TNFRSF17 and plasma cell myeloma: Severe toxicity was significantly less in recent trials utilizing 4-1BB costimulatory CARs ide-cel and ciltacabtagene autoleucel (cilta-cel) targeting BCMA for the treatment of multiple myeloma with rates of grade ≥ 3 CRS or ICANS observed in only 4–5% and 3–9% of patients, respectively [14,15].