New ways of treating Cancer - Research in biological and targeted therapies.
Biological therapies work in different ways to kill, control or change the behaviour of cancer cells. These therapies use natural or artificial substances that act like (mimic) or block natural cell responses.
Some types of biological therapy interfere with specific molecules (for example, proteins) involved in the growth of a tumour and its spread (progression). These biological therapies are also referred to as targeted therapies.
Targeted therapies may allow doctors to tailor cancer treatment for a person. In time, treatments may be selected based on a certain set of molecular targets made by a person’s tumour. Targeted therapies are also more selective in the way they work, so they may harm fewer normal cells, cause fewer side effects and improve a person’s quality of life. For these reasons, researchers are developing and studying many targeted therapy drugs that can be used alone or in combination with other cancer treatments.
Immunotherapy is a form of biological therapy that uses the immune system to help destroy cancer cells. The immune system is a complex system of cells and organs that work together to defend our bodies against disease and infection. Cancer, and some cancer treatments, can weaken the immune system. Sometimes the immune system doesn’t recognize cancer cells as different (foreign) and so it doesn’t work to destroy them. Immunotherapy boosts the immune system to help it recognize and fight cancer cells.
Immunotherapy may work better for some types of cancer than for other types. It may be used alone, but for some types of cancer, immunotherapy seems to work best when it is used with other types of treatment.
Researchers continue to study how immunotherapy can be used to treat people with cancer. The following are the main types of immunotherapy that researchers are studying.
Cytokines are chemicals that are made by many immune system cells. Cytokines allow immune system cells to communicate with each other and so help carry out the immune system’s defence response.
Interferon is naturally made in the body in small amounts. It can also be made in the lab so that it can be given in larger amounts to treat cancer. Interferon can improve the way the immune system acts against cancer cells. It can also act directly on cancer cells to slow their growth or help them develop into cells that look and behave more like normal cells. Find out more about interferon.
Interleukin occurs naturally in the body. It can also be made in the lab. It stimulates the growth and activity of certain immune cells that recognize and destroy cancer cells, such as lymphocytes and killer T cells. Find out more about interleukin.
Tumour necrosis factor (TNF) is a cytokine made by macrophages and lymphocytes (types of white blood cells) in the body. TNF stimulates the immune system to attack tumour cells and their blood vessels. Researchers are studying TNF in clinical trials.
Monoclonal antibodies are made in the lab. They find and bind to a specific antigenantigenA foreign substance that stimulates the immune system to produce antibodies against it. on a cancer cell. Monoclonal antibodies may:
- trigger the immune system to attack and kill cancer cells (act as a biological therapy)
- stop cancer cells from taking up proteins they need to grow (act as a targeted therapy)
- carry anticancer drugs or radiation to the cancer cells (act as a targeted therapy)
Researchers are studying new monoclonal antibody drugs for many types of cancer including breast cancer, ovarian cancer, leukemia and lymphoma.
Find out more about monoclonal antibodies.
Colony-stimulating factors (CSFs) don’t directly affect tumour cells. They stimulate the bone marrow to make more red blood cells, white blood cells and platelets. CSFs are used to treat bone marrow suppression and low blood cell counts, which are side effects of cancer treatments that may make a person more vulnerable to anemia, infection or bleeding.
Find out more about colony-stimulating factors.
Doctors are studying cancer vaccines to treat cancer. These vaccines delay or stop the growth of cancer cells and shrink tumours. People who have a healthy immune system and are in an early stage of the disease may be the best candidates for treatment with cancer vaccines.
Cancer vaccine research is still in the very early stages. Researchers are studying cancer vaccines in people with bladder, brain and spinal, breast, cervical, colorectal, kidney, lung, pancreatic, ovarian and prostate cancers as well as leukemia, lymphoma, melanoma and multiple myeloma.
Researchers are studying different cancer vaccines, including the following. Find out more about cancer vaccines.
Tumour cell vaccines are made from cancer cells removed during a biopsy or surgery. The cancer cells are killed with radiation, and then the cells are injected back into the person. The radiation doesn’t kill antigens on the surface of the cells, so these antigens stimulate an immune response. The immune system recognizes and attacks cancer cells containing these antigens.
Antigen vaccines use specific proteins or parts of proteins (antigens) from the surface of cancer cells to stimulate the immune system to fight these cells.
Dendritic cells are a type of white blood cell that helps fight infection by producing signals (antigens) to boost the immune response. Dendritic cell vaccines use cancer cells mixed with a person’s own dendritic cells to stimulate the immune system to fight cancer cells.
DNA vaccines use DNA, sometimes from a person’s own cells. The DNA helps the body maintain the immune response longer by giving it a steady supply of antigens.
Anti-idiotype vaccines trigger an immune system response in almost the same way as antigen vaccines. They stimulate the body to make antibodies against cancer cells. An idiotype is the part of an antibody that determines the specific antigen the antibody will act against.
