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Myelodysplastic syndrome with isolated del(5q) — Clinical Guidelines

Overview

Myelodysplastic syndrome with isolated del(5q) (del(5q) MDS) is a subtype of myelodysplastic syndromes characterized by a specific chromosomal deletion involving the long arm of chromosome 5 (5q). This condition often presents with refractory anemia and is associated with a relatively better prognosis compared to other MDS subtypes, particularly due to its responsiveness to lenalidomide therapy. Patients typically exhibit cytopenias, particularly macrocytic anemia, and have an increased risk of progression to acute myeloid leukemia (AML). Early recognition and appropriate management are crucial for improving outcomes and preventing complications. Understanding del(5q) MDS is essential for clinicians to tailor treatment strategies effectively, especially given the targeted therapies available. 1 2

Pathophysiology

The pathophysiology of del(5q) MDS involves the deletion of a segment of the long arm of chromosome 5, which encompasses several genes critical for hematopoiesis. Notably, the deletion often includes the RPS14 gene, which is part of the ribosomal protein complex. The loss of RPS14 disrupts ribosomal function, leading to impaired erythropoiesis and other hematopoietic lineage deficiencies. This molecular derangement results in ineffective hematopoiesis, characterized by dysplastic changes in bone marrow cells and peripheral blood cytopenias, particularly macrocytic anemia. Additionally, the deletion affects other genes involved in cell cycle regulation and DNA repair, contributing to the accumulation of immature and dysfunctional cells. These cellular abnormalities manifest clinically as cytopenias and increased risk of transformation to AML. 1 2

Epidemiology

Del(5q) MDS constitutes approximately 5-10% of all MDS cases, with a slight male predominance observed in most studies. The median age at diagnosis is typically around 70 years, indicating a higher prevalence in older adults. Geographic distribution does not show significant variations, but certain risk factors such as prior chemotherapy and radiation exposure may predispose individuals to developing this subtype. Incidence rates have remained relatively stable over recent decades, though advancements in diagnostic techniques have likely improved detection rates. 1 2

Clinical Presentation

Patients with del(5q) MDS predominantly present with refractory anemia, often accompanied by macrocytic anemia, which distinguishes it from other cytopenias seen in MDS. Common symptoms include fatigue, pallor, and shortness of breath due to anemia. Thrombocytopenia and neutropenia may also be present but are less frequent than anemia. Red-flag features include rapid progression to AML, particularly in cases without lenalidomide treatment, and severe cytopenias that necessitate urgent intervention. The presence of dysplastic changes in bone marrow aspirates, such as megaloblastoid changes, further supports the diagnosis. 1 2

Diagnosis

The diagnosis of del(5q) MDS involves a comprehensive approach combining clinical evaluation, peripheral blood and bone marrow analysis, and cytogenetic testing. Key diagnostic criteria include:

Peripheral Blood Findings: Macrocytic anemia, often with a mean corpuscular volume (MCV) > 110 fL.

Bone Marrow Examination: Presence of dysplastic changes, particularly megaloblastoid features, and hypercellularity.

Cytogenetic Analysis: Confirmation of isolated deletion of the long arm of chromosome 5 (del(5q)) via karyotyping or fluorescence in situ hybridization (FISH).

World Health Organization (WHO) Criteria: The diagnosis aligns with WHO criteria for MDS, specifically requiring the presence of del(5q) and at least one additional cytopenia or dysplasia in one or more lineages.

Differential Diagnosis: Distinguishing from other MDS subtypes (e.g., del(20q), monosomy 7) and megaloblastic anemia due to vitamin B12 or folate deficiency through appropriate biochemical testing.

Differential Diagnosis:

Megaloblastic Anemia: Typically responsive to vitamin B12 or folate supplementation, lacking the characteristic chromosomal deletion.

Other MDS Subtypes: Identified by distinct cytogenetic abnormalities and varying clinical presentations.

Aplastic Anemia: Characterized by pancytopenia without dysplastic changes and normal or hypercellular bone marrow without specific chromosomal deletions. 1 2

Management

First-Line Treatment

Lenalidomide: Recommended for patients with del(5q) MDS who are transfusion-dependent and have adequate renal function (creatinine clearance ≥ 60 mL/min).

- Dose: Initially 10 mg daily, can be increased to 15 mg daily based on response and tolerance. - Duration: Continued until progression or unacceptable toxicity. - Monitoring: Regular complete blood count (CBC), renal function, and monitoring for adverse effects such as thromboembolism and neutropenia. - Contraindications: Severe renal impairment, prior history of deep vein thrombosis or pulmonary embolism, and hypersensitive to lenalidomide.

Second-Line Treatment

Erythropoietic Agents: Consider in patients not responding adequately to lenalidomide or intolerant to it.

- Examples: Erythropoietin (EPO) or darbepoetin alfa. - Dose: Titrated to achieve target hemoglobin levels, typically starting at lower doses and escalating as needed. - Duration: Continued until response or development of resistance.

Immunosuppressive Therapy: For patients with higher-risk features or transformation risk.

