Discontinuation of tyrosine kinase inhibitors in pediatric chronic myeloid leukemia

Quality of Life and Adherence to Tyrosine Kinase Inhibitors Among Pediatric, Adolescent, and Young Adult Chronic Myeloid Leukemia Patients: A Systematic Review

The chronic nature of chronic myeloid leukemia (CML) has a negative impact on patients' health-related quality of life (HRQOL) and the need for prolonged oral tyrosine kinase inhibitors (TKIs) poses a risk to low or nonadherence over time. This systematic review seeks to analyze HRQOL outcomes and adherence to TKIs among pediatric, adolescent, and young adult (AYA) patients with CML. Full-text screening ultimately led to the inclusion of 12 articles focused on HRQOL, patient-reported outcomes (PRO) and medication adherence. There was heterogeneity in the findings among the included studies, especially in HRQOL and PROs. TKIs adherence ranged from 45%-78% using self-report and 58%-100% using medical and pharmacy records. Increased TKI adherence was significantly associated with better clinical outcomes, including overall survival. Our findings could inform efforts to develop behavioral interventions to optimize TKI adherence and improve HRQOL outcomes among AYA patients with CML.

Which Is the Best Tyrosine Kinase Inhibitor for Newly Diagnosed Chronic Myelogenous Leukemia?

The choice of frontline therapy for a patient with chronic phase chronic myeloid leukemia (CP-CML) can have a profound effect on the long-term clinical outcome. Currently, five tyrosine kinase inhibitors (TKIs-imatinib, dasatinib, nilotinib, bosutinib, and asciminib) are available for frontline therapy, but no single TKI is optimal for all patients. EUTOS long-term survival (ELTS) risk score, comorbidities, and treatment-free remission (TFR) priority are the key determinants of frontline TKI selection. Higher ELTS score, low age and comorbidity score, and a high priority for achievement of TFR would all favor the frontline use of a more potent TKI than imatinib. However, no TKI has improved survival compared with imatinib. In children with CP-CML, imatinib, dasatinib, and nilotinib have similar long-term efficacy, with ease of administration and impact of toxicities on quality of life being key considerations. Recent adult trials of reduced-dose dasatinib frontline showed that efficacy may be equivalent to standard-dose dasatinib with a better tolerability and safety profile, but experience is limited in patients with high-risk ELTS scores. The ASC4FIRST trial has confirmed that tolerability and molecular response with asciminib are superior to those with both imatinib and the second-generation (2G)-TKIs. While the overall treatment failure rate was lower with asciminib, the rate of BCR::ABL1 mutations that emerged with asciminib appeared to be higher. The risk of emergent mutations appears to be highly associated with the presence of ASXL1 mutations in the CML cells at diagnosis, but more work is needed to understand the implications of this finding.

Management of children and adolescents with chronic myeloid leukemia in chronic phase: International pediatric chronic myeloid leukemia expert panel recommendations

The treatment strategy for children and adolescents with chronic myeloid leukemia in the chronic phase (CML-CP) has evolved from allogeneic hematopoietic stem cell transplantation (HSCT) to tyrosine kinase inhibitors (TKIs). With the advent of next-generation TKIs and new targeted therapies in the CML field, an international pediatric CML expert panel provides recommendations based on the medical literature (including previous pediatric guidelines), national standards, and treatment principles used in adults with CML-CP. Recommendations include diagnosis of the disease and details on managing the initial steps of care of children and adolescents with newly diagnosed CML-CP, including complications such as leukostasis. The treatment recommendations are based on the initiation of therapy with a first- or second-generation TKI according to the allocated European Treatment and Outcome Study (EUTOS) long-term survival score risk group of the patient. The subsequent steps are based on the results of recommended monitoring which can justify a switch to another TKI or a drug in development if there is resistance or toxicity. The panel also provides recommendations regarding the discontinuation criteria for TKIs in children and adolescents in sustained deep molecular response. Allogeneic HSCT is not recommended as the first-line of treatment for children with CML-CP but is to be considered in case of progression to the advanced phase or failure of several lines of treatment. The present treatment and management recommendations are intended to provide advice to clinicians in view of optimizing the care and the outcome of children and adolescents with CML-CP.

