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Drugs A–Z

Zolbetuximab

Zolbetuximab is a prescription medicine (Claudin 18.2-directed Cytolytic Antibody). The sections below reproduce one FDA label for it, named under "Label". Products in other forms, strengths or from other makers have their own labels, which can differ.

Type
Prescription only (Rx)
Brand names
Vyloy
Drug class
Claudin 18.2-directed Cytolytic Antibody
Taken
Intravenous
Label
Astellas Pharma US, Inc., revised August 11, 2026 · full label on DailyMed
Biosimilars
1 approved · details

What it is used for

VYLOY, in combination with fluoropyrimidine- and platinum-containing chemotherapy, is indicated for the first-line treatment of adults with locally advanced unresectable or metastatic human epidermal growth factor receptor 2 (HER2)‑negative gastric or gastroesophageal junction (GEJ) adenocarcinoma whose tumors are claudin (CLDN) 18.2 positive as determined by an FDA-approved test [see Dosage and Administration ( 2.1 ) and Clinical Studies ( 14 )]. VYLOY is a claudin 18.2-directed cytolytic antibody and is indicated in combination with fluoropyrimidine- and platinum-containing chemotherapy for the first-line treatment of adults with locally advanced unresectable or metastatic human epidermal growth factor receptor 2 (HER2)-negative gastric or gastroesophageal junction adenocarcinoma whose tumors are claudin (CLDN) 18.2 positive as determined by an FDA-approved test ( 1 ).

Forms and strengths

For injection: 100 mg and 300 mg of zolbetuximab-clzb as a white to off-white lyophilized powder in a single-dose vial. For injection: 100 mg and 300 mg lyophilized powder in a single-dose vial. ( 3 )

Who should not take it (contraindications)

None. None. ( 4 )

Warnings and precautions

  • Hypersensitivity reactions including serious anaphylaxis reactions and serious and fatal infusion-related reactions have occurred. Monitor patients during and for at least 2 hours after infusion with VYLOY. Interrupt, slow the rate of infusion or permanently discontinue VYLOY based on severity and type of reaction. Premedicate with antihistamines for subsequent infusions after a hypersensitivity reaction. ( 2.4 , 5.1 )
  • Severe nausea and vomiting: Premedicate patients with antiemetics prior to each infusion. Interrupt or permanently discontinue VYLOY based on the severity of the nausea and/or vomiting. Manage patients during and after infusion with antiemetics or fluid replacement. ( 2.4 , 5.2 )

5.1 Hypersensitivity reactions, including anaphylaxis reactions, and infusion related reactions Hypersensitivity reactions, including serious anaphylaxis reactions, and serious and fatal infusion-related reactions (IRR) have been reported in clinical studies when VYLOY has been administered. Any grade hypersensitivity reactions, including anaphylactic reactions, occurring with VYLOY in combination with mFOLFOX6 or CAPOX was 18%. Severe (Grade 3 or 4) hypersensitivity reactions, including anaphylactic reactions, occurred in 2% of patients. Seven patients (1.3%) permanently discontinued VYLOY for hypersensitivity reactions, including two patients (0.4%) who permanently discontinued VYLOY due to anaphylactic reactions. Seventeen (3.2%) patients required dose interruption, and three patients (0.6%) required infusion rate reduction due to hypersensitivity reactions. All grade IRRs occurred in 3.2% in patients administered VYLOY in combination with mFOLFOX6 or CAPOX. Severe (Grade 3) IRRs occurred in 2 (0.4%) patients who received VYLOY. An IRR led to permanent discontinuation of VYLOY in 2 (0.4%) patients and dose interruption in 7 (1.3%) patients. The infusion rate was reduced for VYLOY for 2 (0.4%) patients due to an IRR. Monitor patients during infusion with VYLOY and for 2 hours after completion of infusion or longer if clinically indicated, for hypersensitivity reactions with symptoms and signs that are highly suggestive of anaphylaxis (urticaria, repetitive cough, wheeze and throat tightness/change in voice). Monitor patients for signs and symptoms of IRRs including nausea, vomiting, abdominal pain, salivary hypersecretion, pyrexia, chest discomfort, chills, back pain, cough and hypertension. If a severe or life-threatening hypersensitivity or IRR reaction occurs, discontinue VYLOY permanently, treat symptoms according to standard medical care, and monitor until symptoms resolve. For any Grade 2 hypersensitivity or IRR, interrupt the VYLOY infusion until Grade ≤1, then resume at a reduced infusion rate for the remaining infusion. Premedicate the patient with antihistamines for the subsequent infusions, administer per the infusion rates in Table 2 and closely monitor the patient for symptoms and signs of a hypersensitivity reaction. The infusion rate may be gradually increased as tolerated [see Dosage and Administration ( 2.4 )] .

