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175 A Fas-4–1BB immunomodulatory fusion protein converts a pro-death to a pro-survival signal, enhancing T cell function and efficacy of adoptive cell therapy in murine models of AML and pancreatic cancer
  1. Shannon Oda1,
  2. Kristin Anderson2,
  3. Philip Greenberg3,
  4. Nicolas Garcia3,
  5. Pranali Ravikumar3,
  6. Patrick Bonson3,
  7. Cody Jenkins3,
  8. Summer Zhuang3,
  9. Andrew Daman3,
  10. Shannon1
  1. 1Seattle Children’s Research Institute, Seattle, WA, USA
  2. 2University of Washington, Seattle, USA
  3. 3Fred Hutchinson Cancer Research Center, Seattle, WA, USA


Background Adoptive cell therapy (ACT) with genetically-modified T cells has shown impressive results against some hematologic cancers, but limited efficacy against tumors with restrictive tumor microenvironments (TMEs). FasL is a particular obstacle for ACT;1 it is expressed in many tumors and TMEs,1 including AML,2 ovarian3 and pancreatic cancers,4 and upregulated on activated T cells, where it can mediate activation-induced cell death (AICD).5

Methods We engineered T cells to boost function with novel immunomodulatory fusion proteins (IFPs) that combine an inhibitory ectodomain with a costimulatory endodomain. Like current checkpoint-blocking therapies, IFPs can abrogate an inhibitory signal, but also provide an often absent costimulatory signal. Additionally, IFP-driven signals are delivered only to the T cells concurrently engineered to be tumor-specific, thereby avoiding systemic T cell activation. For FasL-expressing TMEs, we developed an IFP that replaces the Fas intracellular tail with costimulatory 4-1BB. We tested the the Fas-4-1BB IFP in primary human T cells and in immunocompetent murine models of leukemia and pancreatic cancer.

Results Fas-4-1BB IFP expression enhanced primary human T cell function and enhanced lysis of Panc1 pancreatic tumor cells in vitro. Fas-4-1BB IFP-engineered murine T cells exhibited increased pro-survival signaling, proliferation, antitumor function and altered metabolism in vitro. Notably, the Fas ectodomain is trimeric5 and the 4-1BB intracellular domain requires trimerization to signal.6 In contrast, the CD28 domain is dimeric and did not enhance function when paired with 4-1BB.In vivo, Fas-4-1BB increased T cell persistence and function, and Fas-4-1BB T cell ACT significantly improved survival in a murine AML model. When delivered with a mesothelin-specific TCR, Fas-4-1BB T cells prolonged survival in the autochthonous KPC pancreatic cancer model, increasing median survival to 65 from 37 days (with TCR-only, **P=0.0042). Single-cell RNA sequencing revealed differences in the endogenous tumor-infiltrating immune cells, included changes in cell frequency and programming.

Conclusions We developed an engineering approach to enhance the in vivo persistence and antitumor efficacy of transferred T cells. Our targeted, two-hit strategy uses a single fusion protein to overcome a death signal prevalent in the TME of many cancers and on activated T cells, and to provide a pro-survival costimulatory signal to T cells. Our results suggest that this fusion protein can increase T cell function when combined with murine or human TCRs, and can significantly improve therapeutic efficacy in liquid and solid tumors, supporting clinical translation.


  1. Yamamoto, T.N., et al., T cells genetically engineered to overcome death signaling enhance adoptive cancer immunotherapy. J Clin Invest 2019.

  2. Contini P, et al., In vivo apoptosis of CD8(+) lymphocytes in acute myeloid leukemia patients: involvement of soluble HLA-I and Fas ligand. Leukemia 2007;21(2):p. 253–60.

  3. Motz GT, et al., Tumor endothelium FasL establishes a selective immune barrier promoting tolerance in tumors. Nat Med 2014;20(6):p. 607–15.

  4. Kornmann M, et al., Fas and Fas-ligand expression in human pancreatic cancer. Ann Surg 2000. 231(3): p. 368–79.

  5. Villa-Morales M and J Fernandez-Piqueras, Targeting the Fas/FasL signaling pathway in cancer therapy. Expert Opin Ther Targets 2012;16(1):p. 85–101.

  6. Wyzgol, A., et al., Trimer stabilization, oligomerization, and antibody-mediated cell surface immobilization improve the activity of soluble trimers of CD27L, CD40L, 41BBL, and glucocorticoid-induced TNF receptor ligand. J Immunol 2009;183(3):p. 1851–61.

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