IL6 and congenital rubella syndrome: Multiplexed serum cytokine profiling revealed increases in key cytokines implicated in human CRS including IL-6, MCP-1, IFNγ and IL-10 at or shortly after peak CAR-T levels <i>in vivo</i>.<h4>Conclusion</h4>The observations noted in this case report are consistent with CRS development following CAR-T therapy in a canine patient.