The Immune System

1
Tumor immunology
Points to ponder in this Module

• What are tumor antigens?
• What is the evidence for tumor immunity?
• What immune cells are involved in the recognition
  and killing of tumor cells?
• What are cancer immunotherapies?
• What is the significance of the discovery of
  dendritic cells and their role in cancer
  immunotherapies?
• DVD And The Band Played On

2
Cancer and its interaction with the immune system

• Cancer is a diverse collection of
  life-threatening diseases that are caused by
  abnormal and invasive cell proliferation.
• Cancer cells are very similar to normal cells,
  and the immune system is unable to attack them
  early and effectively.
• Cancer results from mutations (changes in DNA)
  that control cell growth.
• The branch of medicine that deals with cancer is
  called oncology.

3
Cancer Cells are Different

• Escape normal intercellular communication
• Allow for rapid growth
• Increased mobility of cells
• Invade tissues
• Metastasis
• Evade the immune system

4
During oncogenesis, some of the antigens on the
cancer cell surface change ( tumor antigens).
Some of these tumor antigens are shed from the
cancer cells. These shed antigens prompt action
from cytotoxic T cells, NK cells, and
macrophages.
According to the theory of immune surveillance,
patrolling cells of the immune system provide
continuous surveillance, catching and eliminating
cells that undergo malignant transformation.
Tumors develop when this immune surveillance
breaks down or is overwhelmed.
5
Evidence for Tumor Immunity

• The high frequency of cancers in immunosuppressed
  patients
• Extremes of age
• Primary and secondary immunodeficiency
• Immunosuppressive drugs
• Tumors that are infiltrated by T cells and
  monocytes have an improved prognosis
• Spontaneous regression occurs
• Melanoma, breast, lung cancers
• Human tumors are immunogenic
• Tumors antigens have been defined
• Tumor specific T cells and antibodies are found
  in cancer patients

6
Experimental Evidence for Tumor Antigens and
Immune Response
4. No tumor growth
2. Excise tumor
3. Re-challenge with same tumor
1. Inject Tumor
1. Inject Tumor
2. Excise tumor
3. Re-challenge with different tumor
4. Tumor grows
7
Tumor immunity in mice is mediated by T
lymphocytes
MCA
Surgicallycured mouse
control mouse
T cells
T cells
Tumor cells
8
Nude mice cannot reject tumors and have been thus
used to test new anti-cancer therapies

• The nude mice have a dysfunctional immune system,
  and can only live in a sterile environment.
• They cannot reject any transplanted tissue,
  including tumors.
• Nude mice are very useful in cancer research
  because injected human cancer cells can grow into
  tumors allowing new ways to test cancer
  therapies.

Nude mouse with transplanted rabbit skin
9
Tumors Benign vs. malignant

• Mass of abnormally proliferating cells is called
  tumor ( swelling) or neoplasm ( new growth).
• Benign Encapsulated tumors, localized and
  limited in size
• Tumors
• Malignant Invasive tumors, invading adjacent
  tissues

Adenoma benign tumor of glandular tissue
10
Classification of tumors

• Tumors Primary the site of cancer origin
• Secondary the new tumors formed by metastasis
  (cancer cells are carried by blood or lymph
  to distant places)
• Solid tumors Carcinomas - cancers of epithelial
  cells (stomach, lung, breast prostate) 90
  of all cancers
• Sarcomas - cancers of all other cell types
  (bones, muscles) very rare
• Immune system cancers Leukemias cancers of
  blood cells
• Lymphomas cancers of lymphoid tissues
• Myelomas cancers of bone marrow

8 of all cancers
11
Ten Most Frequent Cancers in the United States

1. Breast
2. Prostate
3. Lung
4. Colon/rectum
5. Lymphomas
6. Bladder
7. Uterus
8. Skin
9. Kidney
10. Leukemias

12
A cancer arises from a single cell that has
accumulated multiple mutations

• The proper division of cells is controlled by
  many mechanisms and multiple checkpoints ? the
  control of cell division is never dependent on
  only one protein cell must accumulate multiple
  mutations in order to undergo malignant
  transformation.
• Cell division and malignant transformation are
  controlled by two classes of genes
  proto-oncogenes and tumor suppressor genes.
• Proto-oncogenes are genes that regulate cell
  division and proliferation. The mutant forms of
  proto-oncogenes that contribute to malignant
  transformation are called oncogenes.
• Tumor suppressor genes encode proteins that
  prevent malignant transformation. Loss of these
  proteins results in malignant transformations and
  cancer. One of the most important tumor
  suppressor genes is p53, loss of which is
  responsible for 50 of human cancers.

13
p53 Tumor Suppressor Protein Triggers Cell Suicide
p53 protein
Cell suicide (Apoptosis)
Normal cell
Excessive DNA damage
Normal cell
Cell suicide (Apoptosis)
Excessive DNA damage
One particular tumor suppressor gene codes for a
protein called p53 that can trigger apoptosis.
In cells that have undergone DNA damage, the p53
protein acts like a brake pedal to halt cell
growth and division. If the damage cannot be
repaired, the p53 protein eventually initiates
cell suicide, thereby preventing the genetically
damaged cell from growing out of control.
14
NFkB-dependent genes are involved in different
aspects of oncogenesis

• Recent evidence has accumulated from a large
  variety of human malignancies indicating a role
  for NFkB in promoting oncogenic conversion and in
  facilitating later stage tumor properties such as
  metastasis.

