Prevalence and Types of Myelodysplastic Syndromes (MDS)


Ryan Haumschild, PharmD, MS, MBA, leads a discussion surrounding myelodysplastic syndrome (MDS).

Ryan Haumschild, PharmD, MS, MBA: Hello, and welcome to this Pharmacy Times Peer Exchange. The expanse of supportive care in myelodysplastic syndromes. My name is Dr Ryan Haumschild, director of pharmacy services at Emory Healthcare and the Winship Cancer Institute. Joining me today in this virtual discussion are Robert Mancini, BMT pharmacy program coordinator at St Luke’s Cancer Institute, and Zahra Mahmoudjafari, clinical pharmacy manager, Hematology, Bone Marrow Transplant, and Cellular Therapies at the University of Kansas Health System. Today, we’re going to talk about several topics pertaining to myelodysplastic syndrome, including discussions around diagnosis, supportive care treatment options, as well as future considerations for clinical practice. Let’s get started.

As we get started in this discussion, I think it’s really important that we do an overview of the disease state, especially for our viewers to understand the differences within. We need to discuss the susceptible patients and the presentation of myelodysplastic syndrome and how providers can differentiate them based on the diagnosis. Dr Mancini, I’d like to start with you. Can you give us an overview of what are the different types of myelody­splastic syndromes and how does MDS [myelodysplastic syndrome] compare [with] other hematological malignancies?

Robert Mancini, PharmD, BCOP, FHOPA: Thank you, Ryan, it’s good to be here. I think the big part of that answer is related to which system you use to define MDS. The older, original system, the FAB, or French/American/British system divided MDS into 5 subtypes based on the percentage of blasts in bone marrow and the peripheral bloo­d. This included refractory anemia as well as refractory anemia with ring sideroblasts, both of which have less than 1% blasts in the blood and less than 5% blasts in bone marrow. It also included refractory anemia with excess blasts in what’s called transmission. The definition in that system is now referred to as a subtype of AML [acute myeloid leukemia] rather than MDS.

Excess blasts in transformation, the former of those 2 having about 5% to 20% blasts in the bone marrow, and the latter having more 5% blasts in the blood plus a higher percentage, upwards 21% to 30% blasts in the bone marrow. CMML [chronic myelomonocytic leukemia] had greater than 5% blasts in the blood and about 5% to 20% in bone marrow. As you can see, because of that overlap with the newer leukemia definitions, the system isn’t used as much anymore. The newest and most followed update to classifications in MDS is the 2016 WHO [World Health Organization guidelines], which recognizes 6 types of MDS. The first type is what’s called MDS-SLD, or single lineage dysplasia, and that means only1of the cell lines is affected, whether that be anemia, neutropenia, or thrombocytopenia. Generally, these patients have low blast counts, no Auer rods, and a low percentage of those ring sideroblasts that I mentioned. The next classification is MDS-MLD, or multilineage dysplasia, which is exactly what it sounds like. It’s the same thing, but you have at least 2 or more, potentially all 3, cell lines affected.

Then, there’s MDS-RS, or ring sideroblasts. ring sideroblasts are essentially an immature erythroid precursor that have a deposition or excess deposition in iron in the mitochondria. It creates a ring of dots around the nucleus of those cells. MDS-RS has greater than 15% ring sideroblasts, and it can be either a single lineage, multilineage, or even what’s called a deletion 5q. That’s the next category, MDS deletion 5q, where there’s a specific genetic mutation found, and patients have deletion of that 5q chromosome arm. They don’t meet criteria for excess blasts. Again, excess blasts being the next criteria where these patients have more than 5% blasts in the bone marrow or greater than 1% in the peripheral blood. That’s subdivided into 2 groups, excess blasts 1 or 2, which is dependent on the total percentage of blasts. EB1 has about 5% to 9% blasts, whereas EB2 has about 10% to 19%. The last category is MDS-U, which is unclassified, so they don’t fit into any of these previous criteria, and there are several subtypes to that. From there, you must define risk stratification, each subtype based on the IPSS [International Prognostic Scoring System]. That puts patients into1of 5 categories, including very low, low, intermediate, high, or very high. There [are] lots of factors. We can talk about that more later, but there [are many] factors that go into IPSS scoring. There are other scoring models or prognostic models, including the [The University of Texas] MD Anderson [Cancer Center] MDS Model, and the WHO Prognostic Scoring, but these are not as commonly used as the IPSS score.

Ryan Haumschild, PharmD, MS, MBA: That was a great overview. I appreciate that because I think as we’re looking toward creating an accurate diagnosis and learning how to treat these patients, we really do have to understand the different subtypes of myelodysplastic patients. It is important to build upon that before we go further on treatment options. Before we go further, I want to defer to our colleague, Dr Mahmoudjafari, and think about the prevalence of myelodysplastic syndrome in the United States and upon that, how does the incidence of myelodysplastic syndrome start to change based on age?

Zahra Mahmoudjafari, PharmD, BCOP, DPLA: Thank you Ryan, I appreciate it. It’s good to be here with both you and Dr Mancini. Regarding how prevalent MDS is in the United States, the number of people diagnosed with MDS is not known for sure. In the general population, incidents are anywhere between 4.5 to 5.5 [individuals] per 100,000 [individuals] per year. Regarding the incidents and how it changes with age, it’s pretty rare to see MDS in patients that are children, adolescents, or young adults, but the risk certainly increases with age. Individuals [aged] younger than 40 [years] have an incidence of 0.1 per 100,000 per year, but as the years increase, somewhere between the ages of 70 and 79, the incidence rate certainly increases to closer to 6.9 per 100,000. With those that are greater than 80 years of age, it further increases to 55.4 per 100,000.

Ryan Haumschild, PharmD, MS, MBA: Excellent, so it does look like with myelodysplastic syndrome, we are seeing occurrence go higher with age. As people age and we care for them, we need to be aware of a strategic plan in terms of treatment, diagnosis, and screening.

Transcript edited for clarity.

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