title: A novel form of 4-1BBL has better immunomodulatory activity than an agonistic anti-4-1BB Ab without Ab-associated severe toxicity.
abstract: Agonistic Abs to select costimulatory members of CD28 and TNFR family have shown efficacy in various preclinical cancer immunotherapeutic settings. However, the use of agonistic Abs is often associated with severe toxicity due to non-specific activation of lymphocytes. We hypothesized that natural costimulatory ligands may serve as more potent and safer alternative to agonistic Abs for immunotherapy. In this communication, we focused on 4-1BBL as the molecule of choice because of the pleiotropic effects of 4-1BB signaling in the immune system and the demonstrated therapeutic efficacy of 4-1BB agonistic Abs in preclinical cancer and infection models. We report that a novel form of soluble ligand, SA-4-1BBL, delivered more potent and qualitatively different signals to T cells than an agonistic Ab. Importantly, while treatment of naïve mice with the agonistic Ab resulted in severe toxicity, as assessed by enlarged spleen and peripheral LNs, non-specific T cell proliferation, hepatitis, and systemic inflammatory cytokine production, treatment with SA-4-1BBL lacked these immune anomalies. Agonistic Ab treatment produced full toxicity in FcgammaR(-/-) or complement C1q(-/-) or C3(-/-) knockout mice, suggesting lack of involvement of stimulatory FcgammaRs or complement system in the observed toxicity. Naïve and memory T cells served as direct targets of anti-4-1BB Ab-mediated toxicity. Potent immunostimulatory activity combined with lack of toxicity rationalizes further development of soluble SA-4-1BBL as an immunomodulatory component of therapeutic vaccines against cancer and chronic infections.
authors.affiliation: Institute for Cellular Therapeutics, Department of Microbiology and Immunology, and James Brown Cancer Center, University of Louisville, KY 40202, United States.
authors.forename: Rich-Henry
authors.initials: RH
authors.lastname: Schabowsky
authors.forename: Kutlu G
authors.initials: KG
authors.lastname: Elpek
authors.forename: Shravan
authors.initials: S
authors.lastname: Madireddi
authors.forename: Rajesh K
authors.initials: RK
authors.lastname: Sharma
authors.forename: Esma S
authors.initials: ES
authors.lastname: Yolcu
authors.forename: Laura
authors.initials: L
authors.lastname: Bandura-Morgan
authors.forename: Robert
authors.initials: R
authors.lastname: Miller
authors.forename: Kathryn J
authors.initials: KJ
authors.lastname: MacLeod
authors.forename: Robert S
authors.initials: RS
authors.lastname: Mittler
authors.forename: Haval
authors.initials: H
authors.lastname: Shirwan
mesh_terms: D053330:4-1BB Ligand / Q000009:adverse effects / Q000378:metabolism*; D000276:Adjuvants, Immunologic / Q000009:adverse effects; D000818:Animals; D000906:Antibodies / Q000009:adverse effects / Q000276:immunology*; D005434:Flow Cytometry; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008817:Mice, Mutant Strains; D013601:T-Lymphocytes / Q000276:immunology; D053261:Tumor Necrosis Factor Receptor Superfamily, Member 9 / Q000276:immunology*
chemical_list: D053330:4-1BB Ligand; D000276:Adjuvants, Immunologic; D000906:Antibodies; D053261:Tumor Necrosis Factor Receptor Superfamily, Member 9