Oncogene 25 6817, 2006
15
Constitutive NFkB activation in human cancers
Oncogene 25 6817, 2006
16
Exposure to chemicals, radiation, and viruses can
facilitate the progression to cancer

• The number of mutations in the body can be
  increased by mutagens, chemical and physical
  agents that damage DNA. Mutagens that are known
  to increase the risk of cancer are called
  carcinogens.
• Physical carcinogens (UV light, radiation)
  usually induce extensive DNA mutations DNA
  breaks and chromosome translocations.
• Chemical carcinogens (asbestos, benzene, estrogen
  therapy, tobacco products) usually induce single
  nucleotide substitution in the proto-oncogenes
  and tumor suppressor genes.
• Oncogenic viruses and bacteria Certain viruses
  and bacteria can also induce malignant
  transformation viruses are associated with 15
  of all human cancers. Some oncogenic viruses -
  Papilloma virus, Epstein-Barr virus - bind to
  p53, thus inactivating it and enabling the
  virus-infected cell to proliferate. Bacterium
  Helicobacter pylori is associated with
  pathogenesis of stomach inflammation, ulcers, and
  cancer.

17
Vaccine against HPV now available in the US
18
Cancer therapies

• Surgery
• Chemotherapy
• Radiation therapy
• Immunotherapy
• Types of immunotherapies include
• Cancer vaccines (active specific immunotherapies)
  
• Monoclonal antibody therapy (passive specific
  immunotherapies)
• Nonspecific immunotherapies (cytokines)

Classical New, emerging
19
Immunotherapies

• Cancer vaccines (Active Specific Immunotherapy)
• Contain cancer cells, parts of the cancer cells,
  or pure tumor-associated antigens (antigens
  expressed only on tumor cells but not on healthy
  cells).
• Induce production of tumor-specific antibodies
  and stimulate killer CD8 T cells to attack the
  cancer cells.
• So far used only in clinical trials not approved
  for general use.
• Monoclonal Antibody Therapy (Passive Specific
  Immunotherapy)
• Monoclonal antibody therapy is a passive
  immunotherapy because the antibodies against the
  tumor-associated antigens are produced outside
  the body (in the lab) rather than by the immune
  system. This type of therapy can be effective
  even if the immune system is weakened.
• Approved for treatment of certain cancers (breast
  cancer, leukemias).
• Nonspecific Immunotherapies (Cytokines)
• Stimulate the immune system in a very general
  way.
• Interleukin-2 (IL-2) Stimulates the ability of
  NK cells to kill the cancer cells. Used to treat
  melanomas and kidney cancers.
• Interferons Slow the growth of cancer cells
  stimulate the cancer killing ability of NK cells.
  Used to treat leukemias, lymphomas and melanoma.

20
Immunotherapy
Radioisotope
Herceptin
Growth factor
Herceptin blocks receptor
Antibody
Antigen
Breast cancer cell
Lymphoma cell
Lymphoma cell destroyed
Growth slows
A new approach to cancer therapy uses antibodies
that have been specially made to recognize
specific cancers. When coupled with natural
toxins, drugs, or radioactive substances, the
antibodies seek out their target cancer cells and
deliver their lethal load.
21
HPV Antibodies (Vaccines) Prevent Infection and
Cervical Cancer

• Human papillomavirus (HPV) is the most common
  sexually transmitted virus in the United States.
  At least 70 percent of sexually active persons
  will be infected with HPV at some time in their
  lives. HPV infects both men and women.
• Over 99 percent of cervical cancer cases are
  linked to long-term infections with high-risk
  HPV.
• The vaccination protects a person from future
  infection by the high-risk HPV
• After the vaccination, if an exposure occurs,
  the vaccinated persons antibodies against the
  HPV opsonize the virus and prevent it from
  attachment to the host epithelial cells..

Papillomavirus
Antibodies
22
Monoclonal antibodies (MAbs)

• Monoclonal antibodies are the most widely used
  immunotherapy.
• The first MAbs were made entirely from mouse
  cells. One problem with this is that the human
  immune system will see these antibodies as
  foreign and then will mount a response against
  them. This can cause allergic-type reactions.
• Over time, researchers have learned how to
  replace some parts of these mouse antibody
  proteins with human parts. Depending on how much
  of the MAb is human, these are called chimeric or
  humanized antibodies they are likely to be safer
  and more effective than older MAbs.

