Future of engineered bacteria in cancer immunotherapy

Background: Statistically, different kinds of cancers account for an average of more than 10 million people each year. It is very difficult to deliver anti-tumor agents or treat cancer because of abnormal vasculature. The adverse side effects of conventional strategies like chemotherapy, radiotherapy, and surgery highlight the urgent need for an alternative therapeutic option. Microbial therapy, which uses mainly bacteria, is being used as an alternative therapy to target tumor cells. Main body: The failure of individual strategies resulted in the introduction of holistic approaches such as microbial therapy, which employs the use of facultative or obligate anaerobic bacteria, such as pathogenic and non-pathogenic bacteria, that naturally target and kill tumors. Bacterial-mediated cancer treatments (BMCTs) have gained popularity in recent decades as an alternative method of treating cancer tumors due to the inherent difficulties of conventional treatments. With advancements in genetic engineering and rDNA (recombinant DNA) technology, several strains of bacteria are introduced as cancer immunotherapy model systems. Emancipating from the concerns of cultural stigmas and toxicology, BMCT holds the potential to benefit cancer treatment. The genetic manipulation of a variety of pathogenic and non-pathogenic bacteria to elicit tumor regression, such as pathogenic strain attenuation, genetically engineering them and comprehending motility for better tumor targeting, modifying immunotoxins for cancer therapy, and novel strategies such as radiation mutation technology (RMT) are subjects of the review, which also includes a discussion of recent advancements, challenges, and prospects for bacteria in the context of the development of bacteria-mediated cancer therapy. Additionally, we discuss how tumor regression is caused by the colonization and proliferation of live bacteria in tumor microenvironments (TMEs).