Cases of Patients Treated in Countries With Limited Resources and Discussed by Experts of the International CML Foundation (iCMLf)-Case No. 2: Treatment-Free Remission After 9 Years of Imatinib Treatment Without Prior Achievement of Sustained Deep Molecular Response

Pediatric chronic myeloid leukemia (pCML) is a rare malignancy that nowadays is treated upfront with tyrosine kinase inhibitors (TKIs). As demonstrated in adult CML patients, achieving deep molecular response (DMR) and maintaining this status over 2 years results in the opportunity to discontinue TKI therapy. Following cessation, this treatment-free remission (TFR) status is successfully achieved by approximately 50% of the patients, while the other half experience molecular relapse within ≤ 6 months, requiring a TKI restart. As pCML accounts for only 2%-3% of all childhood leukemias, experience and familiarity with this disease, especially with stopping attempts, are still very limited. Small pCML cohorts enrolled in stopping TKI trials, with strict criteria applied for both depth and maintenance of DMR, have demonstrated the achievable TFR success rates seem comparable to adults. However, recommendations for considering TFR in pCML have yet to be defined. We report on a 9-year-old Brazilian boy diagnosed with CML in a chronic phase. He was treated with imatinib and achieved a molecular response (BCR::ABL1 transcript rate < 0.1%) at Month 12. Not achieving DMR, he responded well, but not optimally, to TKI therapy. Contrary to existing guidelines on TKI cessation in adults, after 9 years, imatinib was stopped. With a follow-up of 24 months, the patient is in TFR and now maintains DMR successfully. With the support of the International CML Foundation (iCMLf), which aims to improve outcomes for CML patients globally, this rare case from Brazil is discussed from the perspective of a pediatric hemato-oncologist from a high-income country, a pediatric hemato-oncologist from a low- and middle-income country, an adult CML hematologist, and the treating physician. Sharing cases of pCML in LMICs and highlighting the resources offered by the iCMLf, particularly the Knowledge Center (available online), will hopefully improve the expertise on pCML treatment worldwide.

Treatment-Free Remissions in Children With Chronic Myeloid Leukemia (CML): A Prospective Study From the Tata Memorial Hospital (TMH) Pediatric CML (pCML) Cohort

Pediatric chronic myeloid leukemia (pCML) is a rare childhood malignancy, representing 2%-3% of all childhood leukemia. Tyrosine kinase inhibitors (TKIs) have greatly improved survival but pose challenges due to their long-term effects on growth and bone health in children. We prospectively studied treatment-free remission (TFR) in 45 children with pCML in chronic phase on imatinib. Eligibility criteria were as per current NCCN guidelines, with a less stringent qPCR monitoring scheduled every 3 months. TFR was successful in 71.1% (32 out of 45) of patients after a median follow-up of 25 (range: 6-42) months. The TFR rates at 12 and 24 months were 70% and 66%, respectively. Children under 5 years had a TFR rate of 88.9%, compared to 61.8% in those over 5 years (p = 0.18). Eleven of the 13 patients who lost MMR did so within 6 months of discontinuation. The cumulative incidence of loss in MMR at 6, 12, and 24 months was 26.4%, 27%, and 33%, respectively. Ten out of 13 (76.9%) patients with discontinuation failure (DF) regained MMR within 3 (2-20) months of restarting imatinib. A significant correlation was found between higher T-regulatory cell levels at baseline and DF (p = 0.005). More than half patients showed improved bone mineral density after 2 years of TFR. Our findings suggest that high TFR rates can be attained in pCML, with added benefits for bone health. Less frequent molecular monitoring was not associated with adverse outcomes and there seems to be a role of the immune system in sustaining TFR. The study is registered in the Clinical Trials Registry-India (CTRI/2020/11/029199).

Long-term outcomes of chronic myeloid leukemia in children and adolescents - Real world data from a single-institute in Taiwan

BACKGROUND/PURPOSE

Tyrosine kinase inhibitors (TKIs) have revolutionized chronic myeloid leukemia (CML) treatment, yet long-term pediatric outcomes and growth effects remain limited. This study describes the long-term efficacy and growth impact of TKIs in children and adolescents with CML.

METHODS

We retrospectively reviewed 14 pediatric CML patients treated with TKIs at our institute. The cohort's molecular responses and growth velocities were evaluated over a median follow-up of 15.9 years. MR4.5 was defined as BCR-ABL1/ABL ratio <0.0032%. Cumulative MR4.5 rates, time to response, and growth impacts were described among first- and second-generation TKIs.

