Overview

Enhertu, the 100 mg vial of fam-trastuzumab deruxtecan, is an antibody-drug conjugate built around a monoclonal antibody directed at HER2 linked to a potent topoisomerase I inhibitor. Its design lets a single targeted antibody carry a cytotoxic payload deep into HER2-expressing tumor cells and release it intracellularly, limiting exposure of healthy tissue.

How It Works

The anti-HER2 antibody binds HER2 on the tumor surface and is internalized by endocytosis. A cleavable tetrapeptide linker releases the deruxtecan payload, a topoisomerase I inhibitor that traps the enzyme-DNA complex and triggers irreversible DNA damage. A key feature is the high drug-to-antibody ratio and the ability of released payload to diffuse into neighboring cells, producing a local bystander effect even against HER2-heterogeneous tumors. This payload-driven kill complements the antibody's own HER2 signaling blockade.

Indications

Enhertu is indicated for HER2-positive metastatic breast cancer after prior anti-HER2 therapy, for HER2-low breast cancer defined by current assays, and for HER2-positive advanced gastric and gastro-esophageal junction adenocarcinoma. Patient eligibility depends on validated HER2 testing, including the lower-expression thresholds used for the HER2-low category.

Dosage & Administration

Each presentation is a 100 mg vial of lyophilized powder reconstituted for intravenous infusion, dosed by body weight on a three-week cycle under institutional protocols. Cold-chain handling is mandatory: keep unopened vials at 2–8°C and protect from light until reconstitution. Infusion must occur in a supervised setting with premedication and cardiac monitoring per label guidance.

Storage & Sourcing

Store unopened vials at 2–8°C; do not freeze and avoid exposure to direct light. After reconstitution the solution is used promptly according to the validated compounding window. B2B buyers should verify GDP-compliant cold-chain transit with data-loggers and quarantine any shipment that exceeds the 2–8°C range before clinical use.

FAQ

Q: What makes the Enhertu payload mechanism distinct from older HER2 antibodies? A: Older HER2 antibodies mainly block signaling, while Enhertu adds a topoisomerase I poison released inside the cell plus a bystander effect, so it can kill neighboring tumor cells regardless of uniform HER2 density.

Q: Why is HER2-low testing relevant to this conjugate? A: The conjugate's payload potency allows activity at lower receptor levels, extending treatment to HER2-low tumors that would not qualify for classical HER2-targeted antibodies.

Q: How should a 100 mg vial be handled in B2B cold-chain logistics? A: Maintain 2–8°C from manufacturer to clinic, use validated refrigerated shippers with temperature loggers, and reject any vial exposed outside the labelled range before reconstitution.