Imatinib is effective in children with previously untreated chronic myelogenous leukemia in early chronic phase: results of the French national phase IV trial

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.

Comparative analysis of RNA expression identifies effective targeted drug in myoepithelial carcinoma

Myoepithelial carcinoma is an ultra-rare pediatric solid tumor with no targeted treatments. Clinical implementation of tumor RNA sequencing (RNA-Seq) for identifying therapeutic targets is underexplored in pediatric cancer. We previously published the Comparative Analysis of RNA Expression (CARE), a framework for incorporating RNA-Seq-derived gene expression into the clinic for difficult-to-treat pediatric cancers. Here, we discuss a 4-year-old male diagnosed with myoepithelial carcinoma who was treated at Stanford Medicine Children's Health. A metastatic lung nodule from the patient underwent standard-of-care tumor DNA profiling and CARE analysis, wherein the patient's tumor RNA-Seq profile was compared to over 11,000 uniformly analyzed tumor profiles from public data repositories. DNA profiling yielded no actionable mutations. CARE identified overexpression biomarkers and nominated a treatment that produced a durable clinical response. These findings underscore the utility of data sharing and concurrent analysis of large genomic datasets for clinical benefit, particularly for rare cancers with unknown biological drivers.

NAMPT-mediated deacetylation of HCLS1 protein promotes clonogenic growth of pediatric CML cells

Pediatric chronic myeloid leukemia (CML) is a rare hematologic malignancy with biological features that differ from that of adult patients. In pediatric patients with CML the burden of tumor cells is higher resulting in a delayed achievement of deep molecular response (DMR) upon treatment with tyrosine kinase inhibitors (TKIs, e.g., imatinib) than what has been reported in adults. Therefore, the probability to develop resistance to TKIs in children with CML is higher than in adults due to much longer exposure to TKIs. Moreover, in children with CML, long-term treatment with imatinib causes hematologic and nonhematologic toxicities. Improvements of CML therapy in pediatric patients based on the targeting of hematopoiesis-specific BCR::ABL1 downstream effectors are needed. Here, we report elevated levels of the nicotinamide phosphoribosyltransferase (NAMPT) in mononuclear cells of pediatric patients with chronic phase CML (CP-CML) and in blastic phase CML cell lines. NAMPT inhibition abrogated in vitro clonogenic capacity and proliferation of CML cells. NAMPT deacetylates and activates the hematopoietic-specific lyn-substrate 1 (HCLS1) protein, which is essential for the proliferation of CML cells. Moreover, IL1RAP - a marker of myeloid leukemia-initiating cells - and LEF-1 - a transcription factor of Wnt signaling - are downstream targets of NAMPT/HCLS1 pathway. Together, our results reveal new treatment avenues of pediatric patients with CML by targeting NAMPT-mediated deacetylation of the hematopoietic-specific HCLS1 protein.

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.

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.

Advancements in leukemia management: Bridging diagnosis, prognosis and nanotechnology (Review)

Leukemia is a cancer that starts in blood stem cells in the bone marrow. Today, the proper diagnosis and prognosis of leukemia are essential in mitigating the morbidity and mortality associated with this malignancy. The advent of novel biomarkers, particularly those related to minimal residual disease, has paved the way for personalized therapeutic strategies and enables the quantitative assessment of patient responses to treatment regimens. Novel diagnostic and targeted drug delivery may be helpful for the improved management of leukemia. Genetic clinical parameters, such as chromosomal abnormalities, are crucial in diagnosing and guiding treatment decisions. These genetic markers also provide valuable prognostic information, helping to predict patient outcomes and tailor personalized treatment plans. In the present review, the studies on the diagnostic and prognostic parameters of leukemia were analyzed. The prognosis of leukemia was investigated in most of the studies, and the remaining were performed on diagnosis. The clinical and laboratory prognostic parameters were the most common, followed by diagnostic hematological parameters, diagnostic blood parameter studies, and diagnostic immunological parameters. Clinical and laboratory prognostic and hematologic parameters were the most extensively studied. The methods used to diagnose and prognose the leukemia cases in these studies were predominantly clinical hematology. Numerous surface proteins and receptors, including CD45, CD27, CD29, CD38, CD27, CD123, CD56 and CD25, react similarly in various kinds of leukemia, which are ideal for targeted drug delivery. Drug delivery to leukemia cells encounters several significant obstacles, including heterogeneity, that hinder the effectiveness of treatment. Nanocarriers play a critical role in targeted drug delivery for leukemia by enhancing the precision of treatments directed at surface proteins and receptors. Additionally, they can be functionalized with targeting drugs and antibodies to target specific tissues and cells.

Imatinib decreases germ cell survival and germline stem cell proliferation in rodent testis ex vivo and in vitro

BACKGROUND

Imatinib and dasatinib are tyrosine kinase inhibitors (TKIs) increasingly used to treat several diseases in both children and adults at fertile age. We have previously shown that imatinib has adverse effects on developing testis, and imatinib-treated male patients have been reported to have reduced sperm counts. However, the cellular level effects of imatinib and dasatinib on adult male germ cells and germline stem cells (mGSCs) have not been thoroughly investigated.

OBJECTIVES

To analyze whether imatinib or dasatinib exposure ex vivo and in vitro is harmful to adult male rodent germ cells and mGSCs.

MATERIALS AND METHODS

Seminiferous tubule segments of adult male mouse or rat were cultured in the presence or the absence of imatinib or dasatinib. Stage-specific effects were monitored by 3H-thymidine incorporation assay (DNA synthesis), immunohistochemistry (cleaved Caspase-3; apoptosis), immunofluorescence (KI67, GFRα1, STRA8, c-KIT, LIN28A; proliferation and spermatogonial differentiation) and flow cytometry (Hoechst). Mouse mGSCs were exposed to imatinib and dasatinib to study proliferation, apoptosis, and differentiation.

RESULTS

Imatinib decreased stage-specific DNA synthesis, and induced apoptosis in cultured rat seminiferous tubule segments. Imatinib also had an adverse effect on mGSC proliferation both in vitro and ex vivo, but did not induce cell death in cultured mGSCs. Imatinib did not impinge on induction of spermatogonial differentiation but suppressed c-KIT expression in nascent differentiating spermatogonia, providing a plausible mechanism for its pro-apoptotic function in spermatogenic cells. Clinically relevant doses of dasatinib did not induce apoptosis in seminiferous tubules but decreased mGSC colony growth in vitro.

CONCLUSIONS

Imatinib exposure ex vivo and in vitro impinges on male rodent germ cell proliferation and survival. The plausible mechanism in spermatogenic cells is the inhibition of SCF/c-KIT signaling, and reduced expression of c-KIT. Dasatinib did not show significant adverse effects with clinical doses ex vivo but inhibited mGSC colony growth in vitro.

Cases of Patients Treated in Countries With Limited Resources and Discussed by Experts of the International CML Foundation (iCMLf)-Case No. 1: A Boy Presenting With Priapism and Loss of Vision

Pediatric chronic myeloid leukemia (pCML) is a rare malignancy accounting for only 2%-3% of all childhood leukemias. Due to this rarity, familiarity with pCML is limited among most pediatric practitioners, including even pediatric hemato-oncologists. In low- and middle-income countries (LMICs), limited financial resources and limited data specific to pCML represent obstacles that healthcare providers must face in diagnosing and treating this rare condition in children. The International CML Foundation (iCMLf) is improving outcomes for people with CML in these countries where resources, diagnostics, and access to medicines may be limited (https://www.cml-foundation.org/lmic-programs.html). Virtual meetings with the purpose of teaching participating pediatricians from LMICs of defined geographical regions were organised by the iCMLf in 2023. At a virtual meeting of the South Asia region, the case of a 14-year-old Indian boy was presented diagnosed with CML in a chronic phase complicated by priapism and loss of vision in his left eye due to hyperleukocytosis. Key aspects of this case are discussed in-depth from the perspective of (i) a pediatric hemato-oncologist practicing in a high-income country, (ii) a pediatric hemato-oncologist practicing in a LMIC, (iii) an adult CML hematologist, and (iv) from the iCMLf in improving the care of children with CML worldwide. Thus by discussing a multifaceted complicated case of pCML in written form as well as pointing to the pediatric module of the iCMLf Knowledge Centre will hopefully contribute to minimize existing knowledge gaps in a rare pediatric malignancy.

