Effect of deferasirox + erythropoietin vs erythropoietin on erythroid response in Low/Int-1-risk MDS patients: Results of the phase II KALLISTO trial

Objectives: Erythropoiesis-stimulating agents (ESAs) remain first-choice to treat symptomatic anemia and delay transfusion dependence in most patients with lower-risk myelodysplastic syndromes (MDS) without del(5q). Deferasirox increased erythroid responses in some lower-risk MDS patients in clinical trials, and adding low-dose deferasirox to ESA treatment may further improve erythroid response.

Methods: KALLISTO (NCT01868477) was a randomized, open-label, multicenter, phase II study. Lower-risk MDS patients received deferasirox at 10 mg/kg/d (dispersible tablets) or 7 mg/kg/d (film-coated tablets) plus erythropoietin (n = 11), or erythropoietin alone (n = 12) for 24 weeks. The primary endpoint was the between-group difference in erythroid response within 12 weeks.

Results: Erythroid response occurred in 27.3% of patients receiving deferasirox plus erythropoietin vs 41.7% of patients receiving erythropoietin alone within 12 weeks (difference 14.4%; 95% CI -24.0, 48.16). Within 24 weeks, the hematologic response rate was 27.3% with deferasirox plus erythropoietin vs 50% with erythropoietin alone, and hematologic improvement rates were 45.5% vs 100%. Deferasirox plus erythropoietin was generally well tolerated.

Conclusions: In this small pilot study, combining low-dose deferasirox with erythropoietin did not improve erythroid response. It remains of interest to investigate early chelation approaches with even lower deferasirox doses plus erythropoietin in lower-risk MDS patients before the onset of transfusion dependence.