Chronic myeloid leukemia: reminiscences and dreams

Asciminib: the next-generation bullet for first-line treatment of chronic myeloid leukemia

The standard of care for chronic myeloid leukemia (CML) involves tyrosine kinase inhibitors (TKIs), which suppress tyrosine kinase activity of BCR::ABL1. Hochhaus et al. reported that asciminib, a BCR::ABL1 inhibitor specifically targeting the ABL myristoyl pocket, showed superior efficacy and favorable safety compared with TKIs in the phase 3 ASC4FIRST trial in patients with newly diagnosed chronic-phase CML.1.

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

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

LncRNA IRAIN overcomes imatinib resistance in chronic myeloid leukemia via NF-κB/CD44 pathway inhibition

The development of tyrosine kinase inhibitors (TKIs) has revolutionarily increased the overall survival of patients with chronic myeloid leukemia (CML). However, drug resistance remains a major obstacle. Here, we demonstrated that a BCR-ABL1-independent long non-coding RNA, IRAIN, is constitutively expressed at low levels in CML, resulting in imatinib resistance. IRAIN knockdown decreased the sensitivity of CD34+ CML blasts and cell lines to imatinib, whereas IRAIN overexpression significantly increased sensitivity. Mechanistically, IRAIN downregulates CD44, a membrane receptor favorably affecting TKI resistance, by binding to the nuclear factor kappa B subunit p65 to reduce the expression of p65 and phosphorylated p65. Therefore, the demethylating drug decitabine, which upregulates IRAIN, combined with imatinib, formed a dual therapy strategy which can be applied to CML with resistance to TKIs.

c-myb is involved in CML progression and is a therapeutic target in the zebrafish CML model

BACKGROUND

Despite the success of tyrosine kinase inhibitors in chronic myeloid leukemia (CML) therapy, CML still faces the challenges of drug resistance and progression to blast crisis. Twenty-five percent of patients have imatinib resistance and treatment difficulties due to heterogeneity after progression, but little is known about the mechanism. A key transcription factor in hematopoiesis, MYB, has been reported to increase abnormally in several types of aggressive blood disorders including CML.

METHODS

This study used a zebrafish model to explore the relationship between BCR/ABL1 and c-myb in CML progression. A CML zebrafish model was crossed with a c-myb hyperactivity transgenic line.

RESULTS

It was found that both exogenous BCR/ABL1 and c-myb could up-regulate the expression of neutrophil-related genes. More seriously, neutrophil accumulation was observed when BCR/ABL1 was combined with c-myb overexpression. Further studies showed that c-myb may be one of the downstream targets of BCR/ABL1 and the effect of BCR/ABL1 on neutrophils was c-myb dependent. Taking advantage of this inheritable in vivo model, it was shown that a combination of imatinib and flavopiridol, a cyclin-dependent kinase inhibitor targeting MYB, could more effectively alleviate the aggressive phenotype of the double transgene line.

CONCLUSION

In summary, this study suggests that c-myb acts downstream of BCR/ABL1 and is involved in CML progression and is therefore a risk factor and a valuable target for the treatment of CML progression. The model used in the study could be helpful in high-throughput drug screening in CML transformation.

Effect of Tyrosine Kinase Inhibitor Therapy on Estimated Glomerular Filtration Rate in Patients with Chronic Myeloid Leukemia

INTRODUCTION

The advent of tyrosine kinase inhibitors (TKIs) was revolutionary in the management of chronic myeloid leukemia (CML). Although TKIs were generally considered to be safe, they can be associated with renal injury. We evaluated the effect of TKIs on renal functions in a cohort of patients with long-term follow-up.

MATERIAL AND METHODS

We retrospectively examined patients with chronic phase CML treated with TKIs. We analyzed the estimated glomerular filtration rate (eGFR) of patients from the initiation of TKI to the last follow-up. eGFR values of CML patients were compared to those of patients with stage 1 or 2 chronic kidney disease (CKD).

RESULTS

A total of 195 patients with CML and 138 patients with CKD were examined. eGFR decline was 1.556 ml/min/1.73m2/year for patients with CML (P = .221). Patients receiving second-generation TKIs (2GTKI) were estimated to have 0.583 ml/min/1.73m2 higher eGFR value than that of the imatinib group, but it was not significant (P = .871). eGFR of patients who had used bosutinib had a downward trend. Duration of TKI therapy, age, and hypertension were found to be significant factors in eGFR decline for CML patients. Lower baseline GFR was associated with an increased risk of CKD development.

CONCLUSION

Imatinib could result in a decline in eGFR which was clinically similar to early-stage CKD patients. We did not observe significant kidney function deterioration in patients receiving 2GTKIs including dasatinib and nilotinib. We recommend close renal function monitoring in patients receiving imatinib, especially for elderly patients with lower baseline eGFR and hypertension.

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

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

miR-181a plays the tumor-suppressor role in chronic myeloid leukemia CD34 + cells partially via SERPINE1

The formation of the BCR-ABL fusion gene drives human chronic myeloid leukemia (CML). The last 2 decades have witnessed that specific tyrosine kinase inhibitors (TKIs, e.g., imatinib mesylate, IM) against ABL1 improve disease treatment, although some patients still suffer from relapse and TKI resistance. Therefore, a better understanding of the molecular pathology of CML is still urgently needed. miR-181a-5p (miR-181a) acts as a tumor suppressor in CML; however, the molecular mechanism of miR-181a in CML stem/progenitor cells remains elusive. Herein, we showed that miR-181a inhibited the growth of CML CD34+ cells, including the quiescent subset, and sensitized them to IM treatment, while miR-181a inhibition by a sponge sequence collaborated with BCR-ABL to enhance the growth of normal CD34+ cells. Transcriptome data and biochemical analysis revealed that SERPINE1 was a bona fide and critical target of miR-181a, which deepened the understanding of the regulatory mechanism of SERPINE1. Genetic and pharmacological inhibition of SERPINE1 led to apoptosis mainly mediated by caspase-9 activation. The dual inhibition of SERPINE1 and BCR-ABL exhibited a significantly stronger inhibitory effect than a single agent. Taken together, this study demonstrates that a novel miR-181a/SERPINE1 axis modulates CML stem/progenitor cells, which likely provides an important approach to override TKI resistance.

Therapeutic Drug Monitoring of Imatinib and N-Desmethyl Imatinib in Chronic Myeloid Leukemia Patients Using LC-MS/MS in a Cohort Study

Imatinib is an oral tyrosine kinase inhibitor (TKI) and first-line therapy for patients with chronic myeloid leukemia (CML). There is a positive correlation between serum imatinib concentrations and treatment response. However, the specific relationship between the blood concentration of imatinib and its influencing factors remains unclear. This study collected basic information from 102 patients using imatinib as first-line treatment for CML. Further, we analyzed the individual differences in imatinib concentration and explored its influencing factors. Through intra-day and inter-day precision studies, we found that the precision for the imatinib assay methodology was within ±13% and that the recovery rate was above 85%. There is notable individual variation in the blood concentration of imatinib; the recommended treatment concentration is 860-1500 ng/mL, with only 41.40% of patients achieving this concentration. Also, there was a negative correlation between age and imatinib trough concentration (Ctrough ), as is observed between age and N-desmethyl imatinib. Moreover, compared with the adolescent group, the serum imatinib Ctrough for groups aged 17-47 and 48-68 years was significantly reduced. Further analysis shows that imatinib Ctrough values reaching therapeutic concentrations (59%) increased dramatically for patients with CML aged 17-47 years. Moreover, groups dosed with 400 mg/day resulted in therapeutic imatinib concentrations for 68% of patients with CML, which was the best performance. The established method was validated, with acceptable accuracy, precision, linearity, and stability, as required, and then successfully applied to the therapeutic drug monitoring of imatinib. Age, dose, and metabolites can influence the imatinib concentration and its therapeutic effect in patients with CML.