5.2 Severe Nausea and Vomiting VYLOY is emetogenic. Nausea and vomiting occurred more often during the first cycle of treatment. All grade nausea and vomiting occurred in 82% and 67%, respectively, of patients treated with VYLOY in combination with mFOLFOX6 and 69% and 66% in combination with CAPOX, respectively. Severe (Grade 3) nausea occurred in 16% and 9% of patients treated with VYLOY in combination with mFOLFOX6 or CAPOX respectively. Severe (Grade 3) vomiting occurred in 16% and 12% of patients treated with VYLOY in combination with mFOLFOX6 or CAPOX. Nausea led to permanent discontinuation of VYLOY in combination with mFOLFOX6 or CAPOX in 18 (3.4%) patients and dose interruption in 147 (28%) patients. Vomiting led to permanent discontinuation of VYLOY in combination with mFOLFOX6 or CAPOX in 20 (3.8%) patients and dose interruption in 150 (28%) patients. Pretreat with antiemetics prior to each infusion of VYLOY [see Dosage and Administration ( 2.2 )] . Manage patients during and after infusion with antiemetics or fluid replacement. Interrupt the infusion, or permanently discontinue VYLOY based on severity [see Dosage and Administration ( 2.4 )] .

Side effects (adverse reactions)

The following serious adverse reactions are described elsewhere in the labeling:

  • Hypersensitivity Reactions, including anaphylaxis, and infusion related reactions [see Warnings and Precautions ( 5.1 )] .
  • Severe Nausea and Vomiting [see Warnings and Precautions ( 5.2 )] . The most common adverse reactions (≥15%) for VYLOY in combination with mFOLFOX6 or CAPOX were nausea, vomiting, fatigue, decreased appetite, diarrhea, peripheral sensory neuropathy, abdominal pain, constipation, decreased weight, hypersensitivity reactions, and pyrexia. The most common laboratory abnormalities (≥15%) for VYLOY in combination with mFOLFOX6 or CAPOX were decreased neutrophil count, decreased leucocyte count, decreased albumin, increased creatinine, decreased hemoglobin, increased glucose, decreased lymphocyte count, increased aspartate aminotransferase, decreased platelets, increased alkaline phosphatase, increased alanine aminotransferase, decreased glucose, decreased sodium, decreased phosphate, decreased potassium, and decreased magnesium ( 6.1 ). To report SUSPECTED ADVERSE REACTIONS, contact Astellas Pharma US, Inc. at 1-800-727-7003 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. The pooled safety population described in the WARNINGS AND PRECAUTIONS reflect exposure to VYLOY in 533 patients at an 800 mg/m 2 initial dose followed by subsequent doses of 600 mg/m 2 every 3 weeks in combination with fluoropyrimidine- and platinum-containing chemotherapy in the SPOTLIGHT (279) and GLOW (254) studies. Among 533 patients who received VYLOY in these studies, 47% were exposed for ≥6 months and 20% were exposed for ≥12 months. In this pooled population, the most common (≥15%) adverse reactions, were nausea, vomiting, fatigue, decreased appetite, diarrhea, peripheral sensory neuropathy, abdominal pain, constipation, decreased weight, hypersensitivity reactions, and pyrexia. The most common (≥15%) laboratory abnormalities in the pooled population were decreased neutrophil count, decreased leucocyte count, decreased albumin, increased creatinine, decreased hemoglobin, increased glucose, decreased lymphocyte count, increased aspartate aminotransferase, decreased platelets, increased alkaline phosphatase, increased alanine aminotransferase, decreased glucose, decreased sodium, decreased phosphate, decreased potassium, and decreased magnesium. SPOTLIGHT The safety of VYLOY was evaluated in SPOTLIGHT in patients with locally advanced unresectable or metastatic gastric or GEJ cancer who received at least one dose of VYLOY at an 800 mg/m 2 initial dose followed by 600 mg/m 2 subsequent doses every 3 weeks in combination with mFOLFOX6 [see Clinical Studies ( 14 )] . The median duration of exposure to VYLOY in combination with mFOLFOX6 was 6.2 months (range: 1 day to 40.9 months). Serious adverse reactions occurred in 45% of patients treated with VYLOY in combination with mFOLFOX6; the most common serious adverse reactions (≥2%) were vomiting (8%), nausea (7%), neutropenia (2.9%), febrile neutropenia (2.9%), diarrhea (2.9%), intestinal obstruction (3.2%), pyrexia (2.5%), pneumonia (2.5%), respiratory failure (2.2%), pulmonary embolism (2.2%), decreased appetite (2.1%) and sepsis (2.0%). Fatal adverse reactions occurred in 5% of patients who received VYLOY in combination with mFOLFOX6 including sepsis (1.4%), pneumonia (1.1%), respiratory failure (1.1%), intestinal obstruction (0.7%), acute hepatic failure (0.4%), acute myocardial infarction (0.4%), death (0.4%), disseminated intravascular coagulation (0.4%), encephalopathy (0.4%), and upper gastrointestinal hemorrhage (0.4%). Permanent discontinuation of VYLOY due to an adverse reaction occurred in 20% of patients; the most common adverse reactions leading to discontinuation (≥2%) were nausea and vomiting. Dosage interruptions of VYLOY due to an adverse reaction occurred in 75% of patients; the most common adverse reactions leading to dose interruption (≥5%) were nausea, vomiting, neutropenia, abdominal pain, fatigue, and hypertension. Tables 3 and 4 summarize the most common (≥15%) adverse reactions and laboratory abnormalities with a difference between arms of ≥5%, respectively, compared to placebo in SPOTLIGHT. Table 3. Adverse Reactions (≥15%) in Patients Treated with VYLOY in SPOTLIGHT with a Difference Between Arms of ≥5% Compared to Placebo Adverse Reaction VYLOY with mFOLFOX6 n=279 Placebo with mFOLFOX6 n=278 All Grades % Grade 3 or 4 % All Grades % Grade 3 or 4 % Gastrointestinal disorders Nausea 82 16 61 7 Vomiting 67 16 36 6 Metabolism and nutrition disorders Decreased appetite 47 6 34

