Prescribing InformationMedication Guide
Ask MerckMedical InformationVisit Patient Site
Ask MerckMedical InformationVisit Patient Site

Adverse Reaction Profile

Adverse reactions occurring in ≥10% of patients treated with WELIREGWELIREG (N=61)
Adverse ReactionAll Gradesa (%)Grade 3-4 (%)
Blood and Lymphatic
Anemia907
General
Fatigueb645
Nervous System
Headachec390
Dizzinessd380
Gastrointestinal
Nausea310
Constipation130
Abdominal paine130
Eye Disorders
Visual impairmentf213.3
Infections
Upper respiratory tract infectiong210
Respiratory, Thoracic, and Mediastinal
Dyspnea201.6
Musculoskeletal and Connective Tissue
Arthralgia180
Myalgia160
Vascular
Hypertension133.3
Metabolism and Nutrition
Weight increased121.6
a
Graded per NCI CTCAE v4.0.
b
Includes fatigue and asthenia.
c
Includes headache and migraine.
d
Includes dizziness and vertigo.
e
Includes abdominal discomfort, abdominal pain, abdominal pain upper, and abdominal pain lower.
f
Includes visual impairment, vision blurred, central retinal vein occlusion, and retinal detachment.
g
Includes bronchitis, sinusitis, upper respiratory tract infection, and viral upper respiratory infection.
The median duration of exposure to WELIREG™ (belzutifan) was 68 weeks (range: 8.4 to 104.7 weeks).
Patients on WELIREG experienced a low rate of permanent discontinuation (3.3%) due to AEs. AEs that resulted in permanent discontinuation of WELIREG were dizziness and opioid overdose (1.6% each).
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).
NCI CTCAE = National Cancer Institute Common Terminology Criteria for Adverse Events; AEs = adverse events.

Learn more about these attributes of WELIREG:

  Mechanism of Action   Efficacy   Guidelines
Indication

WELIREG is indicated for the treatment of 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.

Indication

WELIREG is indicated for the treatment of 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.

Selected Safety Information
WARNING: EMBRYO-FETAL TOXICITY
  • Exposure to WELIREG during pregnancy can cause embryo-fetal harm.
  • Verify pregnancy status prior to the initiation of WELIREG.
  • Advise patients of these risks and the need for effective non-hormonal contraception as WELIREG can render some hormonal contraceptives ineffective.