A conserved ZFX/WNT3 axis modulates the growth and imatinib response of chronic myeloid leukemia stem/progenitor cells

BACKGROUND

Zinc finger protein X-linked (ZFX) has been shown to promote the growth of tumor cells, including leukemic cells. However, the role of ZFX in the growth and drug response of chronic myeloid leukemia (CML) stem/progenitor cells remains unclear.

METHODS

Real-time quantitative PCR (RT-qPCR) and immunofluorescence were used to analyze the expression of ZFX and WNT3 in CML CD34+ cells compared with normal control cells. Short hairpin RNAs (shRNAs) and clustered regularly interspaced short palindromic repeats/dead CRISPR-associated protein 9 (CRISPR/dCas9) technologies were used to study the role of ZFX in growth and drug response of CML cells. Microarray data were generated to compare ZFX-silenced CML CD34+ cells with their controls. Chromatin immunoprecipitation (ChIP) and luciferase reporter assays were performed to study the molecular mechanisms of ZFX to regulate WNT3 expression. RT-qPCR and western blotting were used to study the effect of ZFX on β-catenin signaling.

RESULTS

We showed that ZFX expression was significantly higher in CML CD34+ cells than in control cells. Overexpression and gene silencing experiments indicated that ZFX promoted the in vitro growth of CML cells, conferred imatinib mesylate (IM) resistance to these cells, and enhanced BCR/ABL-induced malignant transformation. Microarray data and subsequent validation revealed that WNT3 transcription was conservatively regulated by ZFX. WNT3 was highly expressed in CML CD34+ cells, and WNT3 regulated the growth and IM response of these cells similarly to ZFX. Moreover, WNT3 overexpression partially rescued ZFX silencing-induced growth inhibition and IM hypersensitivity. ZFX silencing decreased WNT3/β-catenin signaling, including c-MYC and CCND1 expression.

CONCLUSION

The present study identified a novel ZFX/WNT3 axis that modulates the growth and IM response of CML stem/progenitor cells.

Treatment after failure of frontline therapy of chronic myeloid leukemia in chronic phase including allogeneic hematopoietic stem cell transplantation

The treatment outcomes of chronic myeloid leukemia in chronic phase (CML-CP) have dramatically improved with comparable life-expectancy to average of general population in tyrosine kinase inhibitor (TKI) era. However, less than a half of patients who started with TKI can remain on frontline TKI. The reasons of switching TKI can be either intolerance or the lack of efficacy. Although a kinase domain (KD) mutation can guide to select salvage TKI from the point of view on the efficacy of TKIs, many factors need to be considered before choosing next-line TKI such as the high-risk features of CML, the adverse events with prior TKI, and the comorbidities of patients. The therapeutic options for CML-CP after failing frontline TKI due to treatment failure or suboptimal responses will be reviewed including allogeneic hematopoietic stem cell transplantation.

Association of obesity under different metabolic status with adverse outcomes in patients with chronic myeloid leukemia: A retrospective cohort study

BACKGROUND

Little is known about the association between abnormal metabolic obesity states and the outcomes of chronic myeloid leukemia (CML), especially in patients with obesity with different metabolic status. Here, we used the Nationwide Readmissions Database to assess the effects of metabolically defined obesity on adverse outcomes of CML.

METHODS

Of the 35 460 557 (weighted) patients, we included 7931 adults with discharge diagnoses of CML from January 1, 2018 to June 30, 2018. The study population was observed until December 31, 2018 and divided into four groups based on body mass index and metabolic status. The primary outcome was the adverse outcomes of CML, including nonremission (NR)/relapse and severe mortality risk. Multivariate logistic regression analysis was performed to analyze data.

RESULTS

Metabolically unhealthy normal weight and metabolically unhealthy obesity were all risk factors for adverse outcomes of CML compared with metabolically healthy normal weight (all p < 0.01), and a significant difference was not found in the metabolically healthy obese. Female patients with metabolically unhealthy normal weight and metabolically unhealthy obesity had 1.23-fold and 1.40-fold increased NR/relapse risk, while male patients did not have this risk. Moreover, patients with a higher number of metabolic risk factors or with dyslipidemia were at higher risk of adverse outcomes, regardless of obesity status.

CONCLUSIONS

Metabolic abnormalities were associated with adverse outcomes in patients with CML, irrespective of obesity status. Future treatment of patients with CML should consider the effects of obesity on their adverse outcomes under different metabolic status, especially in female patients.

The prognostic and therapeutic potential of HO-1 in leukemia and MDS

BACKGROUND

Heme oxygenase-1 (HO-1), a heme-degrading enzyme, is proven to have anti-apoptotic effects in several malignancies. In addition, HO-1 is reported to cause chemoresistance and increase cell survival. Growing evidence indicates that HO-1 contributes to the course of hematological malignancies as well. Here, the expression pattern, prognostic value, and the effect of HO-1 targeting in HMs are discussed.

MAIN BODY

According to the recent literature, it was discovered that HO-1 is overexpressed in myelodysplastic syndromes (MDS), chronic myeloid leukemia (CML), acute myeloblastic leukemia (AML), and acute lymphoblastic leukemia (ALL) cells and is associated with high-risk disease. Furthermore, in addition to HO-1 expression by leukemic and MDS cells, CML, AML, and ALL leukemic stem cells express this protein as well, making it a potential target for eliminating minimal residual disease (MRD). Moreover, it was concluded that HO-1 induces tumor progression and prevents apoptosis through various pathways.

CONCLUSION

HO-1 has great potential in determining the prognosis of leukemia and MDS patients. HO-1 induces resistance to several chemotherapeutic agents as well as tyrosine kinase inhibitors and following its inhibition, chemo-sensitivity increases. Moreover, the exact role of HO-1 in Chronic Lymphocytic Leukemia (CLL) is yet unknown. While findings illustrate that MDS and other leukemic patients could benefit from HO-1 targeting. Future studies can help broaden our knowledge regarding the role of HO-1 in MDS and leukemia. Video abstract.

Clinical outcomes of second-generation tyrosine kinase inhibitors versus imatinib in older patients with CML

Age and comorbidities are important factors to be considered in the selection of tyrosine kinase inhibitors (TKIs) for first-line treatment in patients with chronic myeloid leukemia in chronic phase (CML-CP). However, it is yet unclear whether TKI selection, particularly, imatinib versus second-generation TKIs (2GTKIs), impacts treatment outcomes in the clinical practice. To address this, we compared the clinical outcomes of prospectively registered 452 patients with CML-CP treated with imatinib and 2GTKIs, taking into consideration their age and/or comorbidities. A total of 136 patients (30.1%) were classified into an older cohort (≥65 years) and 316 (69.9%) into a younger cohort (18-64 years). The TKI selection did not vary based on age (70.6% received 2GTKIs in the younger cohort and 66.2% in the older cohort). The median follow-up period was 5.4 years. Treatment responses including the cumulative incidence of deep molecular response (BCR-ABL1 international scale ≤0.0032%) at any time were similar between the two age cohorts regardless of the type of TKI. The 5-year overall survival (OS) in the older cohort was lower than that in the younger cohort (95.9% vs 83.8%; p < 0.0001), whereas the 5-year OS in patients treated with 2GTKIs was not influenced by age factors and comorbidities. Therefore, our results suggest that the selection of 2GTKIs as first-line treatment is an effective option for both younger and older CML-CP patients with or without comorbidities. This trial was registered at UMIN-CTR as 00003581.

Gbb Regulates Blood Cell Proliferation and Differentiation through JNK and EGFR Signaling Pathways in the Drosophila Lymph Gland

The Drosophila lymph gland is an ideal model for studying hematopoiesis, and unraveling the mechanisms of Drosophila hematopoiesis can improve our understanding of the pathogenesis of human hematopoietic malignancies. Bone morphogenetic protein (BMP) signaling is involved in a variety of biological processes and is highly conserved between Drosophila and mammals. Decapentaplegic (Dpp)/BMP signaling is known to limit posterior signaling center (PSC) cell proliferation by repressing the protooncogene dmyc. However, the role of two other TGF-β family ligands, Glass bottom boat (Gbb) and Screw (Scw), in Drosophila hematopoiesis is currently largely unknown. Here, we showed that the loss of Gbb in the cortical zone (CZ) induced lamellocyte differentiation by overactivation of the EGFR and JNK pathways and caused excessive differentiation of plasmatocytes, mainly by the hyperactivation of EGFR. Furthermore, we found that Gbb was also required for preventing the hyperproliferation of the lymph glands by inhibiting the overactivation of the Epidermal Growth Factor Receptor (EGFR) and c-Jun N-terminal Kinase (JNK) pathways. These results further advance our understanding of the roles of Gbb protein and the BMP signaling in Drosophila hematopoiesis and the regulatory relationship between the BMP, EGFR, and JNK pathways in the proliferation and differentiation of lymph gland hemocytes.

Effects of ABCG2 C421A and ABCG2 G34A genetic polymorphisms on clinical outcome and response to imatinib mesylate, in Iranian chronic myeloid leukemia patients

Background

Chronic myeloid leukemia (CML) is a multifactorial clonal myeloid neoplasm that mainly arises from the Philadelphia chromosome. Even though imatinib mesylate (IM) is considered the gold standard for first-line treatment, a number of CML patients have shown IM resistance that can be influenced by many factors, including pharmacogenetic variability. The present study examined whether two common single nucleotide polymorphisms (SNPs) of ABCG2 (G34A and C421A) contribute to IM resistance and/or good responses.

Material and methods

A total of 72 CML patients were genotyped with high-resolution melting (HRM) and restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR). We also determined the cytogenetic and hematological response, as evaluable factors for measuring response to imatinib.

Results

In the current study, we explored the relationship between the different variants of ABCG2 G34A and C421A and clinical response to imatinib among CML patients. There were no statistically significant differences between genotypes of C421A and G34A and allele frequencies among the resistant and responder groups, with response to IM (P > 0.05). Also, we found no statistically significant association between genotypes and cytogenetic and hematological responses.

Conclusion

This is the first study to investigate the association between genotypes of the G34A and C421A SNPs and the outcome of IM treatment in Iranian population. As a whole, genotyping of these SNPs is unhelpful in predicting IM response in CML patients.

Evaluation of the expression of LC3-II and BECLIN1 genes of autophagy pathway in patients with hematological malignancies

Background

Autophagy is a pathway for the degradation of cytoplasmic components, which plays an essential role in various cellular and physiological processes, including cell renewal and survival, and immune responses. While recent studies have shown that they can play a role in cancer treatment, the precise mechanisms of autophagy in leukemogenesis are not fully understood. We have assessed the expression levels of LC3 and BECLIN1 as two crucial autophagy mediators in patients with leukemia.

Methods

This cross-sectional study was performed on bone marrow or peripheral blood samples of 61 leukemia patients (24 AML, 20 ALL, and 17 CML) and compared to 18 healthy controls. Real-time PCR was used to quantitate gene expression. SPSS statistics 16.0 and Graph Pad Prism 8.4.2 software were applied for statistical analysis.

Results

While BECLIN1 expression was significantly lower in AML, ALL, and CML patients as compared to the control group (p < 0.05), LC3 showed significantly different expression only in the AML patients (P= 0.03). There was no significant correlation between the expression levels of BECLIN1 with LC3 (p> 0.05). Whilst the AML LC3high group had a significantly lower lymphocyte count (P= 0.023), the AML BECLIN1low group had a significantly higher MPV levels (P= 0.044). Furthermore, ALL LC3high group indicated a significantly lower HCT count (P= 0.017).

Conclusion

Significant changes in the expression levels of BECLINI and LC3 in hematologic malignancies may indicate a possible role for autophagy in their pathogenesis. However, further studies are warranted to confirm these findings.

Higher-order interactions of Bcr-Abl can broaden chronic myeloid leukemia (CML) drug repertoire

Bcr-Abl, a nonreceptor tyrosine kinase, is associated with leukemias, especially chronic myeloid leukemia (CML). Deletion of Abl's N-terminal region, to which myristoyl is linked, renders the Bcr-Abl fusion oncoprotein constitutively active. The substitution of Abl's N-terminal region by Bcr enables Bcr-Abl oligomerization. Oligomerization is critical: it promotes clustering on the membrane, which is essential for potent MAPK signaling and cell proliferation. Here we decipher the Bcr-Abl specific, step-by-step oligomerization process, identify a specific packing surface, determine exactly how the process is structured and identify its key elements. Bcr's coiled coil (CC) domain at the N-terminal controls Bcr-Abl oligomerization. Crystallography validated oligomerization via Bcr-Abl dimerization between two Bcr CC domains, with tetramerization via tight packing between two binary assemblies. However, the structural principles guiding Bcr CC domain oligomerization are unknown, hindering mechanistic understanding and drugs exploiting it. Using molecular dynamics (MD) simulations, we determine that the binary complex of the Bcr CC domain serves as a basic unit in the quaternary complex providing a specific surface for dimer-dimer packing and higher-order oligomerization. We discover that the small α1-helix is the key. In the binary assembly, the helix forms interchain aromatic dimeric packing, and in the quaternary assembly, it contributes to the specific dimer-dimer packing. Our mechanism is supported by the experimental literature. It offers the key elements controlling this process which can expand the drug discovery strategy, including by Bcr CC-derived peptides, and candidate residues for small covalent drugs, toward quenching oligomerization, supplementing competitive and allosteric tyrosine kinase inhibitors.

STAT5 inhibitor Pimozide as a probable therapeutic option in overcoming Ponatinib resistance in K562 leukemic cells

Signal Transducer and Activator of Transcription 5 (STAT5) is a transcription factor that plays a key role in neoplasia, triggered by the fusion oncogene BCR-ABL1; it is not only an essential protein for the pathogenesis of chronic myeloid leukemia (CML), but also its overexpression is associated with drug resistance developed toward various generations of Tyrosine Kinase Inhibitors (TKIs); these are still accepted as gold standard therapeutics for the treatment of CML. In this study, it was investigated whether suppression of STAT5 via a "STAT5 inhibitor" Pimozide resulted in any regain of chemosensitivity to third-generation TKI Ponatinib. Accordingly, the experimental work was designed on both parental CML cell line K562WT and its 1 nM Ponatinib-resistant counterpart, indicated as K562-Pon1. Based on the experimental results, Pimozide was more effective in resistant cells compared to wild-type cells for inducing apoptosis and block cell arrest. Combination therapy of Pimozide and Ponatinib demonstrated that STAT5 was a significant protein for regaining chemosensitivity to Ponatinib when its expression was suppressed both at mRNA and protein level. In conclusion, we consider that STAT5 inhibitor Pimozide can be a good alternative or combination therapy with TKIs for patients suffering from chemotherapeutic drug resistance. Communicated by Ramaswamy H. Sarma.