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.

Treatment and follow-up of children with chronic myeloid leukaemia in chronic phase (CML-CP) in the tyrosine kinase inhibitor (TKI) era-Two decades of experience from the Tata Memorial Hospital paediatric CML (pCML) cohort

Tyrosine kinase inhibitors (TKIs) have drastically improved the outcomes of pCML (paediatric CML) but data on long-term off-target toxicities of TKIs in children are scarce. In this single-centre, retrospective cum prospective study of pCML in chronic phase, we report our experience of treating 173 children with imatinib and following them for long-term toxicities. Mean (SD) time to attain CHR, CCyR and MMR were 3.05 (2.1), 10.6 (8.4) and 43.4 (31.8) months respectively. DMR was not attained in 59 (34%) patients at last follow-up. Ten patients were switched to second-generation TKIs (2G-TKIs; nilotinib = 1/dasatinib = 9) due to poor/loss in response, of which seven had kinase domain mutations. Three patients progressed to the blastic phase. At a median follow-up of 84 (3-261) months, the 5-year EFS and OS for the entire cohort were 96.9% (95% CI: 93.4-100) and 98.7% (95% CI: 96.9-100) respectively. Screening for long-term toxicities revealed low bone density and hypovitaminosis D in 70% and 80% respectively. Other late effects included short stature (27%), delayed puberty (15%), poor sperm quality (43%) and miscellaneous endocrinopathies (8%). Children younger than 5 years at diagnosis were more susceptible to growth and endocrine toxicities (p = 0.009). Regular monitoring for long-term toxicities, timely intervention and trial of discontinuation whenever feasible are likely to improve the long-term outlook of pCML.

Bosutinib in Resistant and Intolerant Pediatric Patients With Chronic Phase Chronic Myeloid Leukemia: Results From the Phase I Part of Study ITCC054/COG AAML1921

PURPOSE

Bosutinib is approved for adults with chronic myeloid leukemia (CML): 400 mg once daily in newly diagnosed (ND); 500 mg once daily in resistant/intolerant (R/I) patients. Bosutinib has a different tolerability profile than other tyrosine kinase inhibitors (TKIs) and potentially less impact on growth (preclinical data). The primary objective of this first-in-child trial was to determine the recommended phase II dose (RP2D) for pediatric R/I and ND patients.

PATIENTS AND METHODS

In the phase I part of this international, open-label trial (ClinicalTrials.gov identifier: NCT04258943), children age 1-18 years with R/I (per European LeukemiaNet 2013) Ph+ CML were enrolled using a 6 + 4 design, testing 300, 350, and 400 mg/m2 once daily with food. The RP2D was the dose resulting in 0/6 or 1/10 dose-limiting toxicities (DLTs) during the first cycle and achieving adult target AUC levels for the respective indication. As ND participants were only enrolled in phase II, the ND RP2D was selected based on data from R/I patients.

RESULTS

Thirty patients were enrolled; 27 were evaluable for DLT: six at 300 mg/m2, 11 at 350 mg/m2 (one DLT), and 10 at 400 mg/m2 (one DLT). The mean AUCs at 300 mg/m2, 350 mg/m2, and 400 mg/m2 were 2.20 μg h/mL, 2.52 μg h/mL, and 2.66 μg h/mL, respectively. The most common adverse event was diarrhea (93%; ≥grade 3: 11%). Seven patients stopped because of intolerance and eight because of insufficient response. Complete cytogenetic and major molecular response to bosutinib appeared comparable with other published phase I/II trials with second-generation TKIs in children.

CONCLUSION

Bosutinib was safe and effective. The pediatric RP2D was 400 mg/m2 once daily (max 600 mg/d) with food in R/I patients and 300 mg/m2 once daily (max 500 mg/d) with food in ND patients, which achieved targeted exposures as per adult experience.

Therapeutic drug monitoring of imatinib - how far are we in the leukemia setting?

INTRODUCTION

Tyrosine kinase inhibitors (TKIs) have revolutionized survival rates of chronic myeloid leukemia (CML) and Philadelphia chromosome positive (Ph+) acute lymphoblastic leukemia (ALL) and replaced hematopoietic stem cell transplantation (hSCT) as the key treatment option for these patients. More recently, the so-called Philadelphia chromosome-like (Ph-like) ALL has similarly benefitted from TKIs. However, many patients shift from the first generation TKI, imatinib, due to treatment-related toxicities or lack of treatment efficacy. A more personalized approach to TKI treatment could counteract these challenges and potentially be more cost-effective. Therapeutic drug monitoring (TDM) has led to higher response rates and less treatment-related toxicity in adult CML but is rarely used in ALL or in childhood CML.

AREAS COVERED

This review summarizes different antileukemic treatment indications for TKIs with focus on imatinib and its pharmacokinetic/-dynamic properties as well as opportunities and pitfalls of TDM for imatinib treatment in relation to pharmacogenetics and co-medication for pediatric and adult Ph+/Ph-like leukemias.

EXPERT OPINION

TDM of imatinib adds value to standard monitoring of ABL-class leukemia by uncovering non-adherence and potentially mitigating adverse effects. Clinically implementable pharmacokinetic/-dynamic models adjusted for relevant pharmacogenetics could improve individual dosing. Prospective trials of TDM-based treatments, including both children and adults, are needed.

BCR/ABL-Positive Chronic Myeloid Leukemia in Children: Current Treatment Approach

PURPOSE OF REVIEW

The purpose of this review is to summarize the most updated treatment recommendations for pediatric CML, and to discuss current areas of investigation.

RECENT FINDINGS

There is new phase 1 data to support the safety of the non-ATP competitive tyrosine kinase inhibitor (TKI) asciminib in the pediatric cohort. Ongoing studies are investigating the role of treatment-free remission in children. Chronic phase CML in children is managed with lifelong TKI therapy; however, evidence of deeper remissions sustained with second-generation TKIs may permit shorter treatment courses. Use of more specific TKIs may mitigate some of the side effects specific to the pediatric cohort. Children with advanced phase CML should achieve a complete hematologic remission with use of a second-generation TKI prior to transplant to achieve the best outcome.

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.

The long-term efficacy and safety of nilotinib in pediatric patients with CML: a 5-year update of the DIALOG study

The efficacy and safety of nilotinib in pediatric patients with imatinib/dasatinib resistant/intolerant (R/I) or newly diagnosed (ND) Philadelphia chromosome-positive (Ph+) chronic myeloid leukemia in chronic phase (CML-CP) was demonstrated in the phase 2, open-label DIALOG study. In this final analysis, long-term efficacy and safety are presented for patients who completed 66 cycles (of 28 days) of treatment with nilotinib (230 mg/m2 twice daily) or discontinued early. Overall, 59 patients were enrolled and 58 were treated (R/I, n = 33; ND, n = 25; median time on treatment: 60.5 and 51.9 months, respectively). In the R/I cohort, the cumulative major molecular response (MMR; BCR::ABL1 international scale [IS] ≤ 0.1%) rate was 60.6%, and no patients had a confirmed loss of MMR. Among ND patients, the best overall MMR rate was 76.0%; 3 patients had a confirmed loss of MMR. The cumulative molecular response MR4 (BCR::ABL1IS ≤ 0.01%) and MR4.5 (BCR::ABL1IS ≤ 0.0032%) rates by 66 cycles were 27.3% and 12.1% in the R/I cohort, and 56.0% and 44.0% in the ND cohort, respectively. The safety profile of nilotinib was consistent with those of earlier reports. No on-treatment deaths occurred. These long-term (up to ∼5 years) data support the efficacy and safety of nilotinib in pediatric patients with Ph+ CML-CP. This trial was registered at www.clinicaltrials.gov.uk as #NCT01844765.

