• Generic Name: belzutifan tablets
  • Brand Name: Welireg
Last updated on MDtodate: 10/03/2022


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

  • Anemia.
  • Hypoxia.

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

Table 1: 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 2 summarizes the laboratory abnormalities in Study 004.

Table 2: 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.