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What Essential Thrombocythemia Treatments Are Available?

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Published on August 20, 2020

Treatments For ET: What are My Options?

Why are people with essential thrombocythemia often misdiagnosed? What ET treatments are in development and what side effects do they come with? In this segment from a recent MPN Answers Now program, host Andrew Schorr gets answers to these questions plus more from Dr. Ellen Ritchie from Weill Cornell Medicine. Tune in to hear the full conversation.

This is Part 2 of a 4-part series. Watch the complete series below:

This program is sponsored by Bristol Myers Squibb. This organization has no editorial control. It is produced by Patient Power. Patient Power is solely responsible for program content. 

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Transcript | What Essential Thrombocythemia Treatments Are Available?

Diagnosing Essential Thrombocythemia

Andrew Schorr:

So Dr. Ritchie, I've got a few questions for you as we start. I know that there are 70,000 to 80,000 people in the U.S. living with essential thrombocythemia, more often women than men, but often people take a while to be diagnosed. Why do some people get misdiagnosed? Why is it hard?

Dr. Ritchie:

For several reasons. First of all, high platelet counts can be caused by many other things, including, in women, iron deficiency, which is a pretty common problem, especially in younger women. Also, that primary care doctors may not be so worried about a platelet count that's just slightly high, because there are a lot of reasons why that could be the case.

So oftentimes, when I see new patients, there have been primary care doctors who just haven't really been as fixated on the blood counts as perhaps I am as a hematologist. And as I said, iron deficiency, inflammatory conditions, snoring... all sorts of other things can cause abnormalities in the blood counts which are very benign, and those are horses and the essential thrombocythemia is a zebra; so when primary care doctors are looking at your blood counts, they're thinking horses and not zebras.

Andrew Schorr:

Right. So when people finally get to you, it may have been years before they got this diagnosis.

Dr. Ritchie:

Well, it depends. Some people go to the doctor a lot more than others, and some people go to more doctors instead of fewer doctors, and usually if you go see a gynecologist and your regular MD, you may find one of them is concerned about a particular blood value. So it's hard to say; there are patients who go undiagnosed for years, there are people who get diagnosed fairly rapidly. It really depends on a lot of circumstances as to how quickly people are diagnosed with this disease.

Developments in Treatment for ET Patients

Andrew Schorr:

What could be in development for ET patients? First of all, help us understand what sort of standard of care now, and then how do we build on that to do better?

Dr. Ritchie:

So most patients who are diagnosed with ET are assigned, really, a risk group. Are they very low risk? Are they low risk? Are they at intermediate risk or high risk of having a complication from their ET? There are some patients with ET who are CALR mutated that may not... who are under 60 and have no cardiovascular risk factors... that may not need any treatment at all. It's questionable as to whether or not those patients would benefit by low aspirin therapy, but they may not need anything at all.

As you get older, 60 and older, and if you have cardiovascular events... thrombosis... or if you have risk factors for cardiovascular events, this changes whether or not we think you need baby aspirin or baby aspirin plus cytoreductive therapy, and cytoreductive therapy is very common in patients over the age of 60, where they fall into a higher risk group.

There are many different types of agents which have been used, but none has actually been demonstrated as a standard of care, really, by clinical trial. Hydroxyurea (Hydrea) is commonly used as an initial agent for patients who require cytoreduction with essential thrombocythemia. Hydroxyurea has never been perspective-ly evaluated as the appropriate upfront therapy for ET, but it is commonly used.

Anagrelide (Agrylin) is another drug which is commonly used in patients who have essential thrombocythemia. There are many side effects to anagrelide, and some people find it very difficult to tolerate, and that's not commonly used, really, as an upfront medication for essential thrombocythemia.

Pegasys, or interferon, is also used as a cytoreductive agent, and the difference between Pegasys and the other agents I mentioned are really that Pegasys is a drug which is going to work on the stem cell fraction, the actual MPN stem cell, and is more commonly used in younger patients who need cytoreduction for their essential thrombocythemia.

Ruxolitinib (Jakafi), it's used sometimes on the basis of the data which has been presented in abstract formulation to also treat patients who have high platelet counts, who need cytoreduction, who have essential thrombocythemia. One of the difficulties in creating clinical trials for essential thrombocythemia is, if I have a new agent, what am I going to use as my control arm, because it's not clear what the correct upfront agent is to use for patients who need cytoreduction, who have essential thrombocythemia?