RESULTS

All patients achieved MR4.5, with second-generation TKIs showing faster responses than imatinib. Growth deceleration was observed in patients initiating TKIs at prepubertal ages, regardless of TKI type. Among four patients who discontinued TKIs, three maintained treatment-free remission (TFR) for a median of 4.0 years. Adverse events from second-generation TKIs led to treatment switches in four among eleven patients (36%).

CONCLUSION

This study shows the sustained efficacy of TKIs in achieving MR4.5 in pediatric CML, with second-generation TKIs providing faster responses. Growth retardation remains a concern for TKI treatment. TKI discontinuation in pediatric CML may be feasible and crucial for shortening TKI exposure and optimizing long-term growth outcomes in prepubertal patients.

Haematopoietic stem cell transplantation after reduced intensity conditioning in children and adolescents with chronic myeloid leukaemia: A prospective multicentre trial of the I-BFM Study Group

This prospective multicentre trial evaluated the safety and the efficacy of a thiotepa/melphalan-based reduced intensity conditioning (RIC) haematopoietic stem cell transplantation (HSCT) in children and adolescents with chronic myeloid leukaemia (CML) in chronic phase (CP). Thirty-two patients were transplanted from matched siblings or matched unrelated donors. In 22 patients, HSCT was performed due to insufficient molecular response or loss of response to first- or second-generation tyrosine kinase inhibitor (TKI), with pretransplant BCR::ABL1 transcripts ranging between 0.001% and 33%. The protocol included a BCR::ABL1-guided intervention with TKI retreatment in the first year and donor lymphocyte infusions (DLI) in the second-year post-transplant. All patients engrafted. The 1-year transplant-related mortality was 3% (confidence interval [CI]: 0%-6%). After a median follow-up of 6.3 years, 5-year overall survival and event-free survival are 97% (CI: 93%-100%) and 91% (CI: 79%-100%) respectively. The current 5-year leukaemia-free survival with BCR::ABL1 <0.01% is 97% (CI: 88%-100%) and the current TKI- and DLI-free survival is 95% (CI: 85%-100%). The incidence of chronic graft-versus-host disease (GvHD) was 32%, being severe in four patients (13%). At last follow-up, 31 patients are GvHD-free and have stopped immunosuppression. RIC HSCT following pretreatment with TKI is feasible and effective in children and adolescents with CP-CML with an excellent disease-free and TKI-free survival.

Tyrosine Kinase Inhibitors in pediatric chronic myeloid leukemia: a focused review of clinical trials

Tyrosine Kinase Inhibitors (TKIs) is revolutionizing the management of pediatric Chronic Myeloid Leukemia (CML), offering alternatives to Allogeneic Hematopoietic Stem Cell Transplantation (AHSCT). We conducted a comprehensive review of 16 Randomized Controlled Trials (RCTs) encompassing 887 pediatric CML patients treated with TKIs including Imatinib, Dasatinib, and Nilotinib. The median patient age ranged from 6.5 to 14 years, with a median white blood cell count of 234 x 10^9/uL, median hemoglobin level of 9.05 g/dL, and median platelet count of 431.5 x 10^9/µL. Imatinib seems to be predominant first line TKI, with the most extensive safety and efficacy data. BCR::ABL response rates below 10% ranged from 60% to 78%, CCyR at 24 months ranged from 62% to 94%, and PFS showed variability from 56.8% to 100%, albeit with differing analysis timepoints. The Safety profile of TKIs was consistent with the known safety profile in adults. With the availability of three TKIs as first line options, multiple factors should be considered when selecting first line TKI, including drug formulation, administration, comorbidities, and financial issues. Careful monitoring of adverse events, especially in growing children, should be considered in long term follow-up clinical trials.

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.

