How common is PNH appearing in patients with aplastic anemia?
Are there any areas where the boundaries or definition of one disease appears to overlap with another?
Is PNH treated any differently when it appears in a dual diagnosis with aplastic anemia?
But patients with PNH-aplastic anemia overlap maybe not respond as well to eculizumab if they have a low reticulocyte count. They may need immunosuppression first, and may not be not be able to receive anticoagulants if their platelet count is low.
Conversely, for a PNH-aplastic anemia patient, there can be problems with ATG treatment. The reaction patients get with ATG can trigger hemolysis. In patients a with large PNH red cell population who need aplastic anemia treatment, one thing to do is give them enough red cell transfusions, in order to dilute their PNH red cells so there are very few of them still there that can hemolyze when they receive ATG. This might be two units of red cells a week every week for three weeks, for example. This could be enough to prepare someone with many PNH red cells to get ATG.
Are there possible complications from these treatments?
Another way that the overlap syndrome can be important has to do with kidney function. Patients with aplastic anemia who require cyclosporine can experience an effect of the drug on their kidneys, and rare patients with PNH will develop a serious loss of kidney function as well. I suspect that the use of cyclosporine in a patient with a large PNH clone will be more likely to have an effect on the kidney function-- unless they are also on eculizumab.
Another consequence of the overlap syndrome is the effect of the combination of eculizumab and cyclosporine. In practical terms, if a patient is on either drug, they must go immediately to the hospital if they develop a fever. For cyclosporine, this is to make sure that they do not have one of many possible infections. For patients on eculizumab, in general this would be to make sure that they do not have meningococcal infections. For patients on eculizumab who are also on cyclosporine, there is always a theoretical concern that they might not be able to make antibodies in response to a vaccination because of the effects of the cyclosporine, and that they would be doubly immunosuppressed. However, if one uses this type of caution, patients who need both can be on both.
There are rare cases where patients have a triple diagnosis – PNH, aplastic anemia, MDS. Is there anything different about these?
Dr. David Araten is an assistant professor in the Division of Hematology at the NYU School of Medicine in New York City. Prior to holding this position, he worked as an assistant professor and instructor in hematology at Memorial Sloan-Kettering Cancer Center, also in New York City. His residency was in internal medicine at Columbia-Presbyterian Medical Center and received his medical degree from Harvard Medical School in Boston. Dr. Araten’s research has focused largely on PNH and he has published in a wide variety of peer reviewed journals on this topic. He is also a recipient of the 1997 New Researcher Award & Vernille Family Fund Research Grant awarded by the Aplastic Anemia and MDS International Foundation.