Cancer Immunotherapy
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Cancer immunotherapy (sometimes called immuno-oncology) is the stimulation of the
immune system The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinte ...
to treat
cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
, improving on the immune system's natural ability to fight the disease. It is an application of the
fundamental research Basic research, also called pure research or fundamental research, is a type of scientific research with the aim of improving scientific theories for better understanding and prediction of natural or other phenomena. In contrast, applied resear ...
of
cancer immunology Cancer immunology is an interdisciplinary branch of biology that is concerned with understanding the role of the immune system in the progression and development of cancer; the most well known application is cancer immunotherapy, which utilis ...
and a growing subspecialty of
oncology Oncology is a branch of medicine that deals with the study, treatment, diagnosis and prevention of cancer. A medical professional who practices oncology is an ''oncologist''. The name's etymological origin is the Greek word ὄγκος (''ó ...
. Cancer immunotherapy exploits the fact that cancer cells often have
tumor antigen Tumor antigen is an antigenic substance produced in tumor cells, i.e., it triggers an immune response in the host. Tumor antigens are useful tumor markers in identifying tumor cells with diagnostic tests and are potential candidates for use in c ...
s, molecules on their surface that can be detected by the
antibody An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...
proteins of the immune system, binding to them. The tumor antigens are often
protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
s or other macromolecules (e.g.,
carbohydrate In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or ma ...
s). Normal antibodies bind to external pathogens, but the modified
immunotherapy Immunotherapy or biological therapy is the treatment of disease by activating or suppressing the immune system. Immunotherapies designed to elicit or amplify an immune response are classified as ''activation immunotherapies,'' while immunotherap ...
antibodies bind to the tumor antigens marking and identifying the cancer cells for the immune system to inhibit or kill. Clinical success of cancer immunotherapy is highly variable between different forms of cancer; for instance, certain subtypes of
gastric cancer Stomach cancer, also known as gastric cancer, is a cancer that develops from the lining of the stomach. Most cases of stomach cancers are gastric carcinomas, which can be divided into a number of subtypes, including gastric adenocarcinomas. Lymph ...
react well to the approach whereas immunotherapy is not effective for other subtypes. In 2018, American immunologist
James P. Allison James Patrick Allison (born August 7, 1948) is an American immunologist and Nobel laureate who holds the position of professor and chair of immunology and executive director of immunotherapy platform at the MD Anderson Cancer Center at the Uni ...
and Japanese immunologist
Tasuku Honjo is a Japanese physician-scientist and immunologist. He won the 2018 Nobel Prize in Physiology or Medicine and is best known for his identification of programmed cell death protein 1 (PD-1). He is also known for his molecular identification o ...
received the
Nobel Prize in Physiology or Medicine The Nobel Prize in Physiology or Medicine is awarded yearly by the Nobel Assembly at the Karolinska Institute for outstanding discoveries in physiology or medicine. The Nobel Prize is not a single prize, but five separate prizes that, accord ...
for their discovery of cancer therapy by inhibition of negative immune regulation.


History

"During the 17th and 18th centuries, various forms of immunotherapy in cancer became widespread... In the 18th and 19th centuries, septic dressings enclosing ulcerative tumours were used for the treatment of cancer. Surgical wounds were left open to facilitate the development of infection, and purulent sores were created deliberately... One of the most well-known effects of microorganisms on ... cancer was reported in 1891, when an American surgeon,
William Coley William Bradley Coley (January 12, 1862 – April 16, 1936) was an American bone surgeon and cancer researcher best known for his early contributions to the study of cancer immunotherapy. Although his work was not proven effective in his lifetime ...
, inoculated patients having inoperable tumours with ''Streptococcus_pyogenes''_.html" ;"title="Streptococcus pyogenes">''Streptococcus pyogenes'' ">Streptococcus pyogenes">''Streptococcus pyogenes'' " "Coley adthoroughly reviewed the literature available at that time and found 38 reports of cancer patients with accidental or
iatrogenic Iatrogenesis is the causation of a disease, a harmful complication, or other ill effect by any medical activity, including diagnosis, intervention, error, or negligence. "Iatrogenic", ''Merriam-Webster.com'', Merriam-Webster, Inc., accessed 2 ...
feverish
erysipelas Erysipelas () is a relatively common bacterial infection of the superficial layer of the skin ( upper dermis), extending to the superficial lymphatic vessels within the skin, characterized by a raised, well-defined, tender, bright red rash, t ...
. In 12 patients, the sarcoma or carcinoma had completely disappeared; the others had substantially improved. Coley decided to attempt the therapeutic use of iatrogenic erysipelas..." "Coley developed a toxin that contained heat-killed bacteria ''Serratia_marcescens''_.html" ;"title="Serratia marcescens">''Serratia marcescens'' ">Serratia marcescens">''Serratia marcescens'' Until 1963, this treatment was used for the treatment of sarcoma." "Coley injected more than 1000 cancer patients with bacteria or bacterial products." 51.9% of oley'spatients with inoperable soft-tissue sarcomas showed complete tumour regression and survived for more than 5 years, and 21.2% of the patients had no clinical evidence of tumour at least 20 years after this treatment..." Research continued in the 20th Century under Dr. Maria O'Connor Hornung at Tulane Medical School


Categories

Immunotherapies can be categorized as active or passive. Active immunotherapy specifically targets tumor cells via the immune system. Examples include therapeutic cancer vaccines (also known as treatment vaccines, which are designed to boost the body's immune system to fight cancer),
CAR-T cell In biology, chimeric antigen receptors (CARs)—also known as chimeric immunoreceptors, chimeric T cell receptors or artificial T cell receptors—are receptor proteins that have been engineered to give T cells the new ability to target a specific ...
, and targeted antibody therapies. In contrast, passive immunotherapy does not directly target tumor cells, but enhances the ability of the immune system to attack cancer cells. Examples include
checkpoint inhibitor Checkpoint inhibitor therapy is a form of cancer immunotherapy. The therapy targets immune checkpoints, key regulators of the immune system that when stimulated can dampen the immune response to an immunologic stimulus. Some cancers can protect the ...
s and
cytokine Cytokines are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are peptides and cannot cross the lipid bilayer of cells to enter the cytoplasm. Cytokines have been shown to be involved in autocrin ...
s. Active cellular therapies aim to destroy cancer cells by recognition of distinct markers known as
antigen In immunology, an antigen (Ag) is a molecule or molecular structure or any foreign particulate matter or a pollen grain that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response. ...
s. In cancer vaccines, the goal is to generate an immune response to these antigens through a vaccine. Currently, only one vaccine (
sipuleucel-T Sipuleucel-T, sold under the brand name Provenge, developed by Dendreon Pharmaceuticals, LLC, is a cell-based cancer immunotherapy for prostate cancer (CaP). It is an autologous cellular immunotherapy. Medical uses Sipuleucel-T is indicated ...
for prostate cancer) has been approved. In cell-mediated therapies like CAR-T cell therapy, immune cells are extracted from the patient,
genetically engineer Genetic engineering, also called genetic modification or genetic manipulation, is the modification and manipulation of an organism's genes using technology. It is a set of technologies used to change the genetic makeup of cells, including t ...
ed to recognize tumor-specific antigens, and returned to the patient. Cell types that can be used in this way are natural killer (NK) cells,
lymphokine-activated killer cell In cell biology, a lymphokine-activated killer cell (also known as a LAK cell) is a white blood cell that has been stimulated to kill tumor cells. If lymphocytes are cultured in the presence of Interleukin 2, it results in the development of effect ...
s, cytotoxic T cells and dendritic cells. Finally, specific antibodies can be developed that recognize cancer cells and target them for destruction by the immune system. Examples of such antibodies include
rituximab Rituximab, sold under the brand name Rituxan among others, is a monoclonal antibody medication used to treat certain autoimmune diseases and types of cancer. It is used for non-Hodgkin lymphoma, chronic lymphocytic leukemia (in non-geriatric pa ...
(targeting CD-20),
trastuzumab Trastuzumab, sold under the brand name Herceptin among others, is a monoclonal antibody used to treat breast cancer and stomach cancer. It is specifically used for cancer that is HER2 receptor positive. It may be used by itself or together wi ...
(targeting HER-2), and
cetuximab Cetuximab, sold under the brand name Erbitux, is an epidermal growth factor receptor (EGFR) inhibitor medication used for the treatment of metastatic colorectal cancer and head and neck cancer. Cetuximab is a chimeric (mouse/human) monoclonal a ...
(targeting EGFR). Passive antibody therapies aim to increase the activity of the immune system without specifically targeting cancer cells. For example, cytokines directly stimulate the immune system and increase immune activity. Checkpoint inhibitors target proteins (
immune checkpoint Immune checkpoints are regulators of the immune system. These pathways are crucial for self-tolerance, which prevents the immune system from attacking cells indiscriminately. However, some cancers can protect themselves from attack by stimula ...
s) that normally dampen the immune response. This enhances the ability of the immune system to attack cancer cells. Current research is identifying new potential targets to enhance immune function. Approved checkpoint inhibitors include antibodies such as
ipilimumab Ipilimumab, sold under the brand name Yervoy, is a monoclonal antibody medication that works to activate the immune system by targeting CTLA-4, a protein receptor that downregulates the immune system. Cytotoxic T lymphocytes (CTLs) can recogniz ...
,
nivolumab Nivolumab, sold under the brand name Opdivo, is a medication used to treat a number of types of cancer. This includes melanoma, lung cancer, malignant pleural mesothelioma, renal cell carcinoma, Hodgkin lymphoma, head and neck cancer, urotheli ...
, and
pembrolizumab Pembrolizumab, sold under the brand name Keytruda, is a humanized antibody used in cancer immunotherapy that treats melanoma, lung cancer, head and neck cancer, Hodgkin lymphoma, stomach cancer, cervical cancer, and certain types of breast canc ...
.


