Bacterial cancer therapy: a new prospective
Cancer is one of the deadliest diseases that kill many people all over the world. Continuous research has made a lot of progress and information available in cancer treatments. However, still now there are a lot of limitations. Therefore, cancer is responsible for the death of many people every day.
Traditionally, bioimaging and diagnostic tools are used to locate and identify cancer progression. Mayakrishnan et al. (2022) reported that bacteria can act as bioimaging and diagnostic tools to locate and identify cancer progression. Cancer cell shows resistance to conventional therapies. Bacteria therapy can overcome cancer cell resistance. Genetic modifications can make bacteria more powerful in advanced cancer therapy with no side effects. Besides this, if we add bacterial-mediated systems to other anticancer therapies, we can get better results in cancer therapy. Mayakrishnan et al. (2022) reported that some bacteria species, such as Salmonella, Clostridium, and Listeria have demonstrated efficacy to control tumor growth with improved prognosis in experimental animal models and clinical settings.
How the bacterial species control the tumor and cancer has been determined from the animal and clinical studies. The genetic background and infectious behavior of bacterial species are presumed to play a role within the tumor microenvironment that show their anti-tumor effectiveness in vivo (Kramer et al., 2018). The biological interactions between the bacteria and the host tumor microenvironment provide the direct and immune-mediated anticancer properties of bacterial species. The bacteria have some significant features, such as motility, tumor chemotaxis, invasive capacity, cytotoxic potential, pathogen-associated molecular patterns (PAMP) composition/ abundance and these features vary between strains of bacteria. These features are presumed to affect how they trigger the anti-tumor response (Kramer et al., 2018).
Genetically engineered bacteria can differentiate the tumors from normal tissues with less toxicity (Yang et al., 2021). The live bacteria can identify the tumors and colonize massively around the tumors due to insufficient oxygen and low pH in the tumor microenvironment. Bacteria can show antitumor effects by two different ways: (1) directly killing the cancer cell or tumor; (2) activating innate and adaptive antitumor immune responses.
References
Kramer MG, Masner M, Ferreira FA and Hoffman RM (2018) Bacterial Therapy of Cancer: Promises, Limitations, and Insights for Future Directions. Front. Microbiol. 9:16. Open access.
Mayakrishnan V., Kannappan P., Tharmalingam N., Bose R.J C, Madheswaran T., Ramasamy M., Bacterial cancer therapy: A turning point for new paradigms, Drug Discovery Today, Volume 27, Issue 8, 2022, Pages 2043-2050.
Yang M., Yang F., Chen W., Liu S., Qiu L., Chen J., 2021. Bacteria-mediated cancer therapies: opportunities and challenges. Biomaterials Science 2021,9, issue 17, 5732-5744.
What is hematology?
The study of hematology concentrates on the care of patients with disorders of the blood, bone marrow, and lymphatic systems. It is a subspecialty of internal medicine (ACPI, 2002).
What do hematologists do?
Hematologists perform the treatment of following problems:
- Anemias,
- Hematological malignancies and other clonal processes,
- Congenital and acquired disorders of hemostasis, coagulation, and thrombosis
Hematologists do their own independent practice of hematology or they provide consultative services for other physicians or medical institutions. Hematologists also obtain training in oncology and thus they acquire wide knowledge to diagnose, treat, and manage a wide range of related diseases including oncology and hematology.
References
American College of Physicians, Inc. (ACPI), Hematology. Last accessed on 10/11/2022. Url: https://www.acponline.org/about-acp/about-internal-medicine/subspecialties-of-internal-medicine/hematology.
Leukaemia
Leukaemia is a type of blood cancer which occurs in the blood-forming tissue, usually the bone marrow. Leukaemia causes the over-production of abnormal white blood cells. Leukaemia affects white blood cells. Bone marrow can’t produce the large numbers of normal blood cells which the body needs, because it becomes full of leukaemia cells. Generally, white blood cells fight against infection and disease and protect body.
- There is no obvious cause of leukaemia,
- It is not contagious,
- Leukaemia is not passed on from a parent to a child (inherited)
Age
People older than 55 are most often affected by leukemia occurrence. It is also the most common cancer in children younger than 15.
Blood cell formation in bone marrow
The formation of blood cells occurs in the bone marrow. Bone marrow is the spongy tissue existing inside the bones. Blood-forming stem cells divide to produce either more stem cells or immature cells. Then these cells become mature blood cells over time. A blood stem cell may become a myeloid stem cell or a lymphoid stem cell. A myeloid stem cell becomes one of three types of mature blood cells: (1) red blood cells, (2) platelets, and (3) granulocytes.
- Red blood cells carry oxygen to all tissues of the body.
- Platelets form blood clots to stop bleeding.
- Granulocytes (white blood cells) fight infection and disease.
A lymphoid stem cell becomes a lymphoblast cell and then one of three types of lymphocytes (white blood cells): (1) B lymphocytes, (2) T lymphocytes, and (3) natural killer cells.
- B lymphocytes make antibodies to help fight against infection.
