SDC1 and neoplasm: Albeit no imaging evidence to support tumor infiltration in the liver, immunohistochemistry indeed revealed a scattered distribution of plasma cells expressing CD138 and BCMA (Supplementary Fig. 6h~n), indicating that the 2nd_CRS was probably initiated in the liver with cytotoxic Cilta-cel accumulation, which was most likely relevant to the exposure of localized BCMA antigen.