Cancer immunology 20230512 (1).pptx

Cancer Immunology and Immunotherapy An Introduction 12 May 2023 Florian Kern, BSMS [email protected] Cancer Immunology and Immunotherapy Learning outcomes: (1) Understand how the immune system recognises cancer (or why it doesn’t) (2) Understand the role of the tumour microenvironment for the immu...

Cancer Immunology and Immunotherapy An Introduction 12 May 2023 Florian Kern, BSMS [email protected] Cancer Immunology and Immunotherapy Learning outcomes: (1) Understand how the immune system recognises cancer (or why it doesn’t) (2) Understand the role of the tumour microenvironment for the immune response (3) Be able to describe how the immune system can be manipulated to recognise and destroy tumours Overview • Tumours and immune cells • Cancer susceptibility genes • Tumour-selective antigens (TSAs) • The tumour microenvironment • Use in diagnostics • Tumour-specific mutations • Creating personalised tumour vaccines • The immunological synapse and checkpoints • Checkpoint inhibition • CAR-immune-cell therapy Why T-cells are critical in anti-cancer immunity They recognise mutated peptides Generally, cancer cells are extremely similar to the immunological ‘self’. However, they show a few differences related to the mutated proteins they produce. These proteins give rise to (mutated) peptides, which are presented on their surface class-I MHC molecules (ideally). We discriminate: (1) Tumour-selective proteins (incl. ‘tumour associated’, ‘tumour-specific’ Ags): public/shared Proteins expressed at early cell differentiation stages (higher levels in tumour cells) or mainly expressed in tumours. This is mostly a question of antigen expression levels. (2) Proteins with individual mutations: ‘private’ (i) Germline mutations (affecting all cells of a given cell type, inherited) (ii) Somatic mutations (affecting single tumour cells and their offspring) Some basic facts: T-cells and the MHCcomplex CD8 T-cell No MHC Intracellular protein Proteins made intracellularly are not visible on the outside unless presented by MHC or a T-cells and the MHC-complex CD8 T-cell MHC I Presented peptide Intracellular protein Following intracellular protein processing, the resulting peptides are presented on class-I T-cells and the MHC-complex CD8 T-cell Extracellular antigen MHC I Presented peptide CD4 T-cell MHC II Intracellular antigen Extracellular antigens are processed differently and are presented on class-II MHC T-cells and the MHC-complex CD8 T-cell Extracellular antigen MHC I Presented peptide CD4 T-cell MHC II Intracellular antigen MHC molecules present peptides so that T-cells can recognise them Features of tumourpotential antigens of tumourFeatures and therapeutic For consideration as target antigens for cancer vaccines selective antigens Do not worry about the definitions (‘tumour associated’, ‘tumour-specific’) too much. This diagram shows you the therapeutic potential of tumour-selective antigens depending on expression levels and tissue distribution Tumour-selective antigens in diagnostics They are used in screening and to follow-up patients after an operation (1)Alpha-feto-protein Associated with liver cancer (primary hepatocellular carcinoma), expressed in less cells (early differentiation stages) (2) MAGE-A antigens (Cancer-Testis-Antigens) – higher levels=poorer prognosis in some tumours Non-small cell lung cancer, bladder cancer, oesophageal cancer, ovarian cancer (3) PAP (prostatic acid phosphatase) and PSA (prostate specific antigen) Prostate cancer Neoantigens: tumour and patient-specific Tumours can be biopsied and sequenced in their entirety and mutations Each coloured dot represents one tumour. The median is shown by a black circle and indicated below the plot. Tumour Mutational Burden (TMB) is defined as the number of proteins with a mutation leading to a change in coded amino-acids. TMB is controversial as a prognostic for immunotherapy. (Castle, J, et al. Front. Immunol., 07 August 2019; mutations can be counted. Neoantigens derived from mutations • Neoantigens distinguish tumours from normal cells • If T-cell receptors can bind to HLA-presented, mutated peptides with sufficient affinity they will be activated and and may destroy them • Neoantigen-based vaccines require antigen-presenting cells (APC, e.g. dendritic cells or B-cells) to activate the T cells recognising vaccine-encoded neoantigens (i.e. the mutated peptides) • Transfer of mutation-specific T cells (adoptive cell transfer, ACT) provides ‘prefabricated’ cytotoxic T cells that recognize and may kill tumour cells. • ACT is also in use to treat viral infections after bone marrow transplantation (e.g. EBV, CMV, BK-Virus) Creating a personalised tumour vaccine Patient with Tumour biopsy