Sustained Remission of ITP with Thrombopoietin Receptor Agonists Treatment
Thrombopoietin receptor agonists (TPO-RAs) are highly effective drugs administered in chronic immune thrombocytopenia (ITP). Several studies have shown that they can induce remission and long-term response, even after prolonged discontinuation.
Findings from Studies
Monitoring Patients After Therapy Discontinuation with Ongoing Response
A team from Brno published a retrospective data analysis in the International Journal of Hematology in 2015 of patients with ITP treated with TPO-RAs, for whom therapy was discontinued due to sustained response. At the time, 46 patients were being treated for relapsed or refractory ITP. Treatment was stopped in 11 patients, of whom 7 received romiplostim and 4 eltrombopag, after achieving a response. No adverse effects were observed in any of them. All patients had previously been treated with 1−3 lines of other therapies, and 6 had undergone splenectomy. None of these 11 patients experienced disease relapse after discontinuation of TPO-RAs during a median follow-up of 33 months (range 16−54 months).
Experience with Newly Diagnosed and Non-Splenectomized Patients
Japanese authors in a recent publication also confirm the possibility of discontinuing treatment in some treated patients. The authors focused on newly diagnosed and non-splenectomized patients who achieved sustained complete remission with a platelet count of ≥ 100 × 109/l with TPO-RAs treatment. Between 2011 and 2018, 77 individuals were treated at the authors’ institution; 27 of them achieved total remission, and TPO-RAs treatment was discontinued. The overall response rate among all patients was 79.2%, and the TPO-RAs discontinuation rate was 41.6%. For newly diagnosed patients with ITP who had discontinued TPO-RAs treatment, the response rate without further treatment (TFR) within 2 years of follow-up was 66.4%, with a cumulative incidence of loss of complete remission at 46.7%. Patients who responded within 14 days of initiating TPO-RAs had a higher TFR rate (87.5% vs. 48.5%; p = 0.0106).
Multicentric Experience with Patients with Worse Prognosis
A Spanish group published an experience showing a decrease in disease activity and achievement of sustained TFR in patients with a rather worse prognosis. Multicentric monitoring in 19 Spanish hospitals involved 82 patients who started TPO-RAs treatment between 2012 and 2014; data were collected until 2018. The median time from ITP diagnosis to the start of TPO-RAs treatment was 5.5 years (range 1.1−50.3 years). In all patients, TPO-RAs administration was initiated with the vision of long-term therapy.
During the follow-up, 47.6% of patients discontinued TPO-RAs treatment. With a median prior duration of TPO-RAs therapy of 1.4 years (range 0.1−3.3 years), 19 patients (23.2%) achieved a long-term sustained platelet count of ≥ 50 × 109/l without any additional therapy to increase platelet counts. Worse achievement of TFR seemed to be associated with switching between TPO-RAs. Better chances of achieving TFR were also observed in patients treated with romiplostim. The median time to reduce and discontinue TPO-RAs and achieve a sustained platelet response was 3.3 years (95% confidence interval [CI] 2.7−4.0 years).
Conclusion
A significant group of patients with ITP, whether newly diagnosed or long-term and chronic, can achieve a treatment response lasting even after discontinuation of TPO-RAs. A more favorable prognostic group appears to be patients who were primarily treated with romiplostim and did not switch between TPO-RAs.
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Sources:
1. Červinek L., Mayer J., Doubek M. Sustained remission of chronic immune thrombocytopenia after discontinuation of treatment with thrombopoietin-receptor agonists in adults. Int J Hematol 2015; 102 (1): 7−11, doi: 10.1007/s12185-015-1793-1.
2. Iino M., Sakamoto Y., Sato T. Treatment-free remission after thrombopoietin receptor agonist discontinuation in patients with newly diagnosed immune thrombocytopenia: an observational retrospective analysis in real-world clinical practice. Int J Hematol 2020 Aug; 112 (2): 159−168, doi: 10.1007/s12185-020-02893-y.
3. Lozano M. L., Mingot-Castellano M. E., Perera M. et al. Predictive factors for thrombopoietin receptor agonist free responses in chronic ITP patients: a multicenter retrospective study with long-term follow-up. Blood 2019; 134 (Suppl_1): 2370.
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