Selected Safety Information

WARNING: EMBRYO-FETAL TOXICITY
  • Exposure to WELIREG during pregnancy can cause embryo-fetal harm.
  • Verify pregnancy status prior to the initiation of WELIREG.
  • Advise patients of these risks and the need for effective non-hormonal contraception as WELIREG can render some hormonal contraceptives ineffective.
Anemia
  • WELIREG can cause severe anemia that can require blood transfusion. In Study 004, anemia occurred in 90% of patients and 7% had Grade 3 anemia. Median time to onset of anemia was 31 days (range: 1 day to 8.4 months). In Study 001, a clinical trial in patients with advanced solid tumors (n=58) treated at the recommended dose, anemia occurred in 76% of patients and 28% had Grade 3 anemia.
  • Monitor for anemia before initiation of and periodically throughout treatment. Closely monitor patients who are dual UGT2B17 and CYP2C19 poor metabolizers due to potential increases in exposure that may increase the incidence or severity of anemia.
  • Transfuse patients as clinically indicated. For patients with hemoglobin (Hb) <9 g/dL, withhold WELIREG until Hb ≥9 g/dL, then resume at reduced dose or permanently discontinue depending on the severity of anemia. For life-threatening anemia or when urgent intervention is indicated, withhold WELIREG until Hb ≥9 g/dL, then resume at a reduced dose or permanently discontinue.
  • The use of erythropoiesis stimulating agents (ESAs) for treatment of anemia is not recommended in patients treated with WELIREG.
Hypoxia
  • WELIREG can cause severe hypoxia that may require discontinuation, supplemental oxygen, or hospitalization. In Study 004, hypoxia occurred in 1.6% of patients. In Study 001, a clinical trial in patients with advanced solid tumors (n=58) treated at the recommended dose, hypoxia occurred in 29% of patients; 16% were Grade 3 hypoxia.
  • Monitor oxygen saturation before initiation of and periodically throughout treatment. For decreased oxygen saturation with exercise (eg, pulse oximeter <88% or PaO2 ≤55 mm Hg), consider withholding WELIREG until pulse oximetry with exercise is greater than 88%, then resume at the same or a reduced dose. For decreased oxygen saturation at rest (eg, pulse oximeter <88% or PaO2 ≤55 mm Hg) or when urgent intervention is indicated, withhold WELIREG until resolved and resume at a reduced dose or discontinue. For life-threatening or recurrent symptomatic hypoxia, permanently discontinue WELIREG. Advise patients to report signs and symptoms of hypoxia immediately to a health care provider.
Embryo-Fetal Toxicity
  • Based on findings in animals, WELIREG can cause fetal harm when administered to a pregnant woman.
  • Advise pregnant women and females of reproductive potential of the potential risk to the fetus. Advise females of reproductive potential 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. Advise male patients with female partners of reproductive potential to use effective contraception during treatment with WELIREG and for 1 week after the last dose.
Adverse Reactions
  • In Study 004, serious adverse reactions occurred in 15% of patients, including anemia, hypoxia, anaphylaxis reaction, retinal detachment, and central retinal vein occlusion (1 patient each).
  • WELIREG was permanently discontinued due to adverse reactions in 3.3% of patients for dizziness and opioid overdose (1.6% each).
  • Dosage interruptions due to an adverse reaction occurred in 39% of patients. Those which required dosage interruption in >2% of patients were fatigue, decreased hemoglobin, anemia, nausea, abdominal pain, headache, and influenza-like illness.
  • Dose reductions 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 adverse reactions (≥25%) were decreased hemoglobin (93%), anemia (90%), fatigue (64%), increased creatinine (64%), headache (39%), dizziness (38%), increased glucose (34%), and nausea (31%).
  • In Study 001, a clinical trial in patients with advanced solid tumors (n=58) treated at the recommended dose, the following additional adverse reactions have been reported: edema, cough, musculoskeletal pain, vomiting, diarrhea, and dehydration.
Drug Interactions
  • Coadministration of WELIREG with inhibitors of UGT2B17 or CYP2C19 increases plasma exposure of belzutifan, which may increase the incidence and severity of adverse reactions. Monitor for anemia and hypoxia and reduce the dosage of WELIREG as recommended.
  • Coadministration of WELIREG with CYP3A4 substrates decreases concentrations of CYP3A4 substrates, which may reduce the efficacy of these substrates or lead to therapeutic failures. Avoid coadministration with sensitive CYP3A4 substrates. If coadministration cannot be avoided, increase the sensitive CYP3A4 substrate dosage in accordance with its Prescribing Information. Coadministration of WELIREG with hormonal contraceptives may lead to contraceptive failure or an increase in breakthrough bleeding.
Lactation
  • Because of the potential for serious adverse reactions in breastfed children, advise women not to breastfeed during treatment with WELIREG and for 1 week after the last dose.
Females and Males of Reproductive Potential
  • WELIREG can cause fetal harm when administered to a pregnant woman. Verify the pregnancy status of females of reproductive potential prior to initiating treatment with WELIREG.
  • Use of WELIREG may reduce the efficacy of hormonal contraceptives. Advise females of reproductive potential to use effective non-hormonal contraception during treatment with WELIREG and for 1 week after the last dose. Advise males with female partners of reproductive potential to use effective contraception during treatment with WELIREG and for 1 week after the last dose.
  • Based on findings in animals, WELIREG may impair fertility in males and females of reproductive potential and the reversibility of this effect is unknown.
Pediatric Use
  • Safety and effectiveness of WELIREG in pediatric patients under 18 years of age have not been established.
Before prescribing WELIREG, please read the accompanying Prescribing Information, including the Boxed Warning about embryo-fetal toxicity. The Medication Guide also is available.

Indication

WELIREG is indicated for the treatment of 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.

