Late Responses in Patients With Chronic Myeloid Leukemia Initially Refractory to Tyrosine Kinase Inhibitors

Cytogenetic and epidemiological profile of chronic myeloid leukemia in Morocco

Chronic myeloid leukemia (CML) is a neoplastic disease of genetic origin resulting from clonal proliferation of hematopoietic stem cells (HSCs). The reciprocal translocation t(9;22)(q34;q11) is the main chromosomal abnormality involved in this pathology, usually detected by conventional cytogenetics. This article aims to investigate the epidemiological, cytogenetic, therapeutic, and clinical characteristics of Moroccan patients with CML. This research represents the first large-scale study of CML patients in Morocco and was carried out at Institut Pasteur of Morocco. Bone marrow samples were processed for cytogenetic analysis, and karyotypes were described according to an international system of human cytogenetic nomenclature (ISCN 2016). Patients were studied according to their epidemiological characteristics, clinical information and cytogenetic results. For statistical calculations, R version 4.3.1 was used to analyze the data and calculate the statistical parameters. RStudio and Power BI were used for data visualization. The National Cancer Institute (NCI) Surveillance, Epidemiology, and End Results (SEER) method of incidence estimation was used to calculate our incidence. We received 826 patients (from 1992 to 2023) who were referred for suspected CML or who were undergoing treatment. Only 650 patients with confirmed CML were included in the study, all of whom underwent their first cytogenetic test. The median age of our patients was 45 years and the sex ratio was 1.03. At the time of diagnosis, 147 (30%) of the patients had clinical manifestations. Most patients were diagnosed in the chronic phase (94.5%). Nineteen complex variant translocations of the Philadelphia (Ph) chromosome were detected. At the time of diagnosis, 55 (11.5%) patients had ACAs, of which 30 (54.5%) were high-risk ACAs. Based on data from 174 patients treated with imatinib, the median time to complete cytogenetic response (CCyR) was 11 months, and at the last cytogenetic follow-up, 81 patients (46.6%) achieved CCyR, while 64 patients (36.8%) showed no response to treatment. Regarding adherence to European LeukemiaNet (ELN) guidelines, 58 patients (33%) were followed according to these guidelines, with optimal treatment in 8.6%, suboptimal treatment in 7% and treatment failure in 18%. The estimated incidence of chronic myeloid leukemia calculated is 0.6 cases per 100,000 in the Casablanca region. This study provides a detailed overview of CML in Morocco, highlighting important clinical, cytogenetic and therapeutic aspects despite some limitations. It also highlights the need to deepen our understanding of this complex disease for disease management in our specific context.

Low-Dose Dasatinib (50 mg Daily) Frontline Therapy in Newly Diagnosed Chronic Phase Chronic Myeloid Leukemia: 5-Year Follow-Up Results

BACKGROUND

Dasatinib is a BCR::ABL1 tyrosine kinase inhibitor approved as frontline therapy at a 100 mg daily for chronic myeloid leukemia in chronic phase (CML-CP). The use of a lower dose of dasatinib (50 mg daily) has demonstrated better tolerance and improved outcomes compared with the standard dose. Here, we report the updated results in a large cohort with a 5-year follow-up.

PATIENTS AND METHODS

Patients with newly diagnosed CML-CP were eligible. Entry and response-outcome criteria were standard. Dasatinib was given as 50 mg orally daily.

RESULTS

Eighty-three patients were included. At 3 months, 78 (96%) patients achieved BCR::ABL1 transcripts (IS) ≤10%, and at 12 months, 65 (81%) patients achieved BCR::ABL1 transcript (IS) ≤0.1%. The cumulative incidence of complete cytogenetic, major molecular, and deep molecular responses at 5 years were 98%, 95%, and 82%, respectively. Rates of failures due to resistance (n = 4; 5%) and toxicity (n = 4; 5%) were low. The 5-year overall survival was 96% and event-free survival 90%. No transformations to accelerated or blastic phase were observed. Grade 3 to 4 pleural effusions developed in 2% of patients.

CONCLUSION

Dasatinib 50 mg daily is an effective and safe treatment for newly diagnosed CML-CP.

Revisiting six established practices in the treatment of chronic myeloid leukaemia

After two decades of use in chronic myeloid leukaemia, the risks and benefits of established treatment practices for BCR::ABL1 tyrosine kinase inhibitors (TKIs) in the chronic myeloid leukaemia in chronic phase of the disease should be analysed. In this Viewpoint, we suggest that the use of lower than approved TKI doses in both front-line and later-line therapies would result in similar treatment efficacy, less toxicity, better treatment compliance, and reduced cost of care. The absence of an early molecular response might not warrant a change of a TKI, particularly for second-generation TKIs. Among patients in whom reaching a treatment-free remission is not a therapeutic goal or treatment-free remission is unlikely, changing TKIs to improve the depth of molecular response might result in more harm than good. Reducing the TKI dose in response to mild to moderate, or even serious, reversible side-effects might be better than changing the TKI. The availability of generic imatinib, generic dasatinib, and possibly later other generic second-generation TKIs would offer 90% of patients with chronic myeloid leukaemia an effective, safe, and affordable therapy that normalises life expectancy, and results in treatment-free remission status in 30-50% of patients over the long term. Finally, based on treatment value, any TKI that costs more than US$30 000-40 000 per year should be critically evaluated in relation to alternative modalities, such allogeneic haematopoietic stem-cell transplantation.

