The purpose of this long-term follow-up (LTFU) study is to collect delayed adverse events (AEs) and understand the persistence of KYV-101 (autologous CAR T cell product; gene-modified product), in participants who have been administered KYV-101 (gene-modified product; autologous CAR T cell product). This LTFU protocol will be open to any participant who received at least one infusion of KYV-101 in a previous Kyverna sponsored clinical trial or Investigator Initiated Trial (IIT).