A recently published study in Blood Cells, Molecules and Diseases has revealed that daratumumab can be an effective novel treatment option for patients with pretreated primary immune thrombocytopenia (ITP). The study outlined that the sensitivity of primary ITP to daratumumab is interindividually heterogeneous and that the biomarkers indicating enduring remissions to daratumumab will ﬂank clinical decision-making in the future.
Immune thrombocytopenia (ITP) is a rare, autoimmune-mediated, isolated thrombocytopenia in which platelet-directed autoantibodies are the leading cause of the increased peripheral clearance of the thrombocytes. B-cells and plasma cells are the sources of antiplatelet antibodies, with the majority of antiplatelet antibodies being specifically produced by the long-lived plasma cells in the spleen and the bone marrow. Several single-patient reports and case series with daratumumab treatment in autoimmune cytopenia or, more specifically, secondary ITP in pediatric and adult populations have been reported in the literature.
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The study reports the clinical courses of 2 patients. Patient 1 was an 82-year-old female. Patient 2 was a 54-year-old male. Both patients had primary ITP after multiple relapses. They had exhausted standard therapies. Patient 1 has relevant medical history comprising therapeutic oral anticoagulation with edoxaban and an AV node ablation with severe thrombocytopenia and was later diagnosed with primary ITP. She was given CD38 antibody daratumumab for 6 months after standard therapy options were no use.
Patient 2 has a history of repetitive bruising devoid of adequate trauma, isolated thrombocytopenia, multiple sclerosis, primary ITP, obstructive sleep apnea syndrome, chronic obstructive pulmonary disease, and multivessel coronary artery disease. He was given daratumumab for 8 months after standard therapy options didn’t work. For both patients, daratumumab treatment was considered, initiated, and completed since no reported evidence of the efficacy of daratumumab as a novel therapeutic option for primary ITP was available.
Patient 1 relapsed for the 7th time after the second infusion of daratumumab, and she reported no lasting response to steroids and IVIG. Furthermore, after the 6th daratumumab infusion, her platelet count rose from 93 × 109/L to 219 × 109/L, which persisted within the normal range during subsequent infusions. On the other hand, patient 2 had daratumumab prematurely discontinued since he did not achieve the objective response after 8 weekly infusions. He is reportedly undergoing his 6th-line therapy with fostamatinib and has achieved stable platelet counts above 40 × 109/L for the past 8 months, except for 1 outlier that demanded a dose escalation.
The study has some limitations as it reports the results of only 2 cases of primary ITP. The results need to be confirmed in larger, randomized trials before daratumumab can be used as a standard treatment for ITP.
Vernava I, Schmitt CA. Daratumumab as a novel treatment option in refractory ITP, Blood Cells, Molecules, and Diseases, Published online January 18, 2023.