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

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.

Effect of the tyrosine kinase inhibitors on the growth in children with Philadelphia chromosome-positive acute lymphoblastic leukemia: a case-control study

Background

First-generation ABL-targeted tyrosine kinase inhibitor (TKI) imatinib is known to retard growth in children but it is not known if the second-generation ABL-targeted TKI dasatinib has the same effect. We aimed to determine the impact of the first- or second-generation TKI on the growth of children treated for Philadelphia chromosome-positive (Ph+) childhood acute lymphoblastic leukemia (ALL).

Methods

We evaluated the longitudinal growth changes in 140 children with Ph+ ALL treated with imatinib or dasatinib in additional to intensive cytotoxic chemotherapy and 280 matched controls treated with the same intensity of cytotoxic chemotherapy without TKI on Chinese Children's Cancer Group ALL-2015 protocol between 2015 and 2019. We retrospectively reviewed the height data obtained during routine clinic visits at 4 time points: at diagnosis, the end of therapy, 1 year and 2 years off therapy. Height z Scores were derived with the aid of WHO Anthro version 3.2.2 and WHO AnthroPlus version 1.0.4, global growth monitoring tool.

Findings

This study consisted only patients who have completed all treatment in continuous complete remission without major events, including 33 patients randomized to receive imatinib, 43 randomized to receive dasatinib, and 64 assigned to receive dasatinib. Similar degree of loss of height z scores from diagnosis to the end of therapy was observed for the 33 imatinib- and the 107 dasatinib-treated patients (median △ = -0.84 vs. -0.88, P = 0.41). Adjusting for height z score at diagnosis, puberty status, and sex, there was no significant difference in the longitudinal mean height z scores between patients treated with imatinib and those with dasatinib (0.08, 95% CI, -0.22 to 0.38, P = 0.60). The degree of loss of height z scores from diagnosis to end of therapy was significantly greater in the 140 TKI-treated patients than the 280 controls (median △ = -0.88 vs. -0.18, P < 0.001). The longitudinal mean height z scores in the TKI-treated patients were significantly lower than those of the controls (-0.84, 95% CI, -0.98 to -0.69; P < 0.001).

Interpretation

These data suggest that dasatinib and imatinib have the similar adverse impact on the growth of children with Ph+ ALL.

Funding

This study was supported by the National Natural Science Foundation of China (grant 81670136 [JCai and JT]), the fourth round of Three-Year Public Health Action Plan (2015-2017; GWIV-25 [SS]), Shanghai Health Commission Clinical Research Project (202140161 [JCai]), the US National Cancer institute (CA21765 [C-H Pui]), and the American Lebanese Syrian Associated Charities (CC, JJY, and C-HP). The content of this paper is solely the responsibility of the authors and does not necessarily represent the official views of the US National Institutes of Health.

Effect of Imatinib Mesylate on Growth in Pediatric Chronic Myeloid Leukemia: A Systematic Review and Meta-analysis

The outcomes of pediatric chronic myeloid leukemia (CML) have improved with the use of imatinib mesylate (IM). Multiple reports of growth deceleration with IM have raised concerns, necessitating careful monitoring and evaluation in children with CML. We systematically searched the databases of PubMed, EMBASE, Scopus, CENTRAL, and conferences-abstracts, reporting the effect of IM on growth among children with CML, and published in the English language from inception till March 2022. For observational studies, the modified Newcastle Ottawa Scale was used to assess the risk of bias. Pooled estimates were derived using a random-effects meta-analysis, and heterogeneity was assessed using Cochrane Q statistic test of heterogeneity and I2 statistic. Of the 757 studies identified through electronic search, 15 (n=265) were included in the final analysis. Six studies (n=178) were included in the meta-analysis of the primary outcome. There was a significant deleterious effect of IM on height-standardized mean difference (SMD): -0.52 (95% CI: -0.76; -0.28) ( I2 =13%). The adverse effect of IM on height was significant among studies with a follow-up period <3 years [SMD: -0.66 (95% CI: -0.93, -0.40), I2 =0%, P =0.59] but not in studies with follow-up period ≥3 years [SMD: -0.26 (95% CI: -0.63, 0.11), I2 =0, P =0.44], indicating that the effect of IM on height is a short-term effect. The effect of IM on height was not dependent upon pubertal status at the initiation of therapy. Prospective studies with adequate sample size are required to confirm the findings of the effect of IM on height in children with CML.

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.

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.

[Combination of socio-demographic and clinical co-variates for predicting treatment responses and outcomes in patients with chronic myeloid leukemia in the chronic phase]

Objective: To explore the impacts of socio-demographic and clinical co-variates on treatment responses and outcomes in patients with chronic myeloid leukemia in the chronic phase (CML-CP) receiving tyrosine kinase inhibitor (TKI) and identified the predictive models for them. Methods: Data of newly diagnosed adult patients with CML-CP receiving first-line TKI and having complete socio-demographic data and clinical information were reviewed. Cox model was used to identify the independent variables associated with complete cytogenetic response (CCyR) , major molecular response (MMR) , molecular response 4 (MR(4)) and molecular response 4.5 (MR(4.5)) , as well as failure-free survival (FFS) , progression-free survival (PFS) , overall survival (OS) and CML-related OS. Results: A total of 1414 CML-CP patients treated with first-line imatinib (n=1176) , nilotinib (n=170) or dasatinib (n=68) were reviewed. Median age was 40 (18-83) years and 873 patients (61.7% ) were males. Result of the multivariate analysis showed that lower educational level (P<0.001-0.070) and EUTOS long-term survival intermediate or high-risk (P<0.001-0.009) were significantly associated with lower cumulative incidences of CCyR, MMR, MR(4) and MR(4.5), as well as the inferior FFS, PFS, OS and CML-related OS. In addition, those who were males, from rural households, had white blood cells (WBC) ≥120×10(9)/L, hemoglobin (HGB) <115 g/L and treated with first-line imatinib had significantly lower cumulative incidences of cytogenetic and/or molecular responses. Being single, divorced or widowed, having, rural household registration, WBC≥120×10(9)/L, HGB<15 g/L, and comorbidity (ies) was significantly associated with inferior FFS, PFS, OS, and/or CML-related OS. Thereafter, the patients were classified into several subgroups using the socio-demographic characteristics and clinical variables by cytogenetic and molecular responses, treatment failure and disease progression, as well as overall survival and CML-related OS, respectively. There were significant differences in treatment responses and outcomes among the subgroups (P<0.001) . Conclusion: Except for clinical co-variates, socio-demographic co-variates significantly correlated with TKI treatment responses and outcomes in CML-CP patients. Models established by the combination of independent socio-demographic and clinical co-variates could effectively predict the responses and outcome.

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.