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Summary: Mesenchymal stromal cells (MSCs) have been modified via genetic or pharmacological engineering into potent antigen-presenting cells-like capable of priming responding CD8 T cells. In this study, our screening of a variant library of Accum molecule revealed a molecule (A1) capable of eliciting antigen cross-presentation properties in MSCs. A1-reprogrammed MSCs (ARM) exhibited improved soluble antigen uptake and processing. Our comprehensive analysis, encompassing cross-presentation assays and molecular profiling, among other cellular investigations, elucidated A1’s impact on endosomal escape, reactive oxygen species production, and cytokine secretion. By evaluating ARM-based cellular vaccine in mouse models of lymphoma and melanoma, we observe significant therapeutic potency, particularly in allogeneic setting and in combination with anti-PD-1 immune checkpoint inhibitor. Overall, this study introduces a strong target for developing an antigen-adaptable vaccination platform, capable of synergizing with immune checkpoint blockers to trigger tumor regression, supporting further investigation of ARMs as an effective and versatile anti-cancer vaccine.

Summary: Immunoproteasome-reprogrammed mesenchymal stromal cells (IRMs) can surpass dendritic cells at eliciting tumor-specific immunity. However, the current IRM vaccination regimen remains clinically unsuitable due to the relatively high dose of IRMs needed. Since the administration of a lower IRM dose triggers a feeble anti-tumoral response, we aimed to combine this vaccination regimen with different modalities to fine-tune the potency of the vaccine. In a nutshell, we found that the co-administration of IRMs and interleukin-12 accentuates the anti-tumoral response, whereas the cross-presentation potency of IRMs is enhanced via intracellular succinate build-up, delayed endosomal maturation, and increased endosome-to-cytosol plasticity. Stimulating phagocyte-mediated cancer efferocytosis by blocking the CD47-SIRPα axis was also found to enhance IRM vaccine outcomes. Upon designing a single protocol combining the abovementioned strategies, 60% of treated animals exhibited a complete response. Altogether, this is the first IRM-based vaccination study, optimized to simultaneously target three vaccine-related pitfalls: T-cell response, antigen cross-presentation, and cancer phagocytosis.

Summary: The beginning of the 21st century has been marked by three distinct waves of zoonotic coronavirus outbreaks into the human population. The COVID-19 (coronavirus disease 2019) pandemic is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and emerged as a global threat endangering the livelihoods of millions worldwide. Currently, and despite collaborative efforts, diverse therapeutic strategies from ongoing clinical trials are still debated. To address the need for such an immediate call of action, we leveraged the largest dataset of drug-induced transcriptomic perturbations, public SARS-CoV-2 transcriptomic datasets, and expression profiles from normal lung transcriptomes. Most importantly, our unbiased systems biology approach prioritized more than 50 repurposable drug candidates (e.g., corticosteroids, Janus kinase and Bruton kinase inhibitors). Further clinical investigation of these FDA-approved candidates as monotherapy or in combination with an antiviral regimen (e.g., remdesivir) could lead to promising outcomes in patients with COVID-19.