Anti Cancer Drugs And Development Biology Essay

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Purpose: Anticancer drugs are used to control the growth of cancerous cells. Cancer is commonly defined as the uncontrolled growth of cells, with loss of differentiation and commonly, with metastasis, spread of the cancer to other tissues and organs. Cancers are malignant growths. In contrast, benign growths remain encapsulated and grow within a well-defined area. Although benign tumors may be fatal if untreated, due to pressure on essential organs, as in the case of a benign brain tumor, surgery or radiation are the preferred methods of treating growths which have a well defined location. Drug therapy is used when the tumor has spread, or may spread, to all areas of the body. 6

Description: Several classes of drugs may be used in cancer treatment depending on the nature of the organ involved breast cancers are commonly stimulated by estrogens, and may be treated with drugs that inactivate the sex hormones. prostate cancer may be treated with drugs that inactivate androgens, the male sex hormone. However, the majority of anti cancer drugs act by interfering with cell growth. Since cancerous cells grow more rapidly than other cells, the drugs target those cells that are in the process of reproducing themselves. As a result, anti cancer drugs will commonly affect not only the cancerous cells, but others cells that commonly reproduce quickly, including hair follicles, ovaries and testes, and the blood-forming organs. 6

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Precautions: Because anti cancer drugs agents do not target specific cell types, they have a number of common adverse side effects. Hair loss is common due to the effects on hair follicles, and anemia, immune system impairment, and clotting problems are caused by destruction of the blood-forming organs, leading to a reduction in the number of red cells, white cells, and platelets. Because of the frequency and severity of these side effects, it is common to administer chemotherapy in cycles, allowing time for recovery from the drug effects before administering the next dose. Doses are often calculated, not on the basis of weight, but rather based on blood counts, in order to avoid dangerous levels of anemia (red cell depletion), neutropenia (white cell deficiency), or thrombocytopenia (platelet deficiency.)The health professional has many responsibilities in dealing with patients undergoing chemotherapy. The patient must be well informed of the risks and benefits of chemotherapy, and must be emotionally prepared for the side effects. These may be permanent, and younger patients should be aware of the high risk of sterility after chemotherapy .The patient must also know which side effects should be reported to the practitioner, since many adverse effects do not appear until several days after a dose of chemotherapy. When chemotherapy is self-administered, the patient must be familiar with proper use of the drugs, including dose scheduling and avoidance of drug-drug and food-drug interactions .Appropriate steps should be taken to minimize side effects. These may include administration of antinauseant medications to reduce nausea and vomiting, maintaining fluid levels to reduce drug toxicity, particularly to the kidneys, or application of a scalp tourniquet to reduce blood flow to the scalp and minimize hair loss due to drug therapy. 11

Side effects: Some anticancer may increases the risk of other cancer. It also causes cataracts and other eye problems. Health care providers should keep in close contact with patients to assess the individual risks associated with taking this powerful drug. 13

CANCER

Cancer is word tells about complex group of many different types of cancerous diseases. Cancer can affect just about every organ in the human body.

Each type of cancer is unique with its own causes, symptoms, and methods of treatment. Like with all groups of disease, some types of cancer are more common than others. 

Process of Cancer Development

The organs in our body are made up of cells. Cells divide and multiply as the body needs them. When these cells continue multiplying when the body doesn't need them, the result is a mass or growth, also called a tumor. These growths are considered either benign or malignant. Benign is considered non-cancerous and malignant is cancerous. Benign tumors rarely are life threatening and do not spread to other parts of the body. They can often be removed. Malignant tumors, however, often invade nearby tissue and organs, spreading the disease.

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The cells within malignant tumors have the ability to invade neighboring tissues and organs, thus spreading the disease. It is also possible for cancerous cells to break free from the tumor site and enter the bloodstream, spreading the disease to other organs. This process of spreading is called metastasis. When cancer has metastasized and has affected other areas of the body, the disease is still referred to the organ of origination. For example, if cervical cancer spreads to the lungs, it is still called cervical cancer, not lung cancer. Although most cancers develop and spread this way -- via an organ - blood cancer like leukemia do not. They affect the blood and the organs that form blood and then invade nearby tissues.

Cancer Symptoms

Symptoms of cancer vary based on the type of cancer. As cancer progresses to an advanced stage, common symptoms can include weight loss, fever, and fatigue. These are very non-specific symptoms that are more likely related to other less serious illnesses than cancer. 