Cellular immunotherapy


Dendritic cell therapy

Dendritic cell therapy provokes anti-tumor responses by causing dendritic cells to present tumor antigens to lymphocytes, which activates them, priming them to kill other cells that present the antigen. Dendritic cells are antigen-presenting cells (APCs) in the mammalian immune system. In cancer treatment they aid cancer antigen targeting. The only approved cellular cancer therapy based on dendritic cells is
sipuleucel-T Sipuleucel-T, sold under the brand name Provenge, developed by Dendreon Pharmaceuticals, LLC, is a cell-based cancer immunotherapy for prostate cancer (CaP). It is an autologous cellular immunotherapy. Medical uses Sipuleucel-T is indicated ...
. One method of inducing dendritic cells to present tumor antigens is by vaccination with autologous tumor lysates or short peptides (small parts of protein that correspond to the protein antigens on cancer cells). These peptides are often given in combination with
adjuvants In pharmacology, an adjuvant is a drug or other substance, or a combination of substances, that is used to increase the efficacy#Pharmacology, efficacy or Potency (pharmacology), potency of certain drugs. Specifically, the term can refer to: * Adju ...
(highly
immunogenic Immunogenicity is the ability of a foreign substance, such as an antigen, to provoke an immune response in the body of a human or other animal. It may be wanted or unwanted: * Wanted immunogenicity typically relates to vaccines, where the injectio ...
substances) to increase the immune and anti-tumor responses. Other adjuvants include proteins or other chemicals that attract and/or activate dendritic cells, such as
granulocyte macrophage colony-stimulating factor Granulocyte-macrophage colony-stimulating factor (GM-CSF), also known as colony-stimulating factor 2 (CSF2), is a monomeric glycoprotein secreted by macrophages, T cells, mast cells, natural killer cells, endothelial cells and fibroblasts th ...
(GM-CSF). The most common source of antigens used for dendritic cell vaccine in
glioblastoma Glioblastoma, previously known as glioblastoma multiforme (GBM), is one of the most aggressive types of cancer that begin within the brain. Initially, signs and symptoms of glioblastoma are nonspecific. They may include headaches, personality ch ...
(GBM) as an aggressive brain tumor were whole tumor lysate, CMV antigen RNA and tumor-associated peptides like EGFRvIII. Dendritic cells can also be activated ''
in vivo Studies that are ''in vivo'' (Latin for "within the living"; often not italicized in English) are those in which the effects of various biological entities are tested on whole, living organisms or cells, usually animals, including humans, and ...
'' by making tumor cells express GM-CSF. This can be achieved by either genetically engineering tumor cells to produce GM-CSF or by infecting tumor cells with an
oncolytic virus An oncolytic virus is a virus that preferentially infects and kills cancer cells. As the infected cancer cells are destroyed by oncolysis, they release new infectious virus particles or virions to help destroy the remaining tumour. Oncolytic vir ...
that expresses GM-CSF. Another strategy is to remove dendritic cells from the blood of a patient and activate them outside the body. The dendritic cells are activated in the presence of tumor antigens, which may be a single tumor-specific peptide/protein or a tumor
cell lysate Lysis ( ) is the breaking down of the membrane of a cell, often by viral, enzymic, or osmotic (that is, "lytic" ) mechanisms that compromise its integrity. A fluid containing the contents of lysed cells is called a ''lysate''. In molecular bio ...
(a solution of broken down tumor cells). These cells (with optional adjuvants) are infused and provoke an immune response. Dendritic cell therapies include the use of antibodies that bind to receptors on the surface of dendritic cells. Antigens can be added to the antibody and can induce the dendritic cells to mature and provide immunity to the tumor. Dendritic cell receptors such as
TLR3 Toll-like receptor 3 (TLR3) also known as CD283 (cluster of differentiation 283) is a protein that in humans is encoded by the ''TLR3'' gene. TLR3 is a member of the toll-like receptor family of pattern recognition receptors of the innate immune ...
,
TLR7 Toll-like receptor 7, also known as TLR7, is a protein that in humans is encoded by the ''TLR7'' gene. Orthologs are found in mammals and birds. It is a member of the toll-like receptor (TLR) family and detects single stranded RNA. Function T ...
,
TLR8 Toll-like receptor 8 is a protein that in humans is encoded by the ''TLR8'' gene. TLR8 has also been designated as CD288 (cluster of differentiation 288). It is a member of the toll-like receptor (TLR) family. Function TLR8 seems to function d ...
or
CD40 Cluster of differentiation 40, CD40 is a costimulatory protein found on antigen-presenting cells and is required for their activation. The binding of CD154 ( CD40L) on TH cells to CD40 activates antigen presenting cells and induces a variety of d ...
have been used as antibody targets. Dendritic cell-NK cell interface also has an important role in immunotherapy. The design of new dendritic cell-based vaccination strategies should also encompass NK cell-stimulating potency. It is critical to systematically incorporate NK cells monitoring as an outcome in antitumor DC-based clinical trials.


Drugs

Sipuleucel-T (Provenge) was approved for treatment of asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer in 2010. The treatment consists of removal of antigen-presenting cells from blood by
leukapheresis Leukapheresis () is a laboratory procedure in which white blood cells are separated from a sample of blood. It is a specific type of apheresis, the more general term for separating out one particular constituent of blood and returning the remain ...
and growing them with the fusion protein PA2024 made from GM-CSF and prostate-specific
prostatic acid phosphatase Prostatic acid phosphatase (PAP), also prostatic specific acid phosphatase (PSAP), is an enzyme produced by the prostate. It may be found in increased amounts in men who have prostate cancer or other diseases. The highest levels of acid phosphata ...
(PAP) and reinfused. This process is repeated three times.


CAR-T cell therapy

The premise of CAR-T immunotherapy is to modify T cells to recognize cancer cells in order to target and destroy them. Scientists harvest T cells from people, genetically alter them to add a chimeric antigen receptor (CAR) that specifically recognizes cancer cells, then infuse the resulting CAR-T cells into patients to attack their tumors.


Approved drugs

Tisagenlecleucel Tisagenlecleucel, sold under the brand name Kymriah, is a CAR T cells medication for the treatment of B-cell acute lymphoblastic leukemia (ALL) which uses the body's own T cells to fight cancer (adoptive cell transfer). Serious side effects occu ...
(Kymriah), a
chimeric antigen receptor In biology, chimeric antigen receptors (CARs)—also known as chimeric immunoreceptors, chimeric T cell receptors or artificial T cell receptors—are receptor proteins that have been engineered to give T cells the new ability to target a specific ...
(CAR-T) therapy, was approved by FDA in 2017 to treat
acute lymphoblastic leukemia Acute lymphoblastic leukemia (ALL) is a cancer of the lymphoid line of blood cells characterized by the development of large numbers of immature lymphocytes. Symptoms may include feeling tired, pale skin color, fever, easy bleeding or bruisin ...
(ALL). This treatment removes CD19 positive cells (B-cells) from the body (including the diseased cells, but also normal antibody-producing cells).
Axicabtagene ciloleucel Axicabtagene ciloleucel, sold under the brand name Yescarta, is a medication used for the treatment for large B-cell lymphoma that has failed conventional treatment. T cells are removed from a person with lymphoma and genetically engineered to p ...
(Yescarta) is another CAR-T therapeutic, approved in 2017 for treatment of
diffuse large B-cell lymphoma Diffuse large B-cell lymphoma (DLBCL) is a cancer of B cells, a type of lymphocyte that is responsible for producing antibodies. It is the most common form of non-Hodgkin lymphoma among adults, with an annual incidence of 7–8 cases per 100,00 ...
(DLBCL).


