CERVICAL CANCER VACCINE- A REVIEW
Sagar Institute of Research Technical And Science-pharmacy
Cancer is the uncontrollable growth of cells. Exponential growth and doubling times of cell is 2 times or 3 times than normal cell growth, doubling times is varies among various kind of tumour’s:
in acute leukemia (2 week)
in multiple myeloma (6 to 12 hour)
Tumour detected when the no. of cells reaches approximately 109 to 1010 cells. Cancer vaccines that boost the immune system’s natural ability to protect body against foreign invaders that causes disease. Vaccines are 2 types: prophylactic and therapeutic. Cancer preventive vaccine target infectious agents that cause cancer and prevent cancer in healthy people and therapeutic vaccines treat cancer in cancer suffering patients.
REFERENCE ID: PHARMATUTOR-ART-1898
Types of cancer vaccines:
1. antigen/adjuvant vaccines,
2. whole cell cancer vaccines,
3. dendritic cell(DC) cell vaccines,
4. viral vector and DNA vaccines,
5. Idioptype vaccines.
In 2006, cancer vaccines approved for use by the U.S. food and drug administration (FDA) known as Gardasil for type 6 and 11 and carvarix, a second HPV vaccine manufactured by Glaxosmithklime for type 16 and 18. Research can use certain immune system cells and their product antibodies created in lab. e.g. – Dendritic cells and costimulatory molecules, idiotype vaccines, anti-id.
Side effects-inflammation, pain swelling, itching, rashes, flu, fever, chill, weakness, dizziness, nausea, vomiting, fatigue, headache, hypersensitivity
Vaccines boost the immune system’s natural ability to defend the body against infection and to protect it from dangers posed by certain types of damaged or abnormalcells, including cancer cells. Some cancer vaccines, known as cancer preventive vaccines, are designed to prevent cancer from developing in healthy people. Other cancer vaccines, known as cancer treatment vaccines, are intended to treat cancers that have already occurred. The U.S. Food and Drug Administration (FDA) has approved two types of cancer preventive vaccines: A vaccine against the hepatitis B virus, which can cause liver cancer in chronically infected people, and a vaccine against human papilloma virus types 16 and 18, which are responsible for about 70 percent of all cases of cervical cancer. Cancer treatment vaccines are designed to treat cancer by stimulating the immune system to recognize and attack cancer cells. The FDA has not yet approved a cancer treatment vaccine. Effective cancer treatment vaccines are difficult to develop because some cancers can escape detection by the immune system or weaken natural immune responses against cancer cells. Researchers are developing treatment vaccines against many types of cancer and testing them in clinical trials. The side effects of cancer vaccines vary from patient to patient and according to the type of vaccine being used. Most of the side effects reported thus far have been mild and limited to inflammation at the site of the vaccine injection.Traditional vaccines usually contain harmless versions of microbes—killed or weakened microbes, or parts of microbes—that do not cause disease but are able to stimulate an immune response. When the immune system encounters these substances through vaccination, it responds to them, eliminates them from the body, and develops a memory of them. This vaccine-induced memory enables the immune system to act quickly to protect the body if it becomes infected by the same microbe in the future. The immune system’s role in defending against disease-causing microbes has long been recognized. Scientists have also discovered that the immune system can protect the body against threats posed by certain types of damaged, diseased, or abnormal cells, including cancer cells. White blood cells, or leukocytes, play the main role in immune responses. These cells carry out the many tasks required to protect the body against disease-causing microbes and abnormal cells. Some types of leukocytes patrol the body, seeking foreign invaders and diseased, damaged, or dead cells. These white blood cells provide a general—or nonspecific—level of immune protection.
Other types of leukocytes, known as lymphocytes, provide targeted protection against specific threats, whether from a specific microbe or a diseased or abnormal cell. The most important groups of lymphocytes responsible for carrying out immune responses against such threats are B cells and cytotoxic(cell-killing) T cells.
B cells make antibodies, which are large proteins secreted by B cells that bind to, inactivate, and help destroy foreign invaders or abnormal cells. Most preventive vaccines, including those aimed at hepatitis B virus (HBV) and human papilloma virus (HPV), stimulate the production of antibodies that bind to specific, targeted microbes and block their ability to cause infection. Cytotoxic T cells, which are also known as killer T cells, kill infected or abnormal cells by releasing toxic chemicals or by prompting the cells to self-destruct (apoptosis).
Other types of lymphocytes and leukocytes play supporting roles to ensure that B cells and killer T cells do their jobs effectively. Cells that help fine-tune the activities of B cells and killer T cells include helper T cells and dendritic cells, which help activate killer T cells and enable them to recognize specific threats.
Cancer treatment vaccines work by activating B cells and killer T cells and directing them to recognize and act against specific types of cancer. They do this by introducing one or more molecules known as antigens into the body, usually by injection. An antigen is a substance that stimulates a specific immune response. An antigen can be a protein or another type of molecule found on the surface of or inside a cell.