Front-Line Tyrosine Kinase Inhibitors in Pediatric Chronic Myeloid Leukemia: A Study on Efficacy and Safety

We conducted a retrospective study on 51 pediatric patients with newly diagnosed chronic myeloid leukemia chronic phase or accelerated phase. The patients were classified into the IMA group (N = 33), treated with imatinib, and the DSA group (N = 18), treated with dasatinib, as front-line tyrosine kinase inhibitors (TKIs). At 12 months, the rates of complete cytogenetic response were similar between the IMA group (92.3%) and DSA group (100%) (p = 0.305). However, the rate of early molecular response was higher in the DSA group than in the IMA group (100.0% vs. 80.0%, p = 0.043). By 12 and 24 months, the DSA group showed faster and higher cumulative rates of both major (DSA group: 72.2% and 100%, respectively; IMA group: 41.2% and 68.7%, respectively; p = 0.002) and deep molecular responses (DSA group: 26.0% and 43.6%, respectively; IMA group: 13.8% and 17.5%, respectively; p = 0.004). Both TKIs were well tolerated. Although the height standard deviation scores decreased in both groups, the height decline was greater in the DSA group between one and two years from the start of TKI therapy. In this study, dasatinib achieved faster and higher molecular responses with an acceptable safety profile. Further follow-up is necessary to assess the long-term outcomes of TKI treatment in children.

Dose optimization strategy of the tyrosine kinase inhibitors imatinib, dasatinib, and nilotinib for chronic myeloid leukemia: From clinical trials to real-life settings

With the advent of tyrosine kinase inhibitors (TKIs), the treatment prospects of chronic myeloid leukemia (CML) have changed markedly. This innovation can lengthen the long-term survival of patients suffering from CML. However, long-term exposure to TKIs is accompanied by various adverse events (AEs). The latter affect the quality of life and compliance of patients with CML, and may lead to serious disease progression (and even death). Recently, increasing numbers of patients with CML have begun to pursue a dose optimization strategy. Dose optimization may be considered at all stages of the entire treatment, which includes dose reduction and discontinuation of TKIs therapy. In general, reduction of the TKI dose is considered to be an important measure to reduce AEs and improve quality of life on the premise of maintaining molecular responses. Furthermore, discontinuation of TKIs therapy has been demonstrated to be feasible and safe for about half of patients with a stable optimal response and a longer duration of TKI treatment. This review focuses mainly on the latest research of dose optimization of imatinib, dasatinib, and nilotinib in CML clinical trials and real-life settings. We consider dose reduction in newly diagnosed patients, or in optimal response, or for improving AEs, either as a prelude to treatment-free remission (TFR) or as maintenance therapy in those patients unable to discontinue TKIs therapy. In addition, we also focus on discontinuation of TKIs therapy and second attempts to achieve TFR.

Current childhood chronic myeloid leukemia management under tyrosine kinase inhibitor treatment

Chronic myeloid leukemia (CML) is very rare during childhood. Tyrosine kinase inhibitors (TKI) provide very good results in terms of survival. The medical records of 15 chronic phase (CP)-CML patients in a university hospital pediatric hematology department between 1997 and 2022 were reviewed retrospectively. Complete hematological response was documented in all patients between 20 and 68 (median 30) days of treatment. Major molecular response was achieved in seven patients within 6 months. Median follow-up for the study group was 79 (range 3-330) months and overall survival was 100%. Three patients (2 blastic transformation, 1 therapy resistant) underwent bone marrow transplantation (BMT) and one with blastic transformation is scheduled to undergo BMT. TKI were discontinued in three patients after a median of 86 (range 73-177) months. The complete molecular remission maintenance period before discontinuation of TKI was 81 (range 62-122) months. While no molecular relapse was seen before the last follow-up, the median overall follow-up period was 152 (range 131-300) months. In conclusion, recent advances have led to a very good prognosis for children with CP-CML. With TKI treatment, most patients continue their lives without disease progression. Additionally, in selected patients TKI can be discontinued without molecular relapse.

Recent progress in the management of pediatric chronic myeloid leukemia

Chronic myeloid leukemia (CML) is a rare myeloproliferative disease in children. The primary cause of CML is the chimeric BCR::ABL1 gene in hematopoietic stem cells, which leads to leukocytosis, platelet proliferation, and splenomegaly. Lately, tyrosine kinase inhibitors (TKIs) have replaced hematopoietic cell transplantation, which was previously considered the only curative therapy, as the first-line treatment for chronic-phase CML. However, the clinical efficacy of TKIs, including those effective in adult CML, has not been well-investigated in pediatric CML. This review describes the recommended TKI-based management strategies for pediatric CML according to the literature and guidelines. Furthermore, we discuss the prospects for TKI discontinuation to avoid important adverse events, such as growth impairment, in children.