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Case Reports
. 2025 Oct 1;30(10):oyaf260.
doi: 10.1093/oncolo/oyaf260.

Acquired hemophilia due to immune checkpoint inhibitors: a case series introducing emicizumab treatment

Louis Wolff  1   2 , Carolin Ertl  3 , Lucie Heinzerling  3   4 , Sandrine Aspeslagh  2   5   6 , Marthe Verhaert  2   5 , Raphael Lattenist  7 , Caterina Confente  8 , Catherine Lambert  9 , Maxime Ilzkovitz  1   2
Affiliations
Case Reports

Acquired hemophilia due to immune checkpoint inhibitors: a case series introducing emicizumab treatment

Louis Wolff et al. Oncologist. .

Abstract

Background: Acquired hemophilia A (AHA) is a rare but potentially life-threatening autoimmune bleeding disorder and immune-related adverse event (irAE) associated with immune checkpoint inhibitors (ICI). This study discusses 3 new cases of ICI-induced AHA from Belgium and the SERIO-Side Effect Registry Immuno-Oncology (www.serio-registry.org), placing them in the context of existing literature.

Methods: One case was encountered at a tertiary care center in Belgium. SERIO was queried and yielded another 2 cases. A comprehensive literature review using PubMed identified 8 additional cases.

Results: A total of 11 patients were analyzed, with a median age of 68 years (range: 56-71), 10 were male. Most (9/11) were treated with anti-PD-1 monotherapy. In 5 cases, toxicity appeared before the fourth cycle. Immunosuppressive therapy successfully achieved complete resolution of AHA in 9 of 11 patients. For the first time, one patient was successfully treated with emicizumab, a monoclonal bispecific antibody, which bridges activated factor IX and factor X.

Conclusions: Clinicians should be vigilant about ICI-induced AHA as a potentially severe irAE. Prolonged aPTT requires thorough evaluation. Upon AHA confirmation, eradication of anti-FVIII antibodies with corticosteroids, rituximab, or other immunosuppressant should be attempted. Emicizumab offers advantages over traditional replacement therapy, including ease of use and a potential reduction in immunosuppressive drug requirements-an important consideration in ICI-treated patients. Further research is needed to fully understand the pathophysiology and optimize treatment strategy for AHA.

Keywords: AHA; anti-CTLA4; anti-PD1; anti-PDL1; emicizumab; hemophilia; immune checkpoint inhibitors; immunotherapy.

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Conflict of interest statement

M.V.: Personal PhD mandate from Research Foundation Flanders (1SH4A24N). Honoraria for presentations from Ipsen, MSD, Roche, Domus Medica, Pfizer and Jansen: all paid to institution Travel support to attend meetings from Ipsen and Sanofi. S.A.: membership on an advisory board or board of directors the last 36 months: MSD, Sanofi, Roche, BMS, Pfizer, Ipsen, Galapagos, Astellas. L.W., M.I., M.V., and S.A. are board members of BITOX, the Belgian national multidisciplinary immunotoxicity board, which is sponsored by BMS, MSD, Pfizer, Merck, Roch, AstraZeneca, Ipsen and Sanofi. Sponsorship paid to Belgian Society of Medical Oncology. L.H. is a speaker and a memberof advisory boards for BMS, Immunocore, Novartis, Therakos in 12 last months. Involved in clinical studies in her institution with Agenus, Astrazeneca, BMS, Huya Bioscience, Immunocore, IO Biotech, Merck, Pfizer, Pierre Fabre, Regneron, Replimune, Sanofi, Sol-gel technologies. C.E. reports speaker fees from Bristol Myers Squibb, GSK, Immunocore, Kyowa Kirin, MSD. C.L. reports speakers and members of advisory board for Amgen, CSL Behring, LFB, Octapharma, Sanofi, Sobi, Roche.

References

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    1. Ertl C, Ruf T, Mentzer D, et al. The side effect registry immuno-oncology (SERIO) - a tool for systematic analysis of immunotherapy-­induced side effects. Eur J Cancer. 2024;199:113505. 10.1016/j.ejca.2023.113505 - DOI - PubMed
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