3.2 General disorders and administration site conditions Peripheral edema 18 0.7 9 0 Table 4. Laboratory Abnormalities (≥ 15%) in SPOTLIGHT with a Difference Between Arms of ≥ 5% Compared to Placebo Laboratory Abnormality VYLOY with mFOLFOX6 The denominator used to calculate the rate varied from 271 to 272 based on the number of patients with a baseline value and at least one post-treatment value. Placebo with mFOLFOX6 All Grades % Grade 3 or 4 % All Grades % Grade 3 or 4 % Albumin decreased 78 4.4 47

1.1 Potassium decreased 28 11 21 6 Glucose decreased 45 0.4 35

0.4 Sodium decreased 29 5 21 2.9 GLOW The safety of VYLOY was evaluated in GLOW in patients with locally advanced unresectable or metastatic gastric/GEJ cancer who received at least one dose of VYLOY at an 800 mg/m 2 initial dose followed by 600 mg/m 2 subsequent doses every 3 weeks in combination with CAPOX [see Clinical Studies ( 14 )] . The median duration of exposure to VYLOY in combination with CAPOX was 4.4 months (range: 0.03 to 30.7 months). Serious adverse reactions occurred in 47% of patients treated with VYLOY in combination with CAPOX; the most common serious adverse reactions (≥2%) were vomiting (6%), nausea (4.3%), decreased appetite (3.9%), decreased platelet count (3.1%), upper gastrointestinal hemorrhage (2.8%), diarrhea (2.8%), pneumonia (2.4%), pulmonary embolism (2.3%), and pyrexia (2.0%). Fatal adverse reactions occurred in 8% of patients who received VYLOY in combination with CAPOX including sepsis (1.2%), pneumonia (0.4%), death (0.8%), upper gastrointestinal hemorrhage (0.8%), cerebral hemorrhage (0.8%), abdominal infection (0.4%), acute respiratory distress syndrome (0.4%), cardio‑respiratory arrest (0.4%), decreased platelet count (0.4%), disseminated intravascular coagulation (0.4%), dyspnea (0.4%), gastric perforation (0.4%), hemorrhagic ascites (0.4%), procedural complication (0.4%), sudden death (0.4%), and syncope (0.4%). Permanent discontinuation of VYLOY due to an adverse reaction occurred in 19% of patients; the most common adverse reaction leading to discontinuation (≥2%) was vomiting. Dosage interruption of VYLOY due to an adverse reaction occurred in 55% of patients; the most common adverse reactions leading to dose interruption (≥2%) were nausea, vomiting, neutropenia, thrombocytopenia, anemia, fatigue, infusion-related reaction, and abdominal pain. Tables 5 and 6 summarize the most common (≥15%) adverse reactions and laboratory abnormalities with a difference between arms of ≥5%, respectively compared to placebo in GLOW. Table 5. […]

