Immune thrombocytopenia in patients treated with immune checkpoint inhibitors Available to Purchase

Author(s): Leaf, Rebecca K.1,2; Mones, Jodi V.3; Shenoy, Tushar4; Warsame, Mohamed5; Beltrami-Moreira, Marina6; Panch, Sandhya7,8; Leavitt, Andrew D.9,10; Zon, Rebecca L.2,11; Kendall, Ellen K.12; Shahamatdar, Sahar12; Lim, Tristan L.12; Cui, Can12; Jiang, Debbie1,2; Kaunfer, Sarah A.4; Durai, Lavanya4; Hoge, Steven T.4; Dias, Julie-Alexia4,13; Sha, Carrie3,14; Holmes, Aaron N.3,14; Easton, Neela3,14; Corley, Elizabeth M.3,14; Zhao, Ethan3,14; Li, Xingyi3,14; Spelman, Amy15; Amos, Christina Briggs15; Soebbing, Doris15; Shabih, Maria15; Jamison, Trevor15; Liu, Bolun5; Hussein, Guleid5; Yadav, Sumeet5; Elsaid, Mohamed I.16,17; Owen, Dwight H.17; Meara, Alexa17; Juras, Patrick K.18; Suresh, Arvind10; Heskel, Marina10; Huang, Jennifer J.7,8; Glezerman, Ilya G.19,20; Go, Ronald S.21; Reynolds, Kerry L.1,2; Al-Samkari, Hanny1,2; Kroll, Michael H.15; Leaf, David E.2,4;
Source: Blood (2026) 147 (12): 1351–1364
Original Article
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Dr. Anjan Patel's Thoughts

This is a nice reminder that immune checkpoint inhibitors (ICI)-associated immune thrombocytopenia (ITP) is uncommon but definitely not benign~1 in 400 incidence with a meaningful subset recurring on rechallenge of 30%, and while most patients recover, severity clearly tracks with worse outcomes including higher mortality. It reinforces that even “rare” hematologic irAEs can carry real clinical weight, so early recognition and thoughtful decisions around rechallenge are key.

ABSTRACT

Immune checkpoint inhibitor–associated immune thrombocytopenia (ICI-ITP) has been described in case reports and small case series, but comprehensive data on its incidence, risk factors, clinical features, treatment, and outcomes are lacking. We reviewed medical records of all adults initiating ICI therapy between 2016 and 2023 at 29 US hospitals across 7 major cancer centers to identify patients with ICI-ITP. Multivariable logistic regression was used to identify risk factors, and Cox modeling was performed to assess the association between ICI-ITP, its severity, and mortality. Among 86 467 patients, ICI-ITP occurred in 214 (0.25%). Independent risk factors included lower baseline platelet count, combination ICI therapy, stage IV cancer, and additional immune-related adverse events. ICI-ITP occurred at a median of 8 weeks (interquartile range [IQR], 4-18) after ICI initiation, with a median nadir platelet count of 41 × 109/L (IQR, 17 × 109/L to 64 × 109/L). Patients were treated with glucocorticoids (n = 106 [49.5%]), immune globulin (n = 39 [18.2%]), and thrombopoietin receptor agonists (n = 29 [13.6%]). Recovery occurred in 161 patients (75.2%) at a median of 2.3 weeks (IQR, 1.0-5.3). Of 76 patients rechallenged with ICIs, 23 (30.3%) developed recurrent ICI-ITP. ICI-ITP and its severity were associated with higher all-cause mortality, with a nearly threefold increase in risk among patients with severe ICI-ITP than those without ICI-ITP (adjusted hazard ratio, 2.96 [95% confidence interval, 2.14-4.08]). These findings establish ICI-ITP as a rare but clinically significant complication of ICI therapy, provide, to our knowledge, the first large-scale description of its risk factors and clinical course, and underscore the importance of timely recognition and management.

Author Affiliations

1Division of Hematology and Oncology, Mass General Brigham Cancer Institute, Boston, MA; 2Harvard Medical School, Boston, MA; 3Hematology Service, Memorial Sloan Kettering Cancer Center, New York, NY; 4Division of Renal Medicine, Brigham and Women’s Hospital, Boston, MA; 5Department of Hospital Internal Medicine, Mayo Clinic Health System, Mankato, MN; 6Division of Hematology, Department of Internal Medicine, The Ohio State University Comprehensive Cancer Center, Columbus, OH; 7Clinical Research Division, Fred Hutchinson Cancer Center, Seattle, WA; 8Division of Hematology/Oncology, University of Washington School of Medicine, Seattle, WA; 9Department of Laboratory Medicine, University of California San Francisco, San Francisco, CA; 10Department of Medicine, University of California San Francisco, San Francisco, CA; 11Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA; 12Department of Medicine, Massachusetts General Hospital, Boston, MA; 13Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA; 14Department of Medicine, New York–Presbyterian/Weill Cornell Medical Center, New York, NY; 15Section of Hematology, The University of Texas MD Anderson Cancer Center, Houston, TX; 16Division of Biostatistics and Population Health, Department of Biomedical Informatics, The Ohio State University College of Medicine, Columbus, OH; 17Division of Medical Oncology, Department of Internal Medicine, The Ohio State University Comprehensive Cancer Center, Columbus, OH; 18Department of Internal Medicine, The Ohio State University Comprehensive Cancer Center, Columbus, OH; 19Renal Service, Memorial Sloan Kettering Cancer Center, New York, NY; 20Department of Medicine, Weill Cornell Medical Center, New York, NY; 21Division of Hematology, Mayo Clinic, Rochester, MN

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