GM-CSF inhibition reduces cytokine release syndrome and neuroinflammation but enhances CAR-T cell function in xenografts

Rosalie M. Sterner, Reona Sakemura, Michelle J. Cox, Nan Yang, Roman H. Khadka, Cynthia L. Forsman, Michael J. Hansen, Fang Jin, Katayoun Ayasoufi, Mehrdad Hefazi, Kendall J. Schick, Denise K. Walters, Omar Ahmed, Dale Chappell, Tarek Sahmoud, Cameron Durrant, Wendy K. Nevala, Mrinal M. Patnaik, Larry Pease, Karen E. Hedin, Neil E. Kay, Aaron J. Johnson and Saad S. Kenderian

Key points

  • GM-CSF neutralization with lenzilumab during CART19 therapy prevents CRS and neuro-inflammation and is a viable therapeutic solution.

  • GM-CSF neutralization and GM-CSF knockout in CAR-T cells enhance their anti-tumor functions.


Chimeric antigen receptor T (CAR-T) cell therapy is a new pillar in cancer therapeutics; however, its application is limited by the associated toxicities. These include cytokine release syndrome (CRS) and neurotoxicity. While the IL-6R antagonist tocilizumab is approved for treatment of CRS, there is no approved treatment of neurotoxicity associated with CD19 targeted CAR-T (CART19) cell therapy. Recent data suggest that monocytes and macrophages contribute to the development of CRS and neurotoxicity after CAR-T cell therapy. Therefore, we investigated neutralizing granulocyte macrophage colony-stimulating factor (GM-CSF) as a potential strategy to manage CART19 cell associated toxicities. In this study, we show that GM-CSF neutralization with lenzilumab does not inhibit CART19 function in vitro or in vivo. Moreover, CART19 cell proliferation was enhanced and durable control of leukemic disease was maintained better in patient derived xenografts after GM-CSF neutralization with lenzilumab. In a primary acute lymphoblastic leukemia (ALL) xenograft model of CRS and neuro-inflammation (NI), GM-CSF neutralization resulted in a reduction of myeloid and T cell infiltration in the central nervous system and a significant reduction in NI and prevention of CRS. Finally, we generated GM-CSF deficient CART19 cells through CRISPR/Cas9 disruption of GM-CSF during CAR-T cell manufacturing. These GM-CSFk/o CAR-T cells maintained normal functions, had enhanced anti-tumor activity in vivo, and improved overall survival compared to CART19. Together, these studies illuminate a novel approach to abrogate NI and CRS through GM-CSF neutralization, which may potentially enhance CAR-T cell function. Phase II studies with lenzilumab in combination with CART19 therapy are planned.

  • Submitted October 22, 2018.
  • Accepted November 14, 2018.