KEYTRUDA® (pembrolizumab) Plus WELIREG® (belzutifan) Given as Adjuvant Therapy Reduced the Risk of Disease Recurrence or Death by 28% Compared to KEYTRUDA Monotherapy in Certain Patients With Earlier-Stage Renal Cell Carcinoma (RCC)
KEYTRUDA® (pembrolizumab) Plus WELIREG® (belzutifan) Given as Adjuvant Therapy Reduced the Risk of Disease Recurrence or Death by 28% Compared to KEYTRUDA Monotherapy in Certain Patients With Earlier-Stage Renal Cell Carcinoma (RCC)
This is the first positive Phase 3 trial for WELIREG in earlier-stage disease, the first positive results for a HIF-2α inhibitor and immunotherapy combination and the first study in earlier-stage disease, regardless of tumor type, to demonstrate a disease-free survival improvement compared to KEYTRUDA
Based on these data, the U.S. FDA has accepted for priority review supplemental applications for WELIREG in combination with KEYTRUDA or KEYTRUDA QLEX™ for the adjuvant treatment of certain patients with RCC
RAHWAY, N.J.–(BUSINESS WIRE)–$MRK #MRK–Merck (NYSE: MRK), known as MSD outside of the United States and Canada, today announced the presentation of results from the pivotal Phase 3 LITESPARK-022 trial evaluating KEYTRUDA® (pembrolizumab), Merck’s anti-PD-1 therapy, in combination with WELIREG® (belzutifan), Merck’s first-in-class, oral hypoxia-inducible factor-2 alpha (HIF-2α) inhibitor, given in the adjuvant setting, for patients with clear cell renal cell carcinoma (RCC) following nephrectomy. These late-breaking data will be presented for the first time today during an oral abstract session at the 2026 American Society of Clinical Oncology (ASCO) Genitourinary (GU) Cancers Symposium (abstract #LBA418) and are included in the official ASCO GU Press Program.
At the first pre-specified interim analysis (median follow-up of 28.4 months [range, 15.0-40.1 months]), KEYTRUDA plus WELIREG given in the adjuvant setting significantly improved disease-free survival (DFS), the study’s primary endpoint, reducing the risk of disease recurrence or death by 28% (HR=0.72 [95% CI 0.59-0.87]; p=0.0003) compared to KEYTRUDA plus placebo. Median DFS was not reached in either arm; the estimated 24-month DFS rate was 80.7% (95% CI, 77.7-83.2) for the KEYTRUDA plus WELIREG arm and was 73.7% (95% CI, 70.6-76.6) for the KEYTRUDA plus placebo arm. As previously reported, the trial will continue to evaluate overall survival (OS), a key secondary endpoint.
“Approximately 40% of patients with renal cell cancer may experience tumor growth after initial treatment. Results from LITESPARK-022 mark an important step forward for certain patients with renal cell cancer, showing a significant reduction in the risk of disease recurrence or death compared to pembrolizumab alone,” said Dr. Toni K. Choueiri, director, Lank Center for Genitourinary Oncology, Dana-Farber Cancer Institute and Jerome and Nancy Kohlberg professor of medicine, Harvard Medical School. “The combination of pembrolizumab and belzutifan is the first ever regimen in the adjuvant setting for renal cell cancer to demonstrate an improvement in disease-free survival over pembrolizumab monotherapy, positioning this regimen to potentially reshape clinical practice.”
“LITESPARK-022 is a critical part of our comprehensive RCC clinical development program, and the Phase 3 results presented at ASCO GU underscore the importance of KEYTRUDA and WELIREG in helping to treat patients with certain types of renal cell carcinoma,” said Dr. M. Catherine Pietanza, vice president, Global Clinical Development, Merck Research Laboratories. “These findings represent the first positive Phase 3 data for WELIREG in earlier stages of disease, as well as the first positive Phase 3 results for a HIF‑2α inhibitor and immunotherapy combination, reinforcing our commitment to exploring novel treatment approaches to improve upon established treatment paradigms for patients in need.”
