In a case of a patient with R/R multiple myeloma who received steroids and palliative radiation to the spine for cord compression on days 6–20 after B-cell maturation antigen (BCMA) CAR T-cell infusion, there was a peak in T-cell receptor repertoire expansion, as well as interleukin-6 (IL6) and C-reactive protein (CRP), following RT at a time point later than would be expected with CAR T therapy alone (45). Here, IL6 is linked to plasma cell myeloma.