Intratumoral Bacteria as an Injectable Anti-Cancer Treatment
Scientists at the Japan Advanced Institute of Science and Technology in Ishikawa, Japan have developed an anti-cancer treatment that consists of bacteria that are naturally found inside some tumors. Isolating and then injecting these bacteria into existing tumors appears to provoke a strong immune response that can lead to tumor destruction, without the need for advanced techniques such as bacterial genetic engineering or complex drug delivery. The concept of using bacteria to target tumors is not new, but typically it is studied in the context of using the bacteria to deliver a drug or using genetically engineered bacteria with enhanced anti-tumor properties. Simply using bacteria alone, in specific combinations to achieve maximal efficacy and reduced off-target effects, could represent a low-cost way to target tumors.
Tumors are characterized by erratic and uncontrolled growth. This often leaves their associated blood vessels in an unreliable and leaky state, and the center of solid tumors often demonstrates poor blood supply and low-oxygen conditions. While this can make it difficult to get blood-borne drugs into the tumor core, it also creates a unique microenvironment for bacteria that like to live in such hypoxic conditions.
Recently, researchers have focused on the role of bacteria in fighting cancer. However, much of this research has examined whether bacteria can interfere with conventional anti-cancer therapies or has focused on creating advanced bacterial therapies that often involve nanotechnology, genetic engineering, and other advanced techniques to create tumor targeting bacterial therapies.
But what if none of these fancy methods were required and bacteria can be identified that can help kill tumors all by themselves? Bacteria that naturally like to live in tumors seems like a good place to start looking for such organisms, and these researchers have done just that. Called intratumoral bacteria, these bacterial populations can be exploited to kill tumors provided the right bacterial species are identified. As they already like living in tumors, simply injecting them into a tumor core is a good way to get them in place, and then they can provoke an immune response leading to tumor cell destruction. These researchers have now identified a consortium of bacteria that can achieve this.
“We succeeded in isolating and identifying three types of bacteria from colon cancer tissues, Proteus mirabilis, which we have termed, A-gyo; photosynthetic Rhodopseudomonas palustris, which we have termed UN-gyo; and a complex bacteria that consists of both A-gyo and UN-gyo, which we call AUN,” said Eijiro Miyako, a researcher involved in the study. “This consortium of bacteria, when injected into tumors, show a high antitumor effect.”
So far, the bacteria have shown powerful anti-tumor effects in mouse models of cancer, including in some mice that received just one dose of the therapy.
Study in journal Advanced Science: Discovery of Intratumoral Oncolytic Bacteria Toward Targeted Anticancer Theranostics