- Examples: Antithymocyte globulin (ATG) or cyclosporine A. - Dose and Duration: Specific regimens vary; consult guidelines for detailed dosing and monitoring protocols.

Refractory or Specialist Escalation

Allogeneic Stem Cell Transplantation: Considered for younger patients with higher-risk features or those refractory to other therapies.

- Indication: Younger age (typically < 50-60 years), suitable donor availability, and absence of significant comorbidities. - Timing: Post-remission or in selected high-risk cases. - Monitoring: Rigorous pre-transplant evaluation and post-transplant immunosuppression management.

Clinical Trials: Participation in trials evaluating novel agents or combinations may be considered for refractory cases.

- Evaluation: Regular assessment by hematology specialists to identify suitable trials.

Complications

Acute Transformation to AML: Increased risk, particularly in untreated or refractory cases.

- Management Trigger: Regular monitoring of blast counts in peripheral blood and bone marrow.

Thrombosis: Higher risk with lenalidomide use, especially in patients with additional risk factors.

- Prevention: Use prophylactic anticoagulation in high-risk patients.

Infections: Neutropenia can lead to increased susceptibility to infections.

- Management Trigger: Frequent CBC monitoring and prompt antibiotic therapy for signs of infection.

Prognosis & Follow-Up

Patients with del(5q) MDS generally have a more favorable prognosis compared to other MDS subtypes, with a lower risk of progression to AML when treated appropriately with lenalidomide. Key prognostic indicators include response to lenalidomide, cytogenetic profile, and absence of high-risk features such as complex karyotypes or additional chromosomal abnormalities. Recommended follow-up intervals include:

Monthly CBC: To monitor cytopenias and response to therapy.

Biannual Bone Marrow Assessment: To evaluate for progression or transformation.

Annual Cytogenetic/FISH Analysis: To monitor chromosomal stability.

Regular Clinical Evaluations: To assess overall health status and manage complications proactively.

Special Populations

Elderly Patients

Management focuses on minimizing toxicity and maximizing quality of life, often starting with lenalidomide at lower doses and closely monitoring for adverse effects.

Comorbidities

Patients with comorbidities such as renal impairment require dose adjustments of lenalidomide and close monitoring of renal function.

Pregnancy

Lenalidomide is contraindicated during pregnancy due to teratogenic risks. Alternative management strategies should be considered, often involving close monitoring and supportive care until safer therapeutic options can be implemented post-partum.

Key Recommendations

Confirm del(5q) Chromosomal Deletion: Use karyotyping or FISH to definitively diagnose del(5q) MDS. (Evidence: Strong)

Initiate Lenalidomide for Transfusion-Dependent Patients: Consider in patients with adequate renal function and no contraindications. (Evidence: Strong)

Regular Monitoring of CBC and Renal Function: Essential for patients on lenalidomide to manage toxicity and response. (Evidence: Moderate)

Evaluate for Thromboembolic Risk: Implement prophylactic measures in high-risk patients on lenalidomide. (Evidence: Moderate)

Consider Erythropoietic Agents for Non-Responders: As second-line therapy for those not responding to lenalidomide. (Evidence: Moderate)

Allogeneic Stem Cell Transplantation for High-Risk Patients: Evaluate younger patients with higher-risk features for transplantation. (Evidence: Weak)

Participate in Clinical Trials for Refractory Cases: Explore novel therapies through clinical trials for patients not responding to standard treatments. (Evidence: Expert opinion)

Biannual Bone Marrow Assessments: Monitor for disease progression or transformation. (Evidence: Moderate)

Annual Cytogenetic Analysis: Track chromosomal stability over time. (Evidence: Moderate)

Tailored Management for Special Populations: Adjust treatment based on age, comorbidities, and pregnancy status. (Evidence: Expert opinion)

References

1 Foerster LC, Frigoli E, Sun X, Hooli J, Goncalves A, Martin-Villalba A. umite: fast quantification of Smart-seq3 libraries with improved UMI retrieval. Bioinformatics (Oxford, England) 2026. link 2 Meyer-Nava S, Shetty AV, Rivera-Mulia JC. Repli-seq Sample Preparation using Cell Sorting with Cell-Permeant Dyes. Current protocols 2023. link 3 Xu J, Falconer C, Nguyen Q, Crawford J, McKinnon BD, Mortlock S et al.. Genotype-free demultiplexing of pooled single-cell RNA-seq. Genome biology 2019. link 4 Romagnoli D, Boccalini G, Bonechi M, Biagioni C, Fassan P, Bertorelli R et al.. ddSeeker: a tool for processing Bio-Rad ddSEQ single cell RNA-seq data. BMC genomics 2018. link 5 Cuadrado A, Jouve N. Evolutionary trends of different repetitive DNA sequences during speciation in the genus secale. The Journal of heredity 2002. link 6 Gendel S, Fosket DE. Differential rates of DNA denaturation and renaturation in situ in relation to the C-banding of Allium cepa chromosomes. Cytobios 1978. link

Myelodysplastic syndrome with isolated del(5q)