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bioRxiv · 10.1101/2022.12.19.520931

FAP-retargeted Ad5 enables in vivo gene delivery to stromal cells in the tumor microenvironment

Hartmann, K. P.·van Gogh, M.·Freitag, P. C.·Kast, F.·Nagy-Davidescu, G.·Borsig, L.·Plueckthun, A.
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Abstract

Fibroblast activation protein (FAP) is a cell surface serine protease that is highly expressed on reactive stromal fibroblasts, such as cancer-associated fibroblasts (CAFs), and generally absent in healthy adult tissues. FAP expression in the tumor stroma has been detected in more than 90% of all carcinomas, rendering CAFs excellent target cells for a tumor site-specific adenoviral delivery of cancer therapeutics. Here, we present a tropism-modified human adenovirus 5 (Ad5) vector that targets FAP through trivalent, designed ankyrin repeat protein (DARPin)-based retargeting adapters. We describe the development and validation of these adapters via cell-based screening assays and demonstrate adapter-mediated Ad5 retargeting to FAP+ fibroblasts in vitro and in vivo. We further show efficient in vivo delivery and in-situ production of a therapeutic payload by CAFs in the tumor microenvironment (TME), resulting in attenuated tumor growth. We thus propose using our FAP-Ad5 vector to convert CAFs into a biofactory, secreting encoded cancer therapeutics into the TME to enable a safe and effective cancer treatment.

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Hartmann, K. P., van Gogh, M., Freitag, P. C., Kast, F., Nagy-Davidescu, G., Borsig, L., Plueckthun, A.. 2022-12-19. FAP-retargeted Ad5 enables in vivo gene delivery to stromal cells in the tumor microenvironment. https://doi.org/10.1101/2022.12.19.520931

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