High Rate of Erythroid Response During Iron Chelation Therapy in a Cohort of 105 Patients Affected by Hematologic Malignancies with Transfusional Iron Overload: An Italian Multicenter Retrospective Study

Improvements in hematologic parameters have been associated with iron chelation therapy (ICT) in transfusion-dependent patients with chronic anemia associated with hematologic malignancies. Data from a significant cohort of myelodysplastic syndromes (MDS) patients enrolled in the EPIC study and treated with deferasirox reported a percentage of 22.6% of erythroid responses. Several sporadic reports showed hematologic improvement in patients treated with deferoxamine or deferasirox in patients affected by myelofibrosis (PMF) and Aplastic Anemia (AA). The aim of this study was to retrospectively evaluate the hematologic response in the entire cohort of chronic anemias with iron overload receiving ICT with both deferasirox (DFX) or deferoxamine (DFO) in 6 hematological Italian centers from 1993 to 2011. Methods: 105 patients received ICT for at least 3 months. Sixteen were PMF, 8 AA, 75 MDS, 4 Chronic Myelomonocytic Leukemia (CMML), 2 Acute Myeloid Leukemia (AML). 30 patients received deferoxamine (6 PMF, 3 AA, 1 CMML, 2 AML, 18 MDS), and 68 deferasirox (9 PMF,5 AA, 3 CMML, 51 MDS), and 7 received deferasirox after a prior treatment with deferoxamine (1 PMF, 6 MDS). The median serum ferritin levels at the time of ICT was 1983 ng/ml and it was not significantly different between the two cohorts (p=0,8). Patients, at the time of ICT, had transfused a median of 30 Units of RBC (40 in the DFO cohort and 24.5 in DFX cohort, p=0.001). 25 out of 105 were receiving EPO therapy at the time of chelation, started at least 6 months before ICT, without a significant clinical improvement and three were receiving a JAK2 inhibitor started at least 1 year before ICT. Patients receiving any kind of therapy able to modify the erythroid response including azacitidine were excluded as well as patients receiving EPO started less than 6 months before ICT or JAK2 inhibitors or immunosuppressive therapy less than 12 months before. Hematological response (HR) was evaluated as follow: Achieving a RBC transfusion independency (complete HR) or Hematological improvement (HI-e) for patients showing a Hb increase of 1.5 g/dL or a reduction of 4 RBC transfusions/8 weeks (IWG 2006). Results: We retrospectively analyzed an unselected cohort of patients with transfusion dependent iron overload affected by different hematologic malignancies who received ICT outside clinical trials thus allowing the inclusion of high risk MDS/AML. 13 patients were not evaluable because they were receiving ICT for less than 3 months. 41 patients out of 92 (42.7%) evaluable patients achieved a hematologic response. In details: 18 (19,5%) became completely RBC transfusion independent. Six (1 AA, 3 RARS, 1 RCMD, 1 AML) were under DFO treatment and 12 (3 AA, 2 RA, 3 RARS, 1 RAEBII, 1 CMML, 2 PMF) under DFX. In addition, all 4 AA patients who achieved transfusion independency significantly increased the number of platelets ( median 17.000/mm3 before ICT and 35.000 and 55.000 after 6 and 12 months of ICT). Median time to response was 15 months for DFO and 3 months for DFX. 16 patients (17.3%) (6 RA, 4 RARS,1 RCMD, 1 RAEB, 4 PMF) obtained HI-e defined as a reduction of 4 U/8 weeks (5 in DFO and 11 in DFX cohorts) after a median of 6 months for both DFO and DFX. HI-e defined as an increased of 1.5 g/dL was observed in 7 patients (7.6%) ( 4 RA, 1 RARS, 1 RCMD, 1 PMF) after a median of 6 months for DFO and 3 for DFX. The hematologic improvement is not strictly related to an effective reduction of serum ferritin (p=0,4). Conclusions: Our data show a high rate of complete responses, mainly in AA and RARS but also in high risk MDS/AML representing 11% of those achieving complete transfusion independency. Notably 50% of AA achieved RBC and platelet transfusion independency. Despite the limitation due to the retrospective collection of data we suggest the ICT could result in hematologic improvement in a wide population including patients who are, at present, outside the published ICT guidelines. This study warrants further investigation on the mechanism of action of ICT in inducing erythroid response.

Saglio:Novartis, Brystol Myers: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau.