Andreata, Moynihan, and Fumagalli et al. generated a fusion protein (CD8-IL-2) comprising an anti-mouse CD8β Ab and a murine IL-2 mutein with reduced IL-2Rβγ affinity. CD8-IL-2 selectively activated CD8+ T cells in vitro and in mice, without inducing liver toxicity. In mouse hepatitis models, injecting CD8-IL-2 boosted spleen and liver HBV-reactive effector CD8+ T (but not Treg or NK) cell numbers, revitalized HBV-reactive CD8+ T cells, promoted hepatic immune cell infiltration, and reduced viremia and intrahepatic HBV replication. A human CD8-IL-2 induced IL-2 signaling selectively in human CD8+ T cells in vitro and selectively reduced CD8+ T cell numbers in the blood of injected cynomolgus monkeys.
Contributed by Paula Hochman
ABSTRACT: CD8(+) T cells are key antiviral effectors against hepatitis B virus (HBV), yet their number and function can be compromised in chronic infections. Preclinical HBV models displaying CD8(+) T cell dysfunction showed that interleukin-2 (IL-2)-based treatment, unlike programmed cell death ligand 1 (PD-L1) checkpoint blockade, could reverse this defect, suggesting its therapeutic potential against HBV. However, IL-2's effectiveness is hindered by its pleiotropic nature, because its receptor is found on various immune cells, including regulatory T (T(reg)) cells and natural killer (NK) cells, which can counteract antiviral responses or contribute to toxicity, respectively. To address this, we developed a cis-targeted CD8-IL2 fusion protein, aiming to selectively stimulate dysfunctional CD8(+) T cells in chronic HBV. In a mouse model, CD8-IL2 boosted the number of HBV-reactive CD8(+) T cells in the liver without substantially altering T(reg) or NK cell counts. These expanded CD8(+) T cells exhibited increased interferon-_ and granzyme B production, demonstrating enhanced functionality. CD8-IL2 treatment resulted in substantial antiviral effects, evidenced by marked reductions in viremia and antigenemia and HBV core antigen-positive hepatocytes. In contrast, an untargeted CTRL-IL2 led to predominant NK cell expansion, minimal CD8(+) T cell expansion, negligible changes in effector molecules, and minimal antiviral activity. Human CD8-IL2 trials in cynomolgus monkeys mirrored these results, achieving a roughly 20-fold increase in peripheral blood CD8(+) T cells without affecting NK or T(reg) cell numbers. These data support the development of CD8-IL2 as a therapy for chronic HBV infection.
Author Info: (1) Division of Immunology, Transplantation and Infectious Diseases, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy. Vita-Salute San Raffaele University, 20132 Milan,
Author Info: (1) Division of Immunology, Transplantation and Infectious Diseases, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy. Vita-Salute San Raffaele University, 20132 Milan, Italy. (2) Asher Biotherapeutics, South San Francisco, CA 94080, USA. (3) Division of Immunology, Transplantation and Infectious Diseases, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy. Vita-Salute San Raffaele University, 20132 Milan, Italy. (4) Division of Immunology, Transplantation and Infectious Diseases, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy. (5) Asher Biotherapeutics, South San Francisco, CA 94080, USA. (6) Division of Immunology, Transplantation and Infectious Diseases, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy. (7) Asher Biotherapeutics, South San Francisco, CA 94080, USA. (8) Asher Biotherapeutics, South San Francisco, CA 94080, USA. (9) Division of Immunology, Transplantation and Infectious Diseases, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy. (10) Division of Immunology, Transplantation and Infectious Diseases, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy. (11) Division of Immunology, Transplantation and Infectious Diseases, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy. (12) Asher Biotherapeutics, South San Francisco, CA 94080, USA. (13) Asher Biotherapeutics, South San Francisco, CA 94080, USA. (14) Asher Biotherapeutics, South San Francisco, CA 94080, USA. (15) Asher Biotherapeutics, South San Francisco, CA 94080, USA. (16) Asher Biotherapeutics, South San Francisco, CA 94080, USA. (17) Division of Immunology, Transplantation and Infectious Diseases, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy. Vita-Salute San Raffaele University, 20132 Milan, Italy. Experimental Imaging Centre, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy.
