Nucleotide (DNA/RNA) tumor vaccines

Difference between active and passive immunotherapy

Active immunotherapy	Passive immunotherapy
T-cell induction (active specific vaccination, ASI)	T-cell administration (e.g., TIL therapy)
B-cell induction (active specific vaccination, ASI)	Antibody administration for ADCC (e.g., anti-CD20)
	Antibody administration for receptor/ligand antagonism (e.g., anti-VEGFR or anti-VEGF)

Give 3 approaches for Non-targeted / non-specific immunotherapy

Approach	Examples
Immune checkpoint blockade (ICB)	Anti-PD-1
Systemic immune stimulation	IFN-α or high-dose IL-2
Intratumoral immune stimulation	CpG, STING agonist, or modified HSV-1

Types of T-cell vaccines

• Dendritic-cell (DC) vaccines.

• Long-peptide vaccines.

• Poxvirus-vector vaccines.

• Autologous tumour-cell vaccines.

• Nucleotide or genetic vaccines, divided into RNA and DNA vaccines.

Why targeted cancer immunotherapy?

1. It can be used when little tumour antigen remains.

After primary therapy, the remaining tumour burden may be very small. A vaccine could help establish or reinforce immunity against residual cancer cells or prophylaxis

2. A potentially favourable toxicity profile.

Nucleotide vaccination/ DNA vaccination mechanism

Step 1: DNA delivery → The vaccine delivers plasmid DNA (pDNA) encoding a tumour antigen into cells at the vaccination site, such as muscle cells or keratinocytes.

Step 2: Antigen production → The plasmid DNA enters the nucleus, where it is transcribed into mRNA. The mRNA moves into the cytoplasm and is translated into the tumour antigen protein.

Step 3: Antigen uptake → Antigen-presenting cells (APCs), especially dendritic cells (DCs), take up the antigen produced by the transfected cells.

Step 4: Cross-presentation → Dendritic cells process the antigen into peptides and present them on MHC class I molecules to CD8⁺ T cells. This is called cross-presentation because the dendritic cell presents an antigen produced by another cell.

Step 5: T-cell activation → Antigen presentation activates CD8⁺ cytotoxic T cells, which can recognise and kill tumour cells expressing the same antigen. CD4⁺ helper T cells can also be activated, supporting the immune response.

Step 6: B-cell activation → B cells can recognise the antigen and produce antigen-specific antibodies.

RNA vaccination mechanism

Step 1: Deliver stabilised mRNA. The RNA enters cells, with the diagram emphasising dendritic cells.

Step 2: Translate the mRNA. Ribosomes in the cytoplasm translate the mRNA into the encoded antigen. Unlike DNA, the mRNA does not need to enter the nucleus.

Step 3: Present antigen and activate T cells. The dendritic cells process the antigen and present peptides to T cells. The slide depicts CD4⁺ and CD8⁺ responses and also shows B-cell activation and antibody production.

DNA versus RNA vaccines

Feature	DNA vaccine	RNA vaccine
Genetic material
Required cellular location
Antigen-producing cells in the lecture
Cross-presentation
Stability/cost in the lecture
Immunogenicity in the lecture

Feature	DNA vaccine	RNA vaccine
Genetic material	Plasmid DNA	mRNA
Required cellular location	Must reach the nucleus for transcription	Cytoplasm for translation
Antigen-producing cells in the lecture	Transfected myocytes or keratinocytes	Transfected dendritic cells
Cross-presentation	Required in the model described	Not required in the model described
Stability/cost in the lecture	Cheaper and more stable	More expensive and less stable
Immunogenicity in the lecture	Described as weaker	Described as stronger

what is personalised neoantigen vaccination.

• Obtain a tumour sample.

• Identify mutations in that tumour.

• Predict which mutation-derived peptides may be recognised by the patient's immune system.

• Select suitable neoepitopes.

• Manufacture an RNA vaccine encoding the selected targets.

• Vaccinate and monitor the resulting immune response.

what is recall response. how is cd4 involved / CD4⁺ T-cell help is essential for tumour rejection explain

A recall response is the immune response produced when the immune system encounters an antigen again after prior exposure. It reflects the capacity to respond again, rather than merely showing that T cells were activated during the first vaccination.

Why does CD4⁺ help matter?

1. A vaccine activates antigen-specific T cells.

2. CD4⁺ helper T cells provide signals that support CD8⁺ T-cell expansion and functional development.

3. These signals help establish a more effective response to subsequent antigen exposure.

4. Without adequate help, an initial response may occur but may not develop into an effective recall response.

How to deliver DNA vaccination

Electroporation

Which would you prefer- DNA / RNA vaccine

• Stabilised mRNA vaccination: a potent, but expensive, T-cell vaccination platform in humans.

• Dermal DNA vaccination by DNA tattooing: an easy platform for preclinical T-cell vaccination research in laboratory animals.

Why do DNA vaccines need cross presentation

Antigen are aquired by APCs and presented to T cells. RNA vaccination targets dendritic cells that can produce and present the antigen themselves.

How does B2M loss cause immune escape?

B2M is needed for normal MHC class I expression. Its loss impairs peptide presentation to CD8⁺ T cells, allowing tumour cells to evade those T cells even after successful vaccination.