Continuous therapy response references for BCR::ABL1 monitoring in pediatric chronic myeloid leukemia

Response to tyrosine kinase inhibitor (TKI) therapy in patients with chronic myeloid leukemia (CML) is monitored by quantification of BCR::ABL1 transcript levels. Milestones for assessing optimal treatment response have been defined in adult CML patients and are applied to children and adolescents although it is questionable whether transferability to pediatric patients is appropriate regarding genetic and clinical differences. Therefore, we analyzed the molecular response kinetics to TKI therapy in 129 pediatric CML patients and investigated whether response assessment based on continuous references can support an early individual therapy adjustment. We applied a moving quantiles approach to establish a high-resolution response target curve and contrasted the median responses in all patients with the median of the ideal target curve obtained from a subgroup of optimal responders. The high-resolution response target curve of the optimal responder group presents a valuable tool for continuous therapy monitoring of individual pediatric CML patients in addition to the fixed milestones. By further comparing BCR::ABL1 transcript levels with BCR::ABL1 fusion gene copy numbers, it is also possible to model the differential dynamics of BCR::ABL1 expression and cell number under therapy. The developed methodology can be transferred to other biomarkers for continuous therapy monitoring.

Pediatric and adolescent chronic myeloid leukemia: A follow-up study in Western India

Background

Chronic myeloid leukemia (CML) is relatively rare in pediatric and adolescent age groups. The purpose of this study was to evaluate the clinical, hematopathological, and biochemical parameters of CML in pediatric and adolescent age groups, along with an assessment of the treatment response with first-line tyrosine kinase inhibitors (TKI) and its correlation with the prognostic scoring systems of adults.

Materials and Methods

A retrospective study of 44 Breakpoint Cluster Region-Abelson leukemia virus (BCR-ABL1)-positive pediatric and adolescent CML cases registered at our hospital was done. The clinical and laboratory parameters were evaluated using hospital software. The treatment response was monitored and scoring was performed using mathematical calculations.

Results

The mean age was 11.6 (±4.7) years. The median hemoglobin was 8.4 g/dL and 63.6% of the cases showed white blood cell (WBC) counts >250,000/μL. The average follow-up was 21 months. A total of 97.7 and 78.1% cases achieved complete hematological response (CHR) and molecular response, respectively, during the treatment course. The maximum number of patients had low Sokal and European treatment and Outcomes Study (EUTOS) scores. Seventy-five per cent of the cases achieved CHR at 3 months, while 73.6 and 78.6% CML-Chronic phase (CP) cases with low Sokal and EUTOS scores achieved CHR at 3 months, respectively.

Conclusion

This study revealed that the CML cases in pediatric and adolescent age groups are normally present with higher WBC counts at the time of diagnosis. The association of the prognostic scoring system with treatment response was statistically insignificant. However, a larger cohort study is needed to determine the treatment response of TKI in children and adolescent CML and its correlation with the prognostic scoring systems.

Children with chronic myeloid leukaemia treated with front-line imatinib have a slower molecular response and comparable survival compared with adults: a multicenter experience in Taiwan

BACKGROUND

The direct comparison of molecular responses of front-line imatinib (IM) monitored at the same laboratory between children and adults with chronic phase (CP) of chronic myeloid leukaemia (CML) had not been reported. In this multicenter study, we compared the landmark molecular responses and outcomes of paediatric and adult CML-CP cohorts treated with front-line IM in whom the BCR::ABL1 transcript levels were monitored at the same accredited laboratory in Taiwan.

METHODS

Between June 2004 and July 2020, 55 newly diagnosed paediatric and 782 adult CML-CP patients, with molecular diagnosis and monitoring at the same reference laboratory in Taiwan, were enrolled. The criteria of 2020 European LeukemiaNet were applied to evaluate the molecular responses.

RESULTS

By year 5, the cumulative incidences of IS <1%, MMR, MR4.0 and MR4.5 of paediatric patients were all significantly lower than those of adult patients (58 vs 75%, 48 vs 66%, 25 vs 44%, 16 vs 34%, respectively). The 10-year progression-free survival (PFS) (90%) and overall survival (OS) (94%) of paediatric patients did not differ from those (92%) of adult patients.

CONCLUSIONS

We demonstrated the paediatric cohort had slower molecular responses to front-line IM and similar outcomes in 10-year PFS and OS in real-world practice.

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.

Importance of pharmacologic considerations in the development of targeted anticancer agents for children

PURPOSE OF REVIEW

The purpose of this review is to describe key pharmacologic considerations to inform strategies in drug development for pediatric cancer.

RECENT FINDINGS

Main themes that will be discussed include considering patient specific factors, epigenetic/genetic tumor context, and drug schedule when optimizing protocols to treat pediatric cancers.

SUMMARY

Considering these factors will allow us to more effectively translate novel targeted therapies to benefit pediatric patients.

Priapism as the first symptom of chronic myeloid leukemia: literature review and own clinical case report

Chronic myeloid leukemia is a ph-positive myeloproliferative disease, which is usually manifested by hyperleukocytosis and massive splenomegaly. Chronic myeloid leukemia is rare in childhood and adolescence, it accounts for 2 to 3 % of all leukemias cases. priapism is a rare manifestation of chronic myeloid leukemia and is an urgent urological condition that requires timely treatment to prevent long-term complications, in particular, erectile dysfunction.This review presents the literature information about priapism as the first sign of chronic myeloid leukemia, as well as the first description in the Russian literature of a clinical case of priapism in a 9-year-old patient with chronic myeloid leukemia.

Infectious Complications of Targeted Therapies in Children with Leukemias and Lymphomas

Simple Summary

Targeted therapies in children with hematological malignancies moderate the effects of cytotoxic therapy, thus improving survival rates. They have emerged over the last decade and are used in combination with or after the failure of conventional chemotherapy and as bridging therapy prior to hematopoietic stem cell transplantation (HSCT). Nowadays, there is a growing interest in their efficacy and safety in pediatric patients with refractory or relapsed disease. The compromised immune system, even prior to therapy, requires prompt monitoring and treatment. In children with hematological malignancies, targeted therapies are associated with a comparable incidence of infectious complications to adults. The exact impact of these agents that have different mechanisms of action and are used after conventional chemotherapy or HSCT is difficult to ascertain. Clinicians should be cautious of severe infections after the use of targeted therapies, especially when used in combination with chemotherapy.

Abstract

The aim of this review is to highlight mechanisms of immunosuppression for each agent, along with pooled analyses of infectious complications from the available medical literature. Rituximab confers no increase in grade ≥3 infectious risks, except in the case of patients with advanced-stage non-Hodgkin lymphoma. Gemtuzumab ozogamicin links with high rates of grade ≥3 infections which, however, are comparable with historical cohorts. Pembrolizumab exhibits a favorable safety profile in terms of severe infections. Despite high rates of hypogammaglobulinemia (HGG) with blinatumomab, low-grade ≥3 infection rates were observed, especially in the post-reinduction therapy of relapsed B-acute lymphoblastic leukemia. Imatinib and nilotinib are generally devoid of severe infectious complications, but dasatinib may slightly increase the risk of opportunistic infections. Data on crizotinib and pan-Trk inhibitors entrectinib and larotrectinib are limited. CAR T-cell therapy with tisagenlecleucel is associated with grade ≥3 infections in children and is linked with HGG and the emergence of immune-related adverse events. Off-label therapies inotuzumab ozogamicin, brentuximab vedotin, and venetoclax demonstrate low rates of treatment-related grade ≥3 infections, while the addition of bortezomib to standard chemotherapy in T-cell malignancies seems to decrease the infection risk during induction. Prophylaxis, immune reconstitution, and vaccinations for each targeted agent are discussed, along with comparisons to adult studies.

