Eltrombopag for the Treatment of Thrombocytopenia of Low and Intermediate-1 IPSS Risk Myelodysplastic Syndromes: Interim Results on Efficacy, Safety and Quality of Life of an International, Multicenter Prospective, Randomized, Trial

Background: About 10% of low risk patients with myelodysplastic syndromes (MDS) experience severe thrombocytopenia.  Bleeding and the scarce efficacy of platelet (PLT) transfusions drive research in novel treatments. Eltrombopag is an oral agonist of the thrombopoetin-receptor (TPO-R). Its potential in increasing platelet (PLT) counts in low risk MDS has not been evaluated. We present interim results on the efficacy and safety of eltrombopag in inducing PLT responses in patients with low and intermediate-1 International Prognostic Scoring System (IPSS) risk MDS with severe thrombocytopenia in a Phase II, multicentre, prospective, placebo-controlled, single-blind study (EQoL-MDS).

Methods: Primary endpoints are safety and efficacy of eltrombopag. Secondary endpoints include changes in quality of life (QoL), PLT transfusion requirement, incidence and severity of bleeding, and survival. Inclusion criteria are adult age; PLT<30 Gi/L; ECOG performance status < 4;  ineligibility for, relapsed or refractory to other treatments; and naive to TPO-R agonists. Eltrombopag/placebo (2:1) is administered at a 50 mg daily starting dose with 50 mg increases every 2 weeks to maximum 300 mg to target PLT 100 Gi/L. Dose interruptions or reductions are required for PLT >200 Gi/L or adverse events. Study design is shown in the figure. PLT response, assessed at each visit, is defined as Response if:  1) baseline PLT>20 Gi/L:  absence of bleeding  and increase by at least 30 Gi/L from baseline; 2) baseline PLT<20 Gi/L:  PLT>20 Gi/L and increase by at least 100%, not due to PLT transfusions; and Complete Response if PLT≥100 Gi/L and absence of bleeding. QoL scores are analysed by MDS-specific instrument, QOL-E v. 3.

Results: Seventy patients (46 on eltrombopag – Arm A, 24 on placebo -Arm B) have been randomized at the time of this report. Mean age is 68.3 (SD 13.0) years, M/F 38/32. ECOG performance status was 0 in 47 cases, 1 in 16 cases, 2 in 7 cases. Ten patients had comorbidities. According to the WHO 2008 classification, 22 patients had refractory cytopenia with unilineage dysplasia, 9 had refractory anemia with ringed sideroblasts, 31 had refractory cytopenia with multilineage dysplasia (of which 15 with ringed sideroblasts),  6 had refractory anemia with excess blasts-1 and 2 were unclassified. IPSS score was low in 48 cases. Mean baseline platelet (PLT) count was 17.1 (SD 8.2) Gi/L, mean hemoglobin level 10.8 (SD 2.5) g/dL and mean white blood cell count was 5.0 (SD 3.8) Gi/L.  Twenty-five (36%) patients were red blood cell transfusion-dependent. Thirty-three had a WHO bleeding scale of 1, 2 experienced mild blood loss, 4 a gross blood loss and 1 a debilitating blood loss. Fourteen patients in Arm A and 8 in Arm B had required PLT transfusions in the 8 weeks prior to randomization.  Twenty-three cases (50%) in Arm A have responded versus 2 (8%) in Arm B (p=0.001). Thirty-three patients have completed at least 24 weeks of study. Median time to response was 14 days (IQR 7-46 days) at a median daily dose of 75 (IQR 50-162.5 mg). PLT count increased by mean 53.2 (SD 68.1) Gi/L (p=0.001)  in Arm A versus no significant changes in Arm B by week 24.

QOL-E scores at baseline and 12 weeks in 47 cases in both arms are shown in the table. There was an increase in treatment outcome index,mainly experienced in the first 3 weeks (p=0.034). Fatigue improved from baseline to 12 weeks associated with response (p=0.016).

Related Grade III-IV adverse events (AE) occurred in 10 patients (22%) in Arm A and consisted in: nausea (4), hypertransaminasemia (3), hyperbilirubinemia (1), sepsis (1), pruritis (1), heart failure (1), asthenia (1), vomit (1),  while in Arm B 1 patient (4 %) experienced grade 3 bone marrow fibrosis. MDS disease progression occurred in 5 (11%) in Arm A versus 2 (8%) in Arm B, p=ns.

Conclusions: Preliminary data indicate that lower risk  MDS patients with severe thrombocytopenia  undergoing treatment with eltrombopag experience significant improvements in PLT counts accompanied by improvements in fatigue. The drug appears to be well-tolerated and not associated with MDS progression. Further follow-up is required to evaluate the impact on survival.

 

Figure.  Study design

 

 

 

Table.  QOL-E domains at baseline and 12 weeks between Arm A (eltrombopag) and Arm B (placebo)