Subtypes of MDS

Myelodysplastic syndromes (MDS) are a group of different but related diseases. There are multiple ways of classifying MDS. One classification system divides MDS into 5 groups called subtypes. Your doctor can explain which subtype of MDS you or the person you care for may have.

Many doctors use a tool called the International Prognostic Scoring System (IPSS). It helps them understand their patients' MDS.

The IPSS also helps doctors understand how long patients with MDS may survive. Survival in patients with MDS can vary widely. Patients with more-severe MDS may live for a few months. Patients with less-severe MDS may live for years.¹

VIDAZA is used to treat patients with all 5 subtypes:

• RA: refractory anemia*, or RARS, refractory anemia with ringed sideroblasts
  Patients with RA or RARS have reduced white blood cell counts or platelet counts or need transfusions. About 10% to 40% of people with MDS have RA and about 10% to 20% have RARS²
• RAEB: refractory anemia with excess blasts^†
  Patients with RAEB have a cytopenia, or not enough of at least 2 types of blood cells (red, white, or platelets). About 25% to 30% of people with MDS have RAEB²
• RAEB-T: refractory anemia with excess blasts in transformation
  Patients with RAEB-T have a cytopenia, or not enough of at least 2 types of blood cells (red, white, or platelets). This form of MDS may turn into acute myeloid leukemia. About 10% to 30% of people with MDS have RAEB-T²
• CMMoL: chronic myelomonocytic leukemia
  Patients with CMMoL have an increased number of monocytes, a type of white blood cell. About 10% to 20% of people with MDS have CMMoL²

When you have MDS, your bone marrow doesn't stop making cells altogether. But it usually makes fewer cells, and the cells it does make don't always work the way they should. And this can lead to some of the signs and symptoms of MDS.

For patients with the mildest type of MDS, such as mild refractory anemia, the disease may not require complex treatment. Activity levels may be at or near normal. Health status for such a patient may not change for a number of years.

For patients with a more serious case of MDS, there is a risk that the disease will progress to acute myeloid leukemia (AML). AML is a rapidly growing cancer of bone marrow cells. Therefore, it is very important that regular laboratory tests are done to check the health of the patient’s blood and bone marrow.

*Refractory anemia = low red blood cell counts that do not respond to treatment.
^†Excess blasts = increased number of immature blood cells in the bone marrow.