Abiraterone for Prostate Cancer Treatment

Abiraterone is an androgen production inhibitor used to treat castration resistant and high-risk castration sensitive metastatic prostate cancer, taken orally together with prednisone, an anti-inflammatory steroid medication.

The current mainstay treatment for prostate cancer, androgen deprivation therapy, was developed based on the principle that prostate cancer is mainly hormone driven and that blocking prostate cancer cells from receiving androgens would limit tumor growth.

Unfortunately, prostate cancer cells can eventually grow to rely on androgen hormones produced by alternative routes, for example the adrenal glands, rather than the testes. This bypass results in the development of castration resistant prostate cancer that is no longer responsive to androgen deprivation therapy.

This is then where abiraterone comes into play — by blocking this additional pathway to ensure that your testosterone is reduced to undetectable levels. It does this by inhibiting the work of the CYP17A1 enzyme in androgen production.

A few things you should take note of when considering abiraterone:

• Abiraterone should be taken on an empty stomach, with no eating two hours before, and an hour after taking the drug.

The reason for this is that taking abiraterone with food may result in too much of the drug being absorbed by your body, as the drug easily dissolves in the fats found in food. This isn’t good, as the higher concentration of the drug in your body may not be safe for you and can cause you to experience more side effects.

• Your blood pressure and potassium levels should be measured at least monthly.

Abiraterone is associated with issues with regulating salt and water balance such as high blood pressure, swelling and low potassium levels. This is possibly due to excess mineralocorticoid production triggered by inhibiting the CYP17A1 enzyme. However, taking the prednisone or other corticosteroid medications as prescribed will help to mitigate your risk of such events.

• You may face issues with insufficient stress hormone production due to inhibition of the CYP17A1 enzyme. In stressful situations, this may put you at risk of acute adrenal failure. However, you and your doctor will be able to manage this risk with corticosteroid treatments before, during or after stressful situations.

• Your liver enzymes will likely be closely monitored by blood tests, as some severe side effects can affect your liver function.

If you experience symptoms of liver damage such as nausea, reduced appetite, stomach pain, itching or yellowing around the eyes and skin, you should contact your doctor immediately.

• Due to the risk of fetal toxicity, if your partner is of reproductive potential, effective contraception (e.g. condoms or female birth control pills) should be used when needed, up to three weeks after the final dose.

• If you intend to conceive after, you should note that there is a risk of infertility for you. Unfortunately, this risk is generally commonly associated with prostate cancer treatments as most target the reduction of the sex hormones or the removal of the prostate in order to limit cancer spread.

Below are some common side effects reported after taking abiraterone. You may not experience all of these side effects, but there is a risk that you may encounter a few of these at the same time.

The side effects commonly reported in over 1 in 10 people include:

• Fatigue
• Joint pain
• High blood pressure
• Nausea, vomiting or diarrhea
• Low potassium levels (e.g. muscle weakness or cramps)
• Hot flushes
• Upper respiratory infections or coughs
• Headaches

Other issues commonly identified by blood tests in over 1 in 5 people include:

• Low red blood cell or lymphocyte counts
• High triglyceride or cholesterol levels
• High blood sugar
• Low potassium levels
• High alkaline phosphatase (common indicator of liver issues)

If you experience any severe side effects, do report them to your doctor, who can then follow up with the appropriate recommendations and dose adjustment where necessary.

Abiraterone represents progress in developing new treatments to increase survival and improve outcomes for difficult-to-treat castration-resistant and metastatic prostate cancer cases. While there still remains the risk of side effects, these have been found to be mostly manageable with treatment. With new clinical trials currently ongoing, abiraterone may end up playing a bigger role in other combination treatments for prostate cancer in the future as well.