Cancer Immunotherapy Presented by Md. Farhadur Rahman Phase A Student Department of Microbiology BSMMU

Cancer immunotherapy is the use of the immune system to treat cancer. This can be done in a couple of ways: Stimulating patient’s own immune system to work harder or smarter to attack cancer cells Giving immune system components, such as antibody, from outside

Forms of Cancer Immunotherapy Non-Specific: Generalized, non-antigen- specific immune activation Specific: Antigen-specific response induced in the patient or passively transferred from outside

Non-Specific Cancer Immunotherapy 1. Cytokines: (Can be actively induced or passively transferred) Interleukins (IL-2, IL-4, IL-6, IL-12) Colony stimulating factor (GM-CSF) Interferons (e.g. IFN-α, IFN-β, IFN-ϒ) Tumor Necrosis Factors (TNF-α, TNF-β)

2. Immune Checkpoint Inhibitors Monoclonal antibodies (mAbs) against CTLA-4 mAbs against PD-1 or PDL-1 3. Non-Specific Immune Adjuvants BCG: Bacillus Calmette-Guerin Membrane Extracts of BCG Corynebacterium parvum Bacterial Endotoxins: Muramyl Dipeptide

4. Vaccination against neovascularization e.g. mAbs against VEGF & VEGFR-2

Specific Cancer Immunotherapy 1. mAbs against cancer antigen a. Naked monoclonal antibodies b. Conjugated monoclonal antibodies c. Bispecific monoclonal antibodies

2. Prophylactic vaccines (e.g. HBV, HPV vaccine) 3. Theraputic vaccines – Immunization with whole tumor cells or tumor specific antigen – Dendritic cell vaccine

4. Adoptive T-cell therapy – Tumor infiltrating lymphocytes (TILs) – Engineered T cells e.g. CAR T cell

Non-Specific Cancer Immunotherapy Interleukins: Interleukins are a group of cytokines that act as chemical signals between white blood cells. IL-2 helps ThCs & TCCs grow and divide more quickly. A man-made version of IL-2 alone or in combination with TNF-α is approved to treat advanced kidney cancer and metastatic melanoma.

GM-CSF: Transfected tumor cells with the gene for GM-CSF, creating a local source near the tumor cells. These engineered tumor cells, when reinfused into the patient, will secrete GM-CSF, enhancing the differentiation and activation of host APCs, especially DCs.

IFN-α can be used to treat these cancers: Hairy cell leukemia Chronic myelogenous leukemia (CML) Follicular non-Hodgkin lymphoma Cutaneous (skin) T-cell lymphoma Kidney cancer Melanoma Kaposi sarcoma

Cytokines are difficult to administer locally, and systemic administration of high levels of a given cytokine can lead to serious or even life threatening consequences.

Immune Checkpoint Inhibitors Monoclonal antibodies (mAbs) against CTLA-4: Engagement of CTLA-4 on T cells with the CD80/86 molecule on APCs results in T-cell inhibition. mAbs against CTLA-4 can induce tumor rejection. Unfortunately, a significant number of patients experienced autoimmune side effects.

mAbs against PD-1 or PDL-1: Interaction between PD-1 on T cell & PDL-1 on other cells (e.g. APCs) inhibit TCR mediated proliferation & cytokine production. Some cancer cells produce large amounts of PDL-1, which helps them evade immune attack.

mAb treatments that target either PD-1 or PD-L1 can boost the immune response against cancer cells and have shown a great deal of promise in treating certain cancers, such as melanoma of the skin & non-small cell lung cancer.

Non-Specific Immune Adjuvants BCG (Bacillus Calmette-Guerin): BCG is used to treat early stage bladder cancer. It is a liquid put into the bladder through a catheter. BCG attracts the body’s immune system cells to the bladder, where they can attack the bladder cancer cells.

Vaccination against neovascularization e.g. mAbs against VEGF & VEGFR-2: Antibodies directed against VEGFR-2, or VEGF itself, can block tumor angiogenesis in murine tumor models.

