Abstract 788P
Background
Intravenous (IV) daratumumab administration can cause infusion reaction (IR) and requires a long infusion time. Recently, a subcutaneous formulation (SC) of daratumumab was approved, which shortens administration time and reduces IR occurrence. However, because SC is administered at a fixed dose, side effects may develop in patients with low body weight. Therefore, we investigated blood levels and safety profile of SC daratumumab in multiple myeloma (MM) patients who switched from IV to SC.
Methods
Patients who switched from IV to SC daratumumab between June 2021 and May 2022 at the Kobe City Medical Center General Hospital were enrolled in this study. Blood daratumumab levels were measured using liquid chromatography-tandem mass spectrometry. Safety after switching from IV to SC was evaluated for six months and graded according to the Common Terminology Criteria for Adverse Events version 5.0. We continued to assess safety for an additional six months, for a total evaluation period of one year after switching to SC.
Results
The median body weight of the ten patients included in these analyses was 57.4 kg (range: 45.0–74.4). Blood daratumumab levels increased significantly after switching to SC (p=0.002); median through concentration at the last IV dose was 403.6 μg/mL (range: 96.3–776.3) and that at the third SC dose was 557.1 μg/mL (range: 288.3–997.2). Grade 1–2 IRs were observed in six patients (60.0%) after switching to SC. A new grade 3 adverse event (neutropenia) occurred in only one patient. In the additional six-month investigation period, new grade 1–2 anemia and thrombocytopenia were observed in three patients (30.0%). No new adverse event of Grade 3 or higher was observed.
Conclusions
Blood daratumumab levels significantly increased after switching from IV to SC in patients with MM. However, long-term safety data indicate that the switch was well tolerated.
Clinical trial identification
Editorial acknowledgement
We would like to thank Editage (www.editage.jp) for English language editing.
Legal entity responsible for the study
Kobe City Medical Center General Hospital.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.