Lifting the fog over ITP

Keywords:

• ITP
• platelet
• thrombocytopenia

We seem to be at an inflexion point in our understanding and treatment of ITP. Maturing from the legacy of the international working group recommendations approximately ten years ago, the way we think about ITP has been evolving [1,2]. What was once a mysteriously idiopathic disease is now better understood as a complicated syndrome comprising a range of divergent pathological mechanisms, converging only to manifest with thrombocytopenia [3]. We observe patterns; distinct presentations that mostly fit a narrative – acute childhood ITP that frequently remits spontaneously, young adult female ITP that can be severe and chronic but hazardous during pregnancy, or older adult male ITP sometimes without the need for treatment.

But experienced clinicians treating ITP are wary. Most patients actually fail to follow their lines in the script. Those with the lowest platelet counts don’t always bleed [4]. Some with higher platelet counts bleed spontaneously and dangerously. Some children fail to remit spontaneously, while fortunate adults can enter a deep remission with a single short course of steroids alone [5,6].

Despite the numerous advances in understanding relevant pathologies in ITP, we remain somewhat uncertain about how to select the best treatment for patients with difficult disease – second-line options are presented alphabetically [1,7]. We can count platelets, but we cannot predict who will bleed [8]. We cannot predict relapse [9]. We cannot even agree on which glucocorticoid to use in first-line [10,11].

As the fog lifts, the battle lines become apparent. We need better tools to identify patients at risk of bleeding. We need updated guidelines to inform safe therapies for our current patients. But we also need a better scaffold to test future algorithms that assist the selection of less toxic, more effective therapies. We need to individualize treatment based on patient preference as much as disease biology. We may need to sequence treatment logically for the longest remission intervals, or combine them safely to manage the most refractory cases [12,13].

In this special review series of ITP in Platelets, Swain and Bird describe their expertise in approaching diagnosis and management of a new patient with thrombocytopenia. Deshayes and Godeau share their practical insights on the second-line management of chronic ITP. Eslick and McLintock outline their approach to the vexatious management of ITP in pregnancy. Shaw et al, give an overview of the incidence and clinical burden of ITP in pediatric patients in the United States. And Gardiner et al, discuss current and future translational laboratory advances for interrogating platelet function in ITP.

This Special Focus Issue on ITP is only one step on the long yellow brick road. But with the recent advent of numerous disparate novel therapies effective for subsets of patients with refractory ITP, major stepwise clinical advance seems imminent [14–19].