Cell surface-tethered IL-12 repolarizes the tumor immune microenvironment to enhance the efficacy of adoptive T cell therapy

Immune-activating cytokines such as interleukin-12 (IL-12) hold strong potential for cancer immunotherapy but have been limited by high systemic toxicities. We describe here an approach to safely harness cytokine biology for adoptive cell therapy through uniform and dose-controlled tethering onto the surface of the adoptively transferred cells. Tumor-specific T cells tethered with IL-12 showed superior antitumor efficacy across multiple cell therapy models compared to conventional systemic IL-12 coadministration. Mechanistically, the IL-12-tethered T cells supported a strong safety profile by driving interferon-γ production and adoptively transferred T cell activity preferentially in the tumor. Immune profiling revealed that the tethered IL-12 reshaped the suppressive tumor immune microenvironment, including triggering a pronounced repolarization of monocytic myeloid-derived suppressor cells into activated, inflammatory effector cells that further supported antitumor activity. This tethering approach thus holds strong promise for harnessing and directing potent immunomodulatory cytokines for cell therapies while limiting systemic toxicities.

Abstract PR012: Adoptive transfer of T cells surface-tethered with IL-12 activates a natural killer/dendritic cell axis to promote antigen spreading for enhanced anti-tumor efficacy

Despite the promise of adoptive cell therapy (ACT) in the treatment of some cancer types, success against solid tumors remains elusive due to multiple immune escape pathways. T cell therapies that affect tumor microenvironment or provide adjuvant activity in addition to tumor cell lysis hold strong potential for overcoming immune escape in solid tumors. Interleukin-12 (IL-12) is a potent stimulator of innate and adaptive immune cells that holds strong potential for cancer immunotherapy, but its clinical utility has been limited by high systemic toxicities. We have previously shown that tethering an IL-12 immunocytokine to the surface of T cells prior to adoptive cell transfer (ACT) safely improves anti-tumor efficacy by promoting T cell function specifically in the tumor. Here, we demonstrate that tethered IL-12 further delivers adjuvant activity by initiating an immune cascade involving natural killer cell-mediated activation of cross-priming dendritic cells to resulting in broader anti-tumor T cell responses. In a preclinical cell therapy model tumor-specific T cells tethered with IL-12, but not the T cells alone, triggered proliferation of tumor-specific endogenous tumor infiltrating lymphocytes (TIL). This was accompanied by increased activation and infiltration of cross-presenting dendritic cells (cDC1) in tumor-draining lymph nodes (tdLN). Analyses of cDC1 subsets revealed upregulation of CD86 expression on both migratory and resident cDC1s within the tdLN, two cell types that are critical for both tumor antigen transport to tdLN and activation of naïve CD8 T cells, respectively. This activity was specific to cDC1s, as increased activation or accumulation of type 2 dendritic cells (cDC2) was not observed. Mechanistically, the IL-12 tethered T cells upregulated expression of FLT3 ligand on NK cells, a key cytokine for cDC1 recruitment and expansion. NK cell depletion ablated cDC1 tdLN infiltration and endogenous tumor infiltrating T cell expansion, indicating that recruitment and activation of endogenous tumor-specific T cells is at least partially driven by tethered IL-12-mediated activation of NK cells to recruit and expand the cross-priming dendritic cells. Together, this demonstrates that our surface tethered cytokine technology provides powerful adjuvant activity to adoptively transferred T cells and promotes activation of endogenous anti-tumor adaptive immune response, thus promoting a broad antigenic repertoire. This approach thus holds potential to help overcome challenges of antigen escape and tumor heterogeneity that limit efficacy of T cell therapies against solid tumors.

This abstract is also being presented as PO078.

Citation Format: Kate L. Stokes, Ditte E. Jaehger, Alvin Pratama, Holmfridur R. Halldorsdottir, Gulzar Ahmad, Jon D. Nardozzi, Katharine L. Sackton, Thomas L. Andresen, Douglas S. Jones. Adoptive transfer of T cells surface-tethered with IL-12 activates a natural killer/dendritic cell axis to promote antigen spreading for enhanced anti-tumor efficacy [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PR012.

YA is needed for proper nuclear organization to transition between meiosis and mitosis in Drosophila

BACKGROUND

The Drosophila YA protein is required to initiate the embryonic cleavage divisions. After egg activation, YA enters nuclei and interacts with chromatin and the nuclear lamina. This study was designed to define more precisely the events prior to the first cleavage division that are dependent upon YA.

RESULTS

We find that meiosis is completed normally in the absence of YA function. The first defects in embryos and eggs from mutant mothers first appear just after the completion of meiosis, and are seen as abnormal associations among the resultant haploid nuclei. These defects are associated with asynchronies in the cell cycle-dependent chromatin condensation state of the haploid nuclei. However, we find evidence of DNA replication in the absence of YA function.

CONCLUSION

Our data suggest YA function is needed at a control point, following meiosis II and the initiation of the first postmeiotic S phase, which is sensitive to the chromatin condensation state of the haploid meiotic products.

Modulation of MAPK activities during egg activation in Drosophila

The mitogen-activated protein kinases (MAPKs) play essential roles during oocyte maturation and egg activation and are also active in somatic cell cycle regulation in many animals. In clams, starfish, ascidians, mice, and frogs, the species-specific timing of MAPK activity during oocyte maturation and egg activation correlates with the different meiotic arrest points of these various organisms. Furthermore, MAPKs have been shown to regulate the meiotic cell cycle in marine invertebrates and vertebrates. The initial trigger for egg activation in insects is different from that of marine invertebrates and vertebrates, and it was not previously known whether changes in MAPK activity accompany egg activation in insects. To examine the regulation of MAPKs during Drosophila egg activation and early embryogenesis, we quantified the levels of phosphorylated (active) forms of ERK, p38 and JNK by western blotting with antibodies specific to the phospho-forms of these kinases. Levels of phospho-ERK, phospho-p38 and phospho-JNK are high in Drosophila oocytes. Upon egg activation, levels of all these phospho- (active) forms of MAPKs decrease. Fertilization is not required for this decrease, consistent with the independence of egg activation from fertilization in Drosophila. The decrease in levels of phospho-MAPK occurs normally in embryos laid by sterile females mutant in the egg activation genes cortex, sarah, and prage. We present a model in which the decrease in MAPK activity is an intermediate step in the pathway leading from the calcium signal that initiates egg activation to the downstream events of activation.