Cancer is the main cause of death in dogs. When they are diagnosed as terminally ill, there are usually no treatment options available. According to the latest issue of the journal Stem Cell Research and Treatment, Singapore researchers have developed a new method to treat cancer dogs using stem cell precision engineering technology. In this study, researchers from the Cancer Research Center of the National University of Singapore have modified mesenchymal stem cells (MSCs) that can search for cancer tumors. These modified cells carry an effective "killing switch" (cytosine deaminase), which can produce high concentration of local anticancer drugs (5-fluorouracil) in the tumor environment, and then induce anticancer immunity. Researchers said that in order to change the purpose of stem cells for cancer treatment, people usually use viruses to introduce therapeutic genes into cells. This time, they designed a non-viral gene delivery platform to introduce highly effective therapeutic genes into stem cells, effectively destroying uncontrolled growth of cancer cells. The research team applied this therapy to 65 dogs and two cats, which suffered from perianal adenoma, lung metastasis and sarcoma. The animals first received the precisely designed MSC through direct tumor injection or blood flow, and then took 5-fluorocytosine oral pills within a few days. One week later, before completing the first course of treatment, repeat the cycle for another two weeks. The research team then monitored the animals and repeated the process if necessary. Of the animals with treatment duration ranging from 3 to 8 weeks, 56 showed signs of positive reaction, of which 14 fully recovered, and 46 animals showed good quality of life within 2 to 32 months after treatment. Compared with human cancer therapy, the development of animal cancer therapy still lags behind. Researchers said, "This treatment has been proved to be safe and has shown promising clinical benefits in animals. We hope to develop effective treatment programs to help human cancer patients, which can improve their health without affecting the quality of life."