Microbes and Cancer Flashcards

Question

What are immune check points, and how do tumours exploit these?

Answer 1

Molecules on immune cells (especially T cells) that can turn immune responses down; helps prevent autoimmunity Tumours exploit these checkpoints to hide from the immune system

Answer 2

Immune checkpoint inhibitors are drugs that block these inhibitors, allowing T cells to stay active and attack cancer cells

Answer 3

Some bacteria help activate T cells more effectively. Successful ICI treatment has been strongly associated with a diverse microbiota

Answer 4

Bifidobacterium- boosts anti-tumour T cell activity

Answer 5

- Pembrolizumab = Anti PD-1 (receptor found on T cells) - Prevents T cell exhaustion, promoting tumour killing - Shown to be very effective for some, but unresponsive in others (linked to microbiota)

Answer 6

William Coley was a 19th-century physician who observed that some cancer patients experienced tumour regression after bacterial infections. He developed "Coley’s toxins" — bacterial extracts used to stimulate the immune system. His work laid the foundation for modern cancer immunotherapy.

Answer 7

Modern approaches use bacteria to stimulate anti-tumour immune responses, deliver therapeutic agents directly to tumours, and modulate the tumour microenvironment. Techniques include - TLR activation - Engineered/attenuated bacteria - Oncolytic bacteria.

Answer 8

TLRs (Toll-like receptors) are immune sensors that detect microbial molecules. Bacterial components like LPS or flagellin activate TLRs on immune cells, triggering inflammation and enhancing anti-tumour immunity. TLR agonists are used as adjuvants in cancer immunotherapy.

Answer 9

Engineered bacteria are genetically modified to: - Target tumours selectively - Deliver anti-cancer molecules (e.g., toxins, cytokines, tumour antigens) - Survive in hypoxic, immunosuppressed tumour environments Examples: Salmonella typhimurium, Clostridium novyi

Answer 10

Oncolytic bacteria are microbes that: Directly kill cancer cells Or stimulate immune-mediated tumour destruction They function similarly to oncolytic viruses and are often used in solid tumours.

Answer 11

Tumours often have leaky vasculature, low oxygen (hypoxia), and immune-suppressive microenvironments — conditions where some bacteria (e.g. Salmonella, Clostridium) can thrive while normal tissues cannot, enabling selective tumour targeting.

Answer 12

TLR agonists mimic bacterial signals and activate innate immune pathways. They are used to boost the immune system’s ability to recognise and destroy tumour cells, especially in combination with vaccines or checkpoint inhibitors.

Answer 13

It involves using probiotics, prebiotics, or microbiome-targeted interventions to: Enhance anti-tumour immunity Improve responses to immunotherapy Restore healthy gut flora after dysbiosis or antibiotic use

Answer 14

Probiotics: Live bacteria (e.g. Bifidobacterium, Lactobacillus) that may stimulate immune cells and reduce inflammation. Prebiotics: Nutrients that promote growth of beneficial gut bacteria, potentially boosting checkpoint inhibitor responses.

Answer 15

Tumours often suppress immune responses locally. Bacteria can: Break immune tolerance Activate innate and adaptive immunity Deliver therapies directly into the tumour site

Microbes and Cancer Flashcards

(39 cards)