Are 'phase IV' trials exploratory or confirmatory experiments?

Exploratory experiments are widely characterized as experiments that do not test hypotheses. Experiments that do test hypotheses are characterized as confirmatory experiments. Philosophers have pointed out that research programmes can be both confirmatory and exploratory. However, these definitions preclude single experiments being characterized as both exploratory and confirmatory; how can an experiment test and not test a hypothesis? Given the intuition that some experiments are exploratory, some are confirmatory, and some are both, a recharacterization of the relationship between exploratory and confirmatory experimentation is needed. I discuss 'phase IV' trials to show what this recharacterization could look like. Phase IV trials can be exploratory and confirmatory insofar as they concurrently test hypotheses and explore for unforeseen phenomena. Even if it is uncontroversial that a single experiment can have multiple aims, the recharacterization of the relationship between exploratory and confirmatory experimentation is still required for these aims to be held together coherently. I offer an alternative characterization of the relationship between exploratory and confirmatory experimentation where the former remains a distinct kind of experimentation but is not characterized as non-hypothesis-testing.

Management of Chronic Myeloid Leukemia in Children and Young Adults

Purpose of Review

Due to lack of pediatric-specific data, the management of chronic myeloid leukemia (CML) in pediatric, adolescents, and young adults is guided by adult CML evidence-based recommendations. Pediatric CML presents differently than adult CML and is often a more aggressive disease with different biological and host factors, yet there is sparse literature on how to address those differences.

Recent Findings

Over the past two decades, tyrosine kinase inhibitors (TKIs) have changed the way CML is treated. There are currently three FDA-approved TKIs (imatinib, dasatinib, and nilotinib) for pediatric patients. When choosing which TKI to begin treatment with, there are many factors that should be considered on a case-to-case basis to obtain optimal outcomes. The safety profiles for long-term TKI use in pediatrics require further study. Unlike adults, children are still actively growing during TKI use, and the effect on development can be detrimental. TKI therapy is not recommended during pregnancy with variable but significant risk of fetal abnormalities and miscarriage, warranting counseling for young female patients prior to beginning TKIs. Attempts for treatment-free remission (TFR) by planned TKI cessation in eligible adult patients in deep and sustained molecular remission are now done as a standard of practice. However, data is sparse in the pediatric population. There is currently an ongoing Children’s Oncology Group (COG) study to determine the feasibility of TFR as a treatment goal.

Summary

Further research and additional pediatric trials are needed to characterize the unique aspects of CML in children and adolescents and optimize outcomes.

Discontinuation of tyrosine kinase inhibitors in pediatric chronic myeloid leukemia

BACKGROUND

The feasibility of tyrosine kinase inhibitor (TKI) discontinuation in pediatric chronic myeloid leukemia (CML) remains to be fully elucidated.

PROCEDURES

TKI was prospectively discontinued in patients who were diagnosed with CML at <20 years of age, treated with TKI for ≥3 years, and sustained molecular response 4.0 (MR4.0) for ≥2 years. Molecular relapse was defined as a single loss of major molecular response (MMR) (BCR-ABL1^IS >0.1%). Relapsed patients resumed the same TKI therapy administered before discontinuation.

RESULTS

Twenty-two patients with chronic-phase CML were enrolled, and the median ages at diagnosis and at TKI discontinuation were 9 (range: 1-14) years and 16 (5-26) years, respectively. The median follow-up time after TKI discontinuation was 37 months (range: 24-41 months). The median duration of TKI treatment before discontinuation was 100 (42-178) months, and that of MR4.0 was 53.5 (25-148) months. The treatment-free remission (TFR) rate at 12 months was 50.0% (90% confidence interval: 31.7%-65.8%). Eleven patients experienced loss of MMR within 4 months after TKI discontinuation and resumed TKI as originally prescribed. No progression was observed, and all 11 patients regained MR4.0 after TKI resumption. No patient had a withdrawal syndrome. The quality-of-life analysis suggested that successful TFR may improve academic performance in some patients. In patients who discontinued TKI therapy before puberty, the possibility of improvement in growth velocity upon TKI discontinuation was observed.

CONCLUSIONS

TKI could be discontinued safely in patients with pediatric CML showing a sustained deep MR.

Physician risk perceptions and surveillance practices for tyrosine kinase inhibitor long-term effects in pediatric CML

Chronic myeloid leukemia (CML) is effectively treated with long-term tyrosine kinase inhibitor (TKI) therapy, yet little is known about risks of prolonged TKI exposure in young patients, and long-term effect monitoring is not standardized. We surveyed North American pediatric oncologists (n = 119) to evaluate perceived risk of and surveillance practices for potential toxicities associated with prolonged TKI exposure in children and adolescents/young adults (AYAs) with CML. Survey domains included general and specific risk perceptions and surveillance practices for asymptomatic patients on chronic TKI therapy. We analyzed data descriptively and explored relationships between risk perceptions and surveillance. Risk perceptions varied among oncologists but were similar across six categories (thyroid, cardiac, vascular, metabolic, fertility, psychologic), with less than one-third rating each risk as moderate or high in pediatric and AYA patients. More oncologists perceived moderate or high risk of growth abnormalities in children (62% pediatric, 14% AYA) and financial toxicity in all patients (60% pediatric, 64% AYA). A greater proportion of oncologists with moderate or high perceived risk of thyroid abnormalities reported testing thyroid function compared to those with lower perceived risk; patterns for metabolic risk/lipid tests and cardiac risk/tests were similar. In summary, we found that pediatric oncologists had variable risk perceptions and surveillance practices for potential toxicities associated with prolonged TKI exposure. Standardizing surveillance would help quantify risks and refine recommendations.Supplemental data for this article is available online at https://doi.org/10.1080/08880018.2021.2017085 .

Outcome prediction of chronic myeloid leukemia (CML) in children

We evaluated the feasibility of existing risk assessment tools for chronic myeloid leukemia (CML) in children. Fifty-five patients with newly diagnosed CML between 1996 and 2019 were included. Forty-nine patients presented in chronic phase, thirty-six of whom were treated with upfront tyrosine kinase inhibitor (CP-TKI group); one presented in accelerated phase and four in blastic phase. Treatment, survival, responses, and tolerance were evaluated. All patients in the CP-TKI group received imatinib as their first TKI treatment. The 10-year overall survival (OS), progression-free survival (PFS), and event-free survival (EFS) of TKI-treated group was 97%, 91.4%, and 72.3%, respectively. At 60 months, the rates of major molecular response were 81.2% and deep molecular response was 67.5%. The EUTOS long-term survival (ELTS) risk grouping did not predict OS, PFS, or EFS. The IMAFAIL risk groups were correlated with the risk of imatinib failure. Further studies are required to modify the existing risk assessment tools for children.

