Evaluation of subcutaneous daratumumab injections in the ambulatory care setting

Subcutaneous daratumumab is non-inferior to intravenous daratumumab for the treatment of multiple myeloma and significantly reduced incidence of systemic reactions. However, manufacturer for subcutaneous daratumumab has not provided guidance regarding optimal methods for monitoring for hypersensitivity reactions following subcutaneous daratumumab administration.

A retrospective analysis was performed in two cohorts of patients who received at least two doses of subcutaneous daratumumab for the treatment of plasma cell disorders: patients with previous exposure to intravenous daratumumab (dara-exposed) and patients without history of intravenous daratumumab (dara-naïve). The primary outcome was incidence of systemic and injection-site reactions following first dose of subcutaneous daratumumab. Secondary analysis included time to systemic and injection-site reactions, grading of adverse reaction, and incidence of second systemic reaction.

Thirty-one patients were dara-naïve and 49 patients were dara-exposed. Differences in incidence of systemic (dara-naïve: 9.7% vs dara-exposed: 6.1%, p = 0.67) and injection-site reactions (dara-naïve: 12.9% vs dara-exposed: 14.3%, p = 0.99) did not reach statistical significance. Difference in median time to systemic reaction (dara-naïve: 3 h vs dara-exposed: 12 h, p = 0.18) was clinically important but did not reach statistical significance. Median time to injection-site reactions (dara-naïve: 6 h vs dara-exposed: 24 h, p = 0.03) was shorter in the dara-naïve cohort. No clinically meaningful difference was observed for incidence of second systemic reaction.

Most reactions were mild and did not require medical intervention. Following first subcutaneous daratumumab dose, monitoring for 3 h for dara-naïve patients and no monitoring time for dara-exposed patients for hypersensitivity reactions may be a safe and reasonable practice.