ARX-ABIRATERONE

What it is

ARX-ABIRATERONE is abiraterone acetate, an androgen biosynthesis inhibitor. It selectively inhibits the enzyme 17α hydroxylase/C17,20-lyase (CYP17), which is expressed in and required for androgen biosynthesis in testicular, adrenal and prostatic tumour tissues. ARX-ABIRATERONE is available as 250 mg and 500 mg tablets.

Approved indications

ARX-ABIRATERONE is indicated in combination with prednisolone for the treatment of: — Newly diagnosed high-risk metastatic hormone sensitive prostate cancer (mHSPC) in combination with androgen deprivation therapy (ADT). — Metastatic advanced prostate cancer (castration resistant prostate cancer, mCRPC) in asymptomatic or mildly symptomatic patients after failure of androgen deprivation therapy (ADT). — Metastatic castration resistant prostate cancer (mCRPC) in patients who have received prior chemotherapy containing a taxane.

Dosing overview

The recommended dosage of ARX-ABIRATERONE is 1 g (four 250 mg tablets or two 500 mg tablets) as a single daily dose taken on an empty stomach, at least two hours after eating and with no food for at least one hour after taking the dose. For hormone sensitive prostate cancer (mHSPC), ARX-ABIRATERONE is used with 5 mg prednisolone daily. For metastatic castration-resistant prostate cancer (mCRPC), it is used with 10 mg prednisolone daily. Patients started on ARX-ABIRATERONE who were receiving a LHRH agonist should continue to receive a LHRH agonist.

Key safety warnings

ARX-ABIRATERONE should be used with caution in patients with a history of cardiovascular disease. Before treatment, hypertension must be controlled and hypokalaemia must be corrected. Abiraterone may cause hypertension, hypokalaemia and fluid retention as a consequence of increased mineralocorticoid levels resulting from CYP17 inhibition. In postmarketing experience, QT prolongation and Torsades de Pointes have been observed in patients who develop hypokalaemia or have underlying cardiovascular conditions while taking abiraterone. Marked increases in liver enzymes leading to drug discontinuation or dosage modification occurred in controlled clinical studies. Very rarely hepatitis fulminant and hepatic failure have been seen. Serum transaminase and bilirubin levels should be measured prior to starting treatment, every two weeks for the first three months and monthly thereafter. If clinical symptoms suggestive of hepatotoxicity develop, serum transaminases should be measured immediately. If at any time ALT or AST rises above 5 times the upper limit of normal or bilirubin rises above 3 times the upper limit of normal, treatment should be interrupted immediately. Caution is advised and monitoring for adrenocortical insufficiency should occur if patients need to be withdrawn from prednisolone. If abiraterone is continued after corticosteroids are withdrawn, patients should be monitored for symptoms of mineralocorticoid excess. In patients on prednisolone who are subjected to unusual stress, increased dosage of a corticosteroid may be indicated.

Contraindications

ARX-ABIRATERONE is contraindicated in women who are or may potentially be pregnant. ARX-ABIRATERONE is contraindicated in patients with severe hepatic impairment (Child Pugh Class C). ARX-ABIRATERONE plus prednisolone is contraindicated in combination with XOFIGO (radium 223 dichloride).

PBS listing

Information regarding PBS listing is not available in the provided source documents.

Regulatory history

ARX-ABIRATERONE abiraterone acetate 250 mg tablets (ARTG 490407) and 500 mg tablets (ARTG 490408) were first listed on the Australian Register of Therapeutic Goods on 6 August 2025.