T cell receptor T cell therapy

TCR-T therapies use
heterodimers In biochemistry, a protein dimer is a macromolecular complex formed by two protein monomers, or single proteins, which are usually non-covalently bound. Many macromolecules, such as proteins or nucleic acids, form dimers. The word ''dimer'' ha ...
made of alpha and beta
peptide Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides. A ...
chains to recognize MHC-presented polypeptide fragments molecules. Unlike CAR-T's cell surface antigens, TCR-T can recognize that larger set of intracellular antigen fragments. However, TCR-T cell therapy depends on MHC molecules, limiting its usefulness.


Multifunctional alginate scaffolds for T cell engineering and release

Multifunctional alginate scaffolds for T cell engineering and release (MASTER) is a technique for ''in situ'' engineering, replication and release of genetically engineered T cells. It is an evolution of
CAR T cell In biology, chimeric antigen receptors (CARs)—also known as chimeric immunoreceptors, chimeric T cell receptors or artificial T cell receptors—are receptor (biochemistry), receptor proteins that have been engineered to give T cells the new abi ...
therapy. T cells are extracted from the patient and mixed with a genetically engineered virus that contains a cancer targeting gene (as with CAR T). The mixture is then added to a MASTER (scaffold), which absorbs them. The MASTER contains
antibodies An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...
that activate the T cells and
interleukins Interleukins (ILs) are a group of cytokines (secreted proteins and signal molecules) that are expressed and secreted by white blood cells (leukocytes) as well as some other body cells. The human genome encodes more than 50 interleukins and related ...
that trigger cell proliferation. The MASTER is then implanted into the patient. The activated T cells interact with the viruses to become CAR T cells. The interleukins stimulate these CAR T cells to proliferate, and the CAR T cells exit the MASTER to attack the cancer. The technique takes hours instead of weeks. And because the cells are younger, they last longer in the body, show stronger potency against cancer, and display fewer markers of exhaustion. These features were demonstrated in mouse models. The treatment was more effective and longer lasting against lymphoma.


Antibody therapy

Antibodies An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...
are a key component of the adaptive immune response, playing a central role in both recognizing foreign antigens and stimulating an immune response. Antibodies are Y-shaped proteins produced by some
B cells B cells, also known as B lymphocytes, are a type of white blood cell of the lymphocyte subtype. They function in the humoral immunity component of the adaptive immune system. B cells produce antibody molecules which may be either secreted o ...
and are composed of two regions: an antigen-binding fragment (Fab), which binds to antigens, and a fragment crystallizable (Fc) region, which interacts with so-called Fc receptors that are expressed on the surface of different immune cell types including
macrophages Macrophages (abbreviated as M φ, MΦ or MP) ( el, large eaters, from Greek ''μακρός'' (') = large, ''φαγεῖν'' (') = to eat) are a type of white blood cell of the immune system that engulfs and digests pathogens, such as cancer ce ...
, neutrophils and NK cells. Many immunotherapeutic regimens involve antibodies.
Monoclonal antibody A monoclonal antibody (mAb, more rarely called moAb) is an antibody produced from a cell Lineage made by cloning a unique white blood cell. All subsequent antibodies derived this way trace back to a unique parent cell. Monoclonal antibodies ca ...
technology engineers and generates antibodies against specific antigens, such as those present on tumor surfaces. These antibodies which are specific to the antigens of the tumor can then be injected into a tumor.


Antibody types


Conjugation

Two types are used in cancer treatments: * Naked monoclonal antibodies are antibodies without added elements. Most antibody therapies use this antibody type. * Conjugated monoclonal antibodies are joined to another molecule, which is either cytotoxic or
radioactive Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consi ...
. The toxic chemicals are those typically used as
chemotherapy Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs (chemotherapeutic agents or alkylating agents) as part of a standardized chemotherapy regimen. Chemotherap ...
drugs, but other toxins can be used. The antibody binds to specific antigens on cancer cell surfaces, directing the therapy to the tumor. Radioactive compound-linked antibodies are referred to as radiolabelled. Chemolabelled or immunotoxins antibodies are tagged with chemotherapeutic molecules or toxins, respectively. Research has also demonstrated conjugation of a TLR agonist to an anti-tumor monoclonal antibody.


Fc regions

Fc's ability to bind Fc receptors is important because it allows antibodies to activate the immune system. Fc regions are varied: they exist in numerous subtypes and can be further modified, for example with the addition of sugars in a process called glycosylation. Changes in the
Fc region The fragment crystallizable region (Fc region) is the tail region of an antibody that interacts with cell surface receptors called Fc receptors and some proteins of the complement system. This property allows antibodies to activate the immune s ...
can alter an antibody's ability to engage Fc receptors and, by extension, will determine the type of immune response that the antibody triggers. For example,
immune checkpoint Immune checkpoints are regulators of the immune system. These pathways are crucial for self-tolerance, which prevents the immune system from attacking cells indiscriminately. However, some cancers can protect themselves from attack by stimula ...
blockers targeting PD-1 are antibodies designed to bind PD-1 expressed by T cells and reactivate these cells to eliminate
tumors A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
. Anti-PD-1 drugs contain not only a Fab region that binds PD-1 but also an Fc region. Experimental work indicates that the Fc portion of cancer immunotherapy drugs can affect the outcome of treatment. For example, anti-PD-1 drugs with Fc regions that bind inhibitory Fc receptors can have decreased therapeutic efficacy. Imaging studies have further shown that the Fc region of anti-PD-1 drugs can bind Fc receptors expressed by tumor-associated macrophages. This process removes the drugs from their intended targets (i.e. PD-1 molecules expressed on the surface of T cells) and limits therapeutic efficacy. Furthermore, antibodies targeting the co-stimulatory protein
CD40 Cluster of differentiation 40, CD40 is a costimulatory protein found on antigen-presenting cells and is required for their activation. The binding of CD154 ( CD40L) on TH cells to CD40 activates antigen presenting cells and induces a variety of d ...
require engagement with selective Fc receptors for optimal therapeutic efficacy. Together, these studies underscore the importance of Fc status in antibody-based
immune checkpoint Immune checkpoints are regulators of the immune system. These pathways are crucial for self-tolerance, which prevents the immune system from attacking cells indiscriminately. However, some cancers can protect themselves from attack by stimula ...
targeting strategies.


Human/non-human antibodies

Antibodies can come from a variety of sources, including human cells, mice, and a combination of the two (chimeric antibodies). Different sources of antibodies can provoke different kinds of immune responses. For example, the human immune system can recognize mouse antibodies (also known as murine antibodies) and trigger an immune response against them. This could reduce the effectiveness of the antibodies as a treatment and cause an immune reaction. Chimeric antibodies attempt to reduce murine antibodies'
immunogenicity Immunogenicity is the ability of a foreign substance, such as an antigen, to provoke an immune response in the body of a human or other animal. It may be wanted or unwanted: * Wanted immunogenicity typically relates to vaccines, where the injectio ...
by replacing part of the antibody with the corresponding human counterpart. Humanized antibodies are almost completely human; only the
complementarity determining regions Complementarity-determining regions (CDRs) are part of the variable chains in immunoglobulins (antibodies) and T cell receptors, generated by B-cells and T-cells respectively, where these molecules bind to their specific antigen. A set of CDRs co ...
of the
variable region An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...
s are derived from murine sources. Human antibodies have been produced using unmodified human DNA.


