Welcome to Developing New Medicines and Monoclonal Antibodies!

Ever wondered how a simple pill or a life-saving injection actually makes it to the pharmacy shelf? It’s not a quick process! In this chapter, we will explore the rigorous journey of developing new medicines and look at a cutting-edge technology called monoclonal antibodies. These are like "magic bullets" that can target specific diseases in the human body.

Part 1: Developing New Medicines

Before a drug can be sold, it must be thoroughly tested to make sure it is safe and that it actually works. There are four main stages you need to know.

1. Discovery

This is the "brainstorming" phase. Scientists identify a target (like a protein or a gene) involved in a disease and search for chemicals that might affect it. Many drugs are discovered by looking at natural world examples, like plants or fungi.

2. Development (Preclinical Testing)

Once a potential drug is found, it goes into the lab for preclinical testing. Scientists test the drug on:

  • Human cells and tissues: This helps see if the drug is toxic or has any effect on living cells.
  • Live animals: This is used to see how the drug affects a whole body system (e.g., does it reach the target organ?) and to check for side effects.

3. Clinical Testing

If the drug passes the preclinical stage, it moves to clinical testing on human volunteers. This happens in several steps:

  • Healthy Volunteers: A very low dose is given to a small group of healthy people to check for safety and side effects.
  • Patients (People with the disease): If it's safe, it's given to people who actually have the illness. This tests the efficacy (does it work?) and determines the correct dosage (how much should you take?).

Quick Review: Why do we test?
1. Safety: To make sure it isn't poisonous.
2. Efficacy: To make sure it actually cures or prevents the disease.
3. Dosage: To find the right amount to give.

Part 2: Monoclonal Antibodies (Biology Only & Higher Tier Only)

Don’t worry if this sounds complicated at first! Think of a monoclonal antibody as a "custom-made key" designed to fit into one specific "lock" (an antigen) on a cell.

How Monoclonal Antibodies are Produced

Monoclonal antibodies are identical copies of one specific antibody. We produce them using hybridoma cells. Here is the step-by-step process:

  1. An antigen (the target molecule) is injected into a mouse.
  2. The mouse’s immune system produces B-lymphocytes that make antibodies specific to that antigen.
  3. These B-lymphocytes are extracted from the mouse. However, B-lymphocytes don't divide (reproduce) easily outside the body.
  4. To solve this, scientists fuse a B-lymphocyte with a myeloma cell (a type of cancer cell). Cancer cells are used because they divide very quickly.
  5. The result is a hybridoma cell.
  6. This hybridoma cell has the "best of both worlds": it produces the specific antibody and it divides rapidly to create clones of itself.
  7. These clones all produce the same monoclonal antibodies, which are then collected and purified.

Memory Aid:
B-lymphocyte + Myeloma = Hybridoma
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Uses of Monoclonal Antibodies

Because they can target one specific type of cell or chemical, they are incredibly useful in medicine:

1. Pregnancy Testing

Monoclonal antibodies in pregnancy test sticks are designed to bind to a hormone called HCG, which is only found in the urine of pregnant women. If the hormone is present, the antibodies bind to it and trigger a color change (the blue line!).

2. Diagnosis of Disease

They can be used to locate specific molecules in the body. For example, scientists can attach a fluorescent dye to monoclonal antibodies that target cancer cells. When injected into the patient, the antibodies "stick" to the cancer, and the dye makes the tumor show up clearly on a scan.

3. Treatment (Targeting Specific Cells)

This is the most exciting use! Scientists can attach an anti-cancer drug to a monoclonal antibody. The antibody travels through the blood and attaches only to the cancer cells (because they have specific antigens). This delivers the drug directly to the tumor without damaging healthy body cells. This reduces the nasty side effects often seen with traditional treatments.

Key Takeaway for Monoclonal Antibodies:
The big advantage is specificity. They only target the cells that need treatment, leaving healthy cells alone.

Summary Checklist

  • Can you describe the difference between preclinical and clinical testing?
  • Do you know why healthy volunteers are used before patients?
  • (Higher Tier) Can you explain why we fuse a B-lymphocyte with a myeloma cell?
  • (Higher Tier) Can you name three uses of monoclonal antibodies?

Note: For more information on how the immune system works before these treatments are developed, see the chapter "Human defences, the immune system and immunisation".