A targeted therapy that kills cancer cells: Let's learn about PARP Inhibitors

If you're battling cancer, or if you have a loved one who has it, you're probably familiar with terms like "chemotherapy" and "radiation therapy." You've probably heard about the side effects that come with these treatments. But today we're going to talk about a relatively new class of drugs that target only cancer cells and greatly reduce the damage to healthy cells. These are called PARP Inhibitors .

Simply put, what is this PARP Inhibitor?

To understand this, we first need to understand a small but very important process that takes place inside the cells of our body. Inside every cell in our body is something called DNA. Think of it like a big blueprint that has written down how everything in our body should work. Sometimes, the pages of this DNA blueprint get damaged a little bit.

This is where a protein called PARP comes into play. "PARP" is an abbreviation for Poly (ADP-ribose) polymerase . PARP is like a "repair mechanic" inside our cells. When DNA is damaged, the PARP protein goes in and repairs it. This is essential for the survival of healthy cells.

But the problem is, cancer cells also use this PARP mechanism to their advantage. When the DNA of cancer cells is damaged, they also use this PARP to repair it. As a result, cancer cells do not die, but continue to grow and spread throughout the body.

As a solution to this, doctors use a drug called PARP Inhibitor. "Inhibitor" means "blocker." What this drug does is "block" the PARP mechanism that helps cancer cells. Without PARP's help, the cancer cell gradually weakens, unable to repair the damaged DNA, and eventually dies.

Main types of PARP inhibitors used in the world

There are several PARP inhibitors currently approved for cancer treatment. If your doctor prescribes one of these for you, it may be on this list.

What types of cancer is this medicine used for?

PARP inhibitors are typically used for cancers that are more advanced or have spread to other parts of the body (metastatic). There are several types of cancer for which they are primarily effective.

• Breast cancer
• Ovarian cancer
• Fallopian tube cancer
• Prostate cancer
• Primary peritoneal cancer
• Pancreatic cancer

The special relationship with BRCA gene mutations

Here's something you definitely need to know about the BRCA gene . BRCA is another important gene that helps repair the DNA in our cells and prevents cancer. But some people may have a mutation in this BRCA gene. This means that one of their main DNA repair systems does not work properly. Because of this, they are at higher risk of developing cancer.

Think of a car as having two brake systems. BRCA is one, and PARP is the other. In a cancer cell with a BRCA gene mutation, one brake system (BRCA) is already broken. So that cancer cell relies almost entirely on the other brake system (PARP) to survive.

Now when we give PARP Inhibitor drugs, we turn off that second brake system as well. Then the cancer cell has no way to repair its DNA, and it just dies. This is why PARP Inhibitors are so effective for cancers with BRCA gene mutations.

How do I get the treatment and how long does it take?

One of the conveniences of this treatment is that it all comes in pill form (capsules or tablets). So you only have to take this medicine once or twice a day. Sometimes this medicine alone may be enough. Other times, you may need to take it along with other cancer treatments.

For example, after treatments that damage the DNA of cancer cells, such as chemotherapy or radiation therapy, you can give a PARP inhibitor. Then, since PARP does not help those damaged cancer cells repair themselves, those cells are guaranteed to die.

Treatment time

This varies from person to person.

• Some people are prescribed this medication for a specific period of time, such as two or three years, after chemotherapy treatment is complete.
• Some people continue to take this medicine as long as it works for their body.
• Sometimes, if the side effects outweigh the benefits of the medication, you can talk to your doctor and stop the treatment.

What are the advantages and disadvantages of this treatment?

PARP inhibitors cannot cure cancer completely. However, they can help patients with some types of cancer live longer . These drugs control the growth of the cancer. Doctors call this increasing the "progression-free survival rate." Simply put, they increase the time the cancer remains well-controlled without getting worse. In some cases, they can be more effective than chemotherapy.

However, over time, some cancer cells begin to develop "resistance" to these drugs. This means that the drugs no longer work. This can happen to between 40% and 70% of patients. Scientists are trying to understand why this happens and are researching new ways to make these drugs more effective.

Let's also be aware of the side effects.

Like any cancer treatment, PARP inhibitors can cause some side effects. But not everyone gets them. And many of these can be controlled.

Very rarely, some PARP inhibitors may increase the risk of developing a type of blood cancer called acute myeloid leukemia . However, this is a very rare condition.

When to notify your doctor immediately

If you are taking a PARP inhibitor, it is important to tell your doctor if you experience any new or worsening side effects . He or she may change the dose or prescribe other medications to help with things like nausea.

In particular, if you experience the following symptoms , notify your doctor or the hospital where you are being treated immediately:

• Signs of an infection: fever, chills, and shaking.
• Pneumonitis symptoms: Difficulty breathing, wheezing, chest tightness, etc. (This is an inflammatory condition of the lungs).
• Signs of a blood clot: leg swelling, pain, redness or chest pain, difficulty breathing.

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