Acquired bleeding disorders secondary to immune checkpoint inhibitors: a case report and systematic literature review

Acquired bleeding disorders because of an autoimmune phenomenon are rare events. Acquired von Willebrand disease (aVWD) has been estimated as having a prevalence of 400 per million in the general population. Acquired hemophilia A (AHA), the most common of the acquired hemophilias, has an estimated incidence of 1.3-1.5 cases per million per year. Immune checkpoint inhibitors (ICI) targeting PD-1, PD-L1, and CTLA-4 are being used with increasing frequency for hematologic and oncologic disorders. Acquired hemophilias and aVWD have been reported with the use of ICI therapy. We performed a systematic review of the literature to identify cases of acquired bleeding disorders with ICI therapy and contribute our own institution's experience with a case of AHA after pembrolizumab therapy. Six cases of AHA, one case of aVWD, and one case of factor V inhibitor were identified in the literature. Inhibitors were successfully eradicated in five of the eight cases identified. We propose that a centralized registry, possibly through the Scientific and Standardization Subcommittee on Plasma Coagulation Inhibitors through the International Society on Thrombosis and Hemostasis (ISTH), be developed to record treatment and outcomes of this rare ICI complication in order to prognosticate risk and better understand optimal treatment strategies.