{
  "abstract": "Background Interleukin-12 (IL-12) acts during priming to enhance cytotoxic CD8 + T cell responses but its clinical use is limited by short half-life and dose-limiting toxicities.1 2 Previous attempts using single-agent IL-12 failed to control immune checkpoint blockade (ICB)-refractory orthotopic lung tumors in preclinical mouse models.3 4 To overcome these limitations, we utilized αCD45-IL12, an antibody-cytokine conjugate that selectively delivers IL-12 to CD45+ immune cells, extending its half-life while minimizing off-target effects.5 6 Anti-CD45 antibodies, when delivered intraperitoneally (I.P.), preferentially drain to the mediastinal lymph node (mLN).7 We reasoned that this approach would localize IL-12 to the mLN, the primary tumor-draining lymph node where dendritic cells prime CD8+ T cell responses against murine lung cancers.Methods αCD45-IL12 was administered I.P. to mice with transplantable KP.SIY lung tumors (Kras G12D/+; Trp53-/-; SIYRGYYL antigen) and to KP genetically engineered mice (GEMs) with autochthonous lung adenocarcinomas.8–10 Tumor burden, survival, and immune responses in tumors, draining lymph nodes, and spleens were assessed via flow cytometry and IFN-γ ELISpot assays. Cytokine receptor knockout mice were used for mechanistic studies.Results I.P. delivery of αCD45-IL12 resulted in preferential accumulation of this therapy in the mLN, enabling targeted immunomodulation during CD8 + T cell priming. Treatment significantly reduced tumor burden, improved survival, and cured ~20% of KP.SIY tumor-bearing mice, while untargeted IL-12 showed minimal effect. Similar benefit was observed in KP GEMs with autochthonous lung tumors. Mechanistically, αCD45-IL12 increased the number, migratory capacity, and stimulatory phenotype of type 1 cross-presenting dendritic cells (cDC1s) in the mLN, including upregulation of CD86 and endogenous IL-12. SIY-reactive CD8+ T cells exhibited enhanced activation and cytotoxicity following treatment. Surprisingly, non-SIY reactive CD8+ T cells displayed an even greater increase in expression of effector molecules such as Granzyme B. IFN-γ ELISpot assays and Nur77 reporter mice confirmed epitope spreading against endogenous tumor antigens. This protected mice from rechallenge with SIY-negative KP flank tumors, indicating a systemic, antigen-diverse memory response. Using receptor knockout mice, we found that αCD45-IL12-mediated cDC1 activation and therapeutic benefit were independent of IFNγ but partially dependent on type I interferon signaling.Conclusions αCD45-IL12 therapy shapes DC-T cell interactions in the tumor-draining lymph node to drive broad, multi-epitope CD8 + T cell responses. These findings highlight a previously underappreciated role for IL-12 in directly modulating DCs and support αCD45-IL12 as a promising strategy for ICB-resistant lung cancer.Acknowledgements David H. Koch Graduate FellowshipReferences Propper DJ, Balkwill FR. Harnessing cytokines and chemokines for cancer therapy. Nat Rev Clin Oncol. 2022;19(4):237–253.Tugues S, et al. New insights into IL-12-mediated tumor suppression. Cell Death Differ. 2015;22(2):237–46.Horton BL, et al. Overcoming lung cancer immunotherapy resistance by combining nontoxic variants of IL-12 and IL-2. JCI Insight. 2023;8(19).Horton BL, et al. Lack of CD8(+) T cell effector differentiation during priming mediates checkpoint blockade resistance in non-small cell lung cancer. Sci Immunol. 2021;6(64):eabi8800.Berraondo P, et al. Immunocytokines and cytokine neutralization for cancer immunotherapy. Trends Cancer. 2025.Santollani, L, et al. Local delivery of cell surface-targeted immunocytokines programs systemic antitumor immunity. Nat Immunol. 2024;25(10):1820–1829.Shanahan SL, et al, Longitudinal intravascular antibody labeling identified regulatory t cell recruitment as a therapeutic target in a mouse model of lung cancer. J Immunol. 2024;213(6):906-918.DuPage M, Dooley AL, Jacks T. Conditional mouse lung cancer models using adenoviral or lentiviral delivery of Cre recombinase. Nat Protoc. 2009;4(7):1064–72.Jackson EL, et al. The differential effects of mutant p53 alleles on advanced murine lung cancer. Cancer Res. 2005;65(22):10280–8.Jackson, EL, et al, Analysis of lung tumor initiation and progression using conditional expression of oncogenic K-ras. Genes Dev. 2001;15(24):3243–8.Ethics Approval All mouse experiments in this study were approved by MIT’s Committee on Animal Care (CAC) - DHHS Animal Welfare Assurance # D16-00078.",
  "authors": [
    {
      "affiliations": [
        "Massachusetts Institute of Technology, Cambridge, MA, USA"
      ],
      "name": "Vidit Bhandarkar"
    },
    {
      "affiliations": [
        "Massachusetts Institute of Technology, Cambridge, MA, USA"
      ],
      "name": "Brett Pogostin"
    },
    {
      "affiliations": [
        "Massachusetts Institute of Technology, Cambridge, MA, USA"
      ],
      "name": "Olivia Sheridan"
    },
    {
      "affiliations": [
        "Massachusetts Institute of Technology, Cambridge, MA, USA"
      ],
      "name": "Sean-Luc Shanahan"
    },
    {
      "affiliations": [
        "Massachusetts Institute of Technology, Cambridge, MA, USA"
      ],
      "name": "Lauren Duhamel"
    },
    {
      "affiliations": [
        "The Scripps Research Institute, La Jolla, CA, USA"
      ],
      "name": "Darrell J Irvine"
    },
    {
      "affiliations": [
        "Koch Institute for Integrative Cancer Research at MIT, Cambridge, MA, USA"
      ],
      "name": "Stefani Spranger"
    }
  ],
  "title": "849 Mediastinal lymph node-targeted IL-12 prolongs survival in lung cancer by activating dendritic cells and facilitating epitope spreading",
  "uid": "d422739e-de36-5114-89a9-4990695233a9"
}