Discontinuation of tyrosine kinase inhibitors based on BCR-ABL1 monitoring by digital droplet PCR in pediatric chronic myeloid leukemia

Lifelong treatment of pediatric chronic myeloid leukemia (CML) patients with tyrosine kinase inhibitors (TKIs) can affect their growth and development. For these reasons, clinical trials have explored the feasibility of TKI discontinuation in children with a sufficient TKI response. We evaluated the analytical performance of digital droplet PCR (ddPCR) to quantify BCR-ABL1 and compared the results with reverse transcription quantitative polymerase chain reaction (RT-qPCR). We further investigated whether ddPCR could be used to determine TKI discontinuation in a clinical setting. Performance of ddPCR was evaluated using standard materials for BCR-ABL1, and a total of 197 clinical samples from 45 pediatric CML patients was included for comparison with RT-qPCR. ddPCR showed excellent analytical sensitivity with 0.001% international scale (IS) and linearity with R ² > 0.99 in log scale. BCR-ABL1 % IS results correlated well with those of RT-qPCR (R ² = 0.9435), however, they showed a moderate strength for agreement with a Cohen's kappa of 0.41 due to higher sensitivity of ddPCR. Among 45 pediatric CML patients, 42 were treated with first-line TKIs including imatinib (n = 27, 64%) and dasatinib (n = 12, 29%), and three patients that were started with imatinib were switched to dasatinib. When we evaluated whether follow-up samples fulfilled ABL1 copies ≥ 10,000 required for deep molecular response (DMR), all samples were acceptable by ddPCR, whereas 18% by RT-qPCR did not reached acceptable ABL1 copies. Moreover, 52 and 13% reached ABL1 copies ≥ 32,000 required for MR4.5 by ddPCR and RT-qPCR, respectively. Seven patients discontinued TKI and the median TKI treatment duration was 73 months prior to discontinuation. Prior to discontinuation, the median duration of sustained undetected BCR-ABL1 was 60 months. Two patients experienced loss of major MR (MMR) during follow-up and restarted dasatinib 5 months after discontinuation. They achieved MMR again and maintained better than DMR afterward. Results from those patients demonstrated that RT-qPCR did not match the need for adequate ABL1 copies for MR4.5 while majority of ddPCR could. Therefore, ddPCR was technically more acceptable to decide and monitor pediatric CML patients before and after TKI discontinuation.

The Use of Inhibitors of Tyrosine Kinase in Paediatric Haemato-Oncology-When and Why?

The fundamental pathophysiology of malignancies is dysregulation of the signalling pathways. Protein tyrosine kinases (PTKs) are among the enzymes which, if mutated, play a critical role in carcinogenesis. The best-studied rearrangement, which enhances PTK activity and causes atypical proliferation, is BCR-ABL1. Abnormal expression of PTKs has proven to play a significant role in the development of various malignancies, such as chronic myelogenous leukaemia, brain tumours, neuroblastoma, and gastrointestinal stromal tumours. The use of tyrosine kinase inhibitors (TKIs) is an outstanding example of successful target therapy. TKIs have been effectively applied in the adult oncology setting, but there is a need to establish TKIs’ importance in paediatric patients. Many years of research have allowed a significant improvement in the outcome of childhood cancers. However, there are still groups of patients who have a poor prognosis, where the intensification of chemotherapy could even cause death. TKIs are designed to target specific PTKs, which lead to the limitation of severe adverse effects and increase overall survival. These advances will hopefully allow new therapeutic approaches in paediatric haemato-oncology to emerge. In this review, we present an analysis of the current data on tyrosine kinase inhibitors in childhood cancers.

A Review on the Therapeutic Role of TKIs in Case of CML in Combination With Epigenetic Drugs

Chronic myeloid leukemia is a malignancy of bone marrow that affects white blood cells. There is strong evidence that disease progression, treatment responses, and overall clinical outcomes of CML patients are influenced by the accumulation of other genetic and epigenetic abnormalities, rather than only the BCR/ABL1 oncoprotein. Both genetic and epigenetic factors influence the efficacy of CML treatment strategies. Targeted medicines known as tyrosine-kinase inhibitors have dramatically improved long-term survival rates in CML patients during the previous 2 decades. When compared to earlier chemotherapy treatments, these drugs have revolutionized CML treatment and allowed most people to live longer lives. Although epigenetic inhibitors' activity is disrupted in many cancers, including CML, but when combined with TKI, they may offer potential therapeutic strategies for the treatment of CML cells. The epigenetics of tyrosine kinase inhibitors and resistance to them is being studied, with a particular focus on imatinib, which is used to treat CML. In addition, the use of epigenetic drugs in conjunction with TKIs has been discussed. Resistance to TKIs is still a problem in curing the disease, necessitating the development of new therapies. This study focused on epigenetic pathways involved in CML pathogenesis and tumor cell resistance to TKIs, both of which contribute to leukemic clone breakout and proliferation.

Chronic Myeloid Leukemia in Children: Immune Function and Vaccinations

Children with CML need TKI treatment for many years, and the lack of knowledge about immune dysfunction with TKI has hindered routine immunizations. This review attempts to provide an overview of the effects of TKIs licensed for children (e.g., imatinib, dasatinib, and nilotinib) on immune function, as well as its implications on immunizations. We discuss surveillance strategies (e.g., immunoglobulin blood serum levels and hepatitis B reactivation) and immunizations. All inactivated vaccines (e.g., influenza, pneumococcal, and streptococcal) can be given during the treatment of CML in the chronic phase, although their efficacy may be lower. As shown in single cases of children and adults with CML, live vaccines (e.g., varicella, measles, mumps, rubella, and yellow fever) may be administered under defined circumstances with great precautions. We also highlight important aspects of COVID-19 in this patient population (e.g., the outcome of COVID-19 infection in adults with CML and in children with varying hemato-oncological diseases) and discuss the highly dynamic field of presently available different vaccination options. In conclusion, TKI treatment for CML causes humoral and cellular immune dysfunction, which is mild in most patients, and thus infectious complications are rare. Routine immunizations are important for health maintenance of children, but vaccinations for children with CML on TKI therapy should be carefully considered.

Discontinuation of Imatinib in Children with Chronic Myeloid Leukemia: A Study from the International Registry of Childhood CML

Within the International Registry of Childhood Chronic Myeloid Leukemia (CML), we identified 18 patients less than 18 years old at diagnosis of CML who were in the chronic phase and exhibiting a sustained deep molecular response (DMR) to imatinib defined as BCR-ABL1/ABL1 < 0.01% (MR4) for at least two years followed by discontinuation of imatinib. Before discontinuation, the median duration of imatinib was 73.2 months (range, 32-109) and the median duration of MR4 was 46.2 months (range, 23.9-98.6). Seven patients experienced loss of major molecular response (MMR) 4.1 months (range, 1.9-6.4) after stopping and so restarted imatinib. The median molecular follow-up after discontinuation was 51 months (range, 6-100) for the nine patients without molecular relapse. The molecular free remission rate was 61% (95% CI, 38-83%), 56% (95% CI, 33-79%) and 56% (95% CI, 33-79%) at 6, 12 and 36 months, respectively. Six of the seven children who experienced molecular relapse after discontinuation regained DMR (median, 4.7 months; range, 2.5-18) after restarting imatinib. No withdrawal syndrome was observed. In univariate analysis, age, sex, Sokal and ELTS scores, imatinib treatment and DMR durations before discontinuation had no influence on treatment free remission. These data suggest that imatinib can be safely discontinued in children with sustained MR4 for at least two years.

