Itacitinib (INCB039110), a JAK1 Inhibitor, Reduces Cytokines Associated with Cytokine Release Syndrome Induced by CAR T-cell Therapy

Clin Cancer Res. 2020 Dec 1;26(23):6299-6309. doi: 10.1158/1078-0432.CCR-20-1739. Epub 2020 Sep 30.


Purpose: T cells engineered to express a chimeric antigen receptor (CAR) are a promising cancer immunotherapy. Such targeted therapies have shown long-term relapse-free survival in patients with B-cell leukemia and lymphoma. However, cytokine release syndrome (CRS) represents a serious, potentially life-threatening side effect often associated with CAR T-cell therapy. CRS manifests as a rapid (hyper)immune reaction driven by excessive inflammatory cytokine release, including IFNγ and IL6.

Experimental design: Many cytokines implicated in CRS are known to signal through the JAK-STAT pathway. Here we study the effect of blocking JAK pathway signaling on CAR T-cell proliferation, antitumor activity, and cytokine levels in in vitro and in vivo models.

Results: We report that itacitinib, a potent, selective JAK1 inhibitor, was able to significantly and dose-dependently reduce levels of multiple cytokines implicated in CRS in several in vitro and in vivo models. Importantly, we also report that at clinically relevant doses that mimic human JAK1 pharmacologic inhibition, itacitinib did not significantly inhibit proliferation or antitumor killing capacity of three different human CAR T-cell constructs (GD2, EGFR, and CD19). Finally, in an in vivo model, antitumor activity of CD19-CAR T cells adoptively transferred into CD19+ tumor-bearing immunodeficient animals was unabated by oral itacitinib treatment.

Conclusions: Together, these data suggest that itacitinib has potential as a prophylactic agent for the prevention of CAR T cell-induced CRS, and a phase II clinical trial of itacitinib for prevention of CRS induced by CAR T-cell therapy has been initiated (NCT04071366).

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis
  • Azetidines / pharmacology*
  • Cell Proliferation
  • Cytokine Release Syndrome / drug therapy*
  • Cytokine Release Syndrome / etiology
  • Cytokine Release Syndrome / pathology
  • Cytokines / antagonists & inhibitors*
  • Female
  • Humans
  • Immunotherapy, Adoptive / adverse effects*
  • Isonicotinic Acids / pharmacology*
  • Janus Kinase 1 / antagonists & inhibitors*
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Mice, Inbred NOD
  • Mice, SCID
  • Precursor Cell Lymphoblastic Leukemia-Lymphoma / drug therapy*
  • Precursor Cell Lymphoblastic Leukemia-Lymphoma / immunology
  • Precursor Cell Lymphoblastic Leukemia-Lymphoma / pathology
  • Tumor Cells, Cultured
  • Xenograft Model Antitumor Assays


  • Azetidines
  • Cytokines
  • INCB039110
  • Isonicotinic Acids
  • JAK1 protein, human
  • Janus Kinase 1

Associated data