# High-Dose Intravenous Ferric Carboxymaltose/Derisomaltose Without ESAs for Cancer-Related Anemia in Japan: A Retrospective Single-Center Cohort Study

## TL;DR

This study shows that high-dose intravenous iron can effectively treat anemia in cancer patients in Japan without using erythropoiesis-stimulating agents or blood transfusions.

## Contribution

The study introduces a TSAT-guided clinical pathway for high-dose IV iron therapy in ESA-free cancer-related anemia management in Japan.

## Key findings

- Hemoglobin increased by approximately 1.2 g/dL in patients after one month of treatment.
- 82% of patients avoided blood transfusions, and 50% achieved a clinically meaningful rise in hemoglobin.
- Functional iron deficiency was the most common type and responded well to treatment.

## Abstract

In Japan, erythropoiesis-stimulating agents (ESAs) are not approved for chemotherapy-induced anemia; hence, many patients rely on transfusions. In this real-world data study, we evaluated the newest high-dose intravenous iron (ferric carboxymaltose or ferric derisomaltose) formulations in routine oncology practice. In 55 patients with cancer-related anemia, hemoglobin increased by approximately 1.2 g/dL at 1 month; 50% of the patients achieved a clinically meaningful rise (≥1 g/dL), and 82% avoided transfusion. Functional iron deficiency was the most common phenotype and responded well to treatment. The safety profile was excellent, with no infusion-related reactions or symptomatic hypophosphatemia (only a slight median change in serum phosphate levels). We further developed a transferrin saturation (TSAT)-guided clinical pathway to guide patient and dosing selection. Proactive, TSAT-guided intravenous iron may be a practical, ESA-free option to manage cancer-related anemia and reduce transfusion dependence in Japan.

Background/Objectives: In Japan, cancer-related anemia (CRA) is common, and erythropoiesis-stimulating agents (ESAs) are not approved for chemotherapy-induced anemia. Modern intravenous (IV) iron formulations, such as ferric carboxymaltose (FCM) and ferric derisomaltose (FDI), enable high-dose repletion; however, real-world evidence in ESA-free oncology settings remains limited. Methods: This single-center retrospective study included patients with CRA (N = 55) who received high-dose IV iron (FCM or FDI). Iron phenotypes were classified as absolute iron deficiency (ID), functional ID, or non-ID. The primary endpoint was hemoglobin (Hb) change from baseline to approximately 1 month (21–45 days) in the non-transfused patients. Secondary endpoints included responder rate (ΔHb ≥ 1.0 g/dL), transfusion avoidance rate, dosing adequacy relative to Ganzoni-calculated iron deficit, and safety, particularly hypophosphatemia. Results: Among the non-transfused patients, mean Hb increased from 8.76 ± 1.34 g/dL to 9.73 ± 1.75 g/dL (mean ΔHb +0.92 ± 1.44 g/dL; p < 0.001). The responder and transfusion avoidance rates were 48.9% and 81.8%, respectively. Functional ID was most prevalent (52.7%), with clinically meaningful Hb responses. A total of 38.2% achieved approximately 1000 mg dosing. The safety profile was excellent, and no infusion reactions or symptomatic hypophosphatemia was observed (median serum phosphate changed from 3.4 [3.0–3.9] to 3.2 [2.7–3.8] mg/dL). Conclusions: In this real-world Japanese oncology setting where ESAs were not available for chemotherapy-induced anemia, high-dose IV iron monotherapy (FCM or FDI) was well tolerated and was associated with modest short-term Hb increases and a high observed rate of transfusion avoidance within a 21–45-day assessment window. These findings suggest that a proactive, TSAT-guided IV iron therapy approach may be a pragmatic option for selected patients; however, durability beyond 1 month, optimal re-dosing, and generalizability require confirmation in larger, longer prospective studies.