Activation of 4-1BB on Liver Myeloid Cells Triggers Hepatitis via an Interleukin-27–Dependent Pathway

Abstract

Agonist antibodies targeting the T-cell costimulatory receptor 4-1BB (CD137) are among the most effective immunotherapeutic agents across preclinical cancer models. In the clinic, however, development of these agents has been hampered by dose-limiting liver toxicity. Lack of knowledge of the mechanisms underlying this toxicity has limited the potential to separate 4-1BB agonist-driven tumor immunity from hepatotoxicity. The capacity of 4-1BB agonist antibodies to induce liver toxicity was investigated in immunocompetent mice, with or without coadministration of checkpoint blockade, via (i) measurement of serum transaminase levels, (ii) imaging of liver immune infiltrates, and (iii) qualitative and quantitative assessment of liver myeloid and T cells via flow cytometry. Knockout mice were used to clarify the contribution of specific cell subsets, cytokines, and chemokines. We find that activation of 4-1BB on liver myeloid cells is essential to initiate hepatitis. Once activated, these cells produce interleukin-27 that is required for liver toxicity. CD8 T cells infiltrate the liver in response to this myeloid activation and mediate tissue damage, triggering transaminase elevation. FoxP3 regulatory T cells limit liver damage, and their removal dramatically exacerbates 4-1BB agonist-induced hepatitis. Coadministration of CTLA-4 blockade ameliorates transaminase elevation, whereas PD-1 blockade exacerbates it. Loss of the chemokine receptor CCR2 blocks 4-1BB agonist hepatitis without diminishing tumor-specific immunity against B16 melanoma. 4-1BB agonist antibodies trigger hepatitis via activation and expansion of interleukin-27-producing liver Kupffer cells and monocytes. Coadministration of CTLA-4 and/or CCR2 blockade may minimize hepatitis, but yield equal or greater antitumor immunity. .

Urelumab alone or in combination with rituximab in patients with relapsed or refractory B‐cell lymphoma

“…These studies were designed to assess a lower urelumab dose range, with a focus on liver toxicities, due to liver injury and drug‐related deaths observed in prior studies that evaluated higher doses of urelumab . While the clinical mechanism is unclear, previously published preclinical data suggest that anti‐CD137‐induced liver toxicity may be partially due to infiltration of S100A4 + macrophages into the liver, following activation of CD8 + T cells and secretion of IFN‐γ . The TRAEs leading to discontinuation included grade 3 increased AST in a patient treated with urelumab 8 mg Q3W, grade 4 acute hepatitis in a patient treated with urelumab 0.3 mg/kg, and one death from sepsis syndrome in a patient treated with urelumab 0.3 mg/kg plus rituximab.…”

Differentiated agonistic antibody targeting CD137 eradicates large tumors without hepatotoxicity

“…Neither of these antibodies are mouse cross-reactive, preventing the direct study of their pharmacology and toxicity in mice. However, antibody clone 3H3 has been widely studied and is known to be a strong agonist of mouse CD137 (17) that induces hepatic inflammation (18)(19)(20).…”

“…The first CD137 antibody to enter the clinic, urelumab, demonstrated dose-dependent moderate-to-severe hepatic toxicity (14). Urelumab is not mouse cross-reactive; however, the mouse-specific anti-CD137 agonist antibody 3H3, which binds to a similar epitope as urelumab, has been shown to cause hepatic inflammation in mice (18)(19)(20). To assess the potential of CTX-471, CTX-471-AF, and 3H3 to induce liver inflammation, we administered up to 80 mg/kg of these antibodies to nontumor-bearing mice by weekly i.v.…”

“…Serum levels of transaminases (e.g., ALT and AST) were increased with 3H3 but not with CTX-471 or CTX-471-AF ( Figure 7A and Supplemental Figure 10C). 3H3-induced hepatic inflammation has been shown to involve CD137-mediated activation of liver-specialized macrophages known as Kupffer cells, leading to the production of proinflammatory cytokines including IL-27 and TNF-α that, in concert with autoantigen presentation by the Kupffer cells, triggers a CD8 + T cell-driven autoimmune hepatitis (18). Consistently, we observed elevated plasma levels of proinflammatory cytokines TNF-α ( Figure 7B), expansion of CD8 + T cells in livers and spleens ( Figure 7, C-F, and Supplemental Figure 10D), and expansion and foci formation of Kupffer cells (Figure 7, G-I) in mice treated with 3H3.…”

An engineered 4-1BBL fusion protein with “activity-on-demand”

“…The first 4-1BB agonistic antibody, urelumab, showed promising anti-cancer activity in preclinical models, but unfortunately revealed substantial hepatotoxicity in clinical trials 78 . The hepatic toxicity was mainly due to the activation of liver Kupffer cells and monocytes, leading to a massive infiltration by T cells 78,79 . Efforts are being made to develop 4-1BB agonists with more favorable toxicity profiles that retain potent costimulatory capacities [80][81][82] .…”