The safety profile of KEYTRUDA plus WELIREG was consistent with that observed in previously reported studies for both agents; no new safety signals were observed. Of patients enrolled, 69.5% of those in the KEYTRUDA plus WELIREG arm and 71.1% of those in the KEYTRUDA plus placebo arm completed the assigned treatment. Among treated patients, Grade ≥3 treatment-emergent adverse events (TEAEs) occurred in 52.1% of patients who received KEYTRUDA plus WELIREG and 30.2% of patients who received KEYTRUDA plus placebo. The most common Grade ≥3 TEAEs were anemia (12.1% versus 0.5%), increased alanine aminotransferase (ALT) (6.4% versus 2.0%) and hypoxia (4.6% versus 0%). Grade 5 treatment-emergent (1.1% versus 1.2%) and treatment-related adverse events (0.3% versus 0.3%) were similar between treatment arms.
Based on data from the LITESPARK-022 trial, the U.S. Food and Drug Administration (FDA) has accepted for priority review supplemental applications seeking approval of WELIREG in combination with KEYTRUDA or KEYTRUDA QLEX™ (pembrolizumab and berahyaluronidase alfa-pmph) for the adjuvant treatment of adult patients with RCC with a clear cell component with increased risk of recurrence following nephrectomy. The FDA has set a Prescription Drug User Fee Act (PDUFA), or target action date, of June 19, 2026 for the WELIREG sNDA and the KEYTRUDA and KEYTRUDA QLEX sBLAs. Merck will also discuss these data with global regulatory authorities.
KEYTRUDA is approved for the adjuvant treatment of certain patients with RCC in the U.S., Canada, European Union (EU), Japan and other countries worldwide based on data from KEYNOTE-564.
WELIREG is approved in over 45 countries including the U.S., Canada, EU, and Japan for the treatment of adult patients with advanced RCC following a PD-1/PD-L1 inhibitor and 1-2 VEGF-TKIs based on results from the Phase 3 LITESPARK-005 trial.
Merck has an industry-leading clinical development program in RCC, leveraging multiple approved therapeutic options across multiple settings, including adjuvant and advanced disease.
About LITESPARK-022
LITESPARK-022 is a multicenter, randomized, double-blind Phase 3 trial (ClinicalTrials.gov, NCT05239728) evaluating WELIREG in combination with KEYTRUDA compared to KEYTRUDA plus placebo for the treatment of patients with clear cell RCC following nephrectomy. The primary endpoint is DFS, and key secondary endpoints include OS, safety and quality of life outcomes. The trial enrolled 1,841 patients who were randomized to receive either:
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WELIREG (120 mg orally once daily for approximately one year) plus KEYTRUDA (400 mg intravenously every six weeks for approximately one year), or;
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KEYTRUDA plus placebo.
About renal cell carcinoma
Renal cell carcinoma is the most common type of kidney cancer, with about nine out of 10 kidney cancer diagnoses being RCC. In 2022, there were about 435,000 new cases of kidney cancer diagnosed and approximately 156,000 deaths from the disease worldwide. Renal cell carcinoma is about twice as common in men as in women. Most cases of RCC are discovered incidentally during imaging tests for other abdominal diseases. Approximately 30% of patients with kidney cancer are diagnosed at an advanced stage.
About Merck’s early-stage cancer clinical program
Finding cancer at an earlier stage may give patients a greater chance of long-term survival. Many cancers are considered most treatable and potentially curable in their earliest stage of disease. Building on the strong understanding of the role of KEYTRUDA in later-stage cancers, Merck is evaluating our portfolio of medicines and pipeline candidates in earlier disease states, with more than 30 ongoing registrational studies across multiple types of cancer.
About Merck’s research in genitourinary cancers
Merck is advancing research aimed at helping transform the treatment landscape and broaden options for people with genitourinary (GU) cancers, including bladder, kidney and prostate cancers. Globally, GU cancers account for an estimated 2.6 million new cancer diagnoses each year, equaling over 1 in 8 of all cancer incidences. Through a robust clinical development program with more than 50 ongoing clinical trials evaluating more than 22,000 patients around the world, Merck is investigating the potential of several portfolio medicines and pipeline assets, leveraging multiple novel combination strategies, across various stages of disease, to help address unmet needs in GU cancers.
About WELIREG® (belzutifan) 40 mg tablets, for oral use
WELIREG, Merck’s first-in-class hypoxia-inducible factor 2 alpha (HIF-2α) inhibitor, is an orally administered small-molecule designed to reduce transcription and expression of HIF-2α target genes associated with cellular proliferation, angiogenesis and tumor growth. By inhibiting HIF-2α signaling, WELIREG aims to disrupt key pathways certain tumors may use to adapt to low-oxygen conditions, including those that help promote abnormal blood vessel formation and support tumor survival.
