Stop TPO-receptor agonist in ITP Patients

According to the present guidelines, splenectomy is the therapy of first choice
as second line therapy in primary immune thrombocytopenia (ITP). If splenectomy
fails or patients have contraindications for splenectomy the guideline suggest
the use of thrombopoietin receptor agonists (TPO-RAs). However, recently the
label of the TPO-RAs has been changed, allowing the use of TPO-RAs in patients
that have not been splenectomized and have no comtranindication for
splenectomy. Therefore, TPO-RAs have become an alternative therapy for
splenectomy in ITP patients.The major disadvantage of TPO-RAs is, they are
considered to be symptomatic therapy and have to be given lifelong, resulting
in a possible life-long chance of adverse events and a large impact on the
medical budget. However, retrospective studies have shown that after
discontinuation of TPO-RAs 26-55% of the subjects can achieve prolonged
remission. A meta analysis of 99 studies (Zaja et al, 2020) shows an average
remission rate of 40% in patients after tapering TPO-RA. To date no predictive
values for the successful discontinuation of TPO-RAs are available. This study
has been designed to confrim these numbers. Secondly, to find the value of
predictieve tests as an aid for physicians in predicting successful
discontinuation of TPO-RAs, if possible.

Find/confirm percentage of remission after discontinuing TPO-RA in persistent
and chronic ITP patients.

Single arm intervention prospective cohort study. Per protocol analysis.

1 year TPO-RA use, then tapering off in 6 weeks.

Benefits: Possibly stopping medication for 30-40% of patients cost of drugs
reduction, reduction of adverse events, lowest possible dose.
Risks: Risk of relapse in study, risk of relapse at tapering period
(non-remission). Radiation from ITP-liver/spleen scan (1.56 mSv, considered not
harmful). Extra blood samples will be acquired at the moment of regular blood
sampling, thus no extra vena punctions are needed.
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