VYLOY

What it is

VYLOY is zolbetuximab, supplied in single-dose vials containing either 100 mg or 300 mg after reconstitution for a final concentration of 20 mg/mL. It is a sterile, preservative-free, white to off-white lyophilised powder for reconstitution for intravenous infusion. Zolbetuximab is a genetically engineered, highly purified chimeric (mouse/human IgG1) monoclonal antibody directed against the tight junction molecule CLDN18.2. This medicinal product is subject to additional monitoring in Australia to allow quick identification of new safety information.

Approved indications

— First-line treatment of adult patients with locally advanced unresectable or metastatic human epidermal growth factor receptor 2 (HER2)-negative gastric or gastro-oesophageal junction (GOJ) adenocarcinoma whose tumours are Claudin (CLDN) 18.2 positive, in combination with fluoropyrimidine- and platinum-containing chemotherapy.

Dosing overview

VYLOY is administered at a single loading dose of 800 mg/m² intravenously on Cycle 1, Day 1, followed by maintenance doses of either 600 mg/m² intravenously every 3 weeks beginning 3 weeks after the loading dose, or 400 mg/m² intravenously every 2 weeks beginning 2 weeks after the loading dose. Treatment continues until disease progression or unacceptable toxicity. The recommended dose is administered by intravenous infusion over a minimum of 2 hours. No dose reduction for VYLOY is recommended.

Key safety warnings

Hypersensitivity reactions including anaphylactic reaction or drug hypersensitivity have occurred during clinical studies. Patients should be monitored during and after infusion with VYLOY (at least 2 hours, or longer if clinically indicated) for symptoms and signs highly suggestive of anaphylaxis such as urticaria, repetitive cough, wheeze and throat tightness. Infusion-related reactions have occurred during clinical studies and patients should be monitored for signs and symptoms including nausea, vomiting, abdominal pain, salivary hypersecretion, pyrexia, chest discomfort, chills, back pain, cough and hypertension. Nausea and vomiting were the most frequently observed gastrointestinal adverse reactions during clinical studies. Patients who experience severe vomiting may be at risk of gastrointestinal haemorrhage when receiving VYLOY treatment. Pre-treatment with a combination of antiemetics is recommended prior to each infusion of VYLOY. There is the potential for patients to develop signs and symptoms consistent with Posterior Reversible Encephalopathy Syndrome (PRES), a rare reversible neurological disorder that can present with rapidly evolving symptoms including seizure, headache, confusion, visual and neurological disturbances, with or without associated hypertension and altered mental status. If PRES is suspected, it should be confirmed by brain imaging, preferably magnetic resonance imaging. Discontinuation of treatment in patients who develop PRES is recommended.

Contraindications

VYLOY is contraindicated in patients with known hypersensitivity to zolbetuximab or to any of the excipients in the formulation.

Regulatory history

VYLOY zolbetuximab 100 mg vial was registered on the ARTG on 17 March 2025, and the 300 mg vial was registered on 20 February 2026. The PBAC deferred its decision in March 2025 regarding first-line treatment of locally advanced unresectable or metastatic epidermal growth factor receptor 2-negative gastric or gastro-oesophageal junction adenocarcinoma.