ORSERDU

What it is

ORSERDU is elacestrant dihydrochloride tablets available in 86 mg and 345 mg film coated strengths. Elacestrant is an orally active estrogen receptor-α (ERα) antagonist and degrader. ORSERDU is subject to additional monitoring in Australia to allow quick identification of new safety information.

Approved indications —

Treatment of postmenopausal women and men with estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative, locally advanced or metastatic breast cancer with an activating ESR1 mutation who have disease progression following at least one line of endocrine therapy including a CDK 4/6 inhibitor.

Dosing overview

The recommended dose is 345 mg (one 345 mg film coated tablet), once daily. Treatment should continue as long as clinical benefit is observed or until unacceptable toxicity occurs. ORSERDU should be administered with a light meal. In patients with moderate hepatic impairment (Child-Pugh B), ORSERDU dose should be reduced to 258 mg. If a strong CYP3A4 inhibitor must be used, the elacestrant dose should be reduced to 86 mg once daily with careful monitoring of tolerability. If a moderate CYP3A4 inhibitor must be used, the elacestrant dose should be reduced to 172 mg once daily with careful monitoring of tolerability.

Key safety warnings

The most common (≥ 10%) adverse reactions with ORSERDU were nausea, triglycerides increased, cholesterol increased, vomiting, fatigue, dyspepsia, diarrhoea, calcium decreased, back pain, creatinine increased, arthralgia, sodium decreased, constipation, headache, hot flush, abdominal pain, anaemia, potassium decreased, and alanine aminotransferase increased. The most common Grade ≥3 (≥ 2%) adverse reactions of elacestrant were nausea (2.7%), AST increased (2.7%), ALT increased (2.3%), anaemia (2%), back pain (2%), and bone pain (2%). Thromboembolic events are commonly observed in patients with advanced breast cancer and have been observed in clinical studies with ORSERDU. This should be taken into consideration when prescribing ORSERDU to patients at risk. ORSERDU is metabolised by the liver, and impaired hepatic function can increase the risk for adverse reactions. Therefore, ORSERDU should be used cautiously in patients with hepatic impairment and patients should be regularly and closely monitored for adverse reactions.

Contraindications

Hypersensitivity to elacestrant dihydrochloride or to any of the excipients listed in Section 6.1 LIST OF EXCIPIENTS. ORSERDU should not be used during pregnancy or in women of childbearing potential not using contraception. Based on the mechanism of action of elacestrant and findings from reproductive toxicity studies in animals, ORSERDU can cause fetal harm when administered to pregnant women. Because of the potential for serious adverse reactions in the breast-fed infant, it is recommended that lactating women should not breast-feed during treatment with ORSERDU and one week after the last dose of ORSERDU.

Regulatory history

ORSERDU elacestrant 86 mg and 345 mg film coated tablets were first registered on the ARTG on 01 April 2026. In March 2025, the PBAC did not recommend ORSERDU for listing for ER+/HER2- locally advanced or metastatic breast cancer in patients who have progressed following at least one line of endocrine therapy administered with a cyclin dependent kinase 4/6 inhibitor and have a confirmed estrogen receptor 1 variant.