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\begin{document}

\title{Adalimumab-induced platelet antibodies resulting in severe
thrombocytopenia}



\author[1]{Henk-Jan Boiten}%
\author[2]{Sufia Amini}%
\author[2]{Frank Wolfhagen}%
\author[2]{Peter Westerweel}%
\affil[1]{Albert Schweitzer Hospital Location Dordwijk}%
\affil[2]{Affiliation not available}%


\vspace{-1em}



  
  \date{May 25, 2024}


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\selectlanguage{english}
\begin{abstract}
Anti-tumor necrosis factor alpha (TNF\selectlanguage{greek}α\selectlanguage{english}) agents are effective in diseases
including Crohn's disease (CD) but may cause cytopenias. The mechanisms
involved in anti-TNF\selectlanguage{greek}α \selectlanguage{english}agents induced thrombocytopenia are scarce. We
report a 73-year-old male with Crohn's disease for which he currently
used adalimumab, an anti-TNF\selectlanguage{greek}α \selectlanguage{english}agent. He had received mesalazine and
infliximab before the treatment of adalimumab. No comorbidities were
present. Routine laboratory tests revealed a deep thrombocytopenia
(thrombocytes 24x10*9/L) after which adalimumab was discontinued.
Bleeding symptoms included cutaneous hematomas and mild epistaxis.
Direct monoclonal antibody-specific immobilization of platelet antigens
(MAIPA assay) revealed autoantibodies specific to glycoprotein IIb/IIIa
(GPIIb/IIIa) and glycoprotein V (GPV) platelet receptors. There was no
bone marrow suppression. Other causes of the thrombocytopenia were ruled
out. The platelet count normalized after adalimumab discontinuation. No
further interventions were required. Monitoring thrombocyte levels after
initiating anti-TNF\selectlanguage{greek}α \selectlanguage{english}agents is recommended, which could lead to
prevention of this potential fatal phenomenon.%
\end{abstract}%



\sloppy


\textbf{Introduction}

Anti-tumor necrosis factor alpha (TNF\selectlanguage{greek}α\selectlanguage{english}) agents are effective in the
treatment of Crohn's disease (CD) and ulcerative colitis but may cause
adverse effects including cytopenias (1). Anti-TNF\selectlanguage{greek}α \selectlanguage{english}induced
thrombocytopenia, although not common, is a recognized side effect.
However, the exact mechanisms involved in anti- TNF\selectlanguage{greek}α \selectlanguage{english}thrombocytopenia
are unknown. We therefore present a case of adalimumab (anti-TNF\selectlanguage{greek}α \selectlanguage{english}agent)
- induced immune thrombocytopenia in a patient with CD in whom we were
able to demonstrate drug-induced platelet antibodies. Moreover, we
discuss the proposed mechanisms involved.

\textbf{Methods}

Adalimumab, a human anti-TNF monoclonal antibody, is effective for
inducing and maintaining remission in patients with Crohn disease who
are naive to infliximab (8--10).A 73-year-old male was diagnosed with CD
in 2016. Colonoscopy at that time revealed a mild chronic inflammation
of his sigmoid for which he was initially treated with mesalazine. No
comorbidities were present. Infliximab was started one year later, but
after 14 weeks of treatment the patient developed polyarthralgia,
myalgia and weight loss after which the infliximab was stopped. Analysis
revealed a lupus-like disease with positive antinuclear antibodies (ANA)
and anti-double-stranded DNA (anti-dsDNA), although these antibodies
were also detectable prior to infliximab treatment. Seven months later,
a colonoscopy showed significant chronic, active colitis of the distal
sigmoid with ulcerations. Due to the formation of antibodies against
infliximab, adalimumab was started. Adalimumab treatment was started
with 160mg subcutaneously at week 0, followed by 80mg at week 1 and was
then maintained on 40mg every 2 weeks. His polyarthralgia and myalgia
resolved and his weight stabilized. After three injections of
adalimumab, routine laboratory tests revealed a deep thrombocytopenia
(thrombocytes 24x10\textsuperscript{9}/l) after which adalimumab was
discontinued. His other medication at this time was mesalazine only.
Bleeding symptoms included cutaneous hematomas\textbf{hematomas
hematomas} and mild epistaxis. There were no bleeding symptoms requiring
immediate intervention. He denied any drug and alcohol abuse. Physical
examination revealed no fever, hepatosplenomegaly or lymphadenopathy.

Besides the thrombocytopenia, the complete blood count showed a mild and
stable normocytic anemia (hemoglobin 13.05 g/dL {[}normal 13.5-17.5{]}
with unremarkable leukocyte count and differentiation, and low
C-reactive protein. Thrombocyte counts in citrate anticoagulated blood
excluded EDTA-induced pseudo thrombocytopenia. Levels of folic acid,
vitamin B12, iron, liver enzymes and renal function were all within
normal ranges. Protein electrophoresis showed no monoclonal protein.
Peripheral blood smear revealed rouleaux formation and
macrothrombocytes. A bone marrow aspirate and biopsy showed
hypercellularity with an increased number of megakaryocytes with normal
morphology, consistent with intact megakaryopoiesis. Erythropoiesis and
myelopoiesis were unremarkable. Direct monoclonal antibody-specific
immobilization of platelet antigens (MAIPA assay) revealed
autoantibodies specific to glycoprotein IIb/IIIa (GPIIb/IIIa) and
glycoprotein V (GPV) platelet receptors. The thrombopoietin level was
normal (10 E/ml, normal 4-32).

Platelet count improved 6 days after cessation of adalimumab (platelet
count 71\selectlanguage{ngerman}×10\textsuperscript{9}/L) without further intervention and
increased to 139×10\textsuperscript{9}/L in two weeks. A fully
normalized platelet count (platelet count 203×10\textsuperscript{9}/L)
was observed 4 weeks after the last dose of adalimumab. Therapy for CD
was continued with methotrexate combined with mesalazine. There has been
no recurrence of the thrombocytopenia during further treatment. His CD
remained in clinical remission during treatment with methotrexate.

\textbf{Discussion}

Anti-TNF\selectlanguage{greek}α \selectlanguage{english}induced thrombocytopenia has been reported previously in
patients with rheumatoid arthritis (2), psoriasis (3,4) and CD (5-7).
Patients were treated with both etanercept and infliximab (2),
infliximab monotherapy (5) or adalimumab monotherapy (3,4, 6,7). Of
note, most of these reports have not reported on the presence of
specific autoantibodies against platelets. Furthermore, only two of the
aforementioned reports involved patients with CD who developed
thrombocytopenia associated with exposure to adalimumab (6,7). Salar et
al. (7) describe a patient with CD who received both infliximab and
adalimumab. A thrombocytopenia of 44\selectlanguage{ngerman}×10\textsuperscript{9}/L occurred
with platelet-associated IgG detected with a (undefined) platelet
antibody test. More recently, Casanova et al. (6) reported a patient
with CD who developed severe thrombocytopenia of
25×10\textsuperscript{9}/L after rechallenge treatment with adalimumab.
Tests for the presence of antibodies were not performed. In accordance
with the two patients with CD (6,7) our patient showed an increased
number of megakaryocytes in the bone marrow supporting an ITP-related
mechanism. Although an ITP-related mechanism has been speculated on in
other reports, our report with confirmed GPIIb/IIIa and GV platelet
autoantibodies provides conclusive evidence for this notion.

Our patient developed thrombocytopenia after three weeks of treatment.
In other reports, the time between the first exposure of the anti-TNF\selectlanguage{greek}α
\selectlanguage{english}agent varied and extended up to \textgreater{}2 years. Some reports
(3,6,7) showed an asymptomatic thrombocytopenia detected by routine
blood samples, while other cases presented with bleeding symptoms (1).