[Pharmacological and clinical profile of asciminib hydrochloride, a novel first-in-class tyrosine kinase inhibitor specifically targeting ABL myristoyl pocket]

On March 28th, 2022, asciminib hydrochloride (Scemblix® Tablets 20 ‍mg/40 ‍mg), the world's first tyrosine kinase inhibitor (TKI) specifically targeting the ABL myristoyl pocket (STAMP inhibitor), was approved for chronic myeloid leukemia (CML) resistant or intolerant to prior therapy. Asciminib specifically binds to the myristoyl pocket, an allosteric site of BCR::ABL1, and inhibits the ABL1 family molecules. In vitro and in vivo pharmacology studies demonstrated cell growth inhibition and antitumor effects of asciminib. The international phase I study for patients with chronic or accelerated phase CML investigated the maximum tolerated dose (MTD) and recommended dose for expansion (RDE) of asciminib monotherapy. However, the MTD was not reached, so and RDE was determined based on tolerability, safety, pharmacokinetics (PK) and preliminary efficacy data obtained by the time of the study. RDE was determined to be 40 ‍mg twice daily in chronic or accelerated phase CML without T315I mutation, and 200 ‍mg twice daily in chronic or accelerated phase CML with T315I mutation. The international phase III study for patients with chronic phase CML who were previously treated with ≥2 TKIs and resistant or intolerant to the recent treatment demonstrated the superiority of asciminib over bosutinib in achieving the primary endpoint of a major molecular response (MMR) at week 24. Regarding safety, the most common treatment-related adverse event in asciminib arm was thrombocytopenia, and others included neutropenia. Asciminib is expected to be a new treatment option for CML patients who have limited choices due to resistance or intolerance to previous therapies.

Perspective: Pivotal translational hematology and therapeutic insights in chronic myeloid hematopoietic stem cell malignancies

Despite much of the past 2 years being engulfed by the devastating consequences of the SAR-CoV-2 pandemic, significant progress, even breathtaking, occurred in the field of chronic myeloid malignancies. Some of this was show-cased at the 15th Post-American Society of Hematology (ASH) and the 25th John Goldman workshops on myeloproliferative neoplasms (MPN) held on 9th-10th December 2020 and 7th-10th October 2021, respectively. The inaugural Post-ASH MPN workshop was set out in 2006 by John Goldman (deceased) and Tariq Mughal to answer emerging translational hematology and therapeutics of patients with these malignancies. Rather than present a resume of the discussions, this perspective focuses on some of the pivotal translational hematology and therapeutic insights in these diseases.

A Ten-Year Experience of Treating Chronic Myeloid Leukemia in Rural Rwanda: Outcomes and Insights for a Changing Landscape

PURPOSE

In describing our ten-year experience with treating chronic myeloid leukemia (CML) as part of the Glivec Patient Assistance Program (GIPAP) in rural Rwanda, we evaluate (1) patient characteristics and treatment outcomes, (2) resource-adapted management strategies, and (3) the impact of diagnostic capacity development.

METHODS

We retrospectively reviewed all patients with BCR-ABL-positive CML enrolled in this GIPAP program between 2009 and 2018. Clinical data were analyzed using descriptive statistics, Kaplan-Meier methods, proportional hazards regression, and the Kruskal-Wallis test.

RESULTS

One hundred twenty-four patients were included. The median age at diagnosis was 34 (range 8-81) years. On imatinib, 91% achieved complete hematologic response (CHR) after a median of 49 days. Seven (6%) and 12 (11%) patients had primary and secondary imatinib resistance, respectively. The 3-year overall survival was 80% (95% CI, 72 to 87) for the cohort, with superior survival in imatinib responders compared with those with primary and secondary resistance. The median time from imatinib initiation to CHR was 59 versus 38 days (P = .040) before and after in-country diagnostic testing, whereas the median time to diagnosis (P = .056) and imatinib initiation (P = .170) was not significantly different.

CONCLUSION

Coupling molecular diagnostics with affordable access to imatinib within a comprehensive cancer care delivery program is a successful long-term strategy to treat CML in resource-constrained settings. Our patients are younger and have higher rates of imatinib resistance compared with historic cohorts in high-income countries. High imatinib resistance rates highlight the need for access to molecular monitoring, resistance testing, and second-generation tyrosine kinase inhibitors, as well as systems to support drug adherence. Hematologic response is an accurate resource-adapted predictor of survival in this setting. Local diagnostic capacity development has allowed for continuous, timely CML care delivery in Rwanda.

JAK2 Alterations in Acute Lymphoblastic Leukemia: Molecular Insights for Superior Precision Medicine Strategies

Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer, arising from immature lymphocytes that show uncontrolled proliferation and arrested differentiation. Genomic alterations affecting Janus kinase 2 (JAK2) correlate with some of the poorest outcomes within the Philadelphia-like subtype of ALL. Given the success of kinase inhibitors in the treatment of chronic myeloid leukemia, the discovery of activating JAK2 point mutations and JAK2 fusion genes in ALL, was a breakthrough for potential targeted therapies. However, the molecular mechanisms by which these alterations activate JAK2 and promote downstream signaling is poorly understood. Furthermore, as clinical data regarding the limitations of approved JAK inhibitors in myeloproliferative disorders matures, there is a growing awareness of the need for alternative precision medicine approaches for specific JAK2 lesions. This review focuses on the molecular mechanisms behind ALL-associated JAK2 mutations and JAK2 fusion genes, known and potential causes of JAK-inhibitor resistance, and how JAK2 alterations could be targeted using alternative and novel rationally designed therapies to guide precision medicine approaches for these high-risk subtypes of ALL.

Brazilian chronic myeloid leukemia working group recommendations for discontinuation of tyrosine kinase inhibitors in chronic myeloid leukemia in clinical practice

Introduction

Treatment-free remission (TFR) is a new goal of chronic myeloid leukemia (CML) therapy. TFR is feasible when the patient has achieved a deep and stable molecular response and met the criteria required to ensure its success. Treatment discontinuation should not be proposed to the CML patient if minimum conditions are not met. In Brazil, for example, molecular tests (BCR::ABL1) are not broadly available, making it difficult to monitor the patients adequately.

Objective

In this sense, providing TFR recommendations for Brazilian physicians are therefore necessary. These recommendations include the main criteria checklist to start the TKIs treatment discontinuing process in patients diagnosed with CML and the population-eligible characteristics for treatment discontinuation.

Method

Age, risk score at diagnosis, TKI treatment duration, BCR::ABL1 transcripts type, depth of the molecular response for treatment discontinuation, treatment adherence, patient monitoring and withdrawal syndrome are essential factors to consider in TFR. After TKI discontinuation, BCR::ABL1 transcripts monitoring should be more frequent. When a major molecular response loss is observed during the monitoring of a patient in TFR, the TKI treatment should be resumed.

Conclusion

These recommendations should serve as a basis for medical professionals interested in proposing TKI discontinuation for CML patients in clinical practice. It is important to highlight that, despite the benefits of TFR for the patients and the health system, it should only be feasible following the minimum standards proposed in this recommendation.