Chimeric Antibodies The variable regions of a
mouse antibody are expressed along with human
constant regions. This provides the antibody with
human effector functions. Humanized Antibodies
Only the HVR (CDR) regions from the rodent
antibody V-regions are combined with framework
regions from human V-regions. The idea is that
these antibodies should be more human-like than
chimeric and thus have fewer allergic responses.
22
23
Immature dendritic cells capture antigen but need
to mature to become efficient antigen presenting
cells
24
Making dendritic cell vaccines
IL-4 GM-CSF
Peptide
LPS Poly IC CpG oligo TNFa CD40L
TLR ligands
Mature Dendritic cells
Blood Monocytes
Immature Dendritic cells
Inject i.v.
Freeze for boosts
25
Cancer Immunotherapy Dendritic Cells That
Attack Cancer
By modifying dendritic cells, researchers are
able to activate T cells that attack the cancer
cells. Because a tumor antigen alone is not
enough to result in a strong immune response,
cytokines are first fused to a tumor antigen with
the hope that this will send a strong antigenic
signal. Next, the patient's dendritic cells are
isolated and grown in the incubator to let them
take up this fused cytokine-tumor antigen. This
enables the dendritic cells to mature and
eventually display the same tumor antigens as
appear on the patient's cancer cells. When these
special mature dendritic cells are given back to
the patient, they present their newly acquired
tumor antigens to the T cells that can respond
and attack the patient's cancer cells.
Dendrion FDA approval for prostate cancer
treatment
26
Nobel Prize in Medicine 2011 Dendritic cells and
their role in cancer recognition by the immune
system

• Dr. Steinman received Nobel Prize in Medicine in
  2011 for his discovery of dendritic cells and
  their function
• He used this knowledge for an experimental
  treatment of his pancreatic cancer. This
  prolonged his life for several years.
• He died three days before the Prize was awarded.
  The Nobel Prize Committee decided that his family
  would keep the Prize.
• This was the first time in 50 years the Nobel
  prize was awarded posthumously.

27
Cancer and diet

• Almost 25 centuries ago, Hippocrates remarked
  Let food be the medicine and medicine be the
  food.
• About 1/3 of the cancer deaths in the US each
  year are due to nutrition factors, including
  obesity. (ACS)
• For most Americans who do not smoke, dietary
  choices and physical activity become the most
  important determinants of cancer risk. (ACS)
• Populations with higher consumptions of fruits
  and vegetables have lower incidence of
  gastrointestinal and respiratory tract cancers.
• Consumption of meat, especially red meat, has
  been associated with increased cancer risk at
  several sites, most notably colon and prostate.
  (ACS)

28
Cancer and diet Broccoli

• Broccoli contains certain chemicals that may
  reduce the risk of colorectal, breast, prostate
  and other cancers. Broccoli belongs to the
  cabbage and mustard families, which also includes
  cauliflower, radishes, and brussels sprouts.
• Broccoli is a good source of many phytochemicals
  (chemicals from plants) that may have anti-cancer
  properties. For example, broccoli contains
  several compounds called isothiocyanates,
  including sulforaphane and indole-3-carbinol
  (I3C), which have been suggested as possible
  anti-cancer agents in recent years. Early studies
  have shown these substances may act as
  antioxidants and may boost detoxifying enzymes in
  the body. Some studies have also suggested they
  may alter body estrogen levels, which might
  affect breast cancer risk.

29
Cancer and spices

• Most agents derived from spices have antioxidant
  and anti-inflammatory activities. The antioxidant
  activities of these dietary spices suggest that,
  besides imparting flavor to foods, they possess
  potential health benefits.
• Recent research has also shown that many spices
  (curcumin - curry, garlic, capsaicin - hot chili
  pepper) inhibit activation of the transcription
  factor NFkB, which regulates transcription of
  anti-apoptotic ( pro-survival) genes. Thus,
  these spices can induce apoptosis, and have
  anti-tumor properties.

30
Mechanism of NFkB inhibition in cancer

• Curcumin (curry)
• Capsaicin (hot chili peppers)
• Garlic

Anti-apoptotic (pro-survival) genes, cell growth
regulating genes
31
Prostate Cancer

• The most common cancer in men
• It proceeds from a localized, curable, androgen
  dependent disease to an invasive, metastatic,
  androgen-independent disease, for which there is
  no cure
• The metastatic, androgen-independent prostate
  cancer is characterized by the constitutive
  activation of NFkB
• Activated NFkB induces transcription of
  pro-survival genes such as Bcl-xL and Bcl-2 that
  are associated with the pathogenesis of prostate
  cancer
• Specific inhibition of NFkB represents a prime
  therapeutic target
• Studies from our lab have shown that the
  metastatic prostate cancer cells can be induced
  to undergo apoptosis by inhibiting the
  constitutive NFkB activity by nuclear
  translocation of IkBa

32
Inhibition of NFkB in metastatic prostate cancer
Dr. Hai-Yen Vu, 2008, University of Chicago Dr.
Chandra Ghosh, 2009, Harvard Medical School Dr.
Ashish Juvekar, 2010, Harvard Medical School
33
Inhibition of NFkB in T cell leukemia
Dr. Ram Ramaswami, 2011, Columbia Medical School
Adeel Zubair, 2012, Mount Sinai Medical
School Subrata Manna, 2013