Mechanism of Action


Antibody-dependent cell-mediated cytotoxicity (ADCC)

Antibody-dependent cell-mediated cytotoxicity Antibody-dependent cellular cytotoxicity (ADCC), also referred to as antibody-dependent cell-mediated cytotoxicity, is a mechanism of cell-mediated immune defense whereby an effector cell of the immune system actively lyses a target cell, whose ...
(ADCC) requires antibodies to bind to target cell surfaces. Antibodies are formed of a binding region (Fab) and the Fc region that can be detected by immune system cells via their Fc surface receptors. Fc receptors are found on many immune system cells, including NK cells. When NK cells encounter antibody-coated cells, the latter's Fc regions interact with their Fc receptors, releasing
perforin Perforin-1 is a protein that in humans is encoded by the ''PRF1'' gene and the ''Prf1'' gene in mice. Function Perforin is a pore forming cytolytic protein found in the granules of cytotoxic T lymphocytes (CTLs) and natural killer cells (NK cel ...
and
granzyme B Granzyme B (GrB) is one of the serine protease granzymes most commonly found in the granules of natural killer cells (NK cells) and cytotoxic T cells. It is secreted by these cells along with the pore forming protein perforin to mediate apoptosi ...
to kill the tumor cell. Examples include
rituximab Rituximab, sold under the brand name Rituxan among others, is a monoclonal antibody medication used to treat certain autoimmune diseases and types of cancer. It is used for non-Hodgkin lymphoma, chronic lymphocytic leukemia (in non-geriatric pa ...
,
ofatumumab Ofatumumab is a fully human monoclonal antibody to CD20, which appears to provide rapid B-cell depletion. Under the brand name Kesimpta, it is approved for the treatment of multiple sclerosis in the United States as well as in the European Unio ...
,
elotuzumab Elotuzumab, sold under the brand name Empliciti, is a humanized IgG1 monoclonal antibody medication used in combination with lenalidomide and dexamethasone, for adults that have received 1 to 3 prior therapies for the treatment of multiple myeloma ...
, and
alemtuzumab Alemtuzumab, sold under the brand names Campath and Lemtrada among others, is a medication used to treat chronic lymphocytic leukemia (CLL) and multiple sclerosis. In CLL, it has been used as both a first line and second line treatment. In MS it ...
. Antibodies under development have altered Fc regions that have higher affinity for a specific type of Fc receptor, FcγRIIIA, which can dramatically increase effectiveness.


Complement Activation

The complement system includes blood proteins that can cause cell death after an antibody binds to the cell surface (the
classical complement pathway The classical complement pathway is one of three pathways which activate the complement system, which is part of the immune system. The classical complement pathway is initiated by antigen-antibody complexes with the antibody isotypes IgG and ...
, among the ways of complement activation). Generally, the system deals with foreign pathogens but can be activated with therapeutic antibodies in cancer. The system can be triggered if the antibody is chimeric, humanized, or human; as long as it contains the
IgG1 Immunoglobulin G (Ig G) is a type of antibody. Representing approximately 75% of serum antibodies in humans, IgG is the most common type of antibody found in blood circulation. IgG molecules are created and released by plasma B cells. Each IgG a ...
Fc region The fragment crystallizable region (Fc region) is the tail region of an antibody that interacts with cell surface receptors called Fc receptors and some proteins of the complement system. This property allows antibodies to activate the immune s ...
. Complement can lead to cell death by activation of the
membrane attack complex The membrane attack complex (MAC) or terminal complement complex (TCC) is a complex of proteins typically formed on the surface of pathogen cell membranes as a result of the activation of the host's complement system, and as such is an effector ...
, known as complement-dependent cytotoxicity; enhancement of
antibody-dependent cell-mediated cytotoxicity Antibody-dependent cellular cytotoxicity (ADCC), also referred to as antibody-dependent cell-mediated cytotoxicity, is a mechanism of cell-mediated immune defense whereby an effector cell of the immune system actively lyses a target cell, whose ...
; and CR3-dependent cellular cytotoxicity. Complement-dependent cytotoxicity occurs when antibodies bind to the cancer cell surface, the C1 complex binds to these antibodies and subsequently, protein pores are formed in cancer
cell membrane The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment ( ...
. Blocking Antibody therapies can also function by binding to proteins and physically blocking them from interacting with other proteins. Checkpoint inhibitors (CTLA-4, PD-1, and PD-L1) operate by this mechanism. Briefly, checkpoint inhibitors are proteins that normally help to slow immune responses and prevent the immune system from attacking normal cells. Checkpoint inhibitors bind these proteins and prevent them from functioning normally, which increases the activity of the immune system. Examples include
durvalumab Durvalumab (trade name Imfinzi) is an FDA-approved immunotherapy for cancer, developed by Medimmune/AstraZeneca. It is a human immunoglobulin G1 kappa (IgG1κ) monoclonal antibody that blocks the interaction of programmed cell death ligand 1 ...
,
ipilimumab Ipilimumab, sold under the brand name Yervoy, is a monoclonal antibody medication that works to activate the immune system by targeting CTLA-4, a protein receptor that downregulates the immune system. Cytotoxic T lymphocytes (CTLs) can recogniz ...
,
nivolumab Nivolumab, sold under the brand name Opdivo, is a medication used to treat a number of types of cancer. This includes melanoma, lung cancer, malignant pleural mesothelioma, renal cell carcinoma, Hodgkin lymphoma, head and neck cancer, urotheli ...
, and
pembrolizumab Pembrolizumab, sold under the brand name Keytruda, is a humanized antibody used in cancer immunotherapy that treats melanoma, lung cancer, head and neck cancer, Hodgkin lymphoma, stomach cancer, cervical cancer, and certain types of breast canc ...
.


FDA-approved antibodies


Alemtuzumab

Alemtuzumab Alemtuzumab, sold under the brand names Campath and Lemtrada among others, is a medication used to treat chronic lymphocytic leukemia (CLL) and multiple sclerosis. In CLL, it has been used as both a first line and second line treatment. In MS it ...
(Campath-1H) is an anti-
CD52 CAMPATH-1 antigen, also known as cluster of differentiation 52 (CD52), is a glycoprotein that in humans is encoded by the ''CD52'' gene. CD52 is present on the surface of mature lymphocytes, but not on the stem cells from which these lymphocyt ...
humanized IgG1 monoclonal antibody indicated for the treatment of
fludarabine Fludarabine is a purine analogue and antineoplastic agent. It is generally used as its 5-O-phosphorylated form known as fludarabine phosphate, sold under the brand name Fludara among others. It is a chemotherapy medication used in the treatmen ...
-refractory chronic lymphocytic leukemia (CLL), cutaneous T-cell lymphoma,
peripheral T-cell lymphoma Peripheral T-cell lymphoma refers to a group of T-cell lymphomas that develop away from the thymus or bone marrow. Examples include: * Cutaneous T-cell lymphomas * Angioimmunoblastic T-cell lymphoma * Extranodal natural killer/T-cell lymphoma, nas ...
and
T-cell prolymphocytic leukemia T-cell-prolymphocytic leukemia (T-PLL) is a mature T-cell leukemia with aggressive behavior and predilection for blood, bone marrow, lymph nodes, liver, spleen, and skin involvement. T-PLL is a very rare leukemia, primarily affecting adults over t ...
. CD52 is found on >95% of peripheral blood
lymphocyte A lymphocyte is a type of white blood cell (leukocyte) in the immune system of most vertebrates. Lymphocytes include natural killer cells (which function in cell-mediated, cytotoxic innate immunity), T cells (for cell-mediated, cytotoxic ad ...
s (both T-cells and B-cells) and
monocyte Monocytes are a type of leukocyte or white blood cell. They are the largest type of leukocyte in blood and can differentiate into macrophages and conventional dendritic cells. As a part of the vertebrate innate immune system monocytes also ...
s, but its function in lymphocytes is unknown. It binds to CD52 and initiates its cytotoxic effect by complement fixation and ADCC mechanisms. Due to the antibody target (cells of the immune system), common complications of alemtuzumab therapy are infection, toxicity and
myelosuppression Bone marrow suppression also known as myelotoxicity or myelosuppression, is the decrease in production of cells responsible for providing immunity (leukocytes), carrying oxygen (erythrocytes), and/or those responsible for normal blood clotting (t ...
.


Durvalumab

Durvalumab Durvalumab (trade name Imfinzi) is an FDA-approved immunotherapy for cancer, developed by Medimmune/AstraZeneca. It is a human immunoglobulin G1 kappa (IgG1κ) monoclonal antibody that blocks the interaction of programmed cell death ligand 1 ...
(Imfinzi) is a human immunoglobulin G1 kappa (IgG1κ) monoclonal antibody that blocks the interaction of programmed cell death ligand 1 (PD-L1) with the PD-1 and CD80 (B7.1) molecules. Durvalumab is approved for the treatment of patients with locally advanced or metastatic urothelial carcinoma who: * have disease progression during or following platinum-containing chemotherapy. * have disease progression within 12 months of neoadjuvant or adjuvant treatment with platinum-containing chemotherapy. On 16 February 2018, the Food and Drug Administration approved durvalumab for patients with unresectable stage III non-small cell lung cancer (NSCLC) whose disease has not progressed following concurrent platinum-based chemotherapy and radiation therapy.


