Signal detection of immune thrombocytopenia associated with immune checkpoint inhibitors

Immune checkpoint inhibitors (ICIs) have become an important treatment modality for various malignancies. Due to excessive inflammatory and immune responses, immune-related adverse events (irAEs), such as rash, pruritis, pneumonitis, hepatitis, hypothyroidism, hyperthyroidism and fatigue, can occur. Acquired immune thrombocytopenia is a rare irAE that can lead to severe low platelet counts and hemorrhage. A retrospective observational analysis was conducted on data from the United States Food and Drug Administration Adverse Event Reporting System (FAERS). We searched for all reports recorded in the FAERS covering the period from 2011 Q1 to 2023 Q4 for target agents. Signal analysis was performed using the reporting odds ratio (ROR), proportional reporting ratio (PRR), Bayesian confidence propagation neural network (BCPNN) and multi-item gamma Poisson shrinker (MGPS) algorithm. Nonparametric tests were used to compare the time to onset of thrombocytopenia-associated fractures between different regimens. There were 404 reports of immune thrombocytopenia in the FAERS database. Immune thrombocytopenia was associated with all ICIs except tremelimumab, and signals were detected by all 4 methods. The median time to the onset of immune thrombocytopenia caused by PD-1, PD-L1 and CTLA-4 inhibitors was 47 days (range: 21-139.2), 21 days (range: 13-131) and 9 days (range: 7-27), respectively. The Weibull shape parameter test revealed that pembrolizumab-, durvalumab-, and ipilimumab-induced thrombocytopenia had a random failure-type profile, and nivolumab- and atezolizumab-induced thrombocytopenia were characterized by an early failure-type profile. There was a significant reporting signal of ICI-induced thrombocytopenia associated with most ICIs. Immune thrombocytopenia has a greater incidence in males, elderly individuals and Asian populations, and PD-1 inhibitors were the most common cause. Clinicians should be aware of the signs of potential serious adverse events.