Essential Thrombocythemia (ET) and Multiple Sclerosis

Here is My Question:
I have MS, essential thrombocythemia (ET) and hemochromatosis. I take hydrea for my ET and Gilenya for my MS. My problem is my lymphocytes are .22 and my ast/alt are 4.5x the upper limit. I don't want to stop taking gilenya. It seems the two meds are amplifying the immune system suppression. I have read several cases of taking GILENYA every other day. Any opinion on doing that? Or should I medicate different for my ET? I only take hydrea 500mg every third day.

Answer:
Essential thrombocythemia (ET) is a condition where the megakaryocyte (cell in the bone marrow) release large amounts of platelets into the blood stream to aid the body in blood clotting (and avoiding bleeding out).  ET is a condition where you have way too much platelet production that can lead to several unwanted problems with blood clots, among other things.

There are a few early studies of the use of S1p modulation (this is the target of Gilenya) that may affect the differentiation (development) and activity of megakaryocytes.  Animal models suggested that S1p modulation may increased platelet counts.  On the other hand, there have been reports of lowering of platelet counts on gilenya in patient with multiple sclerosis.  If this is the case for you, then Gilenya may very well be playing a dual role for the MS and ET.  When reviewing the literature, I am not aware of any data that proves Gilenya helps ET.

The bottom line is that Gilenya, like our other therapeutics, are not benign and can cause unwanted problems (in your case, the liver function tests are quite elevated).  I'd strongly suggest that you speak with your neurologist about your unique situation (and your hematologist) to determine if Gilenya is helping the ET.  If the answer is "we don't know" or "probably not", then you may want to look to another DMT if your liver function tests continue to stay elevated.  However, as you point out, we do use Gilenya on an every other day basis with good results (this is off label) for many patients with MS.  That should also play a role in your doctors' (and your) decision making on transitioning to another therapy.

A. Scott Nielsen MD MMSc
Neurologist and MS Specialist at Kaiser Permanente