5 Key Takeaways

• 1

  CAR T-associated enterocolitis after BCMA-directed therapy involved inflammatory changes across intestinal T cells, myeloid cells, stromal cells, and epithelium.

• 2

  Some patients without enterocolitis had similarly profound B-cell and plasma-cell depletion, suggesting depletion alone did not explain the complication.

• 3

  Intestinal CAR T cells showed highly cytotoxic and inflammatory profiles, with activation of interferon and JAK–STAT signaling.

• 4

  In one patient, intestinal CAR T cells remained detectable more than 2 years after infusion despite being undetectable in blood and bone marrow.

• 5

  Two patients treated with upadacitinib had improvements in symptoms, fecal calprotectin, and body weight within 4 weeks.