- T lymphocytes help B lymphocytes make the antibodies that help fight against infection.
- Natural killer cells attack cancer cells and viruses.
Types of Leukaemia
Leukaemia is classified according to the type of white blood cell (myeloid or lymphatic) that becomes cancer and the growth or progression of disease, either faster or slow (acute or chronic). Acute and chronic leukaemia do not indicate the severity of the disease, but it indicates the speed of disease progression.
First type of classification:
Acute leukaemia
The disease becomes worse quickly in acute leukaemia. The abnormal blood cells, which are immature blood cells (blasts), can’t carry out their normal functions, but they multiply rapidly leading to faster worsening of disease. This disease requires aggressive, timely treatment.
Chronic leukaemia
There are many types of chronic leukaemia. Some produce too many cells while others do too few cells. Chronic leukaemia is linked to more-mature blood cells, that replicate or accumulate more slowly and can function normally for a period of time. Therefore, these types of chronic leukemia initially produce no early symptoms and continue long time undiagnosed.
The second type of classification by type of white blood cell:
Lymphocytic leukaemia
This type of leukaemia affects the lymphoid cells (lymphocytes), which form lymphoid or lymphatic tissue. Lymphatic tissue makes up our immune system.
Myelogenous leukemia
This type of leukaemia affects the myeloid cells. Myeloid cells give rise to red blood cells, white blood cells and platelet-producing cells.
Major types of leukaemia are:
Acute lymphocytic leukaemia
This type of leukaemia is most commonly found in young children, but it can also affect the adult people.
Acute myelogenous leukaemia
This is a common type of leukaemia that affects both children and adults. But it is the most common type of acute leukaemia in adults.
Chronic lymphocytic leukaemia
It is the most common chronic leukemia in adult. The patient may feel well for years without needing treatment.
Chronic myelogenous leukemia
This type of leukemia mainly occurs in adults, who may have few or no symptoms for months or years before they move to a phase in which the leukaemia cells grow more quickly.
Other types – There are some other rarer types of leukemia which include hairy cell leukaemia, myelodysplastic syndromes and myeloproliferative disorders.
Symptoms of leukaemia
The leukaemia demonstrates variable symptoms relating to the type of leukaemia. The symptoms are often not clear or specific. Therefore, people overlook early leukaemia symptoms because the symptoms are similar to the symptoms of the flu and other common illnesses. Sometimes leukaemia is identified when people do their blood tests for some other disease or problems.
Common leukemia signs and symptoms include:
- Body temperatures increase or having fever,
- Feeling fatigue, weakness for long time,
- Shortness of breath, light-headedness, and palpitations,
- Having severe infections or frequent infections due to lack of normal white blood cells,
- Unexpected weight loss,
- Swollen lymph nodes in body,
- Bleeding or bruising more easily due to lack of platelets,
- Recurrent nosebleeds,
- Tiny red spots in skin (petechiae),
- Sweating more than normal, especially at night,
- Feeling bone pain or tenderness.
Risk factors
The following factors may augment the risk of developing some types of leukaemia:
Age – older people have high risk of developing most forms of leukaemia. Children may also have high risk of some sorts of leukaemia.
Gender – Generally male more commonly gets leukaemias.
Previous cancer treatment — Some people have high risk of developing certain types of leukaemia if they have had certain types of chemotherapy and radiation therapy for other cancers.
Genetic disorders — Genetic abnormalities may be a factor to develop leukaemia in some people, such as people with Down syndrome. These certain genetic disorders increase the risk of leukaemia.
Exposure to certain chemicals — If people are exposed to certain types of chemicals, such as benzene, they have an increased risk of some kinds of leukaemia. This chemical is found in gasoline and is also used by the chemical industry. Exposure to high levels of radiation may increase the chance of developing leukaemia. These factors are responsible for only a very small proportion of all cases.
Smoking — Smoking cigarettes increases the risk of acute myelogenous leukaemia.
Family history of leukaemia – It is known that leukaemia is not an inherited disease. But if close relatives of someone’s family have been diagnosed with leukaemia, then they have a risk of the disease, although the risk is still very small.
Bone marrow disorders — People who have other bone marrow disorders may have some forms of leukaemia.
Exceptions — However, most people with known risk factors don’t get leukemia. And many people with leukaemia have none of these risk factors.
Treatment options of leukaemia are:
Chemotherapy
Drugs are used to kill cancer cell. In chemotherapy, steroids are normally used along with it for lymphoid leukaemia.
Radiation therapy
Radiation therapy is usually only for stem cell transplant or local disease e.g. in spleen.
Targeted therapy
Drugs are used to specifically recognise and kill leukaemia cells.
Biological therapy
In these treatments, the immune system is used to destroy leukaemia cells by using antibodies against markers on the leukaemia. These treatments used often monoclonal antibodies.
Stem cell transplant
A stem cell transplant (bone marrow transplant) is provided to younger/fitter patients. The patient’s own healthy stem cells or stem cells from a donor can be used for this treatment. If chemotherapy does not cure the disease, then this treatment is used, most commonly for acute leukaemia.