Improved Survival with Iron Chelation Therapy for Lower IPSS Risk MDS Appears to Have a Stronger Association in Patients with a Non-RARS Diagnosis

Several retrospective analyses suggest that transfusional iron overload portends inferior survival in lower risk MDS and that iron chelation therapy (ICT) is associated with improved survival in this group of patients. However an analysis of 126 patients with RARS from the Mayo Clinic showed no association between elevated ferritin level at diagnosis or transfusion burden on overall survival (OS). We performed a retrospective analysis of 268 MDS patients seen at our center to determine whether an association between transfusional iron overload or receiving iron chelation therapy (ICT) and survival differed between RARS and other lower risk MDS.

Patients were identified from the clinical database of the hematology practice. Patients with a diagnosis (dx) of MDS confirmed by bone marrow biopsy (bmbx) were included. Clinical and laboratory data were collected by retrospective chart review. Survival analyses were performed using SPSS version 19.

268 patients with a bmbx confirmed diagnosis of MDS by WHO or FAB criteria were identified. The following patients were excluded: uncertain IPSS score, n=35; intermediate-2 risk, n=33; high risk, n=16; RAEB-t, n=3; concomitant diagnosis of advanced stage non-Hodgkin lymphoma of uncertain type, n=1. The remaining 182 patients had the following characteristics: median age 69.5 (range 30–94) years and 109 (69.9%) were male. Specific MDS dx were: RA, n=27; RARS, n=53; RCMD, n=34; RAEB, n=15; MDS-U, n=22; hypocellular MDS, n=6; 5Q- syndrome, n=6; CMML, n=21. IPSS scores for all patients were: intermediate-1, n=101; low, n=74; uncertain (but IPSS score not >1.0), n=7. The marrow blast count was 6–9 x10⁹/L in 4 patients and <5 x10⁹/L in all others. Specific MDS treatment (rx) was: supportive care, n=82; erythropoiesis stimulating agents (ESA), n=22; immunosuppressive therapy (IST), n=10; lenalidomide, n=7; and chemotherapy, n=6. 137 patients received RBC transfusions and 38 received ICT: deferasirox (DFX), n=19; deferoxamine (DFO), n=9; DFO followed by DFX, n=9; and DFX followed by DFO, n=1. The median duration of ICT was 10.5 (range 0.5–64) months. Clinical features significantly associated with OS in univariate analyses of all 182 patients included: specific MDS dx; IPSS score; total number of red blood cell (RBC) units transfused over the course of follow-up; receiving ICT; specific MDS rx received; requirement for hospitalization; experiencing at least one episode of infection; and AML transformation (P</=0.01 for all); serum ferritin level >1000ng/mL was not significant in this analysis (P=not significant [NS]). In a multivariate analysis (MVA), the following factors remained significant for OS: specific MDS dx; IPSS score; receiving ICT; specific MDS rx; and AML transformation (P</=0.01 for all). In an MVA stratified for RARS, significant were: specific MDS dx (P<0.0001); IPSS score (P=0.005); specific MDS rx (P=0.038) and receiving ICT (P=0.039). At a median follow-up of 28 (0.1–245.9) months, 121 patients were alive (non-RARS, n=83 [64.3%]; RARS, n=38 [71.6%]) and the projected median OS for all patient was 99 months. The projected median OS for non-RARS patients without ICT and with ICT was 44 months and not reached (NR), respectively, and for RARS without and with ICT was 99 and 134.4 months (P<0.0001). The 5 year OS in these four groups was 39.2% and 91.7% (P=0.04); and 72.4% and 76.3%, respectively (P=NS). However, when RARS ICT patients were compared to only RBC transfusion dependent RARS patients not receiving ICT, the median OS was 73.8 vs 134.4 months, respectively, and 5 year OS was 59.9% and 76.3%, respectively (P=0.025).

These results suggest an association between receiving iron chelation therapy and survival in lower IPSS risk MDS, in keeping with prior analyses. However, the association between ICT and OS in non-RARS MDS appeared to be stronger than in RARS, in keeping with data from Mayo suggesting transfusional iron overload may not have a major association with outcome in RARS. The median follow-up in the current study was just over 2 years, and median duration of ICT only 10.5 months; longer follow-up may be needed in RARS to determine whether ICT is potentially beneficial in this subgroup of patients with a relatively long expected survival. As with all retrospective analyses, these results must be considered hypothesis generating, and prospective trials are needed for firm conclusions to be drawn.

Leitch:Novartis Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Off Label Use: Iron chelation agents for the treatment of transfusional iron overload in MDS. Vickars:Novartis Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.