Should management of VITT include a short course of ibrutinib?
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Most guidance on VITT management focuses on 3 main strategies:
- Avoidance of heparin & platelet transfusions
- A short course of IVIG
- DOACs as first line anticoagulants
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- Avoidance of heparin & platelet transfusions
- A short course of IVIG
- DOACs as first line anticoagulants
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This excellent update from @COVIDSciOntario offers guidance on the diagnosis and treatment of VITT covid19-sciencetable.ca/sciencebrief/v…
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@COVIDSciOntario The rationale for IVIG is that it competitively inhibits a critical initiating step in VITT: the binding of immune complexes (anti-PF4/polyanion antibodies) to the platelet surface receptor FcγIIa (aka CD32a)
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Of note, IVIG is sometimes used as an adjunct for the management of autoimmune HIT (aHIT). Here’s a chronology and illustrative case from an exceptionally authoritative review.
tandfonline.com/doi/full/10.10…)
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tandfonline.com/doi/full/10.10…)
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But in platelets, binding of immune complexes to FcγIIa is just the start of things.
FcγIIa activates several kinases, including Bruton tyrosine kinase (Btk). This is a critical step in the subsequent events of platelet activation.
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FcγIIa activates several kinases, including Bruton tyrosine kinase (Btk). This is a critical step in the subsequent events of platelet activation.
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A few weeks ago, this preprint in @TH_journal laid out the theoretical basis for Btk inhibition in VITT using ibrutinib and related drugs thieme-connect.com/products/ejour…
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Enter this new preprint showing that
i) serum from patients with VITT activates platelets from healthy donors, and
ii) that activation is strongly inhibited by IVIG and several other compounds, including ibrutinib
medrxiv.org/content/10.110…
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i) serum from patients with VITT activates platelets from healthy donors, and
ii) that activation is strongly inhibited by IVIG and several other compounds, including ibrutinib
medrxiv.org/content/10.110…
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We will never have an RCT examining the additive value, if any, of ibrutinib to IVIG in the management of VITT.
But I think a case for it can be made on a few grounds.
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But I think a case for it can be made on a few grounds.
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#1: strong biologic plausibility
#2: inhibiting sequential steps in a biological process is intuitively appealing (think TMP-SMX & bacterial folate synthesis)
#3: A short course of ibrutinib is expected to be very safe
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#2: inhibiting sequential steps in a biological process is intuitively appealing (think TMP-SMX & bacterial folate synthesis)
#3: A short course of ibrutinib is expected to be very safe
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My take: A short course of low-dose ibrutinib (say 280 mg on day 1 and 140 mg/d for a week or so) might attenuate the severity of VITT.
(Of course it might not, but it's very unlikely to cause harm.)
Caveat: I'm no thrombosis expert; I welcome the input of those who are.
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(Of course it might not, but it's very unlikely to cause harm.)
Caveat: I'm no thrombosis expert; I welcome the input of those who are.
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