An albumin IL-2 fusion (Alb–IL2) encoded in nucleoside-modified RNA and encapsulated in a nanoparticle (RNP) significantly accumulated in tumors and tdLNs of mice for at least 3 days, while unfused RNP IL-2 was undetectable. Combination with RNA lipoplex (RNA-LPX) vaccines in mice promoted >3-fold peripheral expansion of antigen-specific T cells and upregulation of CD25 (IL-2Rα), with minimal impact on Treg frequency. In CT26 tumor-bearing mice treated with a gp70 RNA-LPX vaccine and anti-PD-L1, the addition of Alb-IL2 RNP significantly improved tumor control and increased tumor-specific CD8+ T cells in the tumor, tDLN, and spleen compared to the addition of Alb-only RNP.

Contributed by Morgan Janes

ABSTRACT: Interleukin-2 (IL-2) is a crucial cytokine in T-cell immunity and a promising combination partner to boost cancer vaccine efficacy. However, therapeutic application of IL-2 is hampered by its short half-life and substantial toxicities. Herein, we report preclinical characterization of a mouse serum albumin-IL-2 fusion protein (Alb-IL2) encoded on nucleoside-modified RNA delivered via a nanoparticle formulation (Alb-IL2 RNA-NP) mediating prolonged cytokine availability. Alb-IL2 RNA-NP was combined with RNA-lipoplex (RNA-LPX) vaccines to evaluate its effect on the expansion of vaccine-induced antigen-specific T-cell immunity. In mice dosed with Alb-IL2 RNA-NP, translated protein was shown to be systemically available up to two days, with an albumin-dependent preferred presence in the tumor and tumor-draining lymph node. Alb-IL2 RNA-NP administration prolonged serum availability of the cytokine compared to murine recombinant IL-2 (rIL-2). In combination with RNA-LPX vaccines, Alb-IL2 RNA-NP administration highly increased expansion of RNA-LPX vaccine-induced CD8+ T cells in the spleen and blood. The combination enhanced and sustained the fraction of IL-2 receptor (IL-2R)_-positive antigen-specific CD8+ T cells and ameliorated the functional capacity of the CD8+ T-cell population. Alb-IL2 RNA-NP strongly improved the antitumor activity and survival of concomitant RNA-LPX vaccination and PD-L1 blockade in a subcutaneous mouse tumor model. The favorable pharmacokinetic properties of Alb-IL2 RNA-NP render it an attractive modality for rationally designed combination immunotherapy. RNA vaccines that induce tumor-specific T-cell immunity for Alb-IL2 RNA-NP to further amplify are particularly attractive combination partners.

Author Info: (1) BioNTech (Germany), Mainz, Germany. (2) BioNTech (Germany), Mainz, Germany. (3) BioNTech (Germany), Germany. (4) Institute for Translational Oncology and Immunology (TRON), Mai

Author Info: (1) BioNTech (Germany), Mainz, Germany. (2) BioNTech (Germany), Mainz, Germany. (3) BioNTech (Germany), Germany. (4) Institute for Translational Oncology and Immunology (TRON), Mainz, Germany. (5) Institute for Translational Oncology and Immunology (TRON), Mainz, Germany. (6) BioNTech (Germany), Germany. (7) BioNTech SE, Mainz, Germany. (8) BioNTech (Germany), Mainz, Germany.