Welireg Side Effects Center

Last updated on RxList: 10/22/2021
Welireg Side Effects Center

Medical Editor: John P. Cunha, DO, FACOEP

What Is Welireg?

Welireg (belzutifan) is a hypoxia-inducible factor inhibitor used to treat adult patients with von Hippel-Lindau (VHL) disease who require therapy for associated renal cell carcinoma (RCC), central nervous system (CNS) hemangioblastomas, or pancreatic neuroendocrine tumors (pNET), not requiring immediate surgery.

What Are Side Effects of Welireg?

Side effects of Welireg include:

Dosage for Welireg

The recommended dosage of Welireg is 120 mg administered orally once daily with or without food.

Welireg In Children

Safety and effectiveness of Welireg have not been established in pediatric patients.

What Drugs, Substances, or Supplements Interact with Welireg?

Welireg may interact with other medicines such as:

  • UGT2B17 or CYP2C19 inhibitors,
  • sensitive CYP3A4 substrates, and
  • hormonal contraceptives.

Tell your doctor all medications and supplements you use.

Welireg During Pregnancy and Breastfeeding

Tell your doctor if you are pregnant or plan to become pregnant before using Welireg; it may harm a fetus.  The pregnancy status of females of reproductive potential should be verified prior to initiating treatment with Welireg. Females of reproductive potential and males with female partners of reproductive potential are advised to use effective non-hormonal contraception during treatment with Welireg and for 1 week after the last dose. Welireg can render some hormonal contraceptives ineffective. Because of the potential for serious adverse reactions in a breastfed child, nursing women should avoid breastfeeding during treatment with Welireg and for 1 week after the last dose.

Additional Information

Our Welireg (belzutifan) Tablets, for Oral Use Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Welireg Professional Information


The following clinically significant adverse reactions are discussed elsewhere in the labeling:


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 safety of WELIREG was evaluated in an open-label clinical trial (Study 004) in 61 patients with VHL disease who had at least one measurable solid tumor localized to the kidney [see Clinical Studies]. Patients received WELIREG 120 mg orally once daily. The median duration of exposure to WELIREG was 68 weeks (range: 8.4 to 104.7 weeks).

Serious adverse reactions occurred in 15% of patients who received WELIREG, including anemia, hypoxia, anaphylaxis reaction, retinal detachment, and central retinal vein occlusion (1 patient each).

Permanent discontinuation of WELIREG due to adverse reactions occurred in 3.3% of patients. Adverse reactions which resulted in permanent discontinuation of WELIREG were dizziness and opioid overdose (1.6% each).

Dosage interruptions of WELIREG due to an adverse reaction occurred in 39% of patients. Adverse reactions which required dosage interruption in >2% of patients were fatigue, decreased hemoglobin, anemia, nausea, abdominal pain, headache, and influenza-like illness.

Dose reductions of WELIREG due to an adverse reaction occurred in 13% of patients. The most frequently reported adverse reaction which required dose reduction was fatigue (7%).

The most common (≥25%) adverse reactions, including laboratory abnormalities, that occurred in patients who received WELIREG were decreased hemoglobin, anemia, fatigue, increased creatinine, headache, dizziness, increased glucose, and nausea.

Table 2 summarizes the adverse reactions reported in patients treated with WELIREG in Study 004.

Table 2: Adverse Reactions Occurring in ≥10% of Patients Who Received WELIREG in Study 004

Adverse Reaction WELIREG
All Grades* (%) Grade 3-4 (%)
Blood and Lymphatic
Anemia 90 7
Fatigue† 64 5
Nervous system
Headache‡ 39 0
Dizziness§ 38 0
Nausea 31 0
Constipation 13 0
Abdominal pain¶ 13 0
Eye Disorders
Visual impairment# 21 3.3
Upper respiratory tract infection Þ 21 0
Respiratory, Thoracic and Mediastinal
Dyspnea 20 1.6
Musculoskeletal and Connective Tissue
Arthralgia 18 0
Myalgia 16 0
Hypertension 13 3.3
Metabolism and Nutrition
Weight increased 12 1.6
*Graded per NCI CTCAE v4.0
† includes fatigue and asthenia
‡ includes headache and migraine
§ incudes dizziness and vertigo
¶ includes abdominal discomfort, abdominal pain, abdominal pain upper and abdominal pain lower
# includes visual impairment, vision blurred, central retinal vein occlusion and retinal detachment includes bronchitis, sinusitis, upper respiratory tract infection, and viral upper respiratory infection

Table 3 summarizes the laboratory abnormalities in Study 004.

Table 3: Select Laboratory Abnormalities (>10%) That Worsened from Baseline in Patients Who Received WELIREG in Study 004

Laboratory Abnormality* WELIREG
Grades 1-4 % Grades 3-4 %
Increased creatinine 64 0
Increased glucose 34 4.9
Increased ALT 20 0
Increased AST 16 0
Decreased calcium (corrected) 10 0
Decreased phosphate 10 1.6
Decreased hemoglobin 93 7
Decreased leukocytes 11 0
*The denominator used to calculate the rate is based on all patients in the safety analysis population.

Other Clinical Trials Experience

In Study 001 (NCT02974738), a clinical trial in patients with advanced solid tumors (n=58) treated at the recommended dose in which the median age of enrollment was 62.5 years (range 39-75) and the median number of prior therapies for cancer was 3 (range 1-9), the following additional adverse reactions have been reported following administration of WELIREG at the recommended dosage: edema, cough, musculoskeletal pain, vomiting, diarrhea, and dehydration.


Effects Of Other Drugs On WELIREG

UGT2B17 Or CYP2C19 Inhibitors

Coadministration of WELIREG with inhibitors of UGT2B17 or CYP2C19 increases plasma exposure of belzutifan [see CLINICAL PHARMACOLOGY], which may increase the incidence and severity of adverse reactions of WELIREG. Monitor for anemia and hypoxia and reduce the dosage of WELIREG as recommended [see DOSAGE AND ADMINISTRATION, WARNINGS AND PRECAUTIONS, ADVERSE REACTIONS].

Effect Of WELIREG On Other Drugs

Sensitive CYP3A4 Substrates

Coadministration of WELIREG with CYP3A4 substrates decreases concentrations of CYP3A substrates [see CLINICAL PHARMACOLOGY], which may reduce the efficacy of these substrates. The magnitude of this decrease may be more pronounced in patients who are dual UGT2B17 and CYP2C19 poor metabolizers [see CLINICAL PHARMACOLOGY]. Avoid coadministration of WELIREG with sensitive CYP3A4 substrates, for which minimal decrease in concentration may lead to therapeutic failures of the substrate. If coadministration cannot be avoided, increase the sensitive CYP3A4 substrate dosage in accordance with its Prescribing Information.

Hormonal Contraceptives

Coadministration of WELIREG with hormonal contraceptives may lead to contraceptive failure or an increase in breakthrough bleeding [see CLINICAL PHARMACOLOGY, Use In Specific Populations].

Read the entire FDA prescribing information for Welireg (Belzutifan Tablets)

© Welireg Patient Information is supplied by Cerner Multum, Inc. and Welireg Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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