Microbes carry antigens that “tell” the immune system they are foreign—or
“non-self”—and, therefore, represent a potential threat that should be destroyed. In contrast, normal cells in the body have antigens that identify them as “self.” Self antigens tell the immune system that normal cells are not a threat and should be ignored.
Cancer cells can carry both types of antigens. They have self antigens, which they share in common with normal cells, but they may also have antigens that are unique to cancer cells. These cancer-associated antigens mark cancer cells as abnormal, or non-self, and can cause B cells and killer T cells to mount an attack against the cancer.
Cancer cells may also make much larger than normal amounts of certain self antigens. These overly abundant self antigens may be viewed by the immune system as being foreign and, therefore, may trigger an immune response against the cancer. Cancer vaccines are medicines that belong to a class of substances known as biological response modifiers. Biological response modifiers work by stimulating or restoring the immune system’s ability to fight infections and disease. There are two broad types of cancer vaccines:
Preventive (or prophylactic) vaccines, which are intended to prevent cancer from developing in healthy people; and Treatment (or therapeutic) vaccines, which are intended to treat already existing cancers by strengthening the body's natural defenses against cancer.Two types of cancer preventive vaccines have been successfully developed and are available in the United States. However, cancer treatment vaccines remain an experimental form of therapy.
Vaccines for cancer represent an alternative approach to the use of therapeutics. In contrast to traditional vaccines that prevent disease, cancer vaccines enlist the patient’s immune system to destroy existing cancer cells. While simple in concept, the development of products has proven difficult. Problems lie in eliciting sufficient, tumor-selective stimulation of an immune system that is already tolerant of cancer cells. Commercially sponsored cancer vaccines first entered clinical studies in the early-1980s and so companies had at least some experience in the area by 1990.
Cervical cancer occurs when abnormal cells on the cervix grow out of control. The cervix is the lower part of the uterus that opens into the vagina. Cervical cancer can often be successfully treated when it's found early. It is usually found at a very early stage through a Pap test.
In 1975, virologist Harald zur Hausen presented provocative evidence that HPV, a common infection spread through skin to skin contact and sex that was believed to lead to serious disease only rarely, could cause cervical cancer. Zur Hausen, who for 20 years headed the German Cancer Research Center in Heidelberg, led a team that by the early 1980s had isolated several genotypes of the virus, some of which they linked to genital warts and others to cervical cancer. “For quite a while, we faced a lot of resistance,” says zur Hausen, now a professsor emeritus. But as the polymerase chain reaction assay improved the ability to detect viral DNA, epidemiological data accumulated that backed zur Hausen’s theories. Indeed, one 1999 report found HPV DNA in 99.7% of cervical cancers studied, conclusive evidence that persistent infection with the virus causes the disease. Nearly half a million women worldwide developed cervical cancer in 2002 and it killed 270,000, according to the latest data from the International
Agency for Research on Cancer (IARC). In developed countries, use of the Papanico- laou test, or Pap smear—which swabs the cervix and looks for abnormal cells—has dramatically cut cervical cancer rates over the past 50 years: Only 5000 American women died from the disease in 2002, a 75% drop in mortality since 1950. But much of the world still does not routinely use the Pap smear, making the need for a vaccine that much more pressing. Scientists have identified more than 100 genotypes of HPV, only 40 of which infect the genital tract; of these, about 15 put women at “high risk” for cervical cancer. In the vast majority of cases, the immune system clears HPV infections before they can cause harm.
What causes cervical cancer?
Most cervical cancer is caused by a virus called human papillomavirus, or HPV. You can get HPV by having sexual contact with someone who has it. There are many types of the HPV virus. Not all types of HPV cause cervical cancer. Some of them cause genital warts, but other types may not cause any symptoms.
You can have HPV for years and not know it. It stays in your body and can lead to cervical cancer years after you were infected. This is why it is important for you to have regular Pap tests. A Pap test can find changes in cervical cells before they turn into cancer. If you treat these cell changes, you may prevent cervical cancer.
Intrauterine device use
Oral contraceptives (birth control pills)
Young age at the first full-term pregnancy
Multiple full-term pregnancies
Family history of cervical cancer
- Sexual intercourse at early age
- Multiple sex partners
- Genital infection e.g. herpes simplex virus type 11, human papilloma virus (HPV)
- Early pregnancy with a first baby before 20 years of age.
- Age 40 – 60 years
- Symptoms of established or invasive cancer of the cervix
- Bleeding after sexual intercourse (Postcoital staining)
- Irregular vaginal bleeding
- Vaginal bleeding one year or more after the menopause (Post-menopausal bleeding)
- Foul-smelling vaginal discharge
- Pre-cancer of the cervix is without symptoms.
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