WELIREG has received regulatory approvals in patients with certain von Hippel-Lindau (VHL) disease-associated tumors, renal cell carcinoma (RCC) and in pheochromocytoma or paraganglioma (PPGL). As part of a broader clinical program, Merck continues to research WELIREG monotherapy and combination approaches for people with RCC and selected solid tumors across a range of treatment settings, to further define where HIF-2a inhibition may provide clinical benefit.
WELIREG® (belzutifan) Indications in the U.S.
Certain von Hippel-Lindau (VHL) disease-associated tumors
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.
Advanced Renal Cell Carcinoma (RCC)
WELIREG is indicated for the treatment of adult patients with advanced renal cell carcinoma (RCC) with a clear cell component following a programmed death receptor-1 (PD-1) or programmed death ligand 1 (PD-L1) inhibitor and a vascular endothelial growth factor tyrosine kinase inhibitor (VEGF-TKI).
Pheochromocytoma or Paraganglioma (PPGL)
WELIREG is indicated for the treatment of adult and pediatric patients 12 years and older with locally advanced, unresectable, or metastatic pheochromocytoma or paraganglioma (PPGL).
Selected Safety Information for WELIREG
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. Monitor for anemia before initiation of, and periodically throughout, treatment. Transfuse patients as clinically indicated. For patients with hemoglobin <8 g/dL, withhold WELIREG until ≥8 g/dL, then resume at the same or reduced dose or permanently discontinue WELIREG, depending on the severity of anemia. For life-threatening anemia or when urgent intervention is indicated, withhold WELIREG until hemoglobin ≥8 g/dL, then resume at a reduced dose or permanently discontinue WELIREG.
In LITESPARK-004 (N=61), decreased hemoglobin occurred in 93% of patients with VHL disease and 7% had Grade 3 events. Median time to onset of anemia was 31 days (range: 1 day to 8.4 months).
The safety of erythropoiesis-stimulating agents (ESAs) for treatment of anemia in patients with VHL disease treated with WELIREG has not been established.
In LITESPARK-005 (n=372), decreased hemoglobin occurred in 88% of patients with advanced RCC with a clear cell component and 29% had Grade 3 events. Median time to onset of anemia was 29 days (range: 1 day to 16.6 months). Of the patients with anemia, 22% received transfusions only, 20% received ESAs only, and 12% received both transfusion and ESAs.
In LITESPARK-015, anemia occurred in 96% of patients and 22% had Grade 3 events. Median time to onset of anemia was 29 days (range: 1 day to 22.1 months). Of the patients with anemia, 20% received transfusions only, 26% received ESAs only, and 6% received both transfusion and ESAs.
Hypoxia
WELIREG can cause severe hypoxia that may require discontinuation, supplemental oxygen, or hospitalization.
Monitor oxygen saturation before initiation of, and periodically throughout, treatment. For decreased oxygen saturation with exercise (e.g., 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 dose or a reduced dose. For decreased oxygen saturation at rest (e.g., 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 hypoxia or recurrent symptomatic hypoxia, permanently discontinue WELIREG. Advise patients to report signs and symptoms of hypoxia immediately to a healthcare provider.
In LITESPARK-004, hypoxia occurred in 1.6% of patients.
In LITESPARK-005, hypoxia occurred in 15% of patients and 10% had Grade 3 events. Of the patients with hypoxia, 69% were treated with oxygen therapy. Median time to onset of hypoxia was 30.5 days (range: 1 day to 21.1 months).
In LITESPARK-015, hypoxia occurred in 13% of patients and 10% had Grade 3 hypoxia. Median time to onset of hypoxia was 35 days (range: 6 days to 23.9 months). Of the patients with hypoxia, 67% were treated with oxygen therapy.
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
Adverse Reactions in LITESPARK-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%), including laboratory abnormalities, that occurred in patients who received WELIREG were decreased hemoglobin (93%), fatigue (64%), increased creatinine (64%), headache (39%), dizziness (38%), increased glucose (34%), and nausea (31%).
Adverse Reactions in LITESPARK-005
Serious adverse reactions occurred in 38% of patients. The most frequently reported serious adverse reactions were hypoxia (7%), anemia (5%), pneumonia (3.5%), hemorrhage (3%), and pleural effusion (2.2%). Fatal adverse reactions occurred in 3.2% of patients who received WELIREG, including sepsis (0.5%) and hemorrhage (0.5%).
