Resumen de Arming Oncolytic Adenoviruses with Transgenes to Engage Stroma Toxicity and Immune Stimulation as a Double Strategy Against Cancer
Marcel Arias Badia Oncolytic virotherapy with Adenoviruses has regained importance in the past years with the appearance of fresh and promising strategies to deal with tumors. Among the major limitations of this therapy are the immune suppression induced in the tumor microenvironment, which prevents the generation of an antitumor immune response, and the presence of stromal barriers which hinder the viral spread and also contain fibroblasts, cells which are highly resistant to viral replication.
In this thesis, both limitations have been addressed in separate chapters. Firstly, aiming to induce immune activation, a panel of viruses expressing, CD200, an immune checkpoint, CD200tr, an N-terminal truncated version of the former with antagonistic effect on its receptor (CD200R), K14, a CD200 homolog from HHV-8, and K14tr, a truncated version of K14 and hence a putative antagonist to CD200R, was generated. Throughout the development of this project, we validated the viability of these viruses, we detected the transgenes in supernatants from infected cultures, we confirmed the inhibitory role of CD200 and K14 and the antagonistic one for CD200tr, but our data did not suggest a similar function for K14tr.
As for the second project, we generated oncolytic Adenoviruses expressing bacteria-derived toxins modified in such a way they become activated only stroma-specific proteases, aiming to induce indiscriminate cell death once activated at the target tissue. Alpha-toxin from Clostridium septicum and aerolysin from Aeromonas hydrophyla were the toxins of choice. During the development of this project, we successfully generated and characterized all the viruses, we detected aerolysin in supernatants from infected cultures, we confirmed toxin-mediated cytotoxicity in cultures that expressed the activating proteases, and we performed in vivo studies to evaluate the antitumor efficacy, toxicity and the effects on the stroma of the toxins. Whilst for Alpha-toxin no promising results were obtained, the aerolysin-expressing virus increased oncolytic potency in our models, indicating that it could be considered as a potential clinical candidate in stroma-abundant tumors and encouraging to follow this research pipeline.
