OBJECTIVES: The use of anti-CD38 monoclonal antibodies, including isatuximab (Isa) and daratumumab (Dara), in combination with carfilzomib (K) and dexamethasone (d), have provided important treatment options for patients with relapsed refractory multiple myeloma (RRMM) who have received 1-3 prior lines of therapy. IsaKd and DaraKd have demonstrated significant improvement in progression free survival (PFS) over Kd (median PFS: 41.7 vs 20.8 months and 28.4 vs 15.2 months, respectively, both p<0.001) with manageable safety profile. This study calculates regimen costs of IsaKd and DaraKd in the first year of treatment from US payer’s perspective.

METHODS: Using drug unit costs and dosing schedules per label, the model estimated first-year regimen cost (13 cycles) of IsaKd and DaraKd for a RRMM patient, assuming weight of 80 kg and body surface area of 1.86 m². The model considered wholesaler acquisition cost (WAC) and average sale price (ASP), once-weekly and twice-weekly dosing schedules for K, and daratumumab intravenous (DaraIV) and subcutaneous (DaraSC) formulations.

RESULTS: Assuming once-weekly K dosing, the first-year regimen costs of IsaKd, DaraIV-Kd, and DaraSC-Kd were $410,030, $438,092, and $450,848 using WAC, and $372,828, $387,156, and $407,404 using ASP, respectively. Assuming twice-weekly K dosing, the first-year regimen costs of IsaKd, DaraIV-Kd, and DaraSC-Kd increased to $554,912, $582,974, and $595,730 using WAC, and $502,316, $516,644, and $536,891 using ASP, respectively.

CONCLUSIONS: IsaKd incurred lower regimen cost than DaraIV-Kd and DaraSC-Kd in the first year assuming same dosing schedule of K. Future research is warranted to characterize real-world utilization pattern of anti-CD38 regimens, such as drug dosing schedule, adherence, and duration of treatment, to better understand the economic impact of treatment choice in RRMM.