Although CEACAM1 (CC1) glycoprotein resides at the interface of immune liver injury and metabolic homeostasis, its role in orthotopic liver transplantation (OLT) remains elusive. We aimed to determine whether/how CEACAM1 signaling may affect hepatic ischemia-reperfusion injury (IRI) and OLT outcomes. In the mouse, donor liver CC1 null mutation augmented IRI-OLT (CC1-KO→WT) by enhancing ROS expression and HMGB1 translocation during cold storage, data supported by in vitro studies where hepatic flush from CC1-deficient livers enhanced macrophage activation in bone marrow–derived macrophage cultures. Although hepatic CC1 deficiency augmented cold stress–triggered ASK1/p-p38 upregulation, adjunctive ASK1 inhibition alleviated IRI and improved OLT survival by suppressing p-p38 upregulation, ROS induction, and HMGB1 translocation (CC1-KO→WT), whereas ASK1 silencing (siRNA) promoted cytoprotection in cold-stressed and damage-prone CC1-deficient hepatocyte cultures. Consistent with mouse data, CEACAM1 expression in 60 human donor liver biopsies correlated negatively with activation of the ASK1/p-p38 axis, whereas low CC1 levels associated with increased ROS and HMGB1 translocation, enhanced innate and adaptive immune responses, and inferior early OLT function. Notably, reduced donor liver CEACAM1 expression was identified as one of the independent predictors for early allograft dysfunction (EAD) in human OLT patients. Thus, as a checkpoint regulator of IR stress and sterile inflammation, CEACAM1 may be considered as a denominator of donor hepatic tissue quality, and a target for therapeutic modulation in OLT recipients.

Interferon regulatory factor-1 (IRF-1) is a master regulator of IFN-γ induced gene transcription. Previously we have shown that IRF-1 transcriptionally induces CEACAM1 via an ISRE (Interferon-Stimulated Response Element) in its promoter. CEACAM1 pre-mRNA undergoes extensive alternative splicing (AS) generating isoforms to produce either a short (S) cytoplasmic domain expressed primarily in epithelial cells or as an ITIM-containing long (L) isoform in immune cells.

Background/Aim: The aim of this study was to investigate radiation-induced tumour vascular damage and its impact thereof on the outcome of stereotactic body radiotherapy (SBRT). Materials and Methods: Vessel densities in animal tumours before and after a single dose of 20 Gy were quantified and used as input for simulations of three-dimensional tumours with heterogeneous oxygenation. SBRT treatments of the modelled tumours in 1-8 fractions were simulated. The impact of vessel collapse on the outcome of SBRT was investigated by calculating tumour control probability (TCP) and the dose required to obtain a TCP of 50% (D₅₀). Results: A radiation-induced increase of acute hypoxia in tumours during SBRT treatment could be simulated based on the experimental data. The D₅₀ values for these tumours were higher than for the simulated tumours without vessel collapse. Conclusion: The vascular changes after high doses of radiation could compromise the outcome of SBRT by increasing tumour hypoxia.

Bispecific T-cell engaging antibodies (BiTES), comprising dual anti-CD3 and anti-tumor antigen scFv fragments, are important therapeutic agents for the treatment of cancer. The dual scFv construct for BiTES requires proper protein folding while their small molecular size leads to rapid kidney clearance. An intact (150 kDa) anti-tumor antigen antibody to CEA was joined in high yield (ca. 30%) to intact (150 kDa) anti-murine and anti-human CD3 antibodies using hinge region specific Click chemistry to form dual-specific, bivalent BiTES (dbBiTES, 300 kDa). dbBiTEs were tested in vitro by EM, flow cytometry and cell cytoxicity and in vivo by PET tumor imaging and redirected T-cell therapy. The interlocked hinge regions are compatible with a structural model that fits the electron micrographs of 300 kDa particles. Compared to intact anti-CEA antibody, dbBiTES exhibit high in vitro cytotoxicity, high in vivo tumor targeting as demonstrated by PET imaging, and redirected dbBiTE coated T-cells (1 microgram/10 million cells) that kill CEA+ target cells in vivo in CEA transgenic mice. dbBiTE redirected T-cell therapy is a promising, efficient approach for targeting and killing cancer cells.

Background: Immunocytokines (ICKs) are antibody directed cytokines produced by genetic fusion of an antibody to a cytokine.Methods: We now show that antibodies conjugated by click chemistry to interleukin‐2 (IL‐2)‐Fc form fully active conjugates, and in one example, equivalent activity to a genetically produced ICK.Results: An IL‐2‐Fc fusion protein was optimized for click chemistry at hinge cysteines using protein stabilizing IL‐2 mutations at Lys35 and Cys125 and Fc hinge mutations at Cys142 and Cys148. The IL‐2‐Fc fusion protein with K35E and C125S mutations with 3 intact hinge cysteines, designated as IL‐2‐Fc Par, was selected based on its minimal tendency to aggregate. IL‐2‐Fc‐antibody clicked conjugates retained high IL‐2 activity and bound target antigens comparable to parent antibodies. An IL‐2‐Fc‐anti‐CEA click conjugate showed comparable anti‐tumor activity to an anti‐CEA‐IL‐2 ICK in immunocompetent CEA transgenic mice bearing CEA positive orthotopic breast tumors. Significant increases in IFNγ⁺/CD8⁺ and decreases in FoxP3⁺/CD4⁺ T‐cells were found for the clicked conjugate and ICK therapies, suggesting a common mechanism of tumor reduction.Conclusion: The production of antibody targeted IL‐2 therapy via a click chemistry approach is feasible with comparable activity to genetically produced ICKs with the added advantage of multiplexing with other monoclonal antibodies.

Background: The potent immune effects of interleukin‐2 (IL‐2) for cancer therapy can be increased by genetic fusion of IL‐2 to the Fc domain of an antibody (IL‐2‐Fc) or tumor targeted by genetic fusion to a whole antibody known as an immunocytokine (ICK).Methods: An anti‐CEA ICK (M5A‐IL‐2) was compared to an IL‐2‐Fc fusion protein using tumor therapy and PET imaging in CEA transgenic immunocompetent mice bearing CEA positive colon or breast tumors. Combination with stereotactic radiation therapy (SRT) was performed with either ICK or IL‐2‐Fc.Results: ICK and IL‐2‐Fc had comparable antitumor effects in both tumor models, although ICK had higher tumor uptake and slower blood clearance than an IL‐2‐Fc. Analysis of IFNγ⁺/CD8⁺ and FoxP3⁺/CD4⁺ T cells revealed higher levels of IFNγ‐producing CD8⁺ T cells in ICK treated mice versus more efficient Treg elimination in IL‐2‐Fc treated mice. No significant or lasting toxicity was detected for either agent. Combination therapies with SRT revealed comparable efficacy and induction of immune memory for both ICK and IL‐2‐Fc when mice were rechallenged post‐therapy.Conclusions: IL‐2‐Fc had comparable antitumor efficacy to CEA‐targeted M5A‐IL‐2 ICK, while both fusion proteins induced immune memory when combined with SRT. Differences in the therapeutic mechanisms of both agents were observed.