Abiraterone acetate and prednisone are medications frequently used in combination to treat advanced prostate cancer. This article explains the reasons behind this dual therapy.
Understanding Abiraterone’s Action
Abiraterone acetate is an oral medication that converts into its active form, abiraterone, inside the body. This compound targets an enzyme called CYP17A1, which plays a role in the production of androgens, male sex hormones.
CYP17A1 is found in various tissues, including the adrenal glands, testes, and prostate tumor cells. By inhibiting this enzyme, abiraterone reduces the levels of androgens, such as testosterone and dehydroepiandrosterone (DHEA), throughout the body. Prostate cancer relies on these androgens to grow and spread, so lowering their levels helps slow or shrink androgen-dependent prostate cancer cells.
The Role of Prednisone in Combination
While abiraterone reduces androgen production by inhibiting CYP17A1, this inhibition can also impact the production of other hormones, specifically cortisol, from the adrenal glands. A decrease in cortisol triggers the body’s feedback, leading to an increase in adrenocorticotropic hormone (ACTH) released from the pituitary gland. This increase in ACTH stimulates the adrenal glands to produce more precursors that have mineralocorticoid activity, such as deoxycorticosterone and corticosterone.
An excess of these mineralocorticoids can lead to several undesirable side effects. These include high blood pressure (hypertension), low potassium levels in the blood (hypokalemia), and fluid retention, which can manifest as swelling. Prednisone, a corticosteroid, is given alongside abiraterone to counteract these effects. Its primary role is to suppress the increased ACTH production, thereby preventing the buildup of mineralocorticoid precursors and mitigating these adverse reactions.
Prednisone also offers additional benefits to patients undergoing cancer treatment. It can help manage common cancer-related symptoms like fatigue, improving energy levels and overall well-being. It can also stimulate appetite, which is often a challenge for individuals with advanced cancer.
Managing Combined Therapy
Patients receiving abiraterone and prednisone together require regular monitoring to ensure the therapy is both effective and well-tolerated. Healthcare providers monitor blood pressure, electrolyte levels (especially potassium), and liver function through periodic blood tests. Liver function tests may be conducted every two weeks for the initial three months, then monthly thereafter, while blood pressure and potassium levels are checked monthly.
Adherence to the prescribed dosage is important, and patients should not stop taking them abruptly without consulting their healthcare team. The combined therapy can lead to side effects, which may include fatigue, joint pain, back pain, nausea, and diarrhea. Other effects observed are hot flashes, fluid retention, and changes in appetite or sleep patterns due to prednisone. Any new or worsening side effects should be communicated to the healthcare provider.