Improving Our Ability to Treat Patients with Qualitative and Quantitative Platelet Disorders

The year 2016 has yielded important results and promising observations for patients with a variety of qualitative and quantitative platelet disorders. I will start this article with a number of “honorable mention” studies from this field, and finish with what I think was the most important 2016 study involving platelets.

In a previous Diffusion article, I summarized a trial that compared a short course of high-dose dexamethasone with a more prolonged prednisone taper; the high-dose dexamethasone showed a faster response, but the long-term efficacy was not different between the two groups.¹  At the 2016 ASH Annual Meeting, Dr. Katja M.J. Heitink-Polle presented the results of a randomized, controlled multicenter trial of children with newly diagnosed immune thrombocytopenia (ITP). They reported that the administration of intravenous immunoglobulin (IVIg) did not significantly reduce the proportion of children who developed chronic ITP, but IVIg did result in faster platelet recovery and less frequent bleeding during the first three months after diagnosis.² 

In other platelet-related news from the 2016 ASH Annual Meeting, a small randomized controlled trial of patients with thrombotic thrombocytopenic purpura (TTP) compared prednisone to cyclosporine; all patients received plasma exchange therapy. Although the trial was not powered to show a difference in clinical outcomes such as mortality or TTP exacerbation, the authors found that improvement in ADAMTS13 activity and suppression of anti-ADAMTS13 antibodies were significantly better in the prednisone-treated patients.³  In another session related to microangiopathic hemolytic anemia, Dr. Maximilien Grall and colleagues described their exploratory study of eight patients with gemcitabine-induced thrombotic microangiopathy, suggesting that eculizumab might be of benefit.⁴ 

The ASH annual meeting also featured two presentations of thrombopoietin mimetic agents in the setting of chemotherapy for acute myeloid leukemia and/or hematopoietic stem cell transplantation.^5,6 

For the best of 2016 in the field of platelet disorders (and within nonmalignant hematology), I have chosen a randomized trial that compared standard care to standard care plus platelet transfusion in adult patients who were taking antiplatelet drugs and experienced intracerebral hemorrhage (ICH).⁷  When compared to the patients who were treated without platelet transfusion, individuals who received platelet transfusions were more likely to die or be disabled (as defined by the modified Rankin Scale for functional independence). Serious adverse events were more frequent in the platelet transfusion arm, and ICH enlargement was similar in both arms, at approximately 15 percent. Although this single randomized trial does not definitively establish that platelet transfusion is harmful in patients who experience ICH while taking antiplatelet medication, it strongly challenges the widely held assumption that donor platelets might bypass the qualitative defect induced by a medication such as aspirin or clopidogrel. At least one other ongoing prospective randomized study will eventually affect our clinical decision-making in these cases. For now, however, there appears to be no benefit (and there may be harm) from platelet transfusion in patients with ICH while taking antiplatelet medications.