Cancer Vaccines Flashcards
What are 4 tumour antigens?
HPV
HBV
Epstein Barr
CEA
What are 4 aims of cancer vaccines?
harness specificity of immune system to: recognize tumours, amplify tumour specific responses & destroy tumour
Which tumour antigen was approved?
Sipuleucel-T (Provenge)
When was antitumour immunity in mice discovered?
1950s
What are 2 vaccines preventing HPV?
Gardasil
Cervarix
What are prophylactic vaccines?
Prevent cancer by targeting viruses & given to healthy individuals
eg Hepatitis B & HPV
What are therapeutic vaccines?
For Pts who already have cancer
eg. metastatic prostrate cancer (Provenge)
& Ebstein Barr virus-associated cancers (WGc-043)
What are 3 treatments for prostrate cancer?
Hormone deprivation therapy
Chemotherapeutic agents
Vaccine therapies
What % of men have recurrence of PC after surgery?
20
What T cells are MHC class I communicating with?
CD8
What T cells are MHC class II communicating with?
CD4 T helper cells
What are 3 APCs?
Dendritic cells
macrophages
B cells
When is MHC class 1 activated?
If antigen that is presented is produced in the cytosol
When is MHC class 2 activated?
If antigen enters from outside via endosomes
What do dendritic cells activate?
naive & memory T cells
How is the Provenge vaccine made?
Harvest APC from blood samples -> incubate with tumour associated antigens called prostatic phosphatase in cytokine presence (GMSF) -> APC shipped back to Pt -> infused with APC -> go to lymph nodes -> initiate cytotoxic T cell response
What are 3 downfalls of Provenge?
Takes 4 days and costs 90,000 & only available in 50 centres in USA
What did the 3 clinical trails for Provenge see?
No sig. change in time to disease progression
What did the study DP9901 see?
Difference of median survival of 4.5 mths
8 fold increase in T cell proliferation
Provenge compared to placebo
What did the study DP9902A see?
Sig. reduction in risk of death of 33% compared to placebo 15%
Less adverse events
no sig change in risk of disease progression
What are 4 cancer vaccine challenges?
Anti-tumour immunity
Failure to produce tumour antigen
Mutation of MHC genes or genes needed for antigen processing
Secretion of immunosuppressive proteins or expression of inhibitory cell surface proteins
What % of cancer Pts do not respond to checkpoint inhibitors?
50
What are 3 suppressive immune cells?
MDSCs
TAMs
T reg
What are 3 benefits of combining tumour vaccine & checkpoint inhibition?
De novo tumour specific T cell response
Amplification of existing tumour specific T cell response
Increased breadth & diversity of tumour-specific T cell response
What are 4 new approaches to improve cancer vaccines?
Better tumour antigens (neoadjuvants)
Better delivery methods
Better adjuvants
Better formulations
What are 4 components of the tumour vaccine?
Tumour antigens eg. TAA
Formulation eg. protein or peptide based
Immune adjuvants eg. TLR agonist
Delivery vehcicle eg. liposomes
What are examples of TAAs?
MART-1
HER-2
if present in normal tissues - can initiate tolerance
What are neoantigens?
random somatic mutations in tumour cells whoch are Pt specific eg. CDK4, catenine & caspase-8
How are neoantigens identified?
whole exosome sequencing
What are 4characteristics of neoantigens?
Potent T cell response
rare
Difficult to predict
recognised as non-self
What is high neoantigen load associated with?
Better survival (65%)
Which TLRs are stimulated with adjuvants?
TLR3/7/8/9
What are 4 TLR agonists?
TLR4 - MPL
TLR3 - poly ICLC
TLR7 - imiquimod
TLR9 - CpG
What are saponins?
Saponin adjuvant with cholesterol & phospholipid to stimulate ER strfess for immune response
What are liposomes?
Delivery to endosome & cytosol to stimulate immune response
What is NY-ESO-1?
Cancer testis antigen (180aa) expressed in a range of tumours & normal cells
What type of response is seen with NY-ESO-1 tumours?
