281 - Tumor Immunology Flashcards
What is pseudoprogression after immunotherapy?
Tumor appears to grow at first
(probably due to lots of immune cells going there)
Be patient! Likely to regress later
Briefly describe the oncolytic virus approach to treating melanoma
HSV-1 is re-engineered to fight melanoma -> TVEC
- TVEC is injected into tumor
- Causes tumor lysis, expression of GM-CSF in the microenvironment
- Attracts lots of immune cells
- -> anti-tumor response
What is the difference between type 1 and type 2 macrophages?
Type 1 (M1) = turn on adaptive immunity
Type 2 (M2) = limits adaptive immunity
- M1’s are eager and excitable*
- M2’s are burnt out ard ready to limit activities*
What is the most significant side effect of immune therapies?
Autoimmunity
- Goal is to maximize immune response to tumor, but also need to prevent autoimmunity*
- Rash/desquamation, colitis, hypophysitis, encephalitis*
List 2 things that can prevent T-cell activation
1 during the priming phase, 1 in the tumor microenvironment
- Priming: T-cell can express CTLA-4
- Binds APC’s B7 with higher affinity than T cell’s CD28
- CD28 needed for secondary activation; if CTLA-4 binds B7, B7-CD28 interaction cannot occur and T-cell does not activate
- Tumor environment: Tumor cell can expres PD-L1
- Binds to T-cell PD-1 receptor
- Prevents T-cell activation
- Anti-PDL1 or Anti-PD1 therapies prevent this interaction, allow the T-cell to become active
Using a combo of Anti-PDL1 and anti-CTLA4 = helpful!!
Which cells activate T cells via the T cell recpetor?
Dendritic cells
Causes T cells to differentiatie into CD4+ helper or CD8+ cytotoxic
Dendritic cells = key link between innate and adaptive immunity
What are the primary and secondary signals that work together to activate T-cells?
- Primary
- APC presents antigen on MHC to T-cell receptor
- Secondary
- APC expresses B7, which binds to CD28 on the T-cell
If T-cell expresses CTLA-4, it has a higher affinity for B7 than CD28; will prevent activation
How does the immune system normally work to fight cancer?
- Innate immune cells cause cancer lysis
- Antigen-indeepndent process
- Creates tumor neoantigens
-
Dendritic cells uptake neoantigens
- Express to T-cells; antigen dependent
- Activates the adaptive immune system
- T-cells become activated
-
CD8+ cytotoxic T cells go to the tumor
- Antigen-dependent cell death
- Goal is to shrink tumor
Things in blue = drugs that can augment this system
How do tumors evade the immune system?
-
Equilibirium
- Tumor cells are there, but they are dormant - hiding from the immune system
-
Escape
- Tumor figures out how to take over without being caught by the immune system
Which cells are involved in the innate and adaptive immune systems?
- Innate
- Macrophages
- Dendritic cells
- NK cells
- Neutrophils
- Adaptive
- T cells
- B cells