Analysis of different types of cytokine release syndrome in patients with relapsed/refractory multiple myeloma: a retrospective study

Abstract Background Chimeric antigen receptor T-cell (CAR-T) therapy has achieved remarkable efficacy in patients with relapsed/refractory multiple myeloma. However, CAR-T-cell therapy-related complications, particularly cytokine release syndrome (CRS), have emerged as major barriers to its widespread application. CRS causes a wide range of clinical symptoms and induces severe systemic inflammation, which can result in treatment failure and even death. This study sought to characterise clinical manifestations among CRS subgroups stratified by three binary clinical dimensions: onset timing, severity and duration, to inform early recognition and individualised symptom‑directed management. Methods This was a retrospective observational study. Data from 128 patients with relapsed/refractory multiple myeloma treated with CAR-T-cell therapy were analysed. Demographic information, haematological indicators and clinical manifestations were collected. CRS was stratified into different subgroups according to three binary clinical dimensions: onset timing, severity and duration. Categorical variables were reported as n (%). Normally distributed continuous variables were expressed as the mean ± standard deviation, whereas non-normally distributed data were presented as the median (P 25 , P 75 ). The groups were compared using the Mann-Whitney U test and chi-square test. Results The predominant manifestations included high fever (86.72%), chills (85.16%), tachycardia (83.59%), sweating (79.69%), mucocutaneous pallor (75.78%), and fatigue (75%). Patients with immediate CRS had a lower rate of mucocutaneous pallor than those with non-immediate CRS (61.4% vs. 87.32%, p = 0.001). Compared with mild CRS, severe CRS was associated with a higher incidence of high fever (81.48% vs. 95.74%, p = 0.022), chest tightness (13.58% vs. 31.91%, p = 0.013), and dyspnoea (17.28% vs. 42.55%, p = 0.002). Patients with persistent CRS exhibited a lower incidence of significant hypotension than those with non-persistent CRS (22.7% vs. 40.0%, p = 0.044). Conclusions The clinical manifestations of CRS are closely associated with its onset timing, duration, and severity. Distinct symptom profiles across CRS subgroups support tailored nursing surveillance and intervention to optimise patient outcomes. Trial registration This was a retrospective observational study. Since it is a non-interventional study, clinical trial registration is not required, and this study was not registered in any clinical trial registry.