Despite the subgroup analysis limited to the small sample size, the occurrence of CRS was associated with the baseline levels of β microglobulin, BCMA+ ratio in MM cells, the peak levels of serum interferon-γ and ferritin, and the ratio of peak to baseline of serum IL-6, interferon-γ and ferritin (Table S3). Here, IL6 is linked to Miyoshi myopathy.