Pregnancy, breastfeeding, children and older adults

Lactation: Advise not to breastfeed. ( 8.2 )

8.1 Pregnancy Risk Summary There are no data with VYLOY use in pregnant women to inform any drug-associated risks. Embryo-fetal toxicity was not observed in pregnant mice intravenously administered zolbetuximab-clzb [see Data] . VYLOY should only be given to a pregnant woman if the benefit outweighs the potential risk. The background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2%-4% and 15%-20%, respectively. Data Animal Data In an embryo-fetal development toxicity study, zolbetuximab-clzb was intravenously administered to pregnant mice during the period of organogenesis and did not result in embryo-fetal toxicity at doses up to 300 mg/kg (approximately 1.9 times the recommended clinical dose based on AUC). Zolbetuximab-clzb crossed the placental barrier resulting in higher fetal serum concentrations on Day 18 of gestation than maternal serum concentrations on Day 16 of gestation.

8.2 Lactation Risk Summary There are no data on the presence of zolbetuximab-clzb in human milk, the effects on the breastfed child, or the effects on milk production. Because antibodies may be excreted in human milk and because of the potential for adverse reactions in a breastfed child, advise a lactating woman not to breastfeed during treatment with VYLOY and for 8 months after the last dose.

8.3 Females and Males of Reproductive Potential VYLOY is used in combination with fluoropyrimidine- or platinum-containing chemotherapy. Refer to the Full Prescribing Information of fluoropyrimidine- and platinum-containing chemotherapy products for pregnancy testing, contraception, and infertility information.

8.4 Pediatric Use The safety and effectiveness of VYLOY in pediatric patients have not been established.

8.5 Geriatric Use Of the 533 patients in clinical studies of VYLOY in combination with mFOLFOX6 or CAPOX , 34% (n=179) were over 65 years, and 5% were over 75 years (n=28) [see Clinical Studies ( 14 )] . No overall differences in safety or effectiveness were observed between patients aged 65 years or older and younger patients.

How it works

Zolbetuximab-clzb is a claudin 18.2 (CLDN18.2)-directed cytolytic antibody that depletes CLDN18.2-positive cells via antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC). Zolbetuximab-clzb in combination with chemotherapy had increased antitumor activity in CLDN18.2-expressing mouse tumor models compared to zolbetuximab-clzb or chemotherapy alone.

Are there biosimilars to Zolbetuximab?

Yes. The FDA has approved 1 biosimilars; 1 of those approvals are active (not discontinued). As with generics, approval does not guarantee a product is stocked or covered.

  • Vyloy Astellas, approved 2024

Biologics have biosimilars rather than generics: highly similar versions with no clinically meaningful differences. Only biosimilars the FDA designates as interchangeable can be swapped at the pharmacy without asking the prescriber, where state law allows; the FDA Purple Book lists which ones are.

Source: Drugs@FDA (via openFDA), checked October 29, 2026. Marketing status is what companies report to the FDA; whether a pharmacy stocks a product, and what your insurance covers, can differ.

Dosage:
we do not reproduce dosing instructions. The right dose depends on the person and the condition and is set by the prescriber or pharmacist. Dosage section of the full label.

Zolbetuximab in the news

We have not covered this medicine yet. Latest news

Recalls

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Source: FDA structured product labeling, retrieved through openFDA. Label text is shown as published by the FDA, without editing; long sections are shortened, marked […]. openFDA data are not validated for clinical use — always check the current label and ask a doctor or pharmacist about your own treatment. Set ID e7695a21-abb6-47ac-93f8-0ece5a9c4409.


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Important: this content is for informational purposes only and is not medical advice, a prescribing instruction, or a recommendation to act. Consult a licensed healthcare professional before taking any medication.

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