Cancer Prevention

Cancer can be prevented in many cases. Learning what causes cancer and what the risk factors are is the first step in cancer prevention. Many cancer risk factors can be avoided. Smoking is the most significant cancer risk factor that we can reduce. It is responsible for not only lung cancer, but many other types of cancer. So, by avoiding these risks many cancers can be prevented

Standard Treatment for Cancer

There are four standard methods of treatment for cancer: surgery, chemotherapy, radiation therapy, immunotherapy and biologic therapy. When initially diagnosed with cancer, a cancer specialist, an oncologist, will provide you with the cancer treatment options. He or she will recommend the best treatment plan based on your type of cancer, how far it has spread, and other important factors like your age and general health. Ultimately, you are the one who makes your treatment decisions based on your doctor's recommendations, possible second opinions, and other information gathered from qualified professionals.

Surgery: Surgery can be used to prevent, treat, stage (advancement of cancer), and diagnose cancer. In relation to cancer treatment, surgery is done to remove tumors or as much of the cancerous tissue as possible. It is often performed in conjunction with chemotherapy or radiation therapy.

Radiation Therapy: Radiation therapy uses certain types of energy to shrink tumors or eliminate cancer cells. It works by damaging a cancer cell's DNA, making it unable to multiply. Cancer cells are highly sensitive to radiation and typically die when treated. Nearby healthy cells can be damaged as well, but they can recover themselves.

Radiation therapy may be given alone, along with chemotherapy, and/or with surgery. The decision to combine radiation therapy with other types of treatment depends on the stage of cancer and many other factors.

Biologic or Targeted Therapy: Biologic therapy is a term for drugs that target characteristics of cancerous tumors. Some types of targeted therapies work by blocking the biological processes of tumors that allow tumors to flourish and grow. Other types of therapies cut off the blood supply to the tumor, causing it to basically waste away and die because of a lack of blood. Targeted therapy is used in select types of cancer and is not available for everyone. It is given in combination with other cancer treatments.

Chemotherapy: Chemotherapy is a type of cancer treatment that uses drugs to eliminate cancer cells. Unlike surgery, chemotherapy affects the entire body, not just a particular part. It works by targeting rapidly multiplying cancer cells. Unfortunately, other types of cells in our bodies also multiply at high rates, like hair follicle cells and the cells that line our stomachs. This is why this therwpy can cause side effects like hair loss and an upset stomach.

Chemotherapy is most commonly given by pill or intravenously (IV), but can be given in other ways. A single type of chemotherapy, or a combination of drugs, may be prescribed for a specific length of time. Like surgery, chemotherapy can be prescribed alone, in conjunction with radiation therapy or biologic therapy.

[www.cancer.about.com]

Anticancer Drugs

   

 

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Definition:-Anticancer drugs are used to treat malignancies, or cancerous growths. Drug therapy may be used alone, or in combination with other treatments such as surgery or radiation therapy.

Purpose: Anticancer drugs are used to control the growth of cancerous cells. Cancer is commonly defined as the uncontrolled growth of cells, with loss of differentiation and commonly, with metastasis, spread of the cancer to other tissues and organs. Cancers are malignant growths. In contrast, benign growths remain encapsulated and grow within a well-defined area. Although benign tumors may be fatal if untreated, due to pressure on essential organs, as in the case of a benign brain tumor, surgery or radiation are the preferred methods of treating growths which have a well defined location. Drug therapy is used when the tumor has spread, or may spread, to all areas of the body.

Description: Several classes of drugs may be used in cancer treatment depending on the nature of the organ involved breast cancers are commonly stimulated by estrogens, and may be treated with drugs that inactivate the sex hormones. prostate cancer may be treated with drugs that inactivate androgens, the male sex hormone. However, the majority of anti cancer drugs act by interfering with cell growth. Since cancerous cells grow more rapidly than other cells, the drugs target those cells that are in the process of reproducing themselves. As a result, anti cancer drugs will commonly affect not only the cancerous cells, but others cells that commonly reproduce quickly, including hair follicles, ovaries and testes, and the blood-forming organs.