WELIREG was permanently discontinued due to adverse reactions in 6% of patients. Adverse reactions which resulted in permanent discontinuation (≥0.5%) were hypoxia (1.1%), anemia (0.5%), and hemorrhage (0.5%).
Dosage interruptions due to an adverse reaction occurred in 39% of patients. Of the patients who received WELIREG, 28% were 65 to 74 years, and 10% were 75 years and over. Dose interruptions occurred in 48% of patients ≥65 years of age and in 34% of younger patients. Adverse reactions which required dosage interruption in ≥2% of patients were anemia (8%), hypoxia (5%), COVID-19 (4.3%), fatigue (3.2%), and hemorrhage (2.2%).
Dose reductions due to an adverse reaction occurred in 13% of patients. Dose reductions occurred in 18% of patients ≥65 years of age and in 10% of younger patients. The most frequently reported adverse reactions which required dose reduction (≥1.0%) were hypoxia (5%) and anemia (3.2%).
The most common (≥25%) adverse reactions, including laboratory abnormalities, were decreased hemoglobin (88%), fatigue (43%), musculoskeletal pain (34%), increased creatinine (34%), decreased lymphocytes (34%), increased alanine aminotransferase (32%), decreased sodium (31%), increased potassium (29%), and increased aspartate aminotransferase (27%).
Adverse Reactions in LITESPARK-015
Serious adverse reactions occurred in 36% of patients. The most frequently reported serious adverse reactions were anemia and hypertension (4.2% each) and pyelonephritis, pneumonia, hypoxia, dyspnea and hemorrhage (2.8% each).
WELIREG was permanently discontinued due to adverse reactions in 2 patients (2.8%). Adverse reactions which resulted in permanent discontinuation were increased alanine aminotransferase and paraparesis (1.4% each).
Dosage interruptions due to an adverse reaction occurred in 40% of patients. Of the patients who received WELIREG, 13% were ≥65 years old and 4.2% were ≥75 years. Adverse reactions which required dosage interruption in >3% of patients were hypoxia, nausea and fatigue (4.2% each).
Dose reductions due to an adverse reaction occurred in 14% of patients. The most frequently reported adverse reaction which required dose reduction was hypoxia (4.2%).
The most common (≥25%) adverse reactions, including laboratory abnormalities, that occurred in patients were anemia (96%), fatigue (56%), musculoskeletal pain (56%), decreased lymphocytes (54%), increased alanine aminotransferase (51%), increased aspartate aminotransferase (42%), increased calcium (34%), dyspnea (33%), increased potassium (31%), decreased leukocytes (30%), headache (29%), increased alkaline phosphatase (25%), dizziness (26%) and nausea (25%).
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
The safety and effectiveness of WELIREG have been established in pediatric patients aged 12 years and older for the treatment of locally advanced, unresectable, or metastatic pheochromocytoma or paraganglioma.
Renal Impairment
For patients with severe renal impairment (eGFR 15-29 mL/min estimated by MDRD), monitor for increased adverse reactions and modify the dosage as recommended.
Hepatic Impairment
WELIREG has not been studied in patients with severe hepatic impairment (total bilirubin >1.5 x ULN and any AST). For patients with moderate and severe hepatic impairment, monitor for increased adverse reactions and modify the dosage as recommended.
Please see Prescribing Information, including information for the Boxed Warning about embryo-fetal toxicity, for WELIREG (belzutifan) at https://www.merck.com/product/usa/pi_circulars/w/welireg/welireg_pi.pdf and Medication Guide for WELIREG at https://www.merck.com/product/usa/pi_circulars/w/welireg/welireg_mg.pdf.
About KEYTRUDA® (pembrolizumab) injection for intravenous use, 100 mg
KEYTRUDA is an anti-programmed death receptor-1 (PD-1) therapy that works by increasing the ability of the body’s immune system to help detect and fight tumor cells. KEYTRUDA is a humanized monoclonal antibody that blocks the interaction between PD-1 and its ligands, PD- L1 and PD-L2, thereby activating T lymphocytes which may affect both tumor cells and healthy cells.
Merck has the industry’s largest immuno-oncology clinical research program. There are currently more than 1,600 trials studying KEYTRUDA across a wide variety of cancers and treatment settings. The KEYTRUDA clinical program seeks to understand the role of KEYTRUDA across cancers and the factors that may predict a patient’s likelihood of benefitting from treatment with KEYTRUDA, including exploring several different biomarkers.
About KEYTRUDA QