Effect of multi-targeting bacterial gene therapy on tumour regression and survival in mouse models of ovarian and intraperitoneal cancer.

Abstract

e17550 Background: With a prevalence of more than 2 million cases, a 5-year survival below 20% in stage 3 and 4, and limited treatment options, ovarian cancer represents a significant unmet medical need. We assessed the efficacy of AUP-55, a genetically engineered Lactococcus cremoris for the treatment of ovarian cancer and peritoneal carcinomatosis. We evaluated the efficacy of two AUP-55 leads producing human therapeutic proteins in situ; namely interleukin 18 (IL-18), granulocyte-macrophage colony stimulating factor (GM-CSF), interleukin-12 (IL-12) and interferon alpha (IFN-A) in syngeneic intraperitoneal ID8 ovarian cancer and B16F1 melanoma models in mice. Methods: ID8-Luc-mCherry-Puro ovarian cancer model was used for survival and tumor burden by bioluminescent imaging with post-mortem pathology for all animals, whereas the B16F1 melanoma model was used solely for survival. Animals were treated daily or every other day with i.p injections of the AUP-55 leads (1e8 CFU/dose for 12-22 times). Results: In the ID8 model treatment was started 14 days after tumor implantation. Most untreated mice were terminated due to the disease progress. Treatment with AUP-55 resulted in 91.3 % survival and lower tumor load during the study duration of 81 days compared to the 0 % survival and massively increased tumor load in untreated mice. When compared to the available data from the CRO, the survival advantage was superior to, for example anti-PD1 and cisplatin treatments in the same model. In the B16F1 model, treatment with AUP-55 led to 90 % survival in comparison to 10 % untreated mice. All AUP-55 treatments were well tolerated. In the pathology post-mortem, all untreated animals had typical findings for ovarian cancer, such as ascites and high number of tumor nodules present in abdominal cavity, liver, spleen, kidney and pancreas. In the group treated with AUP-55 there were no macroscopic tumor deposits detected. Conclusions: Cytokine armed Lactococcus cremoris AUP-55 enables multimodal action. Treatment with AUP-55 suggests anti-tumor activity as a single therapeutic entity for the treatment of ovarian cancer and peritoneal carcinomatosis.