Newer methods of anti cancer drug therapy have taken different approaches, including angiogenesis-the inhibition of formation of blood vessels feeding the tumor and contributing to tumor growth. Although these approaches hold promise, they are not yet in common use. Developing new anticancer drugs is the work of ongoing research

List of Some Anti Cancer Drugs

Generic (Brand Name)

Clinical Uses

Common Side

Effects To Drug

Altretamine (Hexalen)

Treatment of

advanced ovarian

cancer

Bone marrow

depression, nausea

and vomiting

Asparaginase (Elspar)

Commonly used in

combination with

other drugs; refrac-

tory acute lymphocy-

tic leukemia

Liver, kidney,

pancreas, CNS

abnormalities,

Bleomycin (Blenoxane)

Lymphomas,

Hodgkin's disease,

testicular cancer

Hair loss, stomatitis,

pulmonary toxicity,

hyperpigmentation

of skin

Busulfan (Myleran)

Chronic granulocytic

leukemia

Bone marrow

depression,

pulmonary toxicity

Carboplatin (Paraplatin)

Pallilation of ovarian

cancer

Bone marrow

depression, nausea

and vomiting

Carmustine

Hodgkin's disease,

brain tumors, multi-

ple myeloma, malig-

nant melanoma

Bone marrow

depression, nausea

and vomiting, toxic damage to liver

Chlorambucil (Leukeran)

Chronic lymphocytic

leukemia, non-

Hodgkin's

lymphomas, breast

and ovarian cancer

Bone marrow

depression, excess

uric acid in blood

Cisplatin (Platinol)

Treatment of bladder,

ovarian,

uterine, testicular,

head and neck

cancers

Renal toxicity and

ototoxicity

Cladribine (Leustatin)

Hairy cell leukemia

Bone marrow

depression, nausea

and vomiting, fever

Cyclophosphamide

(Cytoxan)

Hodgkin's disease,

non-Hodgkin's lym-

phomas, neuroblas-

toma. Often used

with other drugs for

breast, ovarian, and

lung cancers; acute

lymphoblastic leuke-

mia in children; mul-

tiple myeloma

Bone marrow

depression, hair loss,

nausea and vomiting,

inflammation of the

bladder

Cytarabine (Cytosar-U)

Leukemias occurring

in adults and children

Bone marrow

depression, nausea

and vomiting,

diarrhea, stomatitis

Dacarbazine (DTIC-

Dome)

Hodgkin's disease,

malignant melanoma

Bone marrow

depression, nausea

and vomiting

Diethylstilbestrol (DES)

(Stilbestrol)

Breast cancer in

post-menopausal

women, prostate

cancer

Hair loss, nausea and

vomiting, edema,

excess calcium in

blood; feminizing

effects in men

Ethinyl

estradiol (Estinyl)

Advanced breast

cancer in post-

menopausal women,

prostate cancer

Excess calcium in

blood, anorexia,

edema, nausea and

vomiting; feminizing

effects in men

Etoposide (VePesid)

Acute leukemias,

lymphomas, testicu-

lar cancer

Bone marrow

depression, nausea

and vomiting, hair loss

Generic (Brand Name)

Clinical Uses

Common Side

Effects to Drug

Mitomycin (Mutamycin)

Bladder, breast,

colon, lung,

pancreas, rectum

cancers, head and

neck cancer, malig-

nant melanoma

Bone marrow

depression, nausea

and vomiting,

diarrhea, stomatitis,

possible tissue

damage

Mitotane (Lysodren)

Cancer of the adrenal

cortex (inoperable)

Damage to adrenal

cortex, nausea,

anorexia

Mitoxantrone (Novantrone)

Acute nonlymphocy-

tic leukemia

Cardiac arrhythmias,

labored breating,

nausea and vomiting,

diarrhea, fever,

congestive heart

failure

Paclitaxel (Taxol)

Advanced ovarian

cancer

Bone marrow

depression, hair loss,

nausea and vomiting,

hypotension, allergic

reactions, slow heart

action, muscle and

joint pain

Pentastatin (Nipent)

Hairy cell leukemia

unresponsive to

alpha-interferon

Bone marrow

depression, fever,

skin rash, liver

damage, nausea and

vomiting

Pipobroman (Vercyte)

Chronic granulocytic

leukemia

Bone marrow

depression

Plicamycin (Mithracin)

Testucular tumors

Toxicity/damage

to bone marrow,

kidneys, and liver

Prednisone (Meticorten)

Used in adjunct ther-

apy for palliation of

symptoms in lympho-

mas, acute leukemia

Hodgkin's disease

May be toxic to all

body systems

Procarbazine (Matulane)

Hodgkin's disease

Bone marrow

depression, nausea

and vomiting

Streptozocin (Zanosar)

Islet cell carcinoma of

pancreas

Nausea and vomiting,

toxicity to kidneys

Tamoxifen (Nolvadex)

