Orserdu (Elacestrant)

• Orserdu, an oral selective estrogen receptor degrader, is used in the management of hormone‑responsive breast cancer.
• Estrogen receptor‑positive (ER+) HER2‑negative advanced breast cancer: slows disease progression and may improve overall survival.
• Metastatic ER+ HER2‑negative breast cancer after prior endocrine therapy: provides an oral SERD treatment option.
• Advanced breast cancer with disease progression on prior SERD or CDK4/6 inhibitor therapy: offers a targeted hormonal control strategy.

• Elacestrant binds competitively to estrogen receptors in tumor cells, promoting receptor ubiquitination and proteasomal degradation. By removing functional estrogen receptors, it blocks estrogen‑mediated transcriptional activity and downstream proliferative signaling pathways, thereby inhibiting growth of ER‑positive breast cancer cells. The oral formulation enables systemic exposure sufficient to achieve receptor down‑regulation throughout the body.

Elacestrant may cause a range of adverse reactions, which are categorized by frequency and severity.

Common Side Effects

• Nausea
• Fatigue
• Diarrhea
• Headache
• Hot flashes
• Decreased appetite

Serious or Rare Side Effects

• Elevated liver enzymes (ALT/AST)
• Thrombocytopenia
• Interstitial lung disease or pneumonitis
• Severe allergic reactions (anaphylaxis)
• QT interval prolongation
• Tumor progression despite therapy

• When prescribing Elacestrant, clinicians should consider several precautionary measures to ensure patient safety.
• Pregnancy: avoid use; discuss risks and benefits with a qualified healthcare professional.
• Breastfeeding: not recommended; advise cessation of breastfeeding during treatment.
• Liver impairment: use with caution; monitor hepatic function regularly.
• Concomitant CYP3A4 inhibitors or inducers: adjust therapy as needed and monitor drug levels.
• Monitoring: perform periodic complete blood counts and electrocardiograms.
• Store at ambient temperature: keep below 25 °C in the original container, protect from moisture and light.

Elacestrant can interact with other medicines, requiring attention to both major and moderate interaction potentials.

Major Interactions (Avoid)

• Strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole): may increase Elacestrant exposure.
• Strong CYP3A4 inducers (e.g., rifampin, carbamazepine): may reduce therapeutic effect.
• QT‑prolonging agents (e.g., certain antiarrhythmics): increase risk of cardiac arrhythmia.

Moderate Interactions (Monitor Closely)

• Moderate CYP3A4 inhibitors (e.g., erythromycin, fluconazole): may modestly raise drug levels.
• Anticoagulants (e.g., warfarin): monitor INR for potential changes.
• Hormonal therapies (e.g., aromatase inhibitors): assess combined endocrine effects.