Salmonella bacterium the same agent which used to cause disastrous diseases like septic shock and food poisoning is now used by Yale Cancer Centre researchers to fight one of the most dreaded diseases for mankind today-Cancer. As of today the bacterium has already been enrolled in phase I clinical trials in humans with the bacterium being administered to monitored patients. A genetically engineered form of the wild virulent variety is used to target solid tumors and thus inhibit cancer growth in a series of tests on laboratory animals. Scientists through years and years of observations have come to realize that cancer patients when exposed to an infection get better after the infection ends. This may somehow have a correlation to the high penetration of parasitic organisms to the cancer cells which usually have high rates of metabolism and need adequate nutrition and blood supply. This provision for luxurious growth is sure to hinder the growth of cancer cells. Thus utilizing this hypothesis scientists have been trying to develop such organisms that hinder cancer cell growth without producing any original side effects.
Salmonella bacterium is usually transmitted through faeco-oral route. As it gets entry into the body it undertakes variety of mechanisms to circumvent the body's immune system. It also produces a protein that impairs the normal inflammatory response of the body. This usually affects the epithelial layer in the gastrointestinal tract i.e. wall of stomach and intestine. Thus providing ample opportunity and time for the bacteria to reproduce and spread throughout the body. Salmonella, in order to obtain important metal ions like zinc and iron produces proteins which circumvent the immune system's mechanisms. Thus the bacteria gains a means for survival at the cost of our body's nutrients and also produces toxic products which lead to a variety of symptoms ranging from the fatal septic shock to the hugely feared food poisoning. The preferred mode of division in Salmonella bacterium is binary fission which results in the creation of multiple identical copies of the bacterium in a short span of time. Thus the bacteria created provide the same susceptibility to antibiotics.
Through the course of the scientific study, researchers stripped the "wild" variety of the bacterium of its virulence by the help of the technique of genetic engineering. Once devoid of its ability to cause illness in humans and animals it has been successfully tested in animals to cause the shrinkage of solid tumors of the gut us. The ability to circumvent immune system makes it an ideal client to target the cancer which themselves have developed the ability to befool the body's immune system. Moreover the ability to replicate enormously without any apparent genetic mutation enables the maintenance of therapeutic utility throughout a number of generations of the bacteria. The virus utilizes the same mechanism as the virulent strain to permeate the gut wall and spread itself extensively. Thankfully instead of its virulent effect it produces anti cancer effects.
The phase 1 clinical trials have led to positive results in humans who were administered the bacteria, monitored in the hospitals and then allowed to go home after being discharged. The tests on animals resulted in a significant increase in the life span of animals that had melanoma resulting in the shrinkage of solid tumors in the test animals. This is a huge prospect for the clinical trials. The modified bacteria were found to inhibit the growth of tumor cells as an added advantage. Thus the genetic engineering has led to drastic minimization of the adverse effects while amplifying the efficacy of the bacterium against cancer cells. According to established protocol the scientists are continuing to monitor the efficacy and potential safety through all stages of the trials to minimize the damaging effects of the new innovative cure. The patients used in the study until now have been diagnosed with cancer that is beneath or in the skin.
While viruses such as measles virus, the vesicular stomatitis virus and the human reovirus are also considered prospective cures for the dreaded cancer, research is currently undergoing to the creation of genetically modified virus that will target cancer cells specifically. These viruses search and infiltrate only cancer cells and replicate in them thus reducing the growth of tumor substantially. Viruses are also being studied in their role to improve the body's immune response to cancer cells.
About Author / Additional Info:
Maitree Baral holds Masters degree in Bioinformatics and shows profound interest in sharing and discussing various biological issues.