Advanced breast can-

cer in post

menopausal

Nausea and vomiting,

ocular toxicity, hot

flashes

Teniposide (Vumon)

Acute lymphocytic

leukemia in children

Etoposide

Vinblastine (Velban)

Breast cancer,

Hodgkin's disease,

metastatic testicular

cancer

Bone marrow

depression,

neurotoxicity

Vincristine (Oncovin)

Acute leukemia,

Hodgkin's disease,

lymphomas

Constipation,

neurotoxicity,

possible tissue

necrosis

Anti cancer drugs may be divided into two classes: cycle specific and non-cycle specific. Cycle specific drugs act only at specific points of the cell's duplication cycle, such as anaphase or metaphase, while non-cycle specific drugs may act at any point in the cell cycle. In order to gain maximum effect, anti cancer drugs are commonly used in combinations.

Precautions: Because anti cancer drugs agents do not target specific cell types, they have a number of common adverse side effects. Hair loss is common due to the effects on hair follicles, and anemia, immune system impairment, and clotting problems are caused by destruction of the blood-forming organs, leading to a reduction in the number of red cells, white cells, and platelets. Because of the frequency and severity of these side effects, it is common to administer chemotherapy in cycles, allowing time for recovery from the drug effects before administering the next dose. Doses are often calculated, not on the basis of weight, but rather based on blood counts, in order to avoid dangerous levels of anemia (red cell depletion), neutropenia (white cell deficiency), or thrombocytopenia (platelet deficiency.)The health professional has many responsibilities in dealing with patients undergoing chemotherapy. The patient must be well informed of the risks and benefits of chemotherapy, and must be emotionally prepared for the side effects. These may be permanent, and younger patients should be aware of the high risk of sterility after chemotherapy .The patient must also know which side effects should be reported to the practitioner, since many adverse effects do not appear until several days after a dose of chemotherapy. When chemotherapy is self-administered, the patient must be familiar with proper use of the drugs, including dose scheduling and avoidance of drug-drug and food-drug interactions .Appropriate steps should be taken to minimize side effects. These may include administration of antinauseant medications to reduce nausea and vomiting, maintaining fluid levels to reduce drug toxicity, particularly to the kidneys, or application of a scalp tourniquet to reduce blood flow to the scalp and minimize hair loss due to drug therapy.

Patients receiving chemotherapy also are at risk of infections due to reduced white blood counts. While prophylactic antibiotics may be useful, the health care professional should also be sure to use standard precautions, including gowns and gloves when appropriate. Patients should be alerted to avoid risks of viral contamination, and live virus immunizations are contraindicated until the patient has fully recovered from the effects of chemotherapy. Similarly, the patient should avoid contact with other people who have recently had live virus immunizations.

Other precautions which should be emphasized are the risks to pregnant or nursing women. Because anti cancer drugs are commonly harmful to the fetus, women of childbearing potential should be cautioned to use two effective methods of birth control while receiving cancer chemotherapy. This also applies if the woman's male partner is receiving chemotherapy. Breastfeeding should be avoided while the mother is being treated.

Before prescribing or administering anticancer drugs, health care providers should inquire whether the patient has any of the following conditions:

chickenpox or recent exposure to someone with chickenpox

shingles (Herpes zoster)

mouth sores

current or past seizures

head injury

nerve or muscle disease

hearing problems

infection of any kind

gout

colitis

intestine blockage

stomach ulcer

kidney stones

kidney disease

liver disease

current or past alcohol abuse

immune system disease

cataracts or other eye problem

high cholesterol

Patients should be given advice on the effects of sun exposure and the use of alcohol and pain relievers.

Side effects: Some anticancer may increases the risk of other cancer. It also causes cataracts and other eye problems. Health care providers should keep in close contact with patients to assess the individual risks associated with taking this powerful drug.

These side effects are not common, but could be a sign of a serious problem. Health care providers should immediately be consulted if any of the following occur:

black, tarry, or bloody stools

blood in the urine

diarrhea

fever or chills

cough or hoarseness

wheezing or shortness of breath

sores in the mouth or on the lips

unusual bleeding or bruising

swelling of the face

red "pinpoint" spots on the skin

redness, pain, or swelling at the point where an inject-able anticancer drug is given

pain in the side or lower back

problems urinating or painful urination

dizziness or faintness

fast or irregular heartbeat

Other side effects do not need immediate care, but should have medical attention. They are:

joint pain

skin rash

hearing problems or ringing in the ears

numbness or tingling in the fingers or toes

trouble walking or balance problems

swelling of the feet or lower legs

unusual tiredness or weakness

loss of taste

seizures

dizziness

confusion

agitation

headache

dark urine

yellow eyes or skin

flushing of the face

In addition, there are other possible side effects that do not need medical attention unless they persist or interfere with normal activities. These include changes in menstrual period, itchy skin, nausea and vomiting, and loss of appetite.