Ipilimumab

Ipilimumab Ipilimumab, sold under the brand name Yervoy, is a monoclonal antibody medication that works to activate the immune system by targeting CTLA-4, a protein receptor that downregulates the immune system. Cytotoxic T lymphocytes (CTLs) can recogniz ...
(Yervoy) is a human
IgG1 Immunoglobulin G (Ig G) is a type of antibody. Representing approximately 75% of serum antibodies in humans, IgG is the most common type of antibody found in blood circulation. IgG molecules are created and released by plasma B cells. Each IgG a ...
antibody that binds the surface protein CTLA4. In normal physiology T-cells are activated by two signals: the
T-cell receptor The T-cell receptor (TCR) is a protein complex found on the surface of T cells, or T lymphocytes, that is responsible for recognizing fragments of antigen as peptides bound to major histocompatibility complex (MHC) molecules. The binding b ...
binding to an
antigen In immunology, an antigen (Ag) is a molecule or molecular structure or any foreign particulate matter or a pollen grain that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response. ...
- MHC complex and T-cell surface receptor CD28 binding to
CD80 The Cluster of differentiation 80 (also CD80 and B7-1) is a B7, type I membrane protein in the immunoglobulin superfamily, with an extracellular immunoglobulin constant-like domain and a variable-like domain required for receptor binding. It is cl ...
or
CD86 Cluster of Differentiation 86 (also known as CD86 and B7-2) is a protein constitutively expressed on dendritic cells, Langerhans cells, macrophages, B-cells (including memory B-cells), and on other antigen-presenting cells. Along with CD80, CD8 ...
proteins. CTLA4 binds to CD80 or CD86, preventing the binding of CD28 to these surface proteins and therefore negatively regulates the activation of T-cells. Active
cytotoxic T-cell A cytotoxic T cell (also known as TC, cytotoxic T lymphocyte, CTL, T-killer cell, cytolytic T cell, CD8+ T-cell or killer T cell) is a T lymphocyte (a type of white blood cell) that kills cancer cells, cells that are infected by intracellular p ...
s are required for the immune system to attack melanoma cells. Normally inhibited active melanoma-specific cytotoxic T-cells can produce an effective anti-tumor response. Ipilimumab can cause a shift in the ratio of regulatory T-cells to cytotoxic T-cells to increase the anti-tumor response. Regulatory T-cells inhibit other T-cells, which may benefit the tumor.


Nivolumab

Nivolumab Nivolumab, sold under the brand name Opdivo, is a medication used to treat a number of types of cancer. This includes melanoma, lung cancer, malignant pleural mesothelioma, renal cell carcinoma, Hodgkin lymphoma, head and neck cancer, urotheli ...
is a human
IgG4 Immunoglobulin G (Ig G) is a Antibody#Classes, type of antibody. Representing approximately 75% of blood plasma, serum immunoglobulins, antibodies in humans, IgG is the most common type of antibody found in Circulatory system, blood circulation. I ...
antibody that prevents T-cell inactivation by blocking the binding of
programmed cell death 1 ligand 1 Programmed death-ligand 1 (PD-L1) also known as cluster of differentiation 274 (CD274) or B7 homolog 1 (B7-H1) is a protein that in humans is encoded by the ''CD274'' gene. Programmed death-ligand 1 (PD-L1) is a 40kDa type 1 transmembrane protei ...
or programmed cell death 1 ligand 2 (PD-L1 or PD-L2), a protein expressed by cancer cells, with
PD-1 Programmed cell death protein 1, also known as PD-1 and CD279 (cluster of differentiation 279), is a protein on the surface of T and B cells that has a role in regulating the immune system's response to the cells of the human body by down-regula ...
, a protein found on the surface of activated T-cells. Nivolumab is used in advanced melanoma, metastatic renal cell carcinoma, advanced lung cancer, advanced head and neck cancer, and Hodgkin's lymphoma.


Ofatumumab

Ofatumumab Ofatumumab is a fully human monoclonal antibody to CD20, which appears to provide rapid B-cell depletion. Under the brand name Kesimpta, it is approved for the treatment of multiple sclerosis in the United States as well as in the European Unio ...
is a second generation human
IgG1 Immunoglobulin G (Ig G) is a type of antibody. Representing approximately 75% of serum antibodies in humans, IgG is the most common type of antibody found in blood circulation. IgG molecules are created and released by plasma B cells. Each IgG a ...
antibody that binds to
CD20 B-lymphocyte antigen CD20 or CD20 is expressed on the surface of all B-cells beginning at the pro-B phase ( CD45R+, CD117+) and progressively increasing in concentration until maturity. In humans CD20 is encoded by the ''MS4A1'' gene. This gene ...
. It is used in the treatment of chronic lymphocytic leukemia (CLL) because the cancerous cells of CLL are usually CD20-expressing B-cells. Unlike
rituximab Rituximab, sold under the brand name Rituxan among others, is a monoclonal antibody medication used to treat certain autoimmune diseases and types of cancer. It is used for non-Hodgkin lymphoma, chronic lymphocytic leukemia (in non-geriatric pa ...
, which binds to a large loop of the CD20 protein, ofatumumab binds to a separate, small loop. This may explain their different characteristics. Compared to rituximab, ofatumumab induces complement-dependent cytotoxicity at a lower dose with less
immunogenicity Immunogenicity is the ability of a foreign substance, such as an antigen, to provoke an immune response in the body of a human or other animal. It may be wanted or unwanted: * Wanted immunogenicity typically relates to vaccines, where the injectio ...
.


Pembrolizumab

As of 2019,
pembrolizumab Pembrolizumab, sold under the brand name Keytruda, is a humanized antibody used in cancer immunotherapy that treats melanoma, lung cancer, head and neck cancer, Hodgkin lymphoma, stomach cancer, cervical cancer, and certain types of breast canc ...
, which blocks
PD-1 Programmed cell death protein 1, also known as PD-1 and CD279 (cluster of differentiation 279), is a protein on the surface of T and B cells that has a role in regulating the immune system's response to the cells of the human body by down-regula ...
, programmed cell death protein 1, has been used via intravenous infusion to treat inoperable or metastatic
melanoma Melanoma, also redundantly known as malignant melanoma, is a type of skin cancer that develops from the pigment-producing cells known as melanocytes. Melanomas typically occur in the skin, but may rarely occur in the mouth, intestines, or eye ( ...
, metastatic
non-small cell lung cancer Non-small-cell lung cancer (NSCLC) is any type of epithelial lung cancer other than small-cell lung carcinoma (SCLC). NSCLC accounts for about 85% of all lung cancers. As a class, NSCLCs are relatively insensitive to chemotherapy, compared to s ...
(NSCLC) in certain situations, as a second-line treatment for
head and neck squamous cell carcinoma Head and neck cancer develops from tissues in the lip and oral cavity (mouth), larynx (throat), salivary glands, nose, sinuses or the skin of the face. The most common types of head and neck cancers occur in the lip, mouth, and larynx. Symptoms ...
(HNSCC), after
platinum-based chemotherapy Platinum-based antineoplastic drugs (informally called platins) are chemotherapeutic agents used to treat cancer. They are coordination complexes of platinum. These drugs are used to treat almost half of people receiving chemotherapy for cancer. I ...
, and for the treatment of adult and pediatric patients with refractory classic
Hodgkin's lymphoma Hodgkin lymphoma (HL) is a type of lymphoma, in which cancer originates from a specific type of white blood cell called lymphocytes, where multinucleated Reed–Sternberg cells (RS cells) are present in the patient's lymph nodes. The condition wa ...
(cHL). linked fro
Index page at FDA website
November 2016
It is also indicated for certain patients with
urothelial carcinoma Transitional epithelium also known as urothelium is a type of stratified epithelium. Transitional epithelium is a type of tissue that changes shape in response to stretching (stretchable epithelium). The transitional epithelium usually appears ...
, stomach cancer and
cervical cancer Cervical cancer is a cancer arising from the cervix. It is due to the abnormal growth of cells that have the ability to invade or spread to other parts of the body. Early on, typically no symptoms are seen. Later symptoms may include abnormal ...
.