A phase 2 study of nilotinib in pediatric patients with CML: long-term update on growth retardation and safety

The phase 2, open-label study (DIALOG) of nilotinib in pediatric patients with Philadelphia chromosome-positive chronic myelogenous leukemia (CML) met its coprimary end points, showing sustained nilotinib efficacy in patients with newly diagnosed (ND) or imatinib/dasatinib resistant/intolerant (R/I) CML. This update assessed growth and safety profiles in patients who had completed ≥48, 28-day treatment cycles of nilotinib 230 mg/m2 twice daily, or previously discontinued the study. Height was assessed regularly and reported using standard deviation scores (SDSs) based on World Health Organization growth charts. All data were summarized descriptively (cutoff, 6 March 2019). Overall, 33 patients in the R/I cohort and 25 patients in the ND cohort received nilotinib. Each cohort showed a negative slope in height SDS over the course of the study, indicating attenuated growth rates during nilotinib treatment: overall median change from baseline in height SDS after 48 cycles was -0.54 SDS (range, - 1.6 to 0.4) and -0.91 SDS (-1.4 to -0.1) in R/I and ND cohorts, respectively. Patients in the R/I cohort were shorter at baseline than those in the ND cohort, and remained so throughout the study. The most common all-cause adverse events were increased blood bilirubin (53.4%), headache (46.6%), pyrexia (37.9%), and increased alanine transferase (36.2%). Apart from the impact on growth, the safety profile of nilotinib was generally consistent with previous reports. This study was registered on www.clinicaltrials.gov at #NCT01844765.

Adolescents experienced more treatment failure than children with chronic myeloid leukemia receiving imatinib as frontline therapy: a retrospective multicenter study

To explore the differences in the clinical features, treatment responses, and outcomes among children, adolescents, and adults with chronic myeloid leukemia in the chronic phase (CML-CP) receiving imatinib as first-line therapy. Data from children (0-8 years for girls and 0-10 years for boys), adolescents (9-19 years for girls and 11-19 years for boys), and adults (age ≥ 20 years) with newly diagnosed CML-CP receiving imatinib as first-line therapy between 2006 and 2019 were retrospectively reviewed. In total, 135 children (cohort 1), 189 adolescents (cohort 2), and 658 adults (cohort 3: age 20-39 years, n = 305; cohort 4: age 40-59 years, n = 270; and cohort 5: age 60-83 years, n = 83) were included in this study. When compared with children, adolescents showed a significantly higher white blood cell count (P = 0.033) and basophil percentage in peripheral blood (P = 0.002) and a significantly higher prevalence of splenomegaly (P = 0.004). Both children and adolescents presented with more aggressive clinical features than adults. During median follow-ups of 28 months (range, 3-161 months) in children, 33 months (range, 3-152 months) in adolescents, and 48 months (range, 3-157 months) in adults, multivariate analysis showed that children and adolescents had higher probabilities of achieving complete cytogenetic response, major molecular response, and molecular response^4.5. Notably, compared with not only adults (cohort 3 vs. cohort 1: HR = 2.03 [1.03, 3.98], P = 0.040; cohort 4 vs. cohort 1: HR = 2.15 [1.07, 4.33], P = 0.033; cohort 5 vs. cohort 1: HR = 4.22 [1.94, 9.15], P < 0.001) but also adolescents (cohort 2 vs. cohort 1: HR = 2.36 [1.18, 4.72], P = 0.015), children had significantly longer failure-free survival. Age was not associated with progression-free survival or overall survival. Although they exhibited more aggressive clinical features at diagnosis, both children and adolescents achieved superior treatment responses than adults. Adolescents showed even more adverse features and a poor FFS than children.

Tyrosine Kinase Inhibitors and Beyond for Chronic Myeloid Leukemia in Children

Chronic myeloid leukemia (CML) is rare in children but presents a unique challenge as recent drug innovations have turned CML into a chronic disease with implications for treatment into adulthood. With the approval of newer-generation tyrosine kinase inhibitors (TKIs) in addition to imatinib, providers have more options for the treatment of chronic-phase CML (CML-CP) in children. The second-generation TKIs approved for use in children, nilotinib and dasatinib, have higher response rates than first-generation imatinib; however, overall survival rates appear to be the same. Even more options may soon become available with ongoing investigations into the use of bosutinib and ponatinib and other new agents in children. Possible long-term side effects of TKIs, including growth failure, should be carefully acknowledged by the treating provider. Although these known associations may not preclude treatment, providers should be aware of them to guide their management of pediatric patients with CML being treated long term with TKI therapy. Treatment-free remission is a desired goal for pediatric patients and providers alike, but current recommendations are for attempts at achieving this to be restricted to clinical study settings.

Patterns of surveillance for late effects of BCR-ABL tyrosine kinase inhibitors in survivors of pediatric Philadelphia chromosome positive leukemias

BACKGROUND

Targeted anticancer therapies such as BCR-ABL tyrosine kinase inhibitors (TKIs) have improved outcomes for chronic myeloid leukemia (CML) and Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph + ALL). However, little is known about long-term risks of TKIs in children. Exposure-based survivorship guidelines do not include TKIs, thus surveillance practices may be variable.

METHODS

We retrospectively examined surveillance for cardiac and endocrine late effects in children receiving TKIs for Ph + leukemias, diagnosed at < 21 years between 2000 and 2018. Frequency of echocardiogram (ECHO), electrocardiogram (EKG), thyroid stimulating hormone (TSH), dual-energy x-ray absorptiometry (DXA), and bone age testing were abstracted. Descriptive statistics were stratified by leukemia type.

RESULTS

66 patients (CML n = 44; Ph + ALL n = 22) met inclusion criteria. Among patients with CML, ≥1 evaluation was done: ECHO (50.0%), EKG (48.8%), TSH (43.9%), DXA (2.6%), bone age (7.4%). Among patients with Ph + ALL, ≥1 evaluation was done: ECHO (86.4%), EKG (68.2%), TSH (59.1%), DXA (63.6%), bone age (44.4%). Over a median 6.3 and 5.7 years of observation, respectively, 2% of patients with CML and 57% with Ph + ALL attended a survivorship clinic.

CONCLUSIONS

Despite common exposure to TKIs in survivors of Ph + leukemias, patterns of surveillance for late effects differed in CML and Ph + ALL, with the latter receiving more surveillance likely due to concomitant chemotherapy exposures. Targeted therapies such as TKIs are revolutionizing cancer treatment, but surveillance for late effects and referral to survivorship clinics are variable despite the chronicity of exposure. Evidence based guidelines and longer follow-up are needed.

Imatinib Efficacy, Safety and Resistance in Iranian Patients with Chronic Myeloid Leukemia: A Review of Literature

Background: Imatinib is the gold standard in the treatment of chronic myeloid leukemia (CML) patients. Resistance to imatinib is interfering with patients’ responses and their survivals.

Materials and Methods: We designed a systematic search to find relevant studies by applying appropriate keywords in PubMed, Web of science, Scopus, Ovid, ProQuest, Science direct and Google scholar for English studies. We also investigated the aforementioned terms’ correspondence in Magiran, Scientific information database (SID) and Google scholar for Persian articles.

Results: 25 studies were selected for final analysis. Reported hematologic responses from adult studies ranged 86-99% and major molecular responses were estimated in 38.84% of our patients within 12 months of treatment. The most frequent reported adverse drug reactions (ADRs) were edema (n=5 studies, 100%) and fatigue and nausea (n=4 studies, 80%); ADR per capita ratio was 1.46. Only one study informed ADRs in pediatrics demonstrating 93% of patients experienced ADRs after receiving imatinib. Most of the Studies (n=4, 67% from 7 studies) considered BCR/ABL point mutation as main reason of imatinib resistance. Drug-binding site and P-loop regions were two common sites for BCR/ABL point mutation.

Conclusion: Imatinib as the first line treatment for CML has been associated with proper and durable responses in Iranian adults and children CML patients. Moreover, Imatinib life-threatening adverse effects were reported uncommon. Various responses to modified regimens have been reported in resistant patients; therefore, individualized treatment based on mutation type could be recommended.

Chronic Myelogenous Leukemia in Childhood

PURPOSE OF REVIEW

Chronic myelogenous leukemia (CML) is rare in children, requiring extrapolation from treatment of adults. In this review, we explore similarities and differences between adult and pediatric CML with a focus on therapeutic advances and emerging clinical questions.