Tumour-infiltrating lymphocyte vaccines are made from immune cells removed from deep inside a tumour (called tumour-infiltrating lymphocytes). The lymphocytes are treated with interleukin-2 in the lab, which makes them multiply. The cells are then injected back into the person where they can help fight cancer.
Angiogenesis means the growth of new blood vessels. A tumour has to make new blood vessels to grow, while normal organs do not. Anti-angiogenesis drugs try to starve the tumour by stopping the development of new blood vessels.
Find out more about anti-angiogenesis drugs.
Growth factors are naturally occurring chemicals that control cell growth. Cancer growth inhibitors work by:
- blocking the growth factors that make cancer cells divide and grow
- lowering the levels of certain growth factors in the body
- blocking signals in cells that tell them to grow (these signals are sent when growth factors trigger a cell receptor)
The different types of cancer growth inhibitors are named after the type of chemical they block. The main types are tyrosine kinase inhibitors, proteasome inhibitors and growth factor receptor inhibitors. Find out more about cancer growth inhibitors.
Researchers are studying the following new cancer growth inhibitors.
mTOR inhibitors block the mammalian target of rapamyin (mTOR). mTOR is a protein that regulates cell growth and reproduction. It is abnormally activated in some types of cancer. mTOR inhibitors block the action of mTOR, which can stop the growth of some types of cancer.
PI3K inhibitors (phosphoinositide 3 kinases) work by switching off PI3K in cells that make them grow and multiply. In some cancers, PI3K is always turned on so the cancer cells continue to grow and divide uncontrollably. Researchers are studying drugs that inhibit PI3K to see if they will kill cancer cells or stop them from growing.
Histone deacetylase inhibitors prevent cells from growing and dividing by blocking a group of enzymesenzymesA protein that speeds up certain chemical reactions in the body. called histone deacetylases.
Hedgehog pathway blockers work by switching off proteins and stopping the growth of cancer cells. The hedgehog pathway is a group of proteins that send signals to help cells grow in the right place and in the right way in a developing embryo. Hedgehog pathway proteins are normally switched off in most adult cells, but they can be switched on in some types of cancer. This causes cancer cells to grow.
Researchers are actively studying gene therapy as a treatment option for cancer. This therapy introduces geneticgeneticHaving to do with genes or genetics and usually referring to the effect or structure of genes. material into a person’s cells to block, repair or replace a mutation. Genetic material may also be introduced to stimulate the immune system to fight disease.
Researchers are studying how gene therapy may be used to treat cancer by:
- blocking, repairing or replacing abnormal genes in cancer cells so they start to behave like normal cells
- causing more genes (in addition to the ones that are not working properly already) in a cancer cell to function abnormally, which may cause the cell to die
- adding genes to cancer cells to make it easier for other treatments or a person’s immune system to kill them
- preventing cancer cells from developing new blood vessels that they need to grow (called anti-angiogenesis therapy)
- injecting cancer cells with special suicide genes that can destroy the cells by turning inactive drugs that don’t harm normal cells into an active form that only harm cancer cells (called pro-drug gene therapy)
- boosting the body’s immune system to attack cancer cells
- making cancer cells more sensitive to cancer treatments like chemotherapy or radiation therapy
- blocking processes that protect cancer cells
- putting genes inside healthy blood stem cells to make them more resistant to the side effects of cancer treatments
Researchers are studying different ways to get genes inside a cancer cell. One way that researchers get genes into cancer cells is to use viruses. Researchers are also studying inactive bacteria as a way to get genes inside cancer cells.
Oncolytic virus therapy uses a virus that infects and breaks down cancer cells but not normal cells. The virus copies itself, or replicates, inside a cancer cell and eventually kills it. Researchers are using mumps, measles, reovirus and other viruses in oncolytic virus therapy. Some oncolytic viruses can be genetically engineered in the lab to only infect cancer cells that have a certain antigen.
Researchers are studying ways to prevent a person’s immune system from attacking and destroying oncolytic viruses. They are using chemotherapy drugs that suppress the immune system, such as cyclophosphamide (Cytoxan, Procytox), along with oncolytic virus therapy. Researchers are also trying to find out if coating the oncolytic virus with a lipid or polymer will prevent the immune system from destroying it.
Researchers are also studying how a person’s immune reaction to an oncolytic virus may help the treatment work better. Once the virus has passed into a cancer cell, an immune reaction may help to destroy the cancer cell.
Clinical trials are looking at using oncolytic virus therapy in combination with other treatments such as chemotherapy and radiation therapy.
Adoptive T-cell transfer therapy uses a person’s T cells to fight cancer. Adoptive T-cell therapy can be done in 2 ways.
Researchers remove T cells from a person’s tumour. In the lab, they find which T cells will best fight cancer and grow these cells. The lab-grown T cells are then given back to the person.
Researchers remove a person’s T cells from a blood sample and insert a gene that recognizes an antigen from the person’s cancer cells. When the genetically changed T cells are given back to the person, these cells attach to an antigen on the surface of a cancer cell, which causes T cells in the body to attack and destroy it.