Zolbetuximab-clzb belongs to a class of claudin 18.2 (CLDN18.2)-directed cytolytic antibodies, a group of targeted cancer therapies that bind to a protein found on the surface of certain gastric cancer cells. It was approved by the U.S. Food and Drug Administration (FDA) on October 18, 2024, in combination with fluoropyrimidine- and platinum-containing chemotherapy, for the first-line treatment of adults with locally advanced unresectable or metastatic HER2-negative gastric or gastroesophageal junction (GEJ) adenocarcinoma whose tumors are CLDN18.2 positive. It is the first and only CLDN18.2-targeted therapy approved for this indication and is marketed globally under the brand name Vyloy.

Zolbetuximab-clzb is used, together with chemotherapy, as a first-line treatment for adults with advanced or metastatic HER2-negative gastric or GEJ adenocarcinoma whose tumors test positive for CLDN18.2, as confirmed by an FDA-approved test.

Zolbetuximab-clzb is administered as an intravenous infusion in a hospital or clinic setting, typically every two to three weeks alongside chemotherapy. When given on the same day as chemotherapy, it is administered first. The first infusion usually takes a minimum of 3.5 hours, with subsequent infusions often taking less time depending on tolerance. Patients are given medicine to help prevent nausea and vomiting before treatment and are monitored closely during and after each infusion, with the infusion rate adjusted, slowed, or stopped if side effects occur.

The Vyloy injection side effects are unwanted symptoms caused by medicines. Even though all drugs cause side effects, not everyone gets them.

Serious:

• Severe allergic or anaphylactic reactions (rash, itching, breathing problems, swelling of face, throat tightness)

• Severe infusion-related reactions (fever, chills, chest pain, difficulty breathing)

• Severe dehydration from persistent vomiting or diarrhoea

Common:

• Nausea and vomiting

• Decreased appetite

• Diarrhoea

• Fatigue

• Weight loss

• Abdominal pain

• Constipation

• Hypersensitivity reactions: Zolbetuximab-clzb may cause hypersensitivity reactions, including serious anaphylaxis.

• Infusion-related reactions: Serious and, in some cases, fatal infusion-related reactions have been reported.

• Nausea and vomiting: These are common, especially during the first treatment cycle, and may occasionally be severe.

• Higher risk: Patients who have not undergone previous stomach surgery may be more likely to experience severe nausea and vomiting.

• Anti-nausea treatment: Patients should receive anti-nausea medication before each infusion to help prevent nausea and vomiting.

• Monitoring: Patients should be closely monitored during and after the infusion for early signs of hypersensitivity or infusion-related reactions.

• Seek medical attention: Prompt medical care is advised if symptoms such as difficulty breathing, swelling, rash, or signs of a severe allergic reaction occur.

• Breastfeeding: Women should not breastfeed during treatment and for 8 months after the final dose.

• Nausea or vomiting: Drink small amounts of fluids frequently. Inform your doctor if you are unable to keep fluids down.

• Infusion reactions: Immediately report symptoms such as fever, chills, wheezing, or chest tightness to your healthcare team during or after the infusion.

• Decreased appetite: Eating smaller, more frequent meals may help manage reduced appetite during treatment.

• Pregnancy prevention: Avoid becoming pregnant during treatment and use an effective method of contraception.

• If pregnancy occurs: Inform your doctor immediately if you become pregnant during treatment.

1. Full Prescribing Information – VYLOY (zolbetuximab-clzb). U.S. Food and Drug Administration. Available at: https://www.accessdata.fda.gov/drugsatfda_docs/label/2024/761365s000lbl.pdf

2. DailyMed – VYLOY (zolbetuximab-clzb) Injection. National Library of Medicine. Available at: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=e7695a21-abb6-47ac-93f8-0ece5a9c4409