Interleukin-5 is an adjunctive biomarker for engraftment syndrome in multiple myeloma patients undergoing autologous hematopoietic stem cell transplantation.

Autologous hematopoietic stem cell transplantation (ASCT) in multiple myeloma (MM) can cause engraftment syndrome (ES), a clinical diagnosis without specific laboratory biomarkers. Herein, six cytokines commonly elevated during transplantation were chronologically detected during ASCT in 96 patients with newly diagnosed MM, 24.0 % of whom experienced ES. Among the molecules demonstrating remarkable peak levels, only IL-5 was able to differentiate ES from non-ES. IL-5 measured on day 12 emerged as an optimal indicator of ES, and its diagnostic value was enhanced when combined with the proportion of endogenous CD8+ T cells after engraftment and daratumumab-naive history. Notably, IL-5 levels on day 6 (IL-5 D6) served as the earliest predictor. 70.8 % of the patients could be predicted as having ES or non-ES via the IL-5 D6 cutoff value and daratumumab treatment history. It suggests that IL-5 can aid in estimating ES, and prior exposure to daratumumab may reduce the incidence of ES.