Other rare side effects may occur. Anyone who has unusual symptoms after taking anticancer drugs should contact the physician who prescribed the medication.Anticancer drugs may interact with a number of other medicines. When this happens, the effects of one or both of the drugs may change or the risk of side effects may be greater. The health care provider should be aware of all other prescription or non-prescription (over-the-counter) medicines a patient is taking. The primary care provider should also be told if the patient has been treated with radiation or has taken other anticancer drugs.

[www.medical-dictionary.thefreedictionary.com]

Disscussion on some anti cancer drugs

Cisplatin: is a platinum-based chemotherapy drug used to treat various types of cancers, such as sarcomas, some carcinomas, lymphomas and germ cell tumors.

Cisplatin works by crosslinking across DNA inter-strands, making it impossible for rapidly dividing cells to duplicate their DNA for cell division (mitosis). The damaged DNA sets off DNA repair mechanisms which fails to work, so in turn activate cell death processes (apoptosis). The trans isomer does not have this pharmacological effect.

In 1965, Rosenberg made a chance observation that electrolysis experiments were having a remarkable effect on E. Coli bacteria. The bacteria were seen to grow 300 times their normal length and then burst rather than undergo normal cell division. The platinum electrode was shown produce very small amounts of solube platinum compounds in solution and this material had the remarkable effect on the cell division. Following up this work in the early 1970, cisplatin was found stop the growth of rapid cell division in certain type of cancer cells and so after in 1978 cisplatin became one of the first major chemotherapy drugs.

Other platinum based drugs are also used such as carboplatin and most recently Eloxatin (oxaliplatin).

Formal Chemical Name (IUPAC)

cis- diamminedichloroplatinum(II)

3-D structure of cisplatin Simple structure of cisplatin

Cisplatin deforming DNA

[http://www.3dchem.com/molecules.asp?ID=214]

Eloxatin:- an anticancer (chemotherapy) drug, is given with two other anticancer drugs, 5-fluorouracil (5-FU) and leucovorin (LV), and is used to treat adults with stage III colon cancer after surgery to remove the tumor.

It is a new platinum based drug. It has the large 1,2-diaminocyclohexane (DACH) bound to the platinum centre, and this bulky group prevents DNA repair mechanisms working correctly. The platinum centre binds to DNA strands and thus prevents DNA replication and transcription, and therefore slows cancer tumor growth.

;

Simple & 3-D structure of Eloxatin

[ http://www.eloxatin.com/ ]

Carboplatin:- it is a chemotherapay agent used for treatment of many types of cancer. The U.S. Food and Drug Administration approved carboplatin for use treating patients with ovarian and non-small cell lung cancer, and oncologists sometimes use carboplatin "off-label" for other cancers. Testicular, stomach, and bladder cancers are among those treated with carboplatin, as well as other carcinomas.

Carboplatin kills cancer cells by binding to DNA and interfering with the cell's repair mechanism, which eventually leads to cell death. It is classified as an alkylating agents. (Alkylating agents can be used for most types of cancer, but are usually considered of greatest value in treating slow-growing cancers.) The platinum agents form strong chemical bonds with thiol sulfurs and amino nitrogens in proteins and nucleic acids.

It is considered a "second-generation" platinum agent. The first generation, cisplatin, is often called the "penicillin of cancer drugs" because it is used so widely. Carboplatin differs chemically from cisplatin by being a bigger molecule, with a dicarboxylate ligand. This slows the metabolic breakdown of the agent (it stays in the body longer) and reduces the rate of formation of toxic by-products.

The ligands that can be displaced by nucleophilic (electron-rich) atoms to form strong bonds with covalent characteristics.

Structure of carboplatin

Carboplatin is less chemically reactive than cisplatin, which is why it is less toxic to the kidneys and nervous system. The downside is that the lower reactivity means a higher concentration is needed to fight the cancer, and bigger doses of the drug. It is estimated that carboplatin is 8 to 45 times less effective than cisplatin.

The most troubling effect of carboplatin tends to be damage to the bone marrow, in a process called myelosuppression. This leads to anemia. Blood cells produced by the marrow can drop to 10% of normal levels. This level bottoms out a few weeks after carboplatin administration.

