Use of Sulfasalazine analogue and PARP inhibitor as a radiosensitizer in cancer treatment
Resistance to radiotherapy is a major challenge in cancer treatment. We previously showed that Sulfasalazine blocks the transmembrane antiporter xCT, thereby reducing the production of the antioxidant glutathione which scavenges reactive oxygen species (ROS) induced by radiotherapy. Thus in animals, Sulfasalazine (SAS) acted as a radiosensitiser that prolonged survival when combined with radiotherapy that was administered to nude rats with experimental brain tumors. However, SAS has limited bioavailability due to intestinal degradation. Hence, we have developed synthetic SAS derivatives to obtain more stable compounds optimised for use as radiosensitisers in patient treatment that inhibit glutathione synthesis in vitro. We have also observed promising radiosensitizing effects in radiation experiments in vitro. The second drug we want to include in this study is a PARP inhibitor that inhibits the PARP1-mediated repair of radiation induced DNA damage. PARP inhibitors are already used for treatment of ovarian cancer and in clinical trial for cancers in lung cancer, pancreatic cancer and prostate cancer. This way, we aim to radiosensitize cancer cells by targeting two radioresistance mechanisms for cancer cells; i.e. increase ROS signals by blocking antioxidant production, and inhibit repair of DNA damage. The animals are implanted with human cancer cells that develop into tumors that mimic the characteristics of human cancers.The animals will be treated with painkillers, and anaesthetics to minimize the pain due to surgery and radiation. We will use the 4 Gy (flank and tumors and lung metastases) and 8 Gy (brain) radiation doses which did not cause toxicity in previous trials. We will use 290 Nod-SCID mice for the study.
The study is designed with the compliance of 3R- The number of animals was reduced by doing an extensive in-vitro experiment that gave a solid ground to do further testing. Despite extensive in vitro testing, in vivo validation is fundamental to determine how the treatment effects are modified by the complex in vivo microenvironment determined by several factors including host cells in the tumor bed and blood-flow. Thus the proposed in vivo study aims to confirm our encouraging in vitro findings and establish the modality for future patient-trials. The number of animals is reduced by using a common control group for the sub-experiments, and standardized experimental setup. Long-acting local anesthesia / anesthesia / NSAIDs reduce the experience of pain. Temperature-/ respiratory monitoring, surgical microscope, stereotatic frame, sterile procedure, two operators and scoring form (human endpoint) makes treatment / follow-up safer and more gentle. The animals will be monitored by clinical inspection and by assessment of weight, heart rate, side effects. (please check details of 3R in the specific section).
We believe that we can increase the radiation damage to the cancer cells without increasing the side effects. We now need to evaluate these compounds in animals to obtain information about their anti-tumor efficacies as a radiosensitiser. We have planned to utilize our already established state-of-the-art animal models and treat the animals with radiation, SAS, SAS analogue, and PARP inhibitor in combination.
The study is designed with the compliance of 3R- The number of animals was reduced by doing an extensive in-vitro experiment that gave a solid ground to do further testing. Despite extensive in vitro testing, in vivo validation is fundamental to determine how the treatment effects are modified by the complex in vivo microenvironment determined by several factors including host cells in the tumor bed and blood-flow. Thus the proposed in vivo study aims to confirm our encouraging in vitro findings and establish the modality for future patient-trials. The number of animals is reduced by using a common control group for the sub-experiments, and standardized experimental setup. Long-acting local anesthesia / anesthesia / NSAIDs reduce the experience of pain. Temperature-/ respiratory monitoring, surgical microscope, stereotatic frame, sterile procedure, two operators and scoring form (human endpoint) makes treatment / follow-up safer and more gentle. The animals will be monitored by clinical inspection and by assessment of weight, heart rate, side effects. (please check details of 3R in the specific section).
We believe that we can increase the radiation damage to the cancer cells without increasing the side effects. We now need to evaluate these compounds in animals to obtain information about their anti-tumor efficacies as a radiosensitiser. We have planned to utilize our already established state-of-the-art animal models and treat the animals with radiation, SAS, SAS analogue, and PARP inhibitor in combination.