RECENT FINDINGS

Pediatric CML is effectively treated with long-term targeted therapy using tyrosine kinase inhibitors (TKIs). Newly diagnosed pediatric patients in chronic phase can now be treated with imatinib, dasatinib, or nilotinib without allogeneic hematopoietic stem cell transplantation. While treatment-free remission is possible in adults in chronic phase with optimal response to therapy, data are currently insufficient to support stopping TKI in pediatrics outside of a clinical trial. Knowledge gaps remain regarding long-term and late effects of TKIs in pediatric CML. Targeted therapy has markedly improved outcomes for pediatric CML, while raising a number of clinical questions, including the possibility of treatment-free remission and long-term health implications of prolonged TKI exposure at a young age.

Definition, Epidemiology, Pathophysiology, and Essential Criteria for Diagnosis of Pediatric Chronic Myeloid Leukemia

Simple Summary

The low incidence (1:1,000,000) of chronic myeloid leukemia (CML) in the first two decades of life presents an obstacle to accumulation of pediatric experience and knowledge on this leukemia. Biological features of CML are shared but also differing between adult and pediatric patients. This review aims; (i) to define the disease based on an unified terminology, (ii) to list the diseases to be considered as a differential diagnosis in children, (iii) to outlines the morphological, histopathological and immuno-phenotypical findings of pediatric CML, (iv) to illustrate rare but classical complications resulting from high white cell and platelet counts at diagnosis, and (v) to recommend a uniform approach for the diagnostic procedures to be applied. Evidently, only a clear detailed picture of all relevant features can lay the basis for standardized treatment approaches.

Abstract

Depending on the analytical tool applied, the hallmarks of chronic myeloid leukemia (CML) are the Philadelphia Chromosome and the resulting mRNA fusion transcript BCR-ABL1. With an incidence of 1 per 1 million of children this malignancy is very rare in the first 20 years of life. This article aims to; (i) define the disease based on the WHO nomenclature, the appropriate ICD 11 code and to unify the terminology, (ii) delineate features of epidemiology, etiology, and pathophysiology that are shared, but also differing between adult and pediatric patients with CML, (iii) give a short summary on the diseases to be considered as a differential diagnosis of pediatric CML, (iv) to describe the morphological, histopathological and immunophenotypical findings of CML in pediatric patients, (v) illustrate rare but classical complications resulting from rheological problems observed at diagnosis, (vi) list essential and desirable diagnostic criteria, which hopefully in the future will help to unify the attempts when approaching this rare pediatric malignancy.

Features and outcome of chronic myeloid leukemia at very young age: Data from the International Pediatric Chronic Myeloid Leukemia Registry

INTRODUCTION

Chronic myeloid leukemia (CML) is rare in the first two decades of life comprising only 3% of newly diagnosed pediatric and adolescent leukemias. We studied the epidemiologic and clinical features of patients with CML diagnosed at younger than 3 years of age and evaluated treatment and long-term outcome.

METHOD

Data from the International Pediatric I-BFM/CML Registry were retrospectively analyzed using the European LeukemiaNet criteria of the year 2006. Characteristics and treatment outcome of patients <3 years old at diagnosis were evaluated from standardized forms.

RESULTS

Twenty-two patients (n = 22/479; 4.6%, male/female:14/8) were enrolled with a median age of 22 months (range, 10-34 m). Major symptoms comprised asthenia (30%), fever (30%), abdominal pain (20%), extramedullary signs (14%), hemorrhage (5%), and weight loss (5%). The extramedullary signs were specified in eight children: blueberry muffin (n = 1), sudden swollen abdomen (n = 1), sustained vomiting (n = 1), and cervical and inguinal lymph nodes (n = 5). Two of five children with cervical and inguinal lymph nodes were categorized as accelerated phase. Overall, 19 of 22 (86%) children were diagnosed in chronic phase, while the remaining three patients were in advanced phase. Median follow-up was 78 months (range, 7-196 m). Twenty-one out of 22 patients initially received imatinib, while one child received IFN + ARA-C. Imatinib was changed to second-line tyrosine kinase inhibitors (TKIs) in 29% of cases. During follow-up, 41% patients underwent stem cell transplantation (SCT). While on TKI, major molecular response (MMR) was achieved in 48% of children. Among the remaining patients, 21% are alive on TKI without MMR and 22% achieved complete molecular response following SCT. Twenty-one of 22 (95%) children are alive, while one patient died of posttransplant complications.

CONCLUSION

This report demonstrates for the first time the efficacy and long-term effects of upfront imatinib in the so far largest cohort of children with CML diagnosed at very young age.

Long-term safety and efficacy of imatinib in pediatric patients with chronic myeloid leukemia: single-center experience from China

Chronic myeloid leukemia (CML) is a rare disease among children. A retrospective study was conducted from November 2002 to March 2019 at a single institution in China. A total of 36 pediatric CML patients (25 male and 11 female) were enrolled. Median follow-up time was 51 months (range 8-144), and 5-year overall survival and event-free survival were 95.5 ± 4.4% and 88.9 ± 6.0%, respectively. Among the 25 patients whose response to imatinib mesylate (IM) was regularly monitored, 92.0% achieved complete hematologic response at 3 months, 80.0% achieved complete cytogenetic response at 12 months, and 64.0% achieved major molecular response at 18 months after IM therapy. A higher WBC count at diagnosis was associated with failure to achieve early molecular response (EMR). Height standard deviation score after long-term treatment was significantly and positively correlated with age at diagnosis and at the start of IM therapy. Overall, IM therapy was effective in treating pediatric CML, and WBC count at diagnosis might be an ideal predictor of EMR. Moreover, retardation of height and weight growth due to IM tended to affect patients younger than 9 years old at diagnosis, and longitudinal growth might normalize further into treatment.

[Effect of imatinib on the height of children with chronic myeloid leukemia in the chronic phase]

目的

评估伊马替尼对慢性髓性白血病慢性期（CML-CP）儿童身高的影响。

方法

2018年7月至2019年7月，在全国范围内对诊断时年龄<18周岁、接受伊马替尼治疗至少3个月的CML儿童或其家长发放问卷，调查受访者伊马替尼治疗前后身高的变化。主要评价指标为身高标准差积分值（HtSDS）以及标准差积分的差值（ΔHtSDS），并分析其相关影响因素。

结果

共有238例受访者符合标准并被纳入研究，男性138例（58.0％），初诊时中位年龄11.0（1.4～17.9）岁，青春期前93例（39.0％），至填写答卷时，中位年龄15.0（2.0～34.0）岁，中位伊马替尼服药时间28（3～213）个月。受访者填写答卷时HtSDS（−0.063±1.361）较治疗前HtSDS（0.391±1.244）显著下降（P<0.001），71.0％的患儿出现身高增长减慢。青春期前服药者治疗后HtSDS下降显著（P<0.05），而青春期开始后服药者HtSDS变化不明显（P>0.05）。多因素分析显示，服药初始年龄较小（偏回归系数为0.122，B＝0.572，t＝10.733，P<0.001）和服药时间较长（偏回归系数为−0.006，B＝−0.211，t＝−4.062，P<0.001）是伊马替尼抑制身高增长的独立影响因素。

结论

伊马替尼引起CML-CP儿童身高增长障碍，服药初始年龄越小、服药时间越长，伊马替尼对身高的影响越明显。

Outcomes of children with chronic myeloid leukemia: A population-based cohort study

OBJECTIVE

Chronic myeloid leukemia (CML) is a rare disease in childhood. While hematopoietic stem cell transplant (HSCT) was the treatment of choice for CML prior to 2000, the introduction of tyrosine kinase inhibitors (TKIs) changed the management of this disease. This population-based analysis was conducted in the province of Ontario, Canada to gather information on treatment choices and outcomes of childhood CML.