Rituximab

Rituximab Rituximab, sold under the brand name Rituxan among others, is a monoclonal antibody medication used to treat certain autoimmune diseases and types of cancer. It is used for non-Hodgkin lymphoma, chronic lymphocytic leukemia (in non-geriatric pa ...
is a chimeric monoclonal IgG1 antibody specific for CD20, developed from its parent antibody Ibritumomab. As with ibritumomab, rituximab targets CD20, making it effective in treating certain B-cell malignancies. These include aggressive and indolent lymphomas such as
diffuse large B-cell lymphoma Diffuse large B-cell lymphoma (DLBCL) is a cancer of B cells, a type of lymphocyte that is responsible for producing antibodies. It is the most common form of non-Hodgkin lymphoma among adults, with an annual incidence of 7–8 cases per 100,00 ...
and follicular lymphoma and
leukemia Leukemia ( also spelled leukaemia and pronounced ) is a group of blood cancers that usually begin in the bone marrow and result in high numbers of abnormal blood cells. These blood cells are not fully developed and are called ''blasts'' or ' ...
s such as B-cell chronic lymphocytic leukemia. Although the function of CD20 is relatively unknown, CD20 may be a
calcium channel A calcium channel is an ion channel which shows selective permeability to calcium ions. It is sometimes synonymous with voltage-gated calcium channel, although there are also ligand-gated calcium channels. Comparison tables The following tables e ...
involved in B-cell activation. The antibody's mode of action is primarily through the induction of ADCC and complement-mediated cytotoxicity. Other mechanisms include apoptosis and cellular growth arrest. Rituximab also increases the sensitivity of cancerous B-cells to chemotherapy.


Cytokine therapy

Cytokine Cytokines are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are peptides and cannot cross the lipid bilayer of cells to enter the cytoplasm. Cytokines have been shown to be involved in autocrin ...
s are proteins produced by many types of cells present within a tumor. They can modulate immune responses. The tumor often employs them to allow it to grow and reduce the immune response. These immune-modulating effects allow them to be used as drugs to provoke an immune response. Two commonly used cytokines are interferons and interleukins.
Interleukin-2 Interleukin-2 (IL-2) is an interleukin, a type of cytokine signaling molecule in the immune system. It is a 15.5–16  kDa protein that regulates the activities of white blood cells (leukocytes, often lymphocytes) that are responsible fo ...
and
interferon Interferons (IFNs, ) are a group of signaling proteins made and released by host cells in response to the presence of several viruses. In a typical scenario, a virus-infected cell will release interferons causing nearby cells to heighten the ...
-α are cytokines, proteins that regulate and coordinate the behavior of the immune system. They have the ability to enhance anti-tumor activity and thus can be used as passive cancer treatments. Interferon-α is used in the treatment of
hairy-cell leukaemia Hairy cell leukemia is an uncommon hematological malignancy characterized by an accumulation of abnormal B lymphocytes. It is usually classified as a subtype of chronic lymphocytic leukemia (CLL). Hairy cell leukemia makes up about 2% of all leu ...
, AIDS-related
Kaposi's sarcoma Kaposi's sarcoma (KS) is a type of cancer that can form masses in the skin, in lymph nodes, in the mouth, or in other organs. The skin lesions are usually painless, purple and may be flat or raised. Lesions can occur singly, multiply in a limit ...
,
follicular lymphoma Follicular lymphoma (FL) is a cancer that involves certain types of white blood cells known as lymphocytes. The cancer originates from the uncontrolled division of specific types of B-cells known as centrocytes and centroblasts. These cells normal ...
, chronic myeloid leukaemia and
malignant melanoma Melanoma, also redundantly known as malignant melanoma, is a type of skin cancer that develops from the Biological pigment, pigment-producing cells known as melanocytes. Melanomas typically occur in the skin, but may rarely occur in the mouth, i ...
. Interleukin-2 is used in the treatment of
malignant melanoma Melanoma, also redundantly known as malignant melanoma, is a type of skin cancer that develops from the Biological pigment, pigment-producing cells known as melanocytes. Melanomas typically occur in the skin, but may rarely occur in the mouth, i ...
and
renal cell carcinoma Renal cell carcinoma (RCC) is a kidney cancer that originates in the lining of the Proximal tubule, proximal convoluted tubule, a part of the very small tubes in the kidney that transport primary urine. RCC is the most common type of kidney cance ...
.


Interferon

Interferon Interferons (IFNs, ) are a group of signaling proteins made and released by host cells in response to the presence of several viruses. In a typical scenario, a virus-infected cell will release interferons causing nearby cells to heighten the ...
s are produced by the immune system. They are usually involved in anti-viral response, but also have use for cancer. They fall in three groups: type I (IFNα and IFNβ), type II (IFNγ) and type III (IFNλ). IFNα has been approved for use in
hairy-cell leukaemia Hairy cell leukemia is an uncommon hematological malignancy characterized by an accumulation of abnormal B lymphocytes. It is usually classified as a subtype of chronic lymphocytic leukemia (CLL). Hairy cell leukemia makes up about 2% of all leu ...
, AIDS-related Kaposi's sarcoma, follicular lymphoma, chronic myeloid leukaemia and melanoma. Type I and II IFNs have been researched extensively and although both types promote anti-tumor immune system effects, only type I IFNs have been shown to be clinically effective. IFNλ shows promise for its anti-tumor effects in
animal model An animal model (short for animal disease model) is a living, non-human, often genetic-engineered animal used during the research and investigation of human disease, for the purpose of better understanding the disease process without the risk of ha ...
s. Unlike type I IFNs,
Interferon gamma Interferon gamma (IFN-γ) is a dimerized soluble cytokine that is the only member of the type II class of interferons. The existence of this interferon, which early in its history was known as immune interferon, was described by E. F. Wheeloc ...
is not approved yet for the treatment of any cancer. However, improved survival was observed when
Interferon gamma Interferon gamma (IFN-γ) is a dimerized soluble cytokine that is the only member of the type II class of interferons. The existence of this interferon, which early in its history was known as immune interferon, was described by E. F. Wheeloc ...
was administrated to patients with
bladder carcinoma Bladder cancer is any of several types of cancer arising from the tissues of the urinary bladder. Symptoms include blood in the urine, pain with urination, and low back pain. It is caused when epithelial cells that line the bladder become mali ...
and
melanoma Melanoma, also redundantly known as malignant melanoma, is a type of skin cancer that develops from the pigment-producing cells known as melanocytes. Melanomas typically occur in the skin, but may rarely occur in the mouth, intestines, or eye ( ...
cancers. The most promising result was achieved in patients with stage 2 and 3 of
ovarian carcinoma Ovarian cancer is a cancerous tumor of an ovary. It may originate from the ovary itself or more commonly from communicating nearby structures such as fallopian tubes or the inner lining of the abdomen. The ovary is made up of three different cel ...
. The ''
in vitro ''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in biology an ...
'' study of IFN-gamma in cancer cells is more extensive and results indicate anti-proliferative activity of IFN-gamma leading to the growth inhibition or cell death, generally induced by
apoptosis Apoptosis (from grc, ἀπόπτωσις, apóptōsis, 'falling off') is a form of programmed cell death that occurs in multicellular organisms. Biochemical events lead to characteristic cell changes (morphology) and death. These changes incl ...
but sometimes by autophagy.


Interleukin

Interleukin Interleukins (ILs) are a group of cytokines (secreted proteins and signal molecules) that are expressed and secreted by white blood cells (leukocytes) as well as some other body cells. The human genome encodes more than 50 interleukins and related ...
s have an array of immune system effects.
Interleukin-2 Interleukin-2 (IL-2) is an interleukin, a type of cytokine signaling molecule in the immune system. It is a 15.5–16  kDa protein that regulates the activities of white blood cells (leukocytes, often lymphocytes) that are responsible fo ...
is used in the treatment of
malignant melanoma Melanoma, also redundantly known as malignant melanoma, is a type of skin cancer that develops from the Biological pigment, pigment-producing cells known as melanocytes. Melanomas typically occur in the skin, but may rarely occur in the mouth, i ...
and
renal cell carcinoma Renal cell carcinoma (RCC) is a kidney cancer that originates in the lining of the Proximal tubule, proximal convoluted tubule, a part of the very small tubes in the kidney that transport primary urine. RCC is the most common type of kidney cance ...
. In normal physiology it promotes both effector T cells and T-regulatory cells, but its exact mechanism of action is unknown.


Combination immunotherapy

Combining various immunotherapies such as PD1 and CTLA4 inhibitors can enhance anti-tumor response leading to durable responses. Combining ablation therapy of tumors with immunotherapy enhances the immunostimulating response and has synergistic effects for curative metastatic cancer treatment. Combining checkpoint immunotherapies with pharmaceutical agents has the potential to improve response, and such combination therapies are a highly investigated area of clinical investigation. Immunostimulatory drugs such as CSF-1R inhibitors and TLR agonists have been particularly effective in this setting.


Polysaccharide-K

Japan's
Ministry of Health, Labour and Welfare The is a cabinet level ministry of the Japanese government. It is commonly known as in Japan. The ministry provides services on health, labour and welfare. It was formed with the merger of the former Ministry of Health and Welfare or and the ...
approved the use of
polysaccharide-K Polysaccharide-K (Krestin, PSK) is a protein-bound polysaccharide isolated from the fruitbody of ''Trametes versicolor''. Research summary PSK has been studied in patients with gastric cancer, breast cancer, colorectal cancer, and lung cancer. T ...
extracted from the mushroom, ''
Coriolus versicolor ''Trametes versicolor''also known as ''Coriolus versicolor'' and ''Polyporus versicolor''is a common polypore mushroom found throughout the world. Meaning 'of several colors', ''versicolor'' reliably describes this fungus that displays a varie ...
'', in the 1980s, to stimulate the immune systems of patients undergoing chemotherapy. It is a dietary supplement in the US and other jurisdictions.


Genetic pre-testing for therapeutic significance

Because of the high cost of many of immunotherapy medications and the reluctance of medical insurance companies to prepay for their prescriptions various test methods have been proposed, to attempt to forecast the effectiveness of these medications. The detection of
PD-L1 Programmed death-ligand 1 (PD-L1) also known as cluster of differentiation 274 (CD274) or B7 homolog 1 (B7-H1) is a protein that in humans is encoded by the ''CD274'' gene. Programmed death-ligand 1 (PD-L1) is a 40kDa type 1 transmembrane protei ...
protein seemed to be an indication of cancer susceptible to several immunotherapy medications, but research found that both the lack of this protein or its inclusion in the cancerous tissue was inconclusive, due to the little-understood varying quantities of the protein during different times and locations within the infected cells and tissue. In 2018 some genetic indications such as
Tumor Mutational Burden A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
(TMB, the number of mutations within a targeted genetic region in the cancerous cell's DNA), and
microsatellite instability Microsatellite instability (MSI) is the condition of genetic hypermutability (predisposition to mutation) that results from impaired DNA mismatch repair (MMR). The presence of MSI represents phenotypic evidence that MMR is not functioning normal ...
(MSI, the quantity of impaired DNA mismatch leading to probable mutations), have been approved by the FDA as good indicators for the probability of effective treatment of immunotherapy medication for certain cancers, but research is still in progress. The patient prioritization for immunotherapy based on TMB is still highly controversial. In some cases the FDA has approved genetic tests for medication that is specific to certain genetic markers. For example, the FDA approved BRAF associated medication for metastatic melanoma, to be administered to patients after testing for the BRAF genetic mutation. Tests of this sort are being widely advertised for general cancer treatment and are expensive. In the past, some genetic testing for cancer treatment has been involved in scams such as the Duke University Cancer Fraud scandal, or claimed to be hoaxes.


Research


Adoptive T-cell therapy

Adoptive T cell therapy is a form of
passive immunization Passive immunity is the transfer of active humoral immunity of ready-made antibodies. Passive immunity can occur naturally, when maternal antibodies are transferred to the fetus through the placenta, and it can also be induced artificially, when ...
by the transfusion of T-cells (
adoptive cell transfer Adoptive cell transfer (ACT) is the transfer of cells into a patient. The cells may have originated from the patient or from another individual. The cells are most commonly derived from the immune system with the goal of improving immune functiona ...
). They are found in blood and tissue and usually activate when they find foreign
pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...
s. Specifically they activate when the T-cell's surface receptors encounter cells that display parts of foreign proteins on their surface antigens. These can be either infected cells, or antigen-presenting cells (APCs). They are found in normal tissue and in tumor tissue, where they are known as
tumor infiltrating lymphocyte Tumor-infiltrating lymphocytes (TIL) are white blood cells that have left the bloodstream and migrated towards a tumor. They include T cells and B cells and are part of the larger category of ‘tumor-infiltrating immune cells’ which consis ...
s (TILs). They are activated by the presence of APCs such as dendritic cells that present
tumor antigen Tumor antigen is an antigenic substance produced in tumor cells, i.e., it triggers an immune response in the host. Tumor antigens are useful tumor markers in identifying tumor cells with diagnostic tests and are potential candidates for use in c ...
s. Although these cells can attack the tumor, the environment within the tumor is highly immunosuppressive, preventing immune-mediated tumour death. Multiple ways of producing and obtaining tumour targeted T-cells have been developed. T-cells specific to a tumor antigen can be removed from a tumor sample (TILs) or filtered from blood. Subsequent activation and culturing is performed ''ex vivo,'' with the results reinfused. Activation can take place through gene therapy, or by exposing the T cells to tumor antigens. As of 2014, multiple ACT clinical trials were underway. Importantly, one study from 2018 showed that clinical responses can be obtained in patients with metastatic melanoma resistant to multiple previous immunotherapies. The first 2 adoptive T-cell therapies,
tisagenlecleucel Tisagenlecleucel, sold under the brand name Kymriah, is a CAR T cells medication for the treatment of B-cell acute lymphoblastic leukemia (ALL) which uses the body's own T cells to fight cancer (adoptive cell transfer). Serious side effects occu ...
and
axicabtagene ciloleucel Axicabtagene ciloleucel, sold under the brand name Yescarta, is a medication used for the treatment for large B-cell lymphoma that has failed conventional treatment. T cells are removed from a person with lymphoma and genetically engineered to p ...
, were approved by the FDA in 2017. Another approach is adoptive transfer of haploidentical γδ T cells or
NK cells Natural killer cells, also known as NK cells or large granular lymphocytes (LGL), are a type of cytotoxic lymphocyte critical to the innate immune system that belong to the rapidly expanding family of known innate lymphoid cells (ILC) and represen ...
from a healthy donor. The major advantage of this approach is that these cells do not cause
GVHD Graft-versus-host disease (GvHD) is a syndrome, characterized by inflammation in different organs. GvHD is commonly associated with bone marrow transplants and stem cell transplants. White blood cells of the donor's immune system which remain wit ...
. The disadvantage is frequently impaired function of the transferred cells.


Anti-CD47 therapy

Many tumor cells overexpress
CD47 CD47 (Cluster of Differentiation 47) also known as integrin associated protein (IAP) is a transmembrane protein that in humans is encoded by the CD47 gene. CD47 belongs to the immunoglobulin superfamily and partners with membrane integrins and ...
to escape immunosurveilance of host immune system. CD47 binds to its receptor
signal-regulatory protein alpha Signal regulatory protein α (SIRPα) is a regulatory membrane glycoprotein from SIRP family expressed mainly by myeloid cells and also by stem cells or neurons. SIRPα acts as inhibitory receptor and interacts with a broadly expressed transmembra ...
(SIRPα) and downregulate
phagocytosis Phagocytosis () is the process by which a cell uses its plasma membrane to engulf a large particle (≥ 0.5 μm), giving rise to an internal compartment called the phagosome. It is one type of endocytosis. A cell that performs phagocytosis is ...
of tumor cell. Therefore, anti-CD47 therapy aims to restore clearance of tumor cells. Additionally, growing evidence supports the employment of tumor antigen-specific T cell response in response to anti-CD47 therapy. A number of therapeutics are being developed, including anti-CD47
antibodies An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...
, engineered decoy receptors, anti-SIRPα
antibodies An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...
and bispecific agents. As of 2017, wide range of solid and hematologic malignancies were being clinically tested.


Anti-GD2 antibodies

Carbohydrate
antigen In immunology, an antigen (Ag) is a molecule or molecular structure or any foreign particulate matter or a pollen grain that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response. ...
s on the surface of cells can be used as targets for immunotherapy. GD2 is a
ganglioside A ganglioside is a molecule composed of a glycosphingolipid (ceramide and oligosaccharide) with one or more sialic acids (e.g. ''N''-acetylneuraminic acid, NANA) linked on the sugar chain. NeuNAc, an acetylated derivative of the carbohydrate si ...
found on the surface of many types of cancer cell including neuroblastoma, retinoblastoma,
melanoma Melanoma, also redundantly known as malignant melanoma, is a type of skin cancer that develops from the pigment-producing cells known as melanocytes. Melanomas typically occur in the skin, but may rarely occur in the mouth, intestines, or eye ( ...
, small cell lung cancer, brain tumors, osteosarcoma, rhabdomyosarcoma, Ewing's sarcoma, liposarcoma, fibrosarcoma, leiomyosarcoma and other soft tissue sarcomas. It is not usually expressed on the surface of normal tissues, making it a good target for immunotherapy. As of 2014, clinical trials were underway.


