Myelodysplastic Syndromes (MDS)

Myelodysplastic syndromes (MDS) are a diverse group of hematopoietic stem cell neoplasms in which clonal abnormalities of various hematopoietic cell lines result in dysplastic changes and cytopenias involving specific cell lineages. The risk of progression to acute myeloid leukemia (AML) is variably increased in MDS. Risk assessment tools such as the Revised International Prognostic Scoring System (IPSS-R) have been developed to classify cases of MDS as low- or high-risk disease. These scoring systems are essential for determining prognosis and guiding treatment of patients with MDS.¹ 

Blood Transfusions

Anemia and thrombocytopenia are almost always present in patients with MDS. Clinically, anemia manifests as easy fatigability, headache, and respiratory distress. Thrombocytopenia, a reduction of platelets in the blood, increases the risk of bleeding. Most patients with MDS require transfusions of red blood cells, platelets, or both at some point during the course of their disease to alleviate symptoms of anemia and thrombocytopenia.² 

Blood transfusions, when needed, may be done on an outpatient basis. The procedure is generally completed within 1 to 3 hours. Blood or blood components collected from a donor are transfused directly into the patient’s venous system.² 

Read more about MDS therapies

Bone Marrow/Stem Cell Transplant

In a bone marrow or stem cell transplant (SCT), a high dose of a chemotherapeutic agent or whole-body irradiation is used to destroy the patient’s bone marrow along with abnormal hematopoietic cells. The marrow is then replenished with normal hematopoietic stem cells. At present, SCT is the only treatment option that offers the possibility of a complete cure of MDS. Unfortunately, not all patients with MDS are eligible to receive SCT therapy.³ 

The 2 main types of SCT are allogeneic and autologous.

Allogeneic Stem Cell Transplant

In allogeneic SCT, a patient receives the bone marrow stem cells of another person after ablation of the native bone marrow. For the best outcome, human leukocyte antigen (HLA) typing should be performed to match donors to the patient’s cell type. Most often, the best HLA match is found in a close blood relative of the patient, such as a brother or sister. In some instances, bone marrow stem cells from an unrelated HLA-matched donor are used when no relative is a suitable donor.³

Although SCT is the only curative treatment, frequent and severe adverse effects may endanger the patient’s life. Therefore, allogeneic SCT is generally reserved for young, otherwise healthy recipients with greater tolerance. However, successful allogeneic SCT in older patients in the sixth or seventh decades of life has been reported. To reduce side effects in older recipients, less intensive chemoradiation is used for marrow ablation, which may not destroy the entire bone marrow but is sufficient to allow transplanted stem cells to grow. But even these precautions cannot eliminate all the side effects of allogeneic SCT.³ 

Read more about MDS risk factors

Autologous Stem Cell Transplant

In autologous SCT, normal stem cells from the patient’s bone marrow are collected before treatment is initiated. After the marrow has been ablated, the collected stem cells are transplanted back into the patient. Autologous SCT is not very useful in MDS because the patient’s bone marrow contains abnormal stem cells.³ 

Chemotherapy 

MDS is generally resistant to chemotherapeutic agents. However, the use of hypomethylating agents has occasionally been successful. Although SCT is invariably needed to treat high-risk and some cases of intermediate-risk disease, patients with low-risk disease can often be managed with systemic chemotherapeutic drugs along with supportive treatment, including blood transfusions and hematopoietic growth factors.⁴ 

Hypomethylating drugs include^2,4:

• Vidaza^® (azacitidine);
• Dacogen^® (decitabine); and
• Inqovi^® (decitabine/cedazuridine).

The US Food and Drug Administration (FDA) has approved both Vidaza and Dacogen for the treatment of any form of MDS, and these can be administered in outpatient settings. It is mainly patients with higher IPSS-R scores who benefit from treatment with these agents. Inqovi, an orally administered drug, is administered once per month with multiple rounds of treatment.²

Conventional chemotherapy drugs used for more-intensive treatment include²:

• Cytosar-U^® (cytarabine); 
• Cerubidine^® (daunorubicin); and
• Idamycin^® (idarubicin). 

Conventional chemotherapeutic agents are used to treat high-risk subtypes of MDS with an increased risk of progression to AML. The recommendation for conventional chemotherapy is based primarily on the patient’s age and physical condition. However, only about one-third patients of MDS have been shown to benefit from conventional chemotherapy.² 

Read more about MDS prognosis

Immunomodulatory Drugs

Revlimid^® (lenalidomide) is an orally administered immunomodulatory drug that has proved beneficial in patients who have low-risk MDS with chromosome 5q aberrations. Testing for chromosome 5q aberrations is essential before this treatment is initiated.²

Growth Factors

Growth factors are molecules that increase the formation and maturation of blood cells in bone marrow, so that blood and blood component transfusions are required less frequently. Erythropoietin is a growth factor responsible for the production and maturation of red blood cells. Granulocyte colony-stimulating factor (G-CSF) is a growth factor that promotes the production of white blood cells. These molecules are available as subcutaneous injectable formulations, and depending on the patient’s symptoms, one or all of them can be administered.⁵ 

Immunotherapy

The human immune system is a natural defense mechanism that removes abnormal cells from the body. Immunotherapy aims to promote immune system attacks on abnormal cells. Despite limited evidence of the utility of immunotherapy in MDS, this mode of treatment may be beneficial in selected cases. Anti-thymocyte globulin (thymoglobulin) is an immunotherapy drug that has shown some promise in the treatment of MDS. However, side effects of immunotherapy may include include skin rashes, flu-like symptoms, loose bowel movements, and metabolic alterations.² 

Read more about MDS experimental therapies

References

1. Bewersdorf JP, Xie Z, Zeidan AM. Novel approaches and future directions in myelodysplastic syndrome treatment. Cancer J. 2023;29(3):195-202. doi:10.1097/PPO.0000000000000658
2. Myelodysplastic syndromes – MDS: types of treatment. Cancer.net. Updated May 2023. Accessed June 14, 2023.
3. Stem cell transplant for myelodysplastic syndrome. American Cancer Society. Accessed June 14, 2023.
4. Dotson JL, Lebowicz Y. Myelodysplastic syndrome. StatPearls [Internet]. Updated July 18, 2022. Accessed June 14, 2023. 
5. Tests and treatment for myelodysplastic syndrome (MDS). Cancer Research UK. Reviewed July 13, 2020. Accessed June 14, 2023.

Reviewed by Kyle Habet, MD, on 6/19/2023.

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Harshi Dhingra, MD

Harshi Dhingra is a licensed medical doctor with specialization in Pathology. She is currently employed as faculty in a medical school with a tertiary care hospital and research center in India. Dr. Dhingra has over a decade of experience in diagnostic, clinical, research, and teaching work, and has written several publications and citations in indexed peer reviewed journals. She holds medical degrees for MBBS and an MD in Pathology.