The tumor-specific Grp78 promoter is overexpressed in aggressive tumors. Cancer patients would benefit greatly from application of this promoter in gene therapy and molecular imaging; however, clinical benefit is limited by lack of strategies to target the systemic delivery of Grp78-driven transgenes to tumors. This study aims to assess the systemic efficacy of Grp78-guided expression of therapeutic and imaging transgenes relative to the standard cytomegalovirus (CMV) promoter. Combination of ligand and Grp78 transcriptional targeting into a single vector would facilitate systemic applications of the Grp78 promoter. We generated a dual tumor-targeted phage containing the arginine-glycine-aspartic acid tumor homing ligand and Grp78 promoter. Next, we combined flow cytometry, Western blot analysis, bioluminescence imaging of luciferase, and HSVtk/ganciclovir gene therapy and compared efficacy to conventional phage carrying the CMV promoter in vitro and in vivo in subcutaneous models of rat and human glioblastoma. We show that double-targeted phage provides persistent transgene expression in vitro and in tumors in vivo after systemic administration compared with conventional phage. Next, we showed significant tumor killing in vivo using the HSVtk/ganciclovir gene therapy and found a systemic antitumor effect of Grp78-driven HSVtk against therapy-resistant tumors. Finally, we uncovered a novel mechanism of Grp78 promoter activation whereby HSVtk/ganciclovir therapy upregulates Grp78 and transgene expression via the conserved unfolded protein response signaling cascade. These data validate the potential of Grp78 promoter in systemic cancer gene therapy and report the efficacy of a dual tumor targeting phage that may prove useful for translation into gene therapy and molecular imaging applications.

Background Perinuclear anti‐neutrophil cytoplasmic antibodies (P‐ANCA) are associated with a multisystem vasculitis affecting small blood vessels in the body. A handful of adult patients who developed vasculitis post‐COVID‐19 have been reported. Although SARS‐CoV‐2 has been shown to drive an exaggerated immune response in the pediatric population, such as in Multisystem Inflammatory Syndrome in Children (MIS‐C), only one case of vasculitis following COVID‐19 has been reported previously in children. Case presentation Seventeen‐year‐old male with a past medical history of COVID‐19 pneumonia two months prior presented with acute kidney injury and diffuse alveolar hemorrhage. Rheumatologic workup revealed P‐ANCA and Myeloperoxidase (MPO) positivity. Kidney biopsy showed necrotizing glomerulonephritis with limited immune complex deposition. Subsequently, he was treated with steroids and plasmapheresis, and ultimately started on cyclophosphamide. Conclusions To our knowledge, this report presents the second reported pediatric case of P‐ANCA/MPO vasculitis following COVID‐19.

Background: Perinuclear anti-neutrophil cytoplasmic antibodies (P-ANCA), a subset of ANCA, are associated with a multisystem vasculitis affecting small blood vessels in the body. A handful of adult patients who developed vasculitis post-COVID-19 infection have been reported. Although COVID-19 infection has been shown to drive an exaggerated immune response in the pediatric population, such as MIS-C (multisystem inflammatory syndrome in children), only one case of vasculitis following COVID-19 infection has been reported previously in children. Case presentation: Seventeen-year-old male with a past medical history of COVID-19 pneumonia two months prior presented with acute kidney injury/failure and diffuse alveolar hemorrhage (DAH). Rheumatologic workup revealed P-ANCA and Myeloperoxidase (MPO) positivity. Kidney biopsy showed necrotizing glomerulonephritis with limited immune complex deposition. Subsequently, he was treated with pulse steroids, plasmapheresis, and ultimately started on cyclophosphamide. Conclusions: To our knowledge, this report presents the second reported pediatric case of P-ANCA / MPO vasculitis following COVID-19 infection.