Specific Cancer Immunotherapy mAbs against cancer antigen: a. Naked monoclonal antibodies: Naked mAbs are antibodies that work by themselves. There is no drug or radioactive material attached to them. These are the most common type of mAbs used to treat cancer.

Naked mAbs can work in different ways: Some boost a person’s immune response against cancer cells by attaching to them and acting as a marker for the body’s immune system to destroy them. Other naked mAbs work mainly by attaching to and blocking antigens on cancer cells (or other nearby cells) that help cancer cells grow or spread.

For example, trastuzumab is an antibody against the HER2 protein. Breast and stomach cancer cells sometimes have large amounts of this protein on their surface. When HER2 is activated, it helps these cells grow. Trastuzumab binds to these proteins and stops them from becoming active.

b. Conjugated monoclonal antibodies: mAbs in clinical use can be coupled with radioactive isotopes, chemotherapy drugs, or potent toxins of biological origin. In such “guided missile” therapies, the toxic agents are delivered specifically to tumor cells. This ideally focuses the toxic effects on the tumor and spares normal tissues.

c.Bispecific monoclonal antibodies: These drugs are made up of parts of 2 different mAbs, meaning they can attach to 2 different proteins at the same time. An example is blinatumomab, which is used to treat some types of acute lymphocytic leukemia (ALL).

One part of blinatumomab attaches to the CD19 protein, which is found on some leukemia and lymphoma cells. Another part attaches to CD3, a protein found on T cells. By binding to both of these proteins, this drug brings the cancer cells and immune cells together, which is thought to cause the immune system to attack the cancer cells.

Theraputic vaccines: Immunization with whole tumor cells or tumor specific antigen: This has the advantage that we do not necessarily have to know the identity of the antigen concerned. The disadvantage is that the majority of tumors are weakly immunogenic, and do not present antigen effectively.

Dendritic cell vaccine: DCs cultured in GM-CSF and incubated with tumor fragments, then re-infused into the mice, have been shown to activate both TH cells and CTLs specific for the tumor antigens. When the mice were subsequently challenged with live tumor cells, they displayed tumor immunity.

Employing this strategy, sipuleucel-T became the first approved therapeutic cancer vaccine against metastatic prostate cancer.

Adoptive T-cell therapy Tumor infiltrating lymphocytes (TILs): Basic steps: 1.Collection of T cells from fresh patient biopsy specimens 2.Proliferation of T cells in vitro 3.Transfusion of T cells

TIL enrichment IL-2 TIL Tumor-infiltrating Lymphocytes

Engineered T cells: T cells engineered to express tumor antigen-specific receptors 1. Bispecific T cells are created by the introduction of genes that encode proteins that recognize antigens expressed by target tumor cells. 2. Chimeric Antigen Receptor (CAR) T cells: Here genes can encode chimeric tumor antigen-specific receptors, or T bodies, that target surface antigens in an MHC- independent fashion.

It is constructed by linking the variable regions of the antibody heavy and light chains to intracellular signaling chains such as CD3-zeta, potentially including costimulatory domains encoding CD28 or CD137.

T cells engineered for enhanced survival: A limitation to adoptive transfer of CTLs is that they have short-term persistence in the host in the absence of antigen- specific Th cells and/or cytokine infusions. CTLs with chimeric GM-CSF–IL- 2 receptors that deliver an IL-2 signal when they bind GM-CSF.

Stimulation of the CTLs with antigen causes GM-CSF secretion and resulted in an autocrine growth loop such that the CTL clones proliferated in the absence of exogenous cytokines.

Augmentation of Efficacy of Adoptive Cell Therapy Strategies to augment the efficacy of adoptively transferred T cells 1. Lymphodepletion by chemothrapy before transfusion 2. Antibody infusion to prevent CTLA-4 inhibitory effect

3. Antibody infusion to block PD L-1 – PD-1 interaction 4. Cytokines administration e.g. IL-2, IL-7, IL-12, IL-15, or IL-21