Some other side effects:

loss of appetite or weight

stomach pain

diarrhea

constipation

peripheral neuropathy

nausea and vomiting

changes in vision and taste

mouth blistering

fatigue

These are common side effects of many chemotherapy drugs, especially the alkylating agents. Carboplatin also is known to damage the kidneys (it is nephrotoxic) and the inner ear (in a process called ototoxicity.)

Nausea and vomiting can be severe in some patients, and antiemetic drugs are often given.

Neoplasms, especially consisting of certain cell types, are known to develop resistance to alkylating agents. This resistance has been linked, at least in part, to the expression of an enzyme known as MGMT (O6-MethylguanineDNAmethyltransferase). MGMT is able to repair DNA errors caused by alkylating agents. For example, temozolomide causes a potentially cytotoxic lesion in oxygen 6 of guanine nucleotides in DNA. MGMT enzymatically removes this methyl group, repairs the DNA, and negates the effect of the chemotherapy. In normal cells this would be advantageous; a cellular mechanism to prevent

[http://www.carboplatin.org/]

Process of Development of Drug

The process of drug development is very long and involved, with maybe only one in ten

thousand of the molecules originally tested finally being clinically used.

As with any pharmaceutical, new anticancer drugs are developed in a three-step process.

Step 1 - Initial discovery

A wide range of compounds, both natural and synthetic, are tested in high-capacity screens

to discover molecules with useful properties.

Step 2 - Molecular modification of a known compound

A molecule that shows suitable properties is chemically altered to give it the best

combination of properties to make the most effective anti-cancer drug.

Step 3 - Development into a useful pharmaceutical

Because the above process is very time-consuming and expensive, the new discovery is

usually patented at this time so that the discoverers can eventually recover some of these

costs. The most effective route for synthesising the molecule is then worked out. A long

process of advanced testing is then begun, ending up with tests on patients in specialised

hospitals. If the results are favourable, the drug is then able to be released for use.

Main types of anti cancer drugs

The drugs used to combat cancer belong to one of two broad categories. The first is

cytotoxic (cell killing) drugs and the second is cytostatic (cell stabilising drugs). Both

categories lead to a reduction in the size of the tumour because cancer cells (for various

reasons) have such a high mortality rate that simply preventing them from dividing will lead

to a reduction in the population.

Cytotoxic drugs

Cytotoxic drugs work by interfering with DNA replication. Because cancer cells are rapidly

dividing they are rapidly synthesizing new DNA - and if this is damaged the cell will die.

There are three main groups of molecules that can be used to interfere with DNA replication:

• antimetabolites: molecules that appear to be nucleotides and so are incorporated into

DNA, leading to non-functional DNA.

• alkylating agents: molecules that permanently attach to the DNA, distorting its shape.

Unfortunately these also attach to many other molecules in cells.

• DNA-binding agents: molecules that attach to the DNA chain, break it, disengage from

the chain and then attach to another chain to repeat the process. These usually function in

conjunction with an enzyme.

DNA-binding agents are currently the most effective drugs used, but usually a patient is

given a combination of drugs from several of these groups to take advantage of the different

ways in which they work.

None of these drugs are 'cancer cell-specific' - they are all simply 'quickly dividing cellspecific'.

This is the explanation of the side effects associated with chemotherapy

the drugs not only attack cancer cells but also any other quickly dividing cells such as those in bone marrow or the gut. For this reason, work is currently being done into targeting drugs more specifically for cancer cells by giving

the patient a precursor of the drug (a 'prodrug') which is only activated in the cancerous

tumour.

Cytostatic drugs

While the prodrug approach is being developed to try and improve the specificity of the

common "cytotoxic" anticancer drugs, another new approach is to use "cytostatic" drugs.

Many of these specifically target the altered biochemical pathways that enable cancer cells to

reproduce quickly. These drugs are designed to deactivate the altered enzymes that result

from changes in the oncogene involved. These drugs are not designed to kill the cell

involved, but simply to prevent it from reproducing. However, because cancer cells have

XII-Biotech-J-Cancer Drugs-6

very high death rates, due largely to the multiple mutations they possess, simply preventing

reproduction is expected to lead to a reduction in tumour size. These drugs are theoretically

'cancer cell-specific' in that they target processes occurring only in cancer cells.

.[ www.chemocare.com]

Future aspects of anti cancer drugs

The researchers are now develolping drugs which will be more specific towards cancer drugs and will create less side effects to body