Identifying Tumour & sequencing Requires therapy proteins Bioinformatics: Vaccine Mutations Most promising neoepitopes Expresses neoepitopes in In proteins are selected (MHC-binding) Personalised RNA tumour vaccines may encode peptides or proteins, similar to the Moderna and Biontech COVID vaccines. • Peptide-expressing vaccines will mainly stimulate T-cells • This stimulation takes place away from the tumour • Fully activated T-cells may subsequently overwhelm the tumour Patient tissue Cancer susceptibility genes indicate a higher cancer risk These relate to hereditary cancers. For example: (1)BCRA1 and BCRA2 mutations Associated with ovarian cancer (30 to 45x higher risk) and breast cancer (3-5 x higher risk); these mutations are found in approximately 1 in 500 women (0.2% of the population) The Risk of developing breast cancer by a woman in UK by the age of 70 is • 60-85% with a mutation in the BRCA1 gene, 40- 85% with a mutation in the BRCA2. • Life-time risk of the average woman UK: 12.5% BCRA1 and 2 genes code for tumour suppressor proteins that regulate RAD51 which is a DNA repair protein assisting in the repair of DNA double strand breaks. In the absence of functional RAD51 double strand breaks are not repaired efficiently, resulting in tumours. Cancer susceptibility genes: preventative mastectomy? Angelina Jolie, 37, shocked and touched the world with her frank admission in a New York Times op-ed that she had undergone an elective double mastectomy because she carries a "faulty" gene, BRCA1, that took her mother at age 56. "I hope that other women can benefit from my experience," she wrote. https://www.nhs.uk/conditions/breast-cancer/prevention/ Is cancer hiding from the immune system? The tumour microenviroment (‘TME’) Tumours tend keep a low profile to avoid stirring up immune cells. T-cells will infiltrate tumours if they recognise peptides on tumour cells. A number of factors influence the fate of these T-cells as well as that of the tumour. For example: (1) Immune status of the patient (i.e. normal immunity, immunosuppressed, immunosenescent) (2) Tumour microenvironment (3) Infections & Inflammation ‘Tumour microenvironment’ refers to the space immediately around the tumour cells and within the tumour tissue, The tumour microenvironment The TME may subdue the immune system Here are some examples: • Cytokines and other factors downregulate (local) inflammation o e.g. IL-10 secretion (an anti-inflammatory cytokine) • Tumour gene-products reduce tumour MHC-I expression o a mechanism used by viruses, too (may triggers NK-cells) • T-cell activity is reduced at immune check-points o expression/upregulation of inhibitory ligands (PD-1 ligand) The TME may protect the tumour from the immune system. Tumour infiltrating lymphocytes may change from T-effector to Treg or lose function altogether. The immunological synapse: enhancing the contact surface area Morphological and cytoskeletal changes in the initial engagement and formation of a stable T-helper-cell synapse. After initial engagement of the T-cell receptor - T cell stops migrating - The microtubule organizing centre (MTOC) is reoriented to beneath the immunological synapse - TCR molecules (yellow) are recruited into the synapse - Other cell-surface molecules (e.g. CD43) are excluded. CD43 = Leukosialin, mediates repulsion - Stimulatory (red) and non-stimulatory (grey) peptide/MHC complexes are presentHuppa, in theJB, Nature Reviews Immunology volume 3, pages 973–983 (2 The immunological synapse – a variety of signals Costimulation (Signal 2 & more) In addition to the interaction between the TCR and the MHC/peptide complex, APCs provide signals that have activating effects on T-cells and molecules that provide adhesion. Examples: • CD80/86 <-> CD28 [activation; antagonist drug: CTLA-4 Ig, immunosuppressive] • ICAM-1 <-> LFA-1 [adhesion, activation] ICAM-1= Intercellular adhesion molecule-1 LFA-1 = leucocyte function antigen-1 Anti-checkpoint therapy – what is it? Checkpoints control the strength of T-cell activation at the immunological synapse. For example, APCs express a molecule called ‘PD-1 ligand’ also found in the immunological synapse. It is the ligand for ‘PD1’ (‘programmed cell death receptor-1’, a 40kDa transmembrane protein). A view of the immunological synapse is shown on the right. Anti-checkpoint therapy – what is it? Signal 1: Under normal circumstances TCR/MHC/peptide complex interaction leads to the phosphorylation of proximal signalling kinases and subsequently T-cell activation. Activatio n Activated T-cells in the TME are bad for tumour cells. Signal 1 Anti-checkpoint therapy – what is it? Signal I interference: Interaction of PD-1 ligand on APCs with PD-1 on T-cells provides an inhibitory signal. Ligation of