Dear Editor,

Kwag et al. [[1] describe splenectomy outcomes in 45 patients with relapsed or refractory immune thrombocytopenia (ITP) according to first-line response to intravenous immunoglobulins (IVIG). Both stable responders and poor responders to IVIG had high initial responses to splenectomy. Although subsequent ITP relapse occurred in over 50% of patients, the relapse rate was only 12.5% in stable responders. Thus, response to IVIG may be a useful predictor of long-term response to splenectomy.

Other investigators have used platelet kinetic studies to predict which ITP patients might benefit most from splenectomy. For example, Palandri et al. [[2] used 111indium-labeled autologous platelet sequestration (ILAPS) studies on 70 ITP patients prior to splenectomy. The overall response rate was 88.5% with 80% complete responses. However, patients who had predominant splenic sequestration had an overall response rate of 96% and a complete response rate of 88%. At 20-year follow up, a stable response to splenectomy was significantly more frequent in patients achieving a complete response compared to patients achieving only a response (89% vs. 50%). Najean et al. [[3] and Sarpatwari et al. [[4] have, likewise, shown similar high rates of complete response following splenectomy for ITP patients with predominant splenic sequestration. More recently, in an Australian single center, retrospective audit of splenectomy for ITP following ILAPS studies, ITP patients with pure or predominant splenic sequestration had a 100% overall response rate with an 83.5% complete response rate [[5].

It appears, therefore, that both ITP patients who are stable responders to IVIG and those with predominant splenic sequestration on ILAPS studies have high rates of long-term remission following splenectomy. It is possible that both methods may be selecting out the same subset of ITP patients for whom splenectomy offers an excellent chance of long-term remission. If so, response to IVIG would be a quicker and cheaper way of selecting out the best candidates for splenectomy. Ideally, a prospective trial of patients undergoing splenectomy for relapsed or refractory ITP, in which response to IVIG and ILAPS are compared, might help to identify the most useful means of predicting response to splenectomy. However, for ITP patients who fail to respond to standard first-line treatments, such as corticosteroids and IVIG, many other effective options are now available, including thrombopoietin receptor agonists, rituximab and fostamatinib [[6]. Therefore, any future trials of splenectomy for ITP might well be difficult to accomplish.

The author reports no conflict of interest.

No funding sources for this work.

Philip Murphy wrote the manuscript.

Kwag D, Yoon J-H, Min GJ, Park S-S, Park S, Lee S-E, et al. Splenectomy outcomes in relapsed or refractory immune thrombocytopenia according to first-line intravenous immunoglobulin response. Acta Haematol. 2022;145(5):465–75.
Palandri F, Polverelli N, Catani L, Sollazzo D, Romano M, Levorato M, et al. The choice of second-line therapy in steroid-resistant immune thrombocytopenia: role of platelet kinetics in a single-centre long term study. Am J Hematol. 2014;89(11):1047–50.
Najean Y, Rain J-D, Billotey C. The site of destruction of autologous 111In-labelled platelets and the efficiency of splenectomy in children and adults with idiopathic thrombocytopenic purpura: a study of 578 patients with 268 splenectomies. Br J Haematol. 1997;97(3):547–50.
Sarpatwari A, Provan D, Erqou S, Sobnack R, David Tai FW, Newland AC. Autologous 111In-labelled platelet sequestration studies in patients with primary immune thrombocytopenia (ITP) prior to splenectomy: a report from the United Kingdom ITP Registry. Br J Haematol. 2010;151(5):477–87.
Ratnasingam S, Reid AS, Ma D, Bucki-Smith D, Gwini SM, Seneviratna L, et al. Indium-labelled autologous platelet sequestration studies predict response to splenectomy in immune thrombocytopenia: an Australian experience. Intern Med J. 2022;52(8):1387–93.
Song F, Al-Samkari H. Management of adult patients with immune thrombocytopenia (ITP): a review on current guidance and experience from clinical practice. J Blood Med. 2021;12:653–64.