The Impact of SKP2 Gene Expression in Chronic Myeloid Leukemia

Introduction: The prognosis of chronic myeloid leukemia (CML) patients has been dramatically improved with the introduction of imatinib (IM), the first tyrosine kinase inhibitor (TKI). TKI resistance is a serious problem in IM-based therapy. The human S-phase kinase-associated protein 2 (SKP2) gene may play an essential role in the genesis and progression of CML. Aim of the study: We try to explore the diagnostic/prognostic impact of SKP2 gene expression to predict treatment response in first-line IM-treated CML patients at an early response stage. Patients and methods: The gene expression and protein levels of SKP2 were determined using quantitative RT-PCR and ELISA in 100 newly diagnosed CML patients and 100 healthy subjects. Results: SKP2 gene expression and SKP2 protein levels were significantly upregulated in CML patients compared to the control group. The receiver operating characteristic (ROC) analysis for the SKP2 gene expression level, which that differentiated the CML patients from the healthy subjects, yielded a sensitivity of 86.0% and a specificity of 82.0%, with an area under the curve (AUC) of 0.958 (p < 0.001). The ROC analysis for the SKP2 gene expression level, which differentiated optimally from the warning/failure responses, yielded a sensitivity of 70.59% and a specificity of 71.21%, with an AUC of 0.815 (p < 0.001). Conclusion: The SKP2 gene could be an additional diagnostic and an independent prognostic marker for predicting treatment responses in first-line IM-treated CML patients at an early time point (3 months).

The Downregulation of Both Giant HERCs, HERC1 and HERC2, Is an Unambiguous Feature of Chronic Myeloid Leukemia, and HERC1 Levels Are Associated with Leukemic Cell Differentiation

Large HERC E3 ubiquitin ligase family members, HERC1 and HERC2, are staggeringly complex proteins that can intervene in a wide range of biological processes, such as cell proliferation, DNA repair, neurodevelopment, and inflammation. Therefore, mutations or dysregulation of large HERCs is associated with neurological disorders, DNA repair defects, and cancer. Though their role in solid tumors started to be investigated some years ago, our knowledge about HERCs in non-solid neoplasm is greatly lagging behind. Chronic Myeloid Leukemia (CML) is a model onco-hematological disorder because of its unique and unambiguous relation between genotype and phenotype due to a single genetic alteration. In the present study, we ascertained that the presence of the BCR-ABL fusion gene was inversely associated with the expression of the HERC1 and HERC2 genes. Upon the achievement of remission, both HERC1 and HERC2 mRNAs raised again to levels comparable to those of the healthy donors. Additionally, our survey unveiled that their gene expression is sensitive to different Tyrosine Kinases Inhibitors (TKIs) in a time-dependent fashion. Interestingly, for the first time, we also observed a differential HERC1 expression when the leukemic cell lines were induced to differentiate towards different lineages revealing that HERC1 protein expression is associated with the differentiation process in a lineage-specific manner. Taken together, our findings suggest that HERC1 might act as a novel potential player in blood cell differentiation. Overall, we believe that our results are beneficial to initiate exploring the role/s of large HERCs in non-solid neoplasms.

A narrative review on adverse effects of dasatinib with a focus on pharmacotherapy of dasatinib-induced pulmonary toxicities

Chronic myeloid leukemia (CML), a myeloproliferative disorder caused by the over activity of BCR-ABL1 (breakpoint cluster region-Abelson), has been successfully treated by Tyrosine kinase inhibitors (TKIs). While imatinib is known as the first-line treatment of CML, in some cases other TKIs including dasatinib, nilotinib, bosutinib, and ponatinib may be preferred. Dasatinib, a second-generation TKI, inhibits multiple family kinases including BCR-ABL, SRC family kinases, receptor kinases, and TEC family kinases. It is effective against most imatinib-resistant cases except T315I mutation. Despite the superiority of dasatinib in its hematologic and cytogenetic responses in CML compared to imatinib, its potentially harmful pulmonary complications including pleural effusion (PE) and pulmonary arterial hypertension (PAH) may limit its use. Appropriate management of these serious adverse reactions is critical in both improving the quality of life and the outcome of the patient. In this narrative review, we will scrutinize the pulmonary complications of dasatinib and focus on the management of these toxicities.

Fluorescent and colorimetric RT-LAMP as a rapid and specific qualitative method for chronic myeloid leukemia diagnosis

The detection of BCR-ABL1 mRNA transcripts is essential to molecular chronic myeloid leukemia (CML) diagnosis. In most cases, the RT-qPCR technique is performed as the gold standard diagnosis tool for clinical cases. However, this method requires expensive reagents and equipment, such as a real-time thermal cycler, probes and master mix. Consequently, the development and validation of simple and low-cost methods are essential for a rapid CML diagnosis in less specialized and equipped centers. In this study, we develop and demonstrate an accessible, rapid, and low-cost method using RT-LAMP for BCR-ABL1 detection in both cell lines and CML clinical samples, using fluorescent and colorimetric assays. Both methods demonstrated diagnostic specificity of 100% and while diagnostic sensitivity reaches more than 90% in samples with RT-qPCR cycle threshold above 31. The obtained data indicates that the proposed method here described is a cheaper, robust and specific approach for CML diagnosis with outstanding performance, especially for CML diagnostic procedure where present high BCR-ABL1 expression.

Expanding the scope of native chemical ligation - templated small molecule drug synthesis via benzanilide formation

We describe a reaction system that enables the synthesis of Bcr–Abl tyrosine kinase inhibitors (TKI) via benzanilide formation in water. The reaction is based on native chemical ligation (NCL). In contrast to previous applications, we used the NCL chemistry to establish aromatic rather than aliphatic amide bonds in coupling reactions between benzoyl and o-mercaptoaniline fragments. The method was applied for the synthesis of thiolated ponatinib and GZD824 derivatives. Acid treatment provided benzothiazole structures, which opens opportunities for diversification. Thiolation affected the affinity for Abl1 kinase only moderately. Of note, a ponatinib-derived benzothiazole also showed nanomolar affinity. NCL-enabled benzanilide formation may prove useful for fragment-based drug discovery. To show that benzanilide synthesis can be put under the control of a template, we connected the benzoyl and o-mercaptoaniline fragments to DNA and peptide nucleic acid (PNA) oligomers. Complementary RNA templates enabled adjacent binding of reactive conjugates triggering a rapid benzoyl transfer from a thioester-linked DNA conjugate to an o-mercaptoaniline-DNA or -PNA conjugate. We evaluated the influence of linker length and unpaired spacer nucleotides within the RNA template on the product yield. The data suggest that nucleic acid-templated benzanilide formation could find application in the establishment of DNA-encoded combinatorial libraries (DEL).

The templated native chemical ligation between benzoyl thioesters and o-mercaptoaniline fragments proceeds in water and provides benzanilides that have nanomolar affinity for Abl1 kinase.

Which Tyrosine Kinase Inhibitors Should Be Selected as the First-Line Treatment for Chronic Myelogenous Leukemia in Chronic Phase?

Simple Summary

This review discusses the optimal selection of BCR-ABL1 tyrosine kinase inhibitors (TKIs) as the first-line treatment for newly diagnosed chronic myelogenous leukemia in chronic phase (CML-CP). With the advent of TKIs, the treatment goals for CML-CP patients have changed from “simply survival” to “survival with adequate quality of life”, hence the number of CML-CP patients aiming to achieve treatment-free remission has increased, irrespective of age or comorbidities. Therefore, optimal selection of TKIs for maximizing the number of patients to achieve treatment-free remission is an important factor for consideration in future studies. To this end, we must understand the advantages and disadvantages of each TKI in terms of treatment response, disease risk at diagnosis, comorbidities, and medical expenses, and use of effective 2GTKIs based on patient background. This review provides insights into “shared decision-making” in individual cases, including the elderly population.

