Understanding and Monitoring Chronic Myeloid Leukemia Blast Crisis: How to Better Manage Patients

Clinical Validation of the Somatic FANCD2 Mutation (c.2022-5C>T) as a Novel Molecular Biomarker for Early Disease Progression in Chronic Myeloid Leukemia: A Case-Control Study

Background: Chronic myeloid leukemia (CML) results from chromosomal translocation t(9;22) leading to the formation of the BCR-ABL fusion oncogene. CML has three stages: the chronic phase (CP), the accelerated phase (AP), and the blast crisis (BC). Tyrosine kinase inhibitors (TKIs) have revolutionized the treatment of CML. TKIs work well in CP-CML, and these patients have a survival rate similar to the normal population, but TKIs are less effective in advanced-phase CML. Even with current advances in treatment, BC-CML patients have an average overall survival of less than a year. Early recognition of CML patients at risk of disease progression can help in timely interventions with appropriate TKIs or other therapeutic modalities. Although some markers of disease progression like BCR-ABL kinase domain, ASXL1, and GATA2 mutations are available, no universal and exclusively specific molecular biomarkers exist to early diagnose CML patients at risk of CML progression for timely therapeutic interventions to delay or minimize blast crisis transformation in CML. A recent study found that all BC-CML patients harbored the FANCD2 (c.2022-5C>T) mutation. Therefore, the current study was designed to detect this FANCD2 mutant in AP-CML (early progression phase) and to clinically validate its potential as a novel molecular biomarker of early CML progression from CP to AP. Methods: Our study comprised 123 CP-CML (control group) and 60 AP-CML patients (experimental group) from 2 oncology centers, from January 2020 to July 2023. Mean hemoglobin level, WBC count, platelet count, treatment type, hepatomegaly, splenomegaly, and survival status of AP-CML patients were significantly different from those of CP-CML patients. However, as these clinical parameters cannot help in the early detection of patients at risk of CML progression, there was a need for a clinically validated biomarker of AP-CML. DNA was extracted from the patients' blood samples, and the FANCD2 gene was sequenced using an Illumina NextSeq500 next-generation sequencer (NGS). Results: The NGS analysis revealed a unique splice-site mutation in the FANCD2 gene (c.2022-5C>T). This mutation was detected in the majority (98.3%) of AP-CML patients but in none of the CP-CML patients or healthy control sequences from genomic databases. The mutation was confirmed by Sanger sequencing. FANCD2 is a member of the Fanconi anemia pathway genes involved in DNA repair and genomic stability, and aberrations of this gene are associated with many cancers. Conclusions: In conclusion, our study shows that the somatic FANCD2 (c.2022-5C>T) mutation is a new molecular biomarker for early CML progression. We recommend further clinical validation of this biomarker in prospective clinical trials.

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.

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.

A Nucleus-Targeting WT1 Antagonistic Peptide Encapsulated in Polymeric Nanomicelles Combats Refractory Chronic Myeloid Leukemia

Chronic myeloid leukemia (CML) is recognized as a classic clonal myeloproliferative disorder. Given the limited treatment options for CML patients in the accelerated phase (AP) and blast phase (BP), there is an evident need to develop new therapeutic strategies. This has the potential to improve outcomes for individuals in the advanced stages of CML. A promising therapeutic target is Wilms' tumor 1 (WT1), which is highly expressed in BP-CML cells and plays a crucial role in CML progression. In this study, a chemically synthesized nucleus-targeting WT1 antagonistic peptide termed WIP2W was identified. The therapeutic implications of both the peptide and its micellar formulation, M-WIP2W, were evaluated in WT1+ BP-CML cell lines and in mice. The findings indicate that WIP2W can bind specifically to the WT1 protein, inducing cell cycle arrest and notable cytotoxicity in WT1+ BP-CML cells. Moreover, subcutaneous injections of M-WIP2W were observed to significantly enhance intra-tumoral accumulation and to effectively inhibit tumor growth. Thus, WIP2W stands out as a potent and selective WT1 inhibitor, and the M-WIP2W nanoformulation appears promising for the therapeutic treatment of refractory CML as well as other WT1-overexpressing malignant cancers.

Telomere biology: from disorders to hematological diseases

Variations in the length of telomeres and pathogenic variants involved in telomere length maintenance have been correlated with several human diseases. Recent breakthroughs in telomere biology knowledge have contributed to the identification of illnesses named "telomeropathies" and revealed an association between telomere length and disease outcome. This review emphasizes the biology and physiology aspects of telomeres and describes prototype diseases in which telomeres are implicated in their pathophysiology. We also provide information on the role of telomeres in hematological diseases ranging from bone marrow failure syndromes to acute and chronic leukemias.

CLINICAL VALIDATION OF ANKRD36 MUTATIONS AS A NOVEL BIOMARKER FOR MONITORING EARLY PROGRESSION AND TIMELY CLINICAL INTERVENTIONS IN BLAST CRISIS CML

Background

Chronic Myeloid Leukemia (CML) is initiated in the bone marrow due to the chromosomal translocation t(9;22), resulting in the fusion oncogene BCR-ABL. Tyrosine kinase inhibitors (TKIs) targeting BCR-ABL have transformed fatal CML into an almost curable disease. However, TKIs lose efficacy during disease progression, and the mechanism of CML progression remains to be fully understood. Additionally, common molecular biomarkers for CML progression are lacking. Our studies previously detected ANKRD36 (c.1183_1184 delGC and c.1187_1188 dupTT) associated exclusively with advanced phase CML. However, clinical validation of this finding was pending. Therefore, this study aimed to clinically validate mutated ANKRD36 as a novel biomarker of CML progression.

Materials and Methods

The study enrolled 124 patients in all phases of CML, recruited from Mayo Hospital and Hameed Latif Hospital in Lahore, Punjab, between January 2019 and August 2021. All response criteria were adopted from the European LeukemiaNet guideline 2020. Informed consent was obtained from all study subjects. The study was approved by scientific and ethical review committees of all participating centers.Sanger sequencing was employed to detect ANKRD36 mutations in CML patients in accelerated phase (AP) (n=11) and blast crisis (BC) (n=10), with chronic-phase CML (CP-CML) patients as controls (n=103). Samples were processed using Big Dye Terminator Cycle Sequencing Ready Reaction kits and sequenced using ABI Prism 3730 Genetic Analyzer, and sequencing using forward and reverse primers for ANKRD36.

Results

During our study, 17% of CML patients progressed to advanced phases AP-CML n=11 (8.9%) and BC-CML n=10 (8.1%). The chronic- and advanced-phase patients showed significant difference with respect to male-to-female ratio, hemoglobin level, WBC count, and platelet count. Sanger sequencing detected ANKRD36 mutations c. 1183 1184 delGC and c. 1187 1185 dupTT exclusively in all AP- and BC-CML patients but in none of the CP-CML patients. Nevertheless, mutations status was not associated with male-to-female ratio, hemoglobin level, WBC count, and platelet count, which makes ANKRD32 as an independent predictor of early and terminal disease progression in CML.

Conclusions

The study confirms ANKRD36 as a novel genomic biomarker for early and late CML progression. Further prospective studies should be carried out in this regard. ANKRD36, although fully uncharacterized in humans, shows the highest expression in bone marrow, particularly myeloid cells. Functional integrated genomic studies are recommended to further explore the role of ANKRD36 in the biology and pathogenesis of CML.