Darbepoetin alfa Maintains Hemoglobin Levels in Patients with Myelodysplastic Syndromes (MDS) after Therapeutic Interchange from Epoetin alfa: Results of a Retrospective Chart Review.
Authors: Patton Jeffrey , Mun Yong , Wallace Joel 
Published: October 2019

Abstract
Patients with MDS often receive erythropoietic therapy for the treatment of anemia resulting from the disease. This retrospective chart review examined the impact of switching patients from their current dosing regimens of epoetin alfa (Procrit®) to darbepoetin alfa (Aranesp®) 200 mcg every two weeks (Q2W) following the implementation of therapeutic substitution guidelines in September 2003. Key eligibility criteria included: ≥ 18 years old with a diagnosis of MDS, and treatment with epoetin alfa therapy between May 2003 and January 2004. Patients receiving epoetin alfa therapy were either switched to darbepoetin alfa, or allowed to remain on epoetin alfa, depending on whether their treating physician had adopted therapeutic substitution guidelines. To ensure full characterization of the patient population, in the 16 weeks prior to the time of the therapeutic substitution, detailed demographic and disease characteristics were collected, in addition to dose requirements, transfusion status and hemoglobin profiles. To assess the impact on clinical outcomes, data were collected for 16 weeks after the therapeutic substitution guidelines were implemented (defined as the treatment period). Patients identified in the chart review who received at least one dose of study drug during both time periods were included in the analysis. Response was defined according to the international working group on MDS definitions (Cheson et al., Blood, 2000; 96(12):3671–4). Kaplan-Meier estimates (95% CL) for the percentage of patients with a major response (hemoglobin [Hb] change ≥ 2 g/dL over baseline or transfusion independence) or a minor response (Hb increase ≥ 1 g/dL to < 2 g/dL or a 50% reduction in transfusion requirements) during the treatment period were calculated. Data were abstracted from 142 patient charts, 112 (62 darbepoetin alfa; 50 epoetin alfa) of whom had confirmatory evidence of MDS available in their records (a documented bone marrow biopsy, French-American-British [FAB] classification, or karyotype [confirmed MDS population]). Baseline demographics for the confirmed MDS population were similar between the two cohorts. For those patients with data available, the majority had a FAB classification of refractory anemia with ≤ 5% bone marrow blasts. Mean baseline Hb was 11.0 g/dL for the darbepoetin alfa cohort (n=61) and 11.3 g/dL for the epoetin alfa cohort (n=48). The Kaplan-Meier percentage (95% CL) of patients with a major response was 27% (15, 39) for the darbepoetin alfa cohort and 19% (7, 30) for the epoetin alfa cohort; a minor response was noted for 46% (33, 59) and 47% (31, 63) of patients in the darbepoetin alfa and epoetin alfa cohorts, respectively. The Kaplan-Meier (95% CL) proportion of patients receiving red blood cell transfusions was similar between the groups: 8% (1, 15) for the darbepoetin alfa cohort and 12% (3, 22) for the epoetin alfa cohort. This study indicates that darbepoetin alfa achieved comparable clinical outcomes with epoetin alfa for the treatment of anemia in patients with confirmed MDS.