The Chemistry of Chemotherapy

Introduction

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It is safe to say that almost everyone has been affected by cancer in some way, but few of these people know anything about its treatment, chemotherapy. Chemotherapy is often simply referred to as “chemo,” which is the use of intracellular, poisonous drugs to treat cancer. It is difficult to narrow this subject down because each treatment is developed personally for every patient, meaning the type of drug and also the administration of the drug, vary. Chemotherapy may be combined with other treatments or given by itself. Moreover, chemo is sometimes given with curative intent. Other times, it is given as palliative therapy to ease the symptoms of more advanced cancer stages.Through understanding how chemotherapy works, we hope that a more efficient and less damaging treatment will transpire.

Composition of ...

I was able to find more than 200 different chemotherapy drugs, so these are five of the most prominent:

  • Asparaginase (crisantaspase)

  • Cytarabine (Ara-C)

  • Doxorubicin (Adriamycin)

  • Mercaptopurine (6-MP)

  • Teniposide (Vumon)


Main Chemicals, Compounds, Components

Since the drugs used during therapy vary according to each case I chose two of the most common.


  1. Asparaginase C1377H2208N382O442S17

Normal cells are able to produce an amino acid called asparagine, however, cancer cells cannot. Asparaginase breaks down the asparagine into aspartic acid and ammonia. Cancer cells cannot create more asparagine; therefore, they die. The neurological side effects are due to all the extra chemicals, such as the aspartic acid and ammonia, circulating the body. This drug is most commonly used for Acute Lymphocytic Leukemia (ALL), which is a blood and bone marrow cancer that affects the white blood cells. Asparaginase may be given as an injection into a large muscle or intravenously, which presents a higher risk of allergic reaction. However, there is no pill form.

  1. Doxorubicin C27H29NO11

Doxorubicin works by damaging the RNA or DNA that tells the cell to keep dividing. It blocks the enzyme topoisomerase 2 that cancer cells need to keep dividing. The faster the division the better the chemo drugs will work at shrinking the tumor. This type of chemo drug is called an antitumor antibiotic. This drug is unable to tell the difference between cancerous cells and normal cells. This is what causes the extreme side effects. Doxorubicin may be given intravenously through a central line or peripheral venous line, given over several minutes. It may also be given through a central catheter line. However, there is no pill form. This type of drug is classified as a vesicant, meaning that if it escapes from the vein it will cause major tissue damage and blistering.



Chemistry's Role

Almost every aspect in chemotherapy involves chemistry in someway. However, we will focus on the previously mentioned drugs, Asparaginase and Doxorubicin.

    Asparaginase is an enzyme made from the bacteria escherichia coli (E. Coli). There are a couple different forms of this. Pegaspargase is the E. coli form linked to a polyethylene glycol molecule. This was developed for people with an allergy to E. coli; however, it is much more expensive. There is also a natural form made by the plant bacteria erwinia carotovora, made for people with severe allergies. Asparaginase is usually given with a combination of steroids.

     Doxorubicin is an anthracycline antibiotic. It is made from a natural product produced by the soil fungus Streptomyces.  It is also available with a polyethylene glycol coating.

    Both of these drugs were initially found in nature, but were probably refined in a lab. Chemists found a way to replicate and produce the enzymes and bacteria, in an easier way, in order to develop them for further use. Without chemistry, these drugs would never have been possibilities for cancer treatment. We have chemistry to thank for the complete  development of chemotherapy.



Resources



About the Author

Katie Jones is a junior at Billings Senior High School. She is involved in Key Club, S.T.E.M Society, Spanish Club, People to People Student Ambassadors, and Billings Youth Leadership. In her free time, she loves being outdoors and enjoys spending time with her friends, family, and  

dogs. She is unsure where her future will take her, but hopes it becomes clearer as time passes.









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