57⁺ NK‐LGL cells had higher TFS relative to other patients (77% vs 18%; P < .0008; 76% vs 10%; P < .0001; 84% vs 46%; P = .0059, respectively). The increase in the number of these NK cells occurred only during dasatinib consolidation. In patients with DMR, dasatinib discontinuation after 2‐year consolidation can lead to high TFS. This outcome depends significantly on a smaller increase in NK cells during dasatinib consolidation.