Abstract

With the use of tyrosine kinase inhibitors (TKIs), chronic myelogenous leukemia in chronic phase (CML-CP) has been transformed into a non-fatal chronic disease. Hence, “treatment-free remission (TFR)” has become a possible treatment goal of patients with CML-CP. Currently, four types of TKIs (imatinib, nilotinib, dasatinib, and bosutinib) are used as the first-line treatment for newly diagnosed CML-CP. However, the second-generation TKI (2GTKI), the treatment response of which is faster and deeper than that of imatinib, is not always recommended as the first-line treatment for CML-CP. Factors involved in TKI selection in the first-line treatment of CML-CP include not only patients’ medical background, but also patients’ choice regarding the desired treatment goal (survival or TFR?). Therefore, it is important that clinicians select an appropriate TKI to successfully achieve the desired treatment goal for each patient, while minimizing the development of adverse events. This review compares the pros and cons of using imatinib and 2GTKI for TKI selection as the first-line treatment for CML-CP, mainly considering treatment outcomes, medical history (i.e., desire for pregnancy, aging factor, and comorbidity), and cost. The optimal use of 2GTKIs is also discussed.

Long non-coding RNAs as the critical regulators of doxorubicin resistance in tumor cells

Resistance against conventional chemotherapeutic agents is one of the main reasons for tumor relapse and poor clinical outcomes in cancer patients. Various mechanisms are associated with drug resistance, including drug efflux, cell cycle, DNA repair and apoptosis. Doxorubicin (DOX) is a widely used first-line anti-cancer drug that functions as a DNA topoisomerase II inhibitor. However, DOX resistance has emerged as a large hurdle in efficient tumor therapy. Furthermore, despite its wide clinical application, DOX is a double-edged sword: it can damage normal tissues and affect the quality of patients’ lives during and after treatment. It is essential to clarify the molecular basis of DOX resistance to support the development of novel therapeutic modalities with fewer and/or lower-impact side effects in cancer patients. Long non-coding RNAs (lncRNAs) have critical roles in the drug resistance of various tumors. In this review, we summarize the state of knowledge on all the lncRNAs associated with DOX resistance. The majority are involved in promoting DOX resistance. This review paves the way to introducing an lncRNA panel marker for the prediction of the DOX response and clinical outcomes for cancer patients.

Crizotinib acts as ABL1 inhibitor combining ATP-binding with allosteric inhibition and is active against native BCR-ABL1 and its resistance and compound mutants BCR-ABL1T315I and BCR-ABL1T315I-E255K

Resistance remains the major clinical challenge for the therapy of Philadelphia chromosome-positive (Ph+) leukemia. With the exception of ponatinib, all approved tyrosine kinase inhibitors (TKIs) are unable to inhibit the common "gatekeeper" mutation T315I. Here we investigated the therapeutic potential of crizotinib, a TKI approved for targeting ALK and ROS1 in non-small cell lung cancer patients, which inhibited also the ABL1 kinase in cell-free systems, for the treatment of advanced and therapy-resistant Ph+ leukemia. By inhibiting the BCR-ABL1 kinase, crizotinib efficiently suppressed growth of Ph+ cells without affecting growth of Ph- cells. It was also active in Ph+ patient-derived long-term cultures (PD-LTCs) independently of the responsiveness/resistance to other TKIs. The efficacy of crizotinib was confirmed in vivo in syngeneic mouse models of BCR-ABL1- or BCR-ABL1^T315I-driven chronic myeloid leukemia-like disease and in BCR-ABL1-driven acute lymphoblastic leukemia (ALL). Although crizotinib binds to the ATP-binding site, it also allosterically affected the myristol binding pocket, the binding site of GNF2 and asciminib (former ABL001). Therefore, crizotinib has a seemingly unique double mechanism of action, on the ATP-binding site and on the myristoylation binding pocket. These findings strongly suggest the clinical evaluation of crizotinib for the treatment of advanced and therapy-resistant Ph+ leukemia.

Biogenesis, cellular effects, and biomarker value of circHIPK3

Competing endogenous RNAs (ceRNAs) can indirectly regulate gene expression by competitively binding to microRNA(miRNA) through miRNA response elements (MREs) to affect miRNA-induced gene regulation, which is of great biological significance. Among them, circular RNA (circRNA) has become a hotspot due to its highest binding capacity. A specific circRNA discussed in this review, circHIPK3, has been studied for its biological characteristics, function, cellular effects and its relationship with tumors and various diseases. Here, we review the recent researches about circHIPK3 in detail and aim to elucidate accurate conclusions from them. These circHIPK3-miRNAs-mRNA pathways will further advance the application of circHIPK3 in diseases development, early diagnosis and gene targeting therapy.

Recurrent Fusion of the GRB2 Associated Binding Protein 1 (GAB1) Gene With ABL Proto-oncogene 1 (ABL1) in Benign Pediatric Soft Tissue Tumors

BACKGROUND/AIM

Fusions of the ABL proto-oncogene 1 gene (ABL1 in 9q34) are common in leukemias but rare in solid tumors. The most notable is the t(9;22)(q34;q11)/BCR-ABL1 coding for a chimeric tyrosine kinase. We herein report an ABL1-fusion in a pediatric tumor.

MATERIALS AND METHODS

G-banding, fluorescence in situ hybridization, reverse transcription polymerase chain reaction and Sanger sequencing were performed on a soft tissue perineurioma found in the left musculus erector spinae of a child.

RESULTS

A der(4)t(4;9)(q31;q34) and a fusion of the GRB2 associated binding protein 1 (GAB1 in 4q31) gene with ABL1 were found. A literature search revealed 3 more cases with similar genetic and clinicopathological characteristics: a soft tissue perineurioma with t(2;9;4)(p23;q34;q31) and ABL1 rearrangement, a soft tissue angiofibroma with a GAB1-ABL1 chimeric gene, and a solitary fibrous tumor carrying a der(4)t(4;9)(q31.1;q34).

CONCLUSION

GAB1-ABL1 is a recurrent fusion gene in benign pediatric tumors.

Association of DNA repair gene XPC Ala499Val (rs2228000 C>T) and Lys939Gln (rs2228001 A>C) polymorphisms with the risk of chronic myeloid leukemia: A case-control study in a South Indian population

BACKGROUND

Xeroderma pigmentosum complementation group C (XPC), a DNA repair protein, plays an important role in the maintenance of genomic integrity and is essential for the nucleotide excision repair pathway. Polymorphisms in the XPC gene may alter DNA repair leading to genetic instability and oncogenesis. The present study aimed to assess the relationship between the XPC Ala499Val (rs2228000 C>T) and Lys939Gln (rs2228001 A>C) non-synonymous polymorphisms and susceptibility to chronic myeloid leukemia (CML) pathogenesis, disease progression and the response to targeted therapeutic regimen, imatinib mesylate.

METHODS

This case-control study included 212 cases and 212 controls, and the genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism assays.

RESULTS

Our results showed significant association of variant CT (odds ratio = 1.92, 95% confidence interval = 1.21-3.06, p = 0.003) and TT (odds ratio = 2.84, 95% confidence interval = 1.22-6.71, p = 0.007) genotypes in patients with the XPC Ala499Val polymorphism and CML risk. In addition, these genotypes were associated with CML progression to advanced phases (p = 0.006), splenomegaly (p = 0.017) and abnormal lactate dehydrogenase levels (p = 0.03). XPC Lys939Gln was found to correlate with a poor response to therapy, showing borderline significant association with minor cytogenetic response (p = 0.08) and a poor molecular response (p = 0.06). Significant association of the Ala499Val and Lys939Gln polymorphisms with prognosis was observed (Hasford high risk, p = 0.031 and p = 0.019, respectively). Haplotype analysis showed a strong correlation of variant TC haplotype with poor therapy responses (minor cytogenetic response, p = 0.019; poor molecular response, p < 0.0001).

CONCLUSIONS

In conclusion, our results suggest that XPC Ala499Val is a high-penetrance CML susceptibility polymorphism. Both polymorphisms studied are considered as genetic markers with respect to assessing disease progression, therapy response and prognosis in CML patients.

