The efficacy of current oncotherapeutics is largely limited by an inability to access avascular tissues, which is in part responsible for forty years of stagnant pancreatic cancer statistics where the median survival remains a mere six months. Oncolytic bacteria such as Clostridium novyi-NT overcome this challenge with its ultrasensitive, innate affinity for hypoxic/necrotic areas found at the center of solid tumors and their metastases. While preclinical and clinical data from intratumoral injections of C. novyi-NT are promising, many tumors are inaccessible to such injections. Preclinical trials of analogous IV injections have uncovered other obstacles such as rapid clearance of C. novyi-NT by the immune system independent of septic complications. To mitigate rapid clearance, CRISPR/Cas9n was used to genetically modify a non-toxic form of C. novyi-NT to express a tumor targeting RGD peptide on the spore surface. Through this novel, first of its kind, methodology, spores with stronger affinity to a surface coated with the targeted binding partner of RGD, aVb3 integrin, have been generated. Importantly, there was no statistically significant difference in the genetically modified spore’s capacity for sporulation or germination when compared to unmodified C. novyi-NT spores, nor was a difference in lytic capacity observed, suggesting no relevant off-target effects from genomic modification. Biodistribution and efficacy of non-toxic RGD-modified spores was evaluated in an immunocompetent, syngeneic, pancreatic cancer murine model. Ongoing efforts to characterize the biodistribution and efficacy of the intravenously injected RGD-modified C. novyi-NT include the application of multiplex immunofluorescence, laser microdissection, and live, whole animal imaging. Supported as a pilot project by funds from NIH COBRE grant 1P20GM109024, Doctoral Dissertation Funds to KMD from NDSU, and by discretionary funds from investigators at UNMC.
Citation Format: Kaitlin M. Dailey, Krysten Vance, Kyle McAndrews, Reed I. Jacobson, Jandro Delgado, Paige R. Johnson, Taylor M. Woolery, Megan Orr, Jiha Kim, Sanku Mallik, Kenneth W. Bayles, Michael A. Hollingsworth, Amanda E. Brooks. Development of an RGD CRISPR-modified Clostridium novyi NT spores as an intravenous oncotherapy [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2021 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2021;81(22 Suppl):Abstract nr PO-037.