IL6 and congenital rubella syndrome: Due to its presumed limited penetration into the cerebrospinal fluid, which may paradoxically result in elevated IL-6 levels within the CNS, some experts recommend avoiding its use in cases of isolated ICANS or when CRS is limited to grade 1.73,97 Further clarification of these clinical nuances, as well as the refinement of current treatment strategies, would require evidence from prospective randomized controlled trials.98