Current and emerging tyrosine kinase inhibitors for the treatment of chronic myeloid leukemia in young adults

INTRODUCTION

Chronic myeloid leukemia (CML) is more common in older adults, but nearly 15-20% of the patients is between 15 and 39 years of age. In this age group, patients may seek clinical care a much later period of the disease and they may have a heavier burden of disease. In addition, young patients with CML may face unique challenges related to their age, such as concerns about health care, fertility, or careers. The current standard of care for CML is the use of tyrosine kinase inhibitors (TKIs), which induce remission in most young patients and can achieve long-term disease control.

AREAS COVERED

This review summarizes age-specific treatment-related conditions, as well as the effectiveness of TKI therapy in this age group. PubMed, Google Scholar, clinicaltrials.gov and other abstract databases were used while preparing this review. The period of 2001-2023 was chosen as the search window.

EXPERT OPINION

Although we do not have sufficient data, young adult population has a special importance for TKI treatment. Clinical features, efficacy of treatments, and specific conditions in this age group should attract more attention of clinicians and more intensive studies should be conducted in the future.

Chronic myeloid leukemia without major molecular response after 2 years of treatment with tyrosine kinase inhibitor

Achieving major molecular response (MMR) with BCR::ABL1 tyrosine kinase inhibitors (TKIs) is associated with lower chances of progression to advanced phase disease and higher chances of treatment-free remission (TFR) in patients with chronic myeloid leukemia (CML). Failure to achieve this molecular milestone after 1 year has been highlighted as "suboptimal" or "warning" sign of treatment failure in CML guidelines and recommendations and implied to predict a poor long-term outcome. In this analysis, we report the long-term outcome of 131 patients who did not achieve MMR within the first 2 years of TKI therapy. Patients who achieved a major cytogenetic response (MCyR; roughly equivalent to BCR::ABL1 transcript levels on the International Scale [IS] <10%) had good long-term overall survival (OS) (10-year OS of 88%) and CML-related overall survival (CML-OS) (10-year CML-OS of 95%). The achievement of MCyR within the first 2 years of treatment predicted a better OS (HR = 0.43, p = .03). The value of MMR was even less pronounced among patients aged 60 years or older at diagnosis, in whom mortality was primarily due to comorbidities unrelated to CML (10-year OS of 55% vs. 10-year CML-OS of 100%). In conclusion, achievement of MCyR within 2 years is a reasonable milestone in CML, and these patients can still have good outcomes even when MMR is not achieved.

SOHO State of the Art Updates and Next Questions | Update on Treatment-Free Remission in Chronic Myeloid Leukemia (CML)

Tyrosine kinase inhibitor (TKI) discontinuation, also known as treatment-free remission (TFR) is currently one of the main goals of chronic myeloid leukemia (CML) therapy. TKI discontinuation should be considered in eligible patients for several reasons. Specifically, TKI therapy is associated with reduced quality of life, long-term side effects, and a heavy financial burden on both the patients and society. TKI discontinuation is a particularly important goal for younger patients diagnosed with CML because of the treatment's effects on their growth and development in addition to potential long-term side-effects. Numerous studies with thousands of patients have demonstrated the safety and feasibility of attempting TKI discontinuation in a select group of patients who have achieved a sustained deep molecular remission. With current TKIs, approximately 50% of patients will be eligible for attempting TFR of which only 50% will achieve a successful TFR. Therefore, in reality, only 20% of patients with newly diagnosed CML will achieve a successful TFR, and the majority of patients will need to continue TKI therapy indefinitely. However, several ongoing clinical trials are investigating treatment options for patients to achieve deeper remission with the ultimate goal of a cure, which is defined as being off drug with no evidence of disease.

Chronic Myeloid Leukemia: 2022 Update on Diagnosis, Therapy and Monitoring

DISEASE OVERVIEW

Chronic Myeloid Leukemia (CML) is a myeloproliferative neoplasm with an incidence of 1-2 cases per 100,000 adults. It accounts for approximately 15% of newly diagnosed cases of leukemia in adults DIAGNOSIS: CML is characterized by a balanced genetic translocation, t (9;22) (q34;q11.2), involving a fusion of the Abelson gene (ABL1) from chromosome 9q34 with the breakpoint cluster region (BCR) gene on chromosome 22q11.2. This rearrangement is known as the Philadelphia chromosome. The molecular consequence of this translocation is the generation of a BCR::ABL1 fusion oncogene, which in turn translates into a BCR::ABL1 oncoprotein.

FRONTLINE THERAPY

Four tyrosine kinase inhibitors (TKIs), imatinib, dasatinib, bosutinib, and nilotinib are approved by the United States Food and Drug Administration for first-line treatment of newly diagnosed CML in chronic phase (CML-CP). Clinical trials with second generation TKIs reported significantly deeper and faster responses but had no impact on survival prolongation, likely because of the availability of effective TKIs salvage therapies for patients who have a cytogenetic relapse with frontline TKI therapy.

SALVAGE THERAPY

For CML post failure on frontline therapy, second-line options include second and third generation TKIs. Although potent and selective, these TKIs exhibit unique pharmacological profiles and response patterns relative to different patient and disease characteristics, such as patients' comorbidities, disease stage, and BCR::ABL1 mutational status. Patients who develop the T315I "gatekeeper" mutation display resistance to all currently available TKIs except ponatinib, asciminib, and olverembatinib. Allogeneic stem cell transplantation remains an important therapeutic option for patients with CML-CP and failure (due to resistance) of at least 2 TKIs, and for all patients in advanced phase disease. Older patients who have a cytogenetic relapse post failure on all TKIs can maintain long-term survival if they continue a daily most effective/least toxic TKI, with or without the addition of non-TKI anti-CML agents (hydroxyurea, omacetaxine, azacitidine, decitabine, cytarabine, busulfan, others). This article is protected by copyright. All rights reserved.