Andrew Schorr:

So, first of all, if somebody else who has diabetes... so, does that put them in a different category?

Dr. Ritchie:

Diabetes puts you at a higher risk of having a cardiovascular event, and so, that gives you a cardiovascular risk factor. So, a patient who is otherwise under 60, has no history of thrombosis, and has no cardiovascular events thus far, but has diabetes, has a significant cardiovascular risk factor. You would also look at their other risk factors... their cholesterol, whether or not they smoke... and come to sort of a composite idea of what their cardiovascular risk is, but it would be a reason that we would think, potentially, of certainly using baby aspirin in those patients, but maybe even cytoreductive therapy, depending on how well their diabetes is controlled.

Andrew Schorr:

First of all, one person wrote in, they said that hydroxyurea blew out their metabolism. They had terrible, not good effects, so what about side effects of the medicines you mentioned?

Dr. Ritchie:

Hydroxyurea is an old medication, so it's been around for a really long time, and it's a medication that doctors are familiar with using. The side effects of the drug can be nausea, vomiting; it can be cytopenia’s, it can be a low white count, a low red blood cell count. It can be also that you can develop sores, either in your mouth, or you can develop ulcerations on the skin that don't heal as long as you're on the drug. So, those are basic side effects of hydroxyurea.

As I said, it's an old drug and has been used for many, many years, so physicians have a lot of familiarity with it. However, for some patients, it's just an intolerable drug to take.

Andrew Schorr:

Wow. Now, someone wrote in, and maybe you can explain this... said, "What is important to know about being a triple-negative patient?" So, what's a triple-negative patient, and what does it mean?

Dr. Ritchie:

Triple-negative means that when we are putting you through the diagnostic criteria for a diagnosis of ET, that we find that you have no mutations that we associate with myeloproliferative diseases; so, no JAK2, no CALR, and no MPL, M-P-L; no gene mutations. If you don't have any of those three gene mutations, you're thought to be triple-negative. In that situation, you're going to look very carefully to see if there's any other explanation as to why you have a high platelet count, and if we find none, certainly you'll have a bone marrow biopsy to look and see whether your biopsy is consistent with essential thrombocythemia.

Sometimes we even find that there are genetic abnormalities that we don't routinely associate with essential thrombocythemia that we see in your bone marrow, but if you don't have those three mutations, you are triple-negative, and there's not a lot of great data with which to guide our therapy of patients who are triple-negative, so it's one of those question marks for which we need to do more research.

Andrew Schorr:

Okay. You mentioned interferon earlier. Here's a question that came in. Is interferon alpha preserved for young patients only, or can it be a first-line treatment for older patients, too?

Dr. Ritchie:

It can be a first-line treatment for nearly anyone, and I would say it's a preferred first-line treatment for younger people. It's the only medication that you could use for cytoreduction, if that's required, that can be used during pregnancy, so it's, in that regard, potentially a safer drug to use in younger patients who need cytoreductive therapy.

There are side effects to interferon, and some of those side effects are less tolerable as you get older. Certainly, it can be used in patients over 60; when you get into your 70s and 80s, I really think it depends on taking a very careful medical history from the patient as to whether you think they would tolerate the medication. Interferon can give some patients a mild flu-like syndrome. It can also create some anemia or some lowering of the blood counts. There can be some abnormalities in the liver function taking this drug. But most importantly, there can be mood abnormalities; so, patients on interferon may be at higher risk of developing depression or anxiety or other psychiatric illness. That is really important that you be aware of and top of when taking or prescribing this medication.

The medication can also, if you have a tendency toward autoimmune disorder, it can unmask that, and you can develop autoimmune disorders on interferon. So, these are all things that you need to keep in mind when you place patients on interferon. So, a 65-year-old woman with rheumatoid arthritis is not a great interferon candidate. A 69-year-old who has been hospitalized before for depression and suicidal ideation would not be a good candidate for interferon. But there are plenty of patients in their 60s and early 70s who would be reasonable candidates for interferon, so it's not a medication only for the young.

Please remember the opinions expressed on Patient Power are not necessarily the views of our sponsors, contributors, partners or Patient Power. Our discussions are not a substitute for seeking medical advice or care from your own doctor. That’s how you’ll get care that’s most appropriate for you.


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