Most patients suffer from symptomatic splenomegaly, and may have a big liver, and they have a bad quality of life. They lose weight, can’t walk, fatigue, weakness, night sweating, fevers. They do benefit from JAK inhibitors that provide anti-inflammatory and anti-proliferative effects, so cells don’t grow as fast, and the quality of life improves.
Unfortunately, many of the standard drugs also lower the blood cell count, and that leads to anemia and thrombocytopenia. So the drugs are limited in what they can do, and patient management may be affected by low platelets and lower red blood cell count.
With the standard practice drugs, you get the spleen as small as possible with the best dose possible. The higher the dose, the better the spleen response, and the longer the therapy works. Now, because of the high doses, you may worsen anemia, you may worsen thrombocytopenia, and so underdosing of those drugs is quite often present in everyday management.