Spontaneous T cell & Ab response
How was the NY-ESO-1 vaccine delivered?
Peptide, whole, fusion protein (HSP70)
range of adjuvants (CpG, Poly-ICLC, resiquimod, lipid matrices)
What is glioblastoma?
Most common form of primary brain tumour in adults - poor survival
What is the standard care for Glioblastoma?
Surgery, radiotherapy & chemo (temozolmide) since 2003
What vaccine has been made for Glioblastomas?
GlioVac
How is GlioVac made?
Surgical resected tumour (only get 80%) -> mixes it with other tumours -> immunised into Pt -> targets immune response at nonresected remnants -> cycles of autologous & allogenic antigens
6 vials from donor
4 vials from Pt
What is added to Glio-Vac?
GM-CSF to stimulate immune response
Was survival extended in GlioVac?
Yes
What phase is GlioVac in?
Phase 3
How are neoantigens being identified?
Comparing tumours to healthy matched control
Look at NS, MHC binding screen
What are 3 parts of the typical workflow for neoadjuvant idenfication?
Single suspension of tumor cells & matched normal cell
HLA typing on normal cells
Antigenicity of NeoAg - predicted by affinity of binding to HLAtype for patient
What is NeoVax?
Phase 1 trial for melanoma Pts
What ere given to Pts in NeoVax?
20-mer Neopeptides specific to Pt tumour with Poly-ICLC
What was the result of NeoVax?
No recurrence for up to 32 mths in stage III
Complete tumor regression after PD-1 therapy for 2 pts in staged 4
What is the aim of mRNA use for delivery strategy?
Potent T cell responses
What is needed for mRNA vaccine?
CD8+ T cells with CD4+
Requires cytolsic delivery for MHC class I
Is an adjuvant added to mRNA?
No mRNA is selfadjuvanting
What is a challenge in mRNA vaccines?
APC targeting
What did Sahin et al 2017 do?
Melanoma vaccine admistered via percutaneous intranasal injection -> mRNA stability & good translation efficiency -> Dc maturation via TLR7
MHC class II restricted
What was the result of Sahin 2017?
2/5 vaccine related responses
1/5 PD-1 + vaccine = complete response
How is mRNA delivered to tumour?
Taken up by DC (adaptive)
Play with charge -> can enter lymphatic system themselves -> activate DC in spleen (innate)
How are neoantigen RNA lipoplex formulations made?
neoepitope discovery
mRNA in vitro transcription
RNA lipoplex formulation
IV injection
APC targeting in spleen
What is IVAC MUTABOME?
13 Pts
combinations of RNA for TAAS with intranodal bossters containing 10 NeoAg RNAs
What was the result of IVAC MUTABOME?
5 pts with metastic disease - 2 had objective response & 1 with complete response
What was the Keynote trial?
mRNA 4157 neoantigen with Pembro reduced death & metastasis by 65%
What is mRNA 4157?
Personalised mRNA encoding 34 different Pt specific neoantigens
What are the 4 stages of the Keynote process?
Sequencing of each Pt tumour & healthy tissues
Identify tumour specific mutations
6 week process
9 mRNA 4157 im doses (every 3 weeks) & 9 IV of Pembro
What afre advances of Keynote trial?
Merck & Moderna - phase III
1089 Pts II - IV
mRNA 4157 + pembrolizumab
What are 3 conclusions of using NeoAg?
CD4+ & CD8+ in all vaccinated Pts
60 -70 % immunising NeoAg recognized
Complete responses with PD-1 blockers
What arfe 3 trials NeoAg used in?
Peptide based eg glioblastoma
Poly-epitope RNA based eg. pancreatic
Peptide loaded DC vaccine eg . colorectal
What 4 things are needed to improve NeoAg?
More CD4+ epitopes than CD8+ atm
Detection of presented antigens on tumour cells
Prediction of class I & II bindng epitopes
Understanding Ag process
better preclinical models for optimization, scheduling & formulation