Myelodysplastic Syndromes Overview

Myelodysplastic syndromes (MDS) are diseases of the blood and bone marrow characterized by ineffective production of red blood cells, white blood cells, or platelets.

In MDS, immature forms of myeloid cells (a type of white blood cell) accumulate in the bone marrow and lead to a decrease in normal hematopoiesis. MDS may be seen as a precursor to acute myeloid leukemia (AML).

MDS is further categorized into three main types: refractory anemia with ring sideroblasts (RARS), low-risk myelodysplastic syndrome (MDS-LR), and intermediate-risk MDS (MDS-IR). The most common type is RARS.

Myelodysplastic syndromes (MDS) are a group of disorders that result in abnormal blood cell development. MDS can affect several types of blood cells, including red blood cells, white blood cells and platelets. MDS is often divided into subtypes based on which specific blood cells are affected and how severely they’re affected.

MDS has three main forms: refractory anemia with excess blasts (RAEB), refractory anemia with excess blasts in transformation (RAEB-T) and chronic myelomonocytic leukemia (CMML).

The RAEB sub type is the most common form of MDS. It involves more than 20 percent of your bone marrow’s being made up of abnormal immature white blood cells called blasts, which cannot function properly. The RAEB-T form, which affects fewer people than RAEB does, is similar to RAEB except that there are some differences in the type of blast cell present in your bone marrow and blood. CMML affects 10 to 15 percent of people with MDS; it’s rarer than the other subtypes but more common than AML or ASM.

Symptoms

Symptoms of MDS include:

• fatigue and weakness
• infections, including fever, flu-like symptoms or pneumonia
• pale skin color, pallor or jaundice (yellowing of the skin)
• anemia (low red blood cell count)
• easy bruising or bleeding
• darkening of the urine
• shortness of breath

Types of Myelodysplastic Syndrome

There are three types of myelodysplastic syndrome:

Refractory anemia with excess blasts (RAEB). This is the most common type of MDS. It affects 95% of patients with MDS. Patients have a low red blood cell count and increased numbers of abnormal white blood cells called blast cells in the bone marrow. The blasts may also be found in the blood, spleen, liver and other organs.

Aggressive myelodysplastic syndrome (MDS). This is a rare form of MDS that usually occurs in older adults. It has a worse prognosis than the other types and tends to progress rapidly. Patients often have multiple organ failure and bleeding problems caused by too many abnormal white blood cells in the body.

Refractory cytopenia with multilineage dysplasia (RCMD). This type accounts for less than 5% of all MDS cases and affects patients who have had treatment for cancer or other diseases that cause damage to their bone marrow cells. RCMD can be difficult to diagnose because it has many features similar to those seen during normal aging in older people.

Treatment

For a high percentage of people with myelodysplastic syndrome, the disease goes into remission after treatment with chemotherapy. But for others, the disease progresses to acute myeloid leukemia (AML).

Treatment for Myelodysplastic Syndrome

The goal of therapy is to stop the progression of myelodysplastic syndrome and prevent it from becoming AML. Treatment usually involves a combination of chemotherapy drugs and blood transfusions or bone marrow transplants.

Chemotherapy drugs used to treat myelodysplastic syndrome include:

• Busulfan (Myleran)
• Cytarabine (Cytosar, Ara-C)
• Daunorubicin (Cerubidine)
• Dexamethasone (Decadron)
• Etoposide (Vepesid)
• Fludarabine phosphate (Fludara)

Prognosis

The prognosis for people with MDS is generally poor, but there are some types that have better survival rates than others. Those diagnosed with chronic myelomonocytic leukemia (CMML) or acute monocytic leukemia (AML) do not live as long as those who are diagnosed with other types of MDS. A person who has undergone chemotherapy will also have a better chance at survival than someone who has not received treatment at all.

Myelodysplastic Syndrome Clinical Trials

The goal of MDS clinical trials is to find new and better ways to detect, treat and prevent MDS.

Types of MDS Clinical Trials

There are several types of MDS clinical trials:

Phase I/II clinical trials test a new drug or treatment in a small group of people to evaluate its safety, determine a safe dosage range and identify side effects. The results from these early stage studies help determine whether larger Phase III studies should be conducted.

Phase III clinical trials compare the effectiveness of one drug, medication or treatment strategy against another one already on the market or an alternative therapy (such as surgery). These large-scale studies provide information about how well the treatment works in different populations with different diagnoses and under what conditions it should (or shouldn’t) be used.