Blood cancer health disparities in the United States Hispanic population

Cancer is a challenging, multifaceted disease that involves a combination of biological and nonbiological factors. Aside from COVID-19, cancer is the second leading cause of death in the United States and the first among Hispanic Americans. The Hispanic population is the largest minority group in the United States, which is rapidly growing in size. Unfortunately, U.S. Hispanics and other minority groups experience many different health disparities, resulting in poor survival outcomes and a reduced quality of life. Factors such as genomic mutations, lower socioeconomic status, lack of education, reduced access to health care, comorbidities, and environmental factors all contribute to these health-care inequalities. In the context of blood cancer health disparities, Hispanic patients are often diagnosed at a younger age and have worse outcomes compared with non-Hispanic individuals. In this commentary, we highlight the existing knowledge about cancer health disparities in the Hispanic population, with a focus on chronic and acute leukemia. In our experience at the U.S./Mexican border, analysis of several different blood cancers demonstrated that younger Hispanic patients with acute lymphoid or myeloid leukemia have higher incidence rates and worse prognoses. A combined approach, involving improved health-care access and better knowledge of the underlying factors, will allow for more timely diagnoses and the development of intervention strategies aimed at reducing or eliminating the disparities.

Chronic myeloid leukemia-from the Philadelphia chromosome to specific target drugs: A literature review

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm and was the first neoplastic disease associated with a well-defined genotypic anomaly - the presence of the Philadelphia chromosome. The advances in cytogenetic and molecular assays are of great importance to the diagnosis, prognosis, treatment, and monitoring of CML. The discovery of the breakpoint cluster region (BCR)-Abelson murine leukemia (ABL) 1 fusion oncogene has revolutionized the treatment of CML patients by allowing the development of targeted drugs that inhibit the tyrosine kinase activity of the BCR-ABL oncoprotein. Tyrosine kinase inhibitors (known as TKIs) are the standard therapy for CML and greatly increase the survival rates, despite adverse effects and the odds of residual disease after discontinuation of treatment. As therapeutic alternatives, the subsequent TKIs lead to faster and deeper molecular remissions; however, with the emergence of resistance to these drugs, immunotherapy appears as an alternative, which may have a cure potential in these patients. Against this background, this article aims at providing an overview on CML clinical management and a summary on the main targeted drugs available in that context.

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.

Inhibition of cystathionine β-synthase promotes apoptosis and reduces cell proliferation in chronic myeloid leukemia

Increased endogenous hydrogen sulfide (H₂S) level by cystathionine β-synthase (CBS) has been shown to closely relate tumorigenesis. H₂S promotes angiogenesis, stimulates bioenergy metabolism and inhibits selective phosphatases. However, the role of CBS and H₂S in chronic myeloid leukemia (CML) remains elusive. In this study, we found that CBS and H₂S levels were increased in the bone marrow mononuclear cells of pediatric CML patients, as well as in the CML-derived K562 cells and CBS expression levels were correlated with different disease phases. Inhibition of CBS reduced the proliferation of the CML primary bone marrow mononuclear cells and induced growth inhibition, apoptosis, cell cycle arrest, and migration suppression in K562 cells and tumor xenografts. The knockdown of CBS expression by shRNA and inhibiting CBS activity by AOAA decreased the endogenous H₂S levels, promoted mitochondrial-related apoptosis and inhibited the NF-κB-mediated gene expression. Our study suggests that inhibition of CBS induces cell apoptosis, as well as limits cell proliferation and migration, a potential target for the treatment of chronic myeloid leukemia.

Predictive indicators of successful tyrosine kinase inhibitor discontinuation in patients with chronic myeloid leukemia

Clinical trials have demonstrated that some patients with chronic myeloid leukemia (CML) treated for several years with tyrosine kinase inhibitors (TKIs) who have maintained a molecular response can successfully discontinue treatment without relapsing. Treatment free remission (TFR) can be reached by approximately 50% of patients who discontinue. Despite having similar levels of deep molecular response and an identical duration of treatment, the factors that influence the successful discontinuation of CML patients remain to be determined. In this review we will explore the factors identified to date that can help predict whether a patient will successfully achieve TFR. We will also discuss the need for the identification of predictive biomarkers associated with a high probability of achieving TFR for the future personalized identification of patients who are suitable for the discontinuation of TKI treatment.

Illuminating novel biological aspects and potential new therapeutic approaches for chronic myeloproliferative malignancies

This review reflects the presentations and discussion at the 14th post-American Society of Hematology (ASH) International Workshop on Chronic Myeloproliferative Malignancies, which took place on the December 10 and 11, 2019, immediately after the 61st ASH Annual Meeting in Orlando, Florida. Rather than present a resume of the proceedings, we address some of the topical translational science research and clinically relevant topics in detail. We consider how recent studies using single-cell genomics and other molecular methods reveal novel aspects of hematopoiesis which in turn raise the possibility of new therapeutic approaches for patients with myeloproliferative neoplasms (MPNs). We discuss how alternative therapies could benefit patients with chronic myeloid leukemia who develop BCR-ABL1 mutant subclones following ABL1-tyrosine kinase inhibitor therapy. In MPNs, we focus on efforts beyond JAK-STAT and the merits of integrating activin receptor ligand traps, interferon-α, and allografting in the current treatment algorithm for patients with myelofibrosis.

Trends in disease burden of chronic myeloid leukemia at the global, regional, and national levels: a population-based epidemiologic study

BACKGROUND

Outcomes of chronic myeloid leukemia (CML) has been improved dramatically in the past two decades, but survival levels of CML patients varied in regions. Comprehensive epidemiological research is necessary to evaluate the global burden of CML.

METHODS

All data used in our study came from the Global Burden of Disease (GBD) study 2017. Incidence cases, death cases, disability-adjusted life-years (DALYs), and its corresponding age-standardized rate between 1990 to 2017 were used to describe the distribution of CML burden, according to age, sex, social-demographic index (SDI), and countries. Data about attributable risk factors contributing to CML deaths and DALYs were also extracted and analyzed.

RESULTS

Globally, the disease burden of CML gradually decreased from 1990 to 2017. Higher SDI countries achieved a remarkable effect on diminishing the CML burden. Conversely, due to population growth, the incidence cases, death cases, and DALYs of CML in lower SDI quintiles showed an upward trend. India had the most incidence cases and death cases of CML in the world. Additionally, smoking was the most significant attributable risk factor contributing to CML deaths and DALYs, followed by high body mass index.

CONCLUSION

The disease burden of CML decreased globally, especially in higher SDI countries in the past 28 years. The increasing incidence cases and death cases were mainly observed in lower SDI countries. Additionally, strategies to control modifiable risk factors such as smoking and high body mass index might be useful in diminishing mortality and DALYs.

The effect of imatinib administered in the prenatal period on testis development in rats

BACKGROUND

The purpose of this study was to examine the effects of exposure to imatinib in the prenatal period on testis development in rats.

METHODS

Although all the study groups received intraperitoneal imatinib on prenatal days 1-8, no pregnancy occurred in the Imatinib-80 group. Immunohistochemical analysis, TUNEL, c-kit and PDGF staining revealed no difference between the groups in terms of positivity scoring.

RESULTS

A significant decrease was detected in total sperm counts in the Imatinib-20 group compared to the control group, but the sperm count was higher in the Imatinib-60 group than in the Imatinib-20 group. At biochemical measurements, the drug increased oxidative stress in the testis and serum in the Imatinib-20 group, but caused a decrease in tissue in the Imatinib-60 group. Thiol measurements revealed a decrease in the testis and serum in the Imatinib-60 group, while an increase in serum measurements was observed in the Imatinib-40 group. Analysis revealed no difference between the groups in terms of protamine and histone gene expression levels in testis tissue exposed to imatinib.