Immune checkpoints

Immune checkpoints affect the immune system function. Immune checkpoints can be stimulatory or inhibitory. Tumors can use these checkpoints to protect themselves from immune system attacks. Currently approved checkpoint therapies block inhibitory checkpoint receptors. Blockade of negative feedback signaling to immune cells thus results in an enhanced immune response against tumors. Immune checkpoint blockade therapies have varied effectiveness. In Hodgkin lymphoma and natural killer T-cell lymphoma, response rates are high, at 50–60%. Response rates are quite low for breast and prostate cancers, however. One ligand-receptor interaction under investigation is the interaction between the transmembrane programmed cell death 1 protein (PDCD1, PD-1; also known as CD279) and its ligand, Programmed cell death 1 ligand 1, PD-1 ligand 1 (PD-L1, CD274). PD-L1 on the cell surface binds to PD1 on an immune cell surface, which inhibits immune cell activity. Among PD-L1 functions is a key regulatory role on T cell activities. It appears that (cancer-mediated) upregulation of PD-L1 on the cell surface may inhibit T cells that might otherwise attack. PD-L1 on cancer cells also inhibits FAS- and interferon-dependent apoptosis, protecting cells from cytotoxic molecules produced by T cells. Antibodies that bind to either PD-1 or PD-L1 and therefore block the interaction may allow the T-cells to attack the tumor.


CTLA-4 blockade

The first checkpoint antibody approved by the FDA was ipilimumab, approved in 2011 for the treatment of melanoma. It blocks the immune checkpoint molecule CTLA-4. Clinical trials have also shown some benefits of anti-CTLA-4 therapy on lung cancer or pancreatic cancer, specifically in combination with other drugs. In on-going trials the combination of CTLA-4 blockade with PD-1 or PD-L1 inhibitors is tested on different types of cancer. However, patients treated with checkpoint blockade (specifically CTLA-4 blocking antibodies), or a combination of check-point blocking antibodies, are at high risk of having immune-related adverse events such as dermatologic, gastrointestinal, endocrine, or hepatic Autoimmunity, autoimmune reactions. These are most likely due to the breadth of the induced T-cell activation when anti-CTLA-4 antibodies are administered by injection in the bloodstream. Using a mouse model of bladder cancer, researchers have found that a local injection of a low dose anti-CTLA-4 in the tumour area had the same tumour inhibiting capacity as when the antibody was delivered in the blood. At the same time the levels of circulating antibodies were lower, suggesting that local administration of the anti-CTLA-4 therapy might result in fewer adverse events.


PD-1 inhibitors

Initial clinical trial results with IgG4 PD1 antibody
nivolumab Nivolumab, sold under the brand name Opdivo, is a medication used to treat a number of types of cancer. This includes melanoma, lung cancer, malignant pleural mesothelioma, renal cell carcinoma, Hodgkin lymphoma, head and neck cancer, urotheli ...
were published in 2010. It was approved in 2014. Nivolumab is approved to treat melanoma, lung cancer, kidney cancer, bladder cancer, head and neck cancer, and
Hodgkin's lymphoma Hodgkin lymphoma (HL) is a type of lymphoma, in which cancer originates from a specific type of white blood cell called lymphocytes, where multinucleated Reed–Sternberg cells (RS cells) are present in the patient's lymph nodes. The condition wa ...
. A 2016 clinical trial for non-small cell lung cancer failed to meet its primary endpoint for treatment in the first line setting, but is FDA approved in subsequent lines of therapy. Pembrolizumab (Keytruda) is another PD1 inhibitor that was approved by the FDA in 2014. Pembrolizumab is approved to treat melanoma and lung cancer. Antibody BGB-A317 is a PD-1 inhibitor (designed to not bind Fc gamma receptor I) in early clinical trials.


PD-L1 inhibitors

In May 2016, PD-L1 inhibitor atezolizumab was approved for treating bladder cancer. Anti-PD-L1 antibodies currently in development include avelumab and
durvalumab Durvalumab (trade name Imfinzi) is an FDA-approved immunotherapy for cancer, developed by Medimmune/AstraZeneca. It is a human immunoglobulin G1 kappa (IgG1κ) monoclonal antibody that blocks the interaction of programmed cell death ligand 1 ...
, in addition to an inhibitory affimer.


CISH

Other modes of enhancing [adoptive] immuno-therapy include targeting so-called intrinsic checkpoint blockades e.g. CISH (gene), CISH. Many cancer patients do not respond to immune checkpoint blockade. Response rate may be improved by combining immune checkpoint blockade with additional rationally selected anticancer therapies, including those that stimulate T cell infiltration. For example, targeted therapies such as radiotherapy, vasculature targeting agents, and immunogenic chemotherapy can improve immune checkpoint blockade response in animal models.


Oncolytic virus

An
oncolytic virus An oncolytic virus is a virus that preferentially infects and kills cancer cells. As the infected cancer cells are destroyed by oncolysis, they release new infectious virus particles or virions to help destroy the remaining tumour. Oncolytic vir ...
is a virus that preferentially infects and kills cancer cells. As the infected cancer cells are destroyed by oncolysis, they release new infectious virus particles or virions to help destroy the remaining tumour. Oncolytic viruses are thought not only to cause direct destruction of the tumour cells, but also to stimulate host anti-tumour immune responses for long-term immunotherapy. The potential of viruses as anti-cancer agents was first realized in the early twentieth century, although coordinated research efforts did not begin until the 1960s. A number of viruses including adenovirus, reovirus, measles morbillivirus, measles, herpes simplex, Newcastle disease virus and vaccinia have now been clinically tested as oncolytic agents. T-Vec is the first FDA-approved
oncolytic virus An oncolytic virus is a virus that preferentially infects and kills cancer cells. As the infected cancer cells are destroyed by oncolysis, they release new infectious virus particles or virions to help destroy the remaining tumour. Oncolytic vir ...
for the treatment of melanoma. A number of other oncolytic viruses are in Phase II-III development.


Polysaccharides

Certain compounds found in Medicinal mushrooms, mushrooms, primarily polysaccharides, can up-regulate the immune system and may have anti-cancer properties. For example, Beta-glucans, beta-glucans such as lentinan have been shown in laboratory studies to stimulate macrophage,
NK cells Natural killer cells, also known as NK cells or large granular lymphocytes (LGL), are a type of cytotoxic lymphocyte critical to the innate immune system that belong to the rapidly expanding family of known innate lymphoid cells (ILC) and represen ...
, T cells and immune system cytokines and have been investigated in clinical trials as immunologic adjuvants.


Neoantigens

Many tumors express mutations. These mutations potentially create new targetable antigens (neoantigens) for use in T-cell immunotherapy. The presence of CD8+ T cells in cancer lesions, as identified using RNA sequencing data, is higher in tumors with a high Tumor Mutational Burden, mutational burden. The level of transcripts associated with the cytolytic activity of natural killer cells and T cells positively correlates with mutational load in many human tumors. In non–small cell lung cancer patients treated with lambrolizumab, mutational load shows a strong correlation with clinical response. In melanoma patients treated with ipilimumab, the long-term benefit is also associated with a higher mutational load, although less significantly. The predicted MHC binding neoantigens in patients with a long-term clinical benefit were enriched for a series of tetrapeptide motifs that were not found in tumors of patients with no or minimal clinical benefit. However, human neoantigens identified in other studies do not show the bias toward tetrapeptide signatures.


See also

* Cancer vaccine * 5T4, Antigen 5T4 * Coley's toxins * Combinatorial ablation and immunotherapy * Cryoimmunotherapy * Photoimmunotherapy


References


External links


A primer on "Immunotherapy to Treat Cancer"
NIH
Immunotherapy – Using the Immune System to Treat Cancer

Cancer Research Institute – What is Cancer Immunotherapy
Association for Immunotherapy of Cancer
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Society for Immunotherapy of Cancer
* * * {{Breakthrough of the Year Cancer immunotherapy, Monoclonal antibodies for tumors Branches of immunology