Treatment of immune thrombocytopenia (ITP) secondary to malignancy: a systematic review

The many facets of immune-mediated thrombocytopenia: Principles of immunobiology and immunotherapy

Immune thrombocytopenia (ITP) is a rare autoimmune condition, due to peripheral platelet destruction through antibody-dependent cellular phagocytosis, complement-dependent cytotoxicity, cytotoxic T lymphocyte-mediated cytotoxicity, and megakaryopoiesis alteration. This condition may be idiopathic or triggered by drugs, vaccines, infections, cancers, autoimmune disorders and systemic diseases. Recent advances in our understanding of ITP immunobiology support the idea that other forms of thrombocytopenia, for instance, occurring after immunotherapy or cellular therapies, may share a common pathophysiology with possible therapeutic implications. If a decent pipeline of old and new agents is currently deployed for classical ITP, in other more complex immune-mediated thrombocytopenic disorders, clinical management is less harmonized and would deserve further prospective investigations. Here, we seek to provide a fresh overview of pathophysiology and current therapeutical algorithms for adult patients affected by this disorder with specific insights into poorly codified scenarios, including refractory ITP and post-immunotherapy/cellular therapy immune-mediated thrombocytopenia.

Refractory immune thrombocytopenia in adults: Towards a new definition

Immune thrombocytopenia (ITP) is an autoimmune haematological disorder characterized by immune-mediated thrombocytopenia and a variable risk of bleeding. Despite the availability of multiple treatment options, some patients are considered refractory since they do not achieve a platelet count response to multiple treatments and are at risk of bleeding. The term 'refractory' has been used to identify this patient group; however, with the advent of multiple lines of treatment, its meaning has become ambiguous. To address this issue, we reviewed previous definitions of refractory ITP, solicited the views of ITP experts and collected data from registries to inform a definition. Twenty ITP experts who attended the 7th Expert Meeting of the Intercontinental Cooperative ITP Study Group in September 2022 answered a web-based survey: 95% felt that there was a need for a new definition of refractory ITP for clinical and research purposes. The use of the term refractory, accompanied by a clear indication of the type and timing of failed treatments, was supported by 85% of respondents. Preliminary data on the frequency of refractory patients from the McMaster and Norwegian ITP Registries demonstrated that the proportion of adult ITP patients who had failed first-line therapy, rituximab, thrombopoietin receptor agonists, any immune suppressant medication and splenectomy ranged from 0.4% to 3.8%. We propose a definition of refractory ITP that could be evaluated in future studies.

Very Early Increased Platelet Count within a Week after Initiation of High-Dose Dexamethasone Treatment Is Associated with Long-Term Response in Newly Diagnosed Immune Thrombocytopenia Patients

To evaluate the long-term efficacy of high-dose dexamethasone (HD-DXM) treatment for immune thrombocytopenia (ITP), we retrospectively analysed 36 newly diagnosed ITP patients treated with HD-DXM as a first-line treatment. An initial response was obtained in 23 (63.9%) patients, including 11 with a complete response (CR) and 12 with a partial response (PR). Six months after HD-DXM treatment, 26 of 33 (78.8%) evaluable patients achieved objective responses, including 18 CR and 8 PR. Among 13 patients without initial response, very early increased platelet count within a week (VEIP) was observed in 7 patients, 5 (71.4%) of whom achieved a response at 6 months. In 29 patients who had available platelet count within a week, patients showing VEIP revealed longer survival than those who did not (p = 0.026). HD-DXM was an effective treatment for newly diagnosed ITP patients. VEIP after HD-DXM treatment initiation was associated with a long-term objective response in newly diagnosed ITP patients.