Orserdu (Elacestrant)

Orserdu is a selective estrogen receptor degrader that targets estrogen‑driven breast cancer pathways.

• Hormone‑positive metastatic breast cancer: Improves progression‑free survival in patients whose disease has progressed on prior endocrine therapy.
• Advanced estrogen‑receptor positive breast cancer: Delays disease progression when combined with other endocrine agents.
• Post‑menopausal breast cancer requiring oral SERD therapy: Provides an oral alternative to injectable SERDs.

• Elacestrant binds to the estrogen receptor α (ERα) and induces a conformational change that promotes receptor degradation via the proteasome pathway. This reduces estrogen‑driven transcriptional activity, leading to inhibition of tumor cell proliferation and induction of apoptosis in estrogen‑dependent cancer cells.

Adverse reactions reported with elacestrant are generally mild to moderate and reflect its mechanism of estrogen modulation.

Common Side Effects

• Nausea: mild to moderate gastrointestinal upset.
• Fatigue: generalized tiredness not related to activity level.
• Diarrhea: watery stools occurring intermittently.
• Hot flashes: transient vasomotor symptoms.
• Decreased appetite: reduced desire to eat.
• Musculoskeletal pain: aches in joints or muscles.

Serious or Rare Side Effects

• Thromboembolic events: deep vein thrombosis or pulmonary embolism.
• Severe liver enzyme elevation: marked increase in ALT/AST.
• Interstitial lung disease: inflammatory lung condition.
• QT interval prolongation: cardiac conduction alteration.
• Severe hypersensitivity: rash, angioedema, or anaphylaxis.
• Bone fracture: increased risk of osteoporotic fractures.

When prescribing elacestrant, clinicians should consider patient‑specific factors and monitor for known risks.

• Pregnancy: contraindicated; teratogenic potential requires effective contraception.
• Breastfeeding: not recommended; drug may be excreted in milk.
• Hepatic impairment: dose adjustment may be required; monitor liver function tests.
• Cardiovascular risk: assess history of thromboembolism before initiating therapy.
• Bone health: evaluate osteoporosis risk and consider calcium/vitamin D supplementation.
• Store at ambient temperature: keep below 25°C, protect from moisture and direct sunlight.

Elacestrant may interact with other medicines that affect its metabolism or cardiac conduction.

Major Interactions (Avoid)

• Strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole): may increase elacestrant exposure and toxicity.
• Strong CYP3A4 inducers (e.g., rifampicin, carbamazepine): may reduce efficacy by lowering plasma levels.
• QT‑prolonging agents (e.g., sotalol, quinidine): additive risk of cardiac arrhythmia.

Moderate Interactions (Monitor Closely)

• Anticoagulants (e.g., warfarin, direct oral anticoagulants): monitor INR or bleeding risk.
• Hormonal contraceptives: reduced effectiveness; consider alternative non‑hormonal methods.
• Proton pump inhibitors: may modestly affect absorption; observe clinical response.