Platelet closure time in the evaluation of efficacy of CAR-T cell therapy in relapsed/refractory multiple myeloma

Abstract Purpose In recent years, many studies of platelet function in multiple myeloma (MM) patients have been reported. However, the role of platelet function in relapse/refractory (R/R) MM after chimeric antigen receptor T (CAR-T) cell therapy remains to be clarified. Methods In this study, we investigated platelet closure time (PCT) in the evaluation of efficacy of CAR-T cell therapy in patients with R/R MM, clinical data of 50 patients were retrospectively analyzed. Collagen/adenosine diphosphate (CADP) and Collagen/Epinephrine (CEPI)-induced PCT of peripheral blood were detected by platelet function analyzer-200, respectively, with 20 healthy individuals as control. Results After the approach of CAR-T cell therapy, CADP PCT and CEPI PCT decreased significantly when compared with those before treatment: (67.22, 95% CI 46.91–87.53, P < 0.01) and (77.46, 95% CI 59.43–95.50, P < 0.01). CADP PCT was positively correlated with TT (r = 0.305, P = 0.047), ISS stage (r = 0.389, P = 0.005) and cytokine release syndrome (CRS) stage (r = 0.328, P = 0.020), whereas negatively associated with λ-type light chain (r = − 0.399, P = 0.014) and IgM (r = − 0.355, P = 0.017). In addition, patients who achieved >PR had a shorter PCT compared with those ≤ PR. Moreover, the PCT of patients with grade 3–5 CRS was considerably longer than grade 0–2 CRS after treatment. Conclusion PCT could be defined as a potential indicator in the evaluation of efficacy of CAR-T cell therapy.