LocaTIAN, locaTIAN, locaTIAN

In this issue ofBlood, Kaulen et al 1 provide, to our knowledge, the first comprehensive description of tumor inflammation-associated neurotoxicity (TIAN) in the setting of chimeric antigen receptor (CAR) T-cell therapy for central nervous system (CNS) lymphoma.With new therapies come new toxicities, and TIAN was recently defined by consensus to capture a pseudoprogression syndrome that has been observed during CAR T-cell therapy for tumors of the brain and spinal cord. 2 The hypothesized mechanism is inflammation around the tumor mass triggered by T-cell antitumor activity, similar to what has been observed with immune checkpoint inhibitors in solid tumors.Unique to the brain, even small changes in lesion volume can be dangerous, especially if there is mass effect on critical structures or obstruction of cerebrospinal fluid flow.