Efficacy of Thrombopoietin Receptor Agonists in Evans Syndrome: An International Multicenter Experience

Background: Evans syndrome (ES) is a rare condition, defined as the presence of two autoimmune cytopenias (AIC), more frequently autoimmune hemolytic anemia (AIHA) and immune thrombocytopenia (ITP), and rarely autoimmune neutropenia (AIN). ES can be classified as primary or secondary to various conditions, including lymphoproliferative disease (LPD), primary immune deficiencies (PID) or other systemic autoimmune diseases (AID). ES onset may be acute and life-threatening, whilst its clinical course is usually chronic and marked by several relapses of AIHA, ITP or both. First line therapy is based on steroids +/- intravenous immunoglobulins (IVIG), followed by rituximab and splenectomy in refractory/relapsing cases. Concerning ITP, splenectomy is not always feasible, and rituximab is poorly effective on the long term. Thrombopoietin receptors agonists (TPO-RA), such as romiplostim (ROMI) and eltrombopag (EPAG), are commonly used in primary ITP with high efficacy; however, their use in ES has never been systematically studied.

Aim: to evaluate the efficacy and safety of TPO-RA in a multicentric cohort of patients with ES.

Methods: all ES patients treated with TPO-RA at 8 European hematologic hospitals (3 Italian, 2 Danish, 1 United Kingdom and 2 Spanish) were retrospectively evaluated. Baseline hematologic parameters, associated conditions, previous treatments and those administered concomitantly to TPO-RA were registered. The time from diagnosis to first TPO-RA was collected. Response rates were evaluated at 1, 3, 6, and 12 months, and classified as partial (PR) or complete (CR), for platelets >30x10^9/L or >100x10^9/L, respectively. Treatment emergent adverse events (TAEs) were registered and graded according to CTCAE.

R esults: As shown in Figure 1, 22 ES patients have been evaluated, 9 of whom secondary (40%). Almost all patients had received steroids +/- IVIG, and the majority at least one further line. The median time from diagnosis to TPO-RA start was 25,74 months (1-1390). Response rates to the first TPO-RA (16 EPAG and 6 ROMI) were: 82% at month 1, 84% at month 3, 83% at month 6 and 93% at month12. Eight patients started TPO-RA within 1 year from ES diagnosis. These patients displayed significantly lower platelets (p=0.01) as compared to others, however response rates were comparable. Of note, 73% of patients required concurrent therapies, including steroids +/- IVIG (N=13), danazol (N=2), rituximab (N=3), and immunosuppressants (N=3). Moreover, 7 patients required the addition of a rescue therapy to control ITP (steroids +/- IVIG N=4, rituximab N=1, danazol N=1, daratumumab N=1, immunosuppressants N=2, parsaclisib N=1), particularly in secondary ES (63% vs 33%). The latters less frequently showed increased bone marrow megakaryocytes (67% vs 92%) but had higher dysplasia (50% of patients vs 33% in primary ES). Interestingly, 5 subjects switched to the alternative TPO-RA (3 ROMI to EPAG and 2 vice versa) 2 because of no response (NR), and 3 for relapses. Three subjects responded but required additional therapies, including splenectomy, steroids +/- IVIG, or platelet transfusions. Ten out of 22 patients developed at least one TEAE: G1 thrombocytosis (N=1), G2 bone marrow fibrosis (N=1), G3/4 thrombosis (3 venous and 2 arterial: 1 pulmonary embolism, 1 cerebral vein thrombosis CVT, and 1 splanchnic thrombosis, 1 atrial thrombus and 1 acute myocardial infarction in the same APS patient experiencing CVT). Thrombosis was associated with the presence of secondary ES (p=0.03). Five patients are still receiving TPO-RA, whilst the other stopped because of persistent CR (N=12), thrombosis (N=3), increase in bone marrow reticulin fibrosis (N=1), or death for infectious complication.

Conclusions: TPO-RAs were effective in more than 80% of ES patients, even heavily pre-treated. However, TPO-RA use was complicated by a high occurrence of thrombotic events that may be also favored by the underlying conditions. Additionally, TPO-RA required a concomitant therapy in the majority of patients, suggesting that in ES autoimmune platelet destruction cannot be completely overcome by bone marrow stimulation.

Figure 1

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Figure 1

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