PD-1 induces the dephosphorylation of proximal signalling kinases. Signal 1 interference Anti-checkpoint therapy – what is it? This interference reduces T-cell activation. PD-1 ligand is also expressed on tumour cells. It helps the tumour to deactivate T-cells coming to attack the tumour cell. A number of anti-tumour approaches target PD-1/PD-1 ligand interaction in order to reinstate normal tumour-induced T-cell activation. Signal 1 interference Anti-checkpoint therapy – what is it? Dostarlimab (Jemperli): This is a PD-1 antibody that blocks its ligation by PD-1 ligand. It is a humanised monoclonal antibody (mAb), produced by recombinant DNA technology in mammalian Chinese hamster ovary (CHO) cells. Dostarlimab is called a ‘checkpoint inhibitor’ and approved for certain prostate cancer patients with a DNA mismatch repair deficiency (dMMR). Signal 1 interference Anti-checkpoint therapy – what is it? Dostarlimab (Jemperli): a checkpoint inhibitor that targets the PD-1/PD-1 ligand pathway; approved for subsets of patients with advanced prostate cancer with DNA mismatch repair deficiency (dMMR) Dostarlimab is a PD-1 antibody that blocks its ligation by PD-1 ligand. It is a humanised monoclonal antibody (mAb), produced by recombinant DNA technology in mammalian Chinese hamster ovary (CHO) cells. Activatio n Signal 1 interference Signal 1 established Molecular Cancer volume 18, Article number: 155 (2019) Established and new targets for immune checkpoint therapy CAR-T-cell therapy rinciple: Single chain antibody-fragment with a TCR-like stem Examples: Axicabtagene ciloceucel (axi-cel) Tisagenlecleucel transmembrane costimulation signalling Tisagenlecleucel Autologous T-cell therapy with genetically modified T-cells, targets CD19 on B-cells and B-ALL Advantage: Thanks to the B-cell receptor (single chain), cytotoxic Tcells can be directed at selected targets at will. CAR-T-cell therapy (Tisagenlecleucel = Kymriah) anti-CD3/anti-CD28 CAR-T-cell therapy is an autologous personalised therapy. This avoids a rejection of the transferred cells by the immune system. It takes about 3 weeks from taking the blood sample to receiving the personalised therapy (that’s faster than you can get a passport). It’s also more expensive. A treatment course costs about £282,000 for one infusion. It is usually a one-time treatment. Severe side effects include cytokine release syndrome, for the treatment of which Toxilizumab (anti-IL-6) and corticosteroids are recommended. CAR-T-cell therapy beyond cancer https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7827151/table/biomedicines-09-00059-t001/? CAR-immune-cell therapy – a powerful novel approach CAR-NK-cells – NK-cells with an Ig-type receptor Advantages: no or little GvHD, no MHC-match required, off-the-shelf-product, less general toxicity, less cytokine release syndrome, less neurotoxicity CAR-B-cells - reprogramming B-cells (they already have an Ig-receptor which is replaced) CAR-macrophages – effective infiltration of tumour micro-environment Chimeric antigen receptors ‘redirect’ immune against targets of interest by providing them with a novel antigen receptor. CAR-NK-cell therapy – a powerful novel approach A large array of activating mechanisms allow CAR-NK cells to eliminate tumour cells – at the same time, they are less susceptible to the mechanisms that tumour cells have developed to subdue T-cells. They have huge therapeutic potential. In addition, they can be used in a therapeutic ‘warehouse’ approach, as they need not be autologous or even HLA-matched. Summary • T-cells are the mainstay of natural anti-tumour immunity, but other immune cells contribute (e.g. NK-cells, Bcell) • Tumour cells try to ‘hide’ from the immune system and calm it down by creating a protective environment around them (the tumour microenvironment or TME) • Cancer-specific T-cells may be subdued by the cancer cells but can be reactivated by anti-checkpoint therapy • Immunotherapy against cancers includes a wide range of other approaches. • RNA vaccines, CAR-T-cell therapy, and newer developments like CAR-NK-cells are very promising. Some therapies can be combined. End Thank you very much for your attention If you have any questions you can e-mail me at [email protected] CAR-NK-cell therapy – a powerful novel approach You will have learned about the mechanisms in the red frame in the past: KIRs/MHCI, NKG2D/NKG2D-L, CD16/AbAg-complexes. They should be remembered. • CD16 is an NK-cell lineage marker • KIRs (‘killer-cell immunoglobulin-like receptors’) can be activating or inhibitory. E.g. a lack of class-I MHC can lead to activation (tumour cells downregulate class-I MHC) and so can the presence of Overview CAR-immune cells – existing and new developments (for your own study)