CONCLUSION

Our findings show that prenatal exposure to imatinib can lead to histopathological and biochemical changes in testis tissue, but that no adverse effect occurs in nuclear maturation of germ cells during spermiogenesis.

Shikonin overcomes drug resistance and induces necroptosis by regulating the miR-92a-1-5p/MLKL axis in chronic myeloid leukemia

Development of resistance to tyrosine kinase inhibitors (TKIs) targeting the BCR/ABL fusion protein represents a major challenge in the treatment of chronic myeloid leukemia (CML). Since apoptosis resistance is the fundamental mechanism impeding TKIs' therapeutic effects, alternative approaches that induce nonapoptotic cell death are being pursued to treat TKI-resistant CML. Induction of necroptosis, a distinct, caspase-independent form of programmed cell death, may be a valuable strategy in this respect. The present study shows that shikonin, an herbal compound used in traditional Chinese medicine, overcomes TKI resistance in BCR/ABL-positive CML cells by inducing necroptosis via activation of RIPK1/RIPK3/MLKL signaling. This effect occurs both in vitro and in vivo and involves downregulation of miR-92a-1-5p, a poor-prognosis marker frequently overexpressed in leukemia patients. Based on gene expression experiments, we conclude that miR-92a-1-5p promotes CML progression by inhibiting MLKL expression. Accordingly, we show that antagomiR-mediated in vivo inhibition of miR-92a-1-5p reduces the growth of CML tumors in mice through necroptosis induction. Our research suggests that therapies that relieve MLKL suppression by targeting miR-92a-1-5p may represent a useful strategy to treat TKI-refractory CML.

Cytotoxic cell populations developed during treatment with tyrosine kinase inhibitors protect autologous CD4+ T cells from HIV-1 infection

Tyrosine kinase inhibitors (TKIs) are successfully used in clinic to treat chronic myeloid leukemia (CML). Our group previously described that CD4+ T cells from patients with CML on treatment with TKIs such as dasatinib were resistant to HIV-1 infection ex vivo. The main mechanism for this antiviral activity was primarily based on the inhibition of SAMHD1 phosphorylation, which preserves the activity against HIV-1 of this innate immune factor. Approximately 50% CML patients who achieved a deep molecular response (DMR) may safely withdraw TKI treatment without molecular recurrence. Therefore, it has been speculated that TKIs may induce a potent antileukemic response that is maintained in most patients even one year after treatment interruption (TI). Subsequent to in vitro T-cell activation, we observed that SAMHD1 was phosphorylated in CD4+ T cells from CML patients who withdrew TKI treatment more than one year earlier, which indicated that these cells were now susceptible to HIV-1 infection. Importantly, these patients were seronegative for HIV-1 and seropositive for cytomegalovirus (CMV), but without CMV viremia. Although activated CD4+ T cells from CML patients on TI were apparently permissive to HIV-1 infection ex vivo, the frequency of proviral integration was reduced more than 12-fold on average when these cells were infected ex vivo in comparison with cells isolated from untreated, healthy donors. This reduced susceptibility to infection could be related to an enhanced NK-dependent cytotoxic activity, which was increased 8-fold on average when CD4+ T cells were infected ex vivo with HIV-1 in the presence of autologous NK cells. Enhanced cytotoxic activity was also observed in CD8 + T cells from these patients, which showed 8-fold increased expression of TCRγδ and more than 18-fold increased production of IFNγ upon activation with CMV peptides. In conclusion, treatment with TKIs induced a potent antileukemic response that may also have antiviral effects against HIV-1 and CMV, suggesting that transient use of TKIs in HIV-infected patients could develop a sustained antiviral response that would potentially interfere with HIV-1 reservoir dynamics.

ATR-CHK1 pathway as a therapeutic target for acute and chronic leukemias

Progress in cancer therapy changed the outcome of many patients and moved therapy from chemotherapy agents to targeted drugs. Targeted drugs already changed the clinical practice in treatment of leukemias, such as imatinib (BCR/ABL inhibitor) in chronic myeloid leukemia (CML) and acute lymphoblastic leukemia (ALL), ibrutinib (Bruton's tyrosine kinase inhibitor) in chronic lymphocytic leukemia (CLL), venetoclax (BCL2 inhibitor) in CLL and acute myeloid leukemia (AML) or midostaurin (FLT3 inhibitor) in AML. In this review, we focused on DNA damage response (DDR) inhibition, specifically on inhibition of ATR-CHK1 pathway. Cancer cells harbor often defects in different DDR pathways, which render them vulnerable to DDR inhibition. Some DDR inhibitors showed interesting single-agent activity even in the absence of cytotoxic drug especially in cancers with underlying defects in DDR or DNA replication. Almost no mutations were found in ATR and CHEK1 genes in leukemia patients. Together with the fact that ATR-CHK1 pathway is essential for cell development and survival of leukemia cells, it represents a promising therapeutic target for treatment of leukemia. ATR-CHK1 inhibition showed excellent results in preclinical testing in acute and chronic leukemias. However, results in clinical trials are so far insufficient. Therefore, the ongoing and future clinical trials will decide on the success of ATR/CHK1 inhibitors in clinical practice of leukemia treatment.

Vaccination With Live Attenuated Vaccines in Four Children With Chronic Myeloid Leukemia While on Imatinib Treatment

Chronic myeloid leukemia (CML) in childhood and adolescence is a rare malignancy that can successfully be treated with the tyrosine kinase inhibitor (TKI) imatinib. According to the current experience, treatment is necessary for years and, in the majority of cases, a lifelong approach is required to control the malignant disease. To what extent imatinib causes immunosuppression in different age cohorts is a controversial discussion. According to general medical recommendations, live vaccines are contraindicated in individuals treated with imatinib. However, a recent increase in the number of globally reported cases of measles has been observed and continues to rise. Due to the high contagiousness of the virus, near-perfect vaccination coverage (herd immunity of 93 to 95%) is required to effectively protect against measles resurgence-a scenario that is not realistic in many countries. When four teenagers with CML (median age 13 years, range 12-15) who were enrolled into pediatric trial CML-paed II while on imatinib treatment (median treatment duration 36 months, range 11-84) were identified without protective measles and/or varicella titers, we carefully balanced the risks of a live vaccination under immunosuppressive TKI medication against the benefit of being protected. The patients underwent live vaccination with the live attenuated vaccines M-M-RVAX Pro® and Varivax® simultaneously (Patient #1), Priorix® and Varilix® consecutively (Patient #2), and Priorix® (Patients #3 and #4). While the first three patients were vaccinated while receiving TKI therapy, treatment with imatinib was interrupted in patient #4 for 1 week prior and 2 weeks after vaccination. Patients #1 and #3 reacted with stable long-term seroconversion. In Patient #2, serum titer conversion against measles and varicella could not be demonstrated and thus revaccination with Priorix® and Varilix® was performed 3 years later. However, protective titers did not develop or were lost again. Patient #4 also lost protective titers against measles when assessed 10 months after vaccination, but revaccination resulted in stable seroprotective titers over 12 months after the last vaccination during ongoing imatinib treatment. We conclude that in all patients, the safety of live vaccines could be documented, as no acute or late adverse events were observed. However, in line with observations that memory B-cells are lost under exposure to imatinib, revaccination may become necessary (two out of four patients in this small series lost their seroprotection). Considering that the number of cases is very small, we also suggest some criteria for decision-making regarding live vaccinations of CML patients treated with imatinib.