Selected Safety Information

WARNING: EMBRYO-FETAL TOXICITY
  • Exposure to WELIREG during pregnancy can cause embryo-fetal harm.
  • Verify pregnancy status prior to the initiation of WELIREG.
  • Advise patients of these risks and the need for effective non-hormonal contraception as WELIREG can render some hormonal contraceptives ineffective.
Anemia
  • WELIREG can cause severe anemia that can require blood transfusion. In Study 004, anemia occurred in 90% of patients and 7% had Grade 3 anemia. Median time to onset of anemia was 31 days (range: 1 day to 8.4 months). In Study 001, a clinical trial in patients with advanced solid tumors (n=58) treated at the recommended dose, anemia occurred in 76% of patients and 28% had Grade 3 anemia.
  • Monitor for anemia before initiation of and periodically throughout treatment. Closely monitor patients who are dual UGT2B17 and CYP2C19 poor metabolizers due to potential increases in exposure that may increase the incidence or severity of anemia.
  • Transfuse patients as clinically indicated. For patients with hemoglobin (Hb) <9 g/dL, withhold WELIREG until Hb ≥9 g/dL, then resume at reduced dose or permanently discontinue depending on the severity of anemia. For life-threatening anemia or when urgent intervention is indicated, withhold WELIREG until Hb ≥9 g/dL, then resume at a reduced dose or permanently discontinue.
  • The use of erythropoiesis stimulating agents (ESAs) for treatment of anemia is not recommended in patients treated with WELIREG.
Hypoxia
  • WELIREG can cause severe hypoxia that may require discontinuation, supplemental oxygen, or hospitalization. In Study 004, hypoxia occurred in 1.6% of patients. In Study 001, a clinical trial in patients with advanced solid tumors (n=58) treated at the recommended dose, hypoxia occurred in 29% of patients; 16% were Grade 3 hypoxia.
  • Monitor oxygen saturation before initiation of and periodically throughout treatment. For decreased oxygen saturation with exercise (eg, pulse oximeter <88% or PaO2 ≤55 mm Hg), consider withholding WELIREG until pulse oximetry with exercise is greater than 88%, then resume at the same or a reduced dose. For decreased oxygen saturation at rest (eg, pulse oximeter <88% or PaO2 ≤55 mm Hg) or when urgent intervention is indicated, withhold WELIREG until resolved and resume at a reduced dose or discontinue. For life-threatening or recurrent symptomatic hypoxia, permanently discontinue WELIREG. Advise patients to report signs and symptoms of hypoxia immediately to a health care provider.
Embryo-Fetal Toxicity
  • Based on findings in animals, WELIREG can cause fetal harm when administered to a pregnant woman.
  • Advise pregnant women and females of reproductive potential of the potential risk to the fetus. Advise females of reproductive potential 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. Advise male patients with female partners of reproductive potential to use effective contraception during treatment with WELIREG and for 1 week after the last dose.
Adverse Reactions
  • In Study 004, serious adverse reactions occurred in 15% of patients, including anemia, hypoxia, anaphylaxis reaction, retinal detachment, and central retinal vein occlusion (1 patient each).
  • WELIREG was permanently discontinued due to adverse reactions in 3.3% of patients for dizziness and opioid overdose (1.6% each).
  • Dosage interruptions due to an adverse reaction occurred in 39% of patients. Those which required dosage interruption in >2% of patients were fatigue, decreased hemoglobin, anemia, nausea, abdominal pain, headache, and influenza-like illness.
  • Dose reductions 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 adverse reactions (≥25%) were decreased hemoglobin (93%), anemia (90%), fatigue (64%), increased creatinine (64%), headache (39%), dizziness (38%), increased glucose (34%), and nausea (31%).
  • In Study 001, a clinical trial in patients with advanced solid tumors (n=58) treated at the recommended dose, the following additional adverse reactions have been reported: edema, cough, musculoskeletal pain, vomiting, diarrhea, and dehydration.
Drug Interactions
  • Coadministration of WELIREG with inhibitors of UGT2B17 or CYP2C19 increases plasma exposure of belzutifan, which may increase the incidence and severity of adverse reactions. Monitor for anemia and hypoxia and reduce the dosage of WELIREG as recommended.
  • Coadministration of WELIREG with CYP3A4 substrates decreases concentrations of CYP3A4 substrates, which may reduce the efficacy of these substrates or lead to therapeutic failures. Avoid coadministration with sensitive CYP3A4 substrates. If coadministration cannot be avoided, increase the sensitive CYP3A4 substrate dosage in accordance with its Prescribing Information. Coadministration of WELIREG with hormonal contraceptives may lead to contraceptive failure or an increase in breakthrough bleeding.
Lactation
  • Because of the potential for serious adverse reactions in breastfed children, advise women not to breastfeed during treatment with WELIREG and for 1 week after the last dose.
Females and Males of Reproductive Potential
  • WELIREG can cause fetal harm when administered to a pregnant woman. Verify the pregnancy status of females of reproductive potential prior to initiating treatment with WELIREG.
  • Use of WELIREG may reduce the efficacy of hormonal contraceptives. Advise females of reproductive potential to use effective non-hormonal contraception during treatment with WELIREG and for 1 week after the last dose. Advise males with female partners of reproductive potential to use effective contraception during treatment with WELIREG and for 1 week after the last dose.
  • Based on findings in animals, WELIREG may impair fertility in males and females of reproductive potential and the reversibility of this effect is unknown.
Pediatric Use
  • Safety and effectiveness of WELIREG in pediatric patients under 18 years of age have not been established.
Before prescribing WELIREG, please read the accompanying Prescribing Information, including the Boxed Warning about embryo-fetal toxicity. The Medication Guide also is available.