Drug-induced thrombocytopenia can be classified into nonimmune and
immune-mediated thrombocytopenia. Drug-induced immune-thrombocytopenia
(ITP) can be categorized into several mechanisms including the formation
of drug-specific antibodies or drug-dependent antibodies (e.g. quinine)
and production of autoantibodies specific to platelets (e.g. gold) (8).

The exact pathophysiological mechanism of adalimumab-induced ITP is not
known. A possible explanation, analogous to Aster et al. (8), is that
adalimumab interacts with the platelets membrane GPIIb/IIIa and GPV
through bridging interactions resulting in removal from the immune
system. Another possible mechanism is that binding of adalimumab to the
platelets membrane can cause a conformational change of the GPIIb/IIIa
and GPV resulting in a neo-epitope which stimulates the formation of
antibodies against platelets. Finally, previous reports hypothesized
that anti-TNF\selectlanguage{greek}α \selectlanguage{english}agents could induce apoptosis of Th1 lymphocytes leading
to a relative excess of Th2 lymphocytes that could in turn lead to the
production of antibodies (6,7).

This report adds to a general understanding of drug-induced
thrombocytopenia induced by adalimumab, which could lead to a better
recognition of this potential fatal phenomenon. Adalimumab-induced
immune-thrombocytopenia is a rare cause of thrombocytopenia reversible
upon adalimumab discontinuation. We report antibodies against multiple
epitopes including GPIIb/IIIa and GPV without bone marrow suppression.
MAIPA assay testing, if available, can be used to determine the platelet
glycoprotein target(s). In order to prevent serious adverse events we
recommend to monitor thrombocyte levels closely after initiation of
anti-TNF\selectlanguage{greek}α \selectlanguage{english}therapy. Although specific studies are lacking for
drug-induced ITP, standard ITP treatment with intravenous
immunoglobulins and/or steroids may be considered if interventions are
clinically warranted.

\textbf{Acknowledgement} : not applicable.

\textbf{Conflict of interest:} all authors state that they have no
conflict of interest

\textbf{Funding:} none.

\textbf{Data availability statement:} the data that support the findings
of this study are available from the corresponding author upon
reasonable request.

\textbf{References}

1. Brunasso AMG, Massone C. Thrombocytopenia associated with the use of
antitumor necrosis factor agents for psoriasis. J Am Acad Dermatol
2009;60:781-85.

2. Pathare SK, Heycock C, Hamilton J. TNFa blocker induced
thrombocytopenia. Rheumatology 2006;45:1314-15.

3. Nakahara T, Konishi S, Yasukochi Y, et al. Thrombocytopenia in a
psoriatic patient sequentially treated with adalimumab, secukinumab and
ustekinumab. J Dermatol 2019;46(5):e157-e158.

4. Chen M, Holland MJ, Mir MR, et al. Frequency of thrombocytopenia in
psoriasis patients treated with tumor necrosis factor-a inhibitors. J
Drugs Dermatol 2011;10:280-84.

5. Selby LA, Hess D, Shashidar H, et al. Crohn's disease, infliximab and
idiopathic thrombocytopenic purpura. Inflamm Bowel Dis 2004;10:698-700.

6. Casanova MJ, Chaparro M, Martinez S, et al. Severe adalimumab-induced
thrombocytopenia in a patient with Crohn's disease. J Crohns Colitis
2012;6:1034-1037.

7. Salar A, Bessa X, Muniz E, Montfort D, Besses C, Andreau M.
Infliximab and adalimumab-induced thrombocytopenia in a woman with
colonic Crohn's disease. Gut 2007;56:1169-1170.

8. Aster RH, Curtis BR, McFarland JG, et al. Drug-induced immune
thrombocytopenia: pathogenesis, diagnosis, and management. J Thromb
Haemost 2009;7:911-18.

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