METHOD

Using a provincial childhood cancer registry and retrospective review of patient medical records for patients < 18 years diagnosed with CML between 1985 and 2018, data on presenting features, treatment, and outcomes were collected from 52 patients.

RESULTS

Patients treated before the introduction of TKIs (before 2002) mainly received HSCT and had an overall survival (OS) of 64% at a median follow up of 6 years. The OS of all patients treated in the TKI era (2002 and after) was 90% at a median follow up of 3 years. All three deaths in the TKI era were related to HSCT complications. Survival of patients who remained on a TKI was significantly improved compared to those who underwent HSCT post-TKI therapy (100% vs 66%, P = .008). TKIs were well tolerated.

CONCLUSION

Given the increased mortality associated with HSCT in our cohort, further advances in HSCT may be required to outweigh the benefits of a TKI monotherapy approach in the majority of childhood CML patients. We believe HSCT should be considered in only a limited subset of pediatric patients with CML.

Lymphoblastic predominance of blastic phase in children with chronic myeloid leukaemia treated with imatinib: A report from the I-CML-Ped Study

BACKGROUND

Chronic myeloid leukaemia (CML) is a rare disease in children. The frequency and outcome of children evolving to accelerated phase (AP) or blastic phase (BP) under treatment with imatinib is unknown. The aim of the current study is to assess the incidence of progression from CML in chronic phase with imatinib frontline in a paediatric setting and describe the management and outcome of these patients.

PATIENTS AND METHODS

In the I-CML-Ped Study database (www.clinicaltrials.gov, #NCT01281735), 19 of 339 paediatric patients in chronic phase treated with imatinib in the frontline evolved to CML-AP or CML-BP.

RESULTS

With a median follow-up of 38 months (range: 2-190 months), the cumulative incidence of progression at 1 and 3 years was 3% (confidence interval [CI] 95%: 1-5%) and 7% (CI 95%: 4-11%), respectively. We observed a large predominance of lymphoid-BP (70%) over myeloid-BP (30%) with imatinib in frontline therapy. Sixteen patients underwent haematopoietic stem cell transplantation, and eight were treated with a tyrosine kinase inhibitor after transplant. Only the transplanted patients are alive. The 5-year overall survival rate of children with CML-AP/BP is 44%, with no statistical difference between the lymphoid-BP and myeloid-BP outcome.

CONCLUSION

Children evolving to AP or BP under treatment with imatinib have a very poor prognosis with an overall survival under 50%, much worse than children with advanced phase at diagnosis.

Ponatinib in childhood Philadelphia chromosome-positive leukaemias: an international registry of childhood chronic myeloid leukaemia study

BACKGROUND

Ponatinib is effective in adults with Philadelphia chromosome-positive (Ph+) leukaemias, but scant data are available regarding the use of this tyrosine kinase inhibitor in children.

AIMS

The aim of this study isto describe the tolerance and efficacy of compassionate use of ponatinib in a paediatric cohort of patients with Ph+ leukaemias.

METHODS

Data from 11 children with chronic myeloid leukaemia (CML) registered to the international registry of childhood chronic myeloid leukaemia and from 3 children with Ph+ acute lymphoblastic leukaemia (Ph+ ALL) treated with ponatinib were collected retrospectively.

RESULTS

In 11 girls and 3 boys (median age 14 years), ponatinib was used as a second- to eighth-line treatment. Ponatinib was administered as single therapy (9 patients) or in combination with chemotherapy (8 patients). The status of the disease when ponatinib was started was as follows: CML in advanced phases (n = 8), CML in chronic phase without achievement of molecular response (n = 2) or presence of T315I mutation (n = 1) and Ph + ALL in molecular (n = 1) or marrow (n = 2) relapses. The median dose administered was 21.4 mg/m² and median duration of ponatinib was 2.5 months. Ponatinib alone or in combination with chemotherapy administered on 16 occasions led to achievement of major molecular response in 50% of cases. Ponatinib was used as a bridge to transplant in 4 cases. Among the 9 patients treated with ponatinib alone, toxicity grade III-IV (2 patients) was exclusively haematologic. No vascular events related to ponatinib were observed.

CONCLUSION

Ponatinib may be a reasonable additional treatment option for children with Ph+ leukaemias who have failed several lines of therapy.

Real-world Experience of Imatinib in Pediatric Chronic Phase Chronic Myeloid Leukemia: A Single-center Experience From India

INTRODUCTION

Chronic myeloid leukemia (CML) is an uncommon malignancy in children in which tyrosine kinase inhibitors (TKIs) have significantly improved outcome in recent years.

PATIENTS AND METHODS

We performed a retrospective analysis of CML patients (≤ 18 years old) presenting to our center between January 2005 and December 2018 with respect to baseline demographics, response to imatinib, and real-world management of those with a suboptimal response.

RESULTS

A total of 124 patients were diagnosed with CML with 99 (80%) in the chronic phase. There was a male preponderance (males:females = 3.1:1) with a median age of 13 years. The common presenting clinical features were splenomegaly (90.9%) and fever (51.5%) with a median leukocyte count of 165 × 103/μL. The proportion of patients attaining a complete hematologic response (CHR) at 3 months, a complete cytogenetic response (CCyR) at 12 months, and a major molecular response at 12 months were 79.7%, 54.1%, and 50.9%, respectively. At a median follow-up of 67.4 months, the 5-year overall survival rate and the event-free survival (EFS) rate were 92% ± 3% and 64% ± 6%, respectively. Failure to achieve CCyR at 12 months was associated with poor EFS beyond 1 year (hazard ratio = 2.865, P = .044). Among 15 patients not achieving CHR at 3 months, dose escalation of imatinib resulted in the attainment of CHR in 13 (87%) patients. Seven patients in the cohort had a loss of the established response to imatinib because of documented poor compliance.

CONCLUSION

Imatinib remains the frontline treatment of choice in CML with a reasonable outcome in children, especially when financial affordability, availability of second-generation TKIs, and poor compliance still remain major challenges in management. Dose escalation of imatinib remains an option in patients with a suboptimal response.

Horn of plenty: Value of the international registry for pediatric chronic myeloid leukemia

Chronic myeloid leukemia (CML) in minors is a rare disease which can be effectively treated by tyrosine kinase inhibitors (TKIs) since the year 2000. A majority of pediatricians will encounter one or two CML patients in the course of their careers and will typically have to rely on written information along with their own intuition to provide care. Knowledge of response to TKIs and of age-specific side effects has an impact on the design of pediatric CML trials in many ways aiming to contribute toward greater predictability of clinical improvements. Information from a registry on a rare disease like CML offers the enormous benefit of enabling treating physicians to interact and share their collective experience. The International Registry on Pediatric CML (IR-PCML) was founded at Poitiers/France almost 10 years ago. Since then, the number of collaboration centers and in parallel of registered patients continuously increased (> 550 patients as of December 2019). Ideally, from a given treatment center in a country data are transferred to a national coordinator who interacts with the IR-PCML. In the sense of quality assurance, the registry can offer dissemination of knowledge on state-of-the-art diagnostics (including reference appraisal), optimal treatment approaches, and follow-up procedures within a network that is exerting its strength via participation. With continuous growth during the recent years, very rare subgroups of patients could be identified (e.g., CML diagnosed at age < 3 years, children presenting with specific problems at diagnosis or during course of treatment) which had not been described before. Publications coming from the IR-PCML disseminated this useful information derived from patients who robustly participate and share information about their disease, among themselves and with their caregivers and clinicians. Patient input driving the collection of data on this rare leukemia is the basis for the considerable success of bringing new therapeutics into clinical use.