Recombinant Bacterium Tumor Targeting Chemotaxis
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Solution Overview
Problem
Conventional cancer therapies, such as radiotherapy and chemotherapy, face challenges in effectively targeting and reducing tumor size, especially in poorly perfused areas of solid tumors, due to drug resistance and toxicity issues, and current gene therapy strategies require local administration and may be non-selective.
Innovation Solution
A recombinant bacterium, such as Salmonella Typhimurium, is engineered to be hyper-invasive, capable of localizing in tumors, stimulating innate immune responses, inducing programmed cell death, and undergoing regulated lysis to release therapeutic antigens or effector proteins, while being attenuated to minimize toxicity and persistence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional chemotherapy and radiotherapy are used to treat cancer, then tumor cells can be targeted, but toxicity to normal tissue increases and drug-resistant tumor cells develop
Solution Approach 1:
The patent applies local quality by engineering bacteria to specifically target and accumulate in tumor tissues through chemotaxis toward necrotic areas, while attenuating their pathogenicity toward normal tissues. The bacteria exhibit different behaviors in tumor versus normal tissue environments, achieving localized therapeutic action with minimal systemic toxicity
Solution Approach 2:
The patent uses attenuated bacteria as intermediary carriers to deliver therapeutic agents directly to tumor sites. These bacterial intermediaries navigate to tumors, penetrate necrotic areas, and deliver anti-cancer agents or stimulate immune responses locally, avoiding direct exposure of normal tissues to toxic chemotherapy or radiation
2Quantity of substance
If chemotherapy agents are administered systemically, then they can reach tumor cells, but they cannot effectively penetrate poorly perfused areas of solid tumors
Solution Approach 1:
The patent employs bacteria with self-propelled motility that actively navigate through tissues using flagellar chemotaxis. The bacteria independently seek out and penetrate into poorly perfused and necrotic tumor areas that are inaccessible to passively administered chemotherapy agents, delivering therapy directly to previously unreachable sites
3Reliability
If gene therapy vectors are used to deliver anti-cancer genes, then tumor growth can be inhibited, but local administration is required which limits usefulness
Solution Approach 1:
The patent extracts the limitation of local administration by using systemically administrable bacteria that autonomously navigate to tumors. Instead of requiring local vector injection, the therapeutic function is separated from the delivery vehicle - the bacteria serve as self-navigating delivery vehicles that can be administered systemically and will automatically target tumors without surgical or local intervention
4Reliability
If bacteria are made hyper-invasive to improve tumor targeting, then tumor localization increases, but toxicity to normal tissues may increase
Solution Approach 1:
The patent applies parameter changes by modifying bacterial properties - enhancing invasiveness parameters (motility, chemotaxis, tissue penetration) while simultaneously reducing pathogenicity parameters (toxin production, immune activation in normal tissues). This creates a differential effect where bacteria are highly active in tumors but benign in normal tissues
Data Source
AI summary
A recombinant bacterium capable of reducing tumor growth is provided, wherein said recombinant bacterium is capable of: a. increased expression of a nucleic acid encoding a chemoreceptor that directs chemotaxis towards tumors, b. accumulation in a quiescent tumor, c. hyper-invasion of a tumor, d. reduced fitness in normal tissue, e. enhanced stimulation of the host innate immune responses, f. delivering a tumor specific DNA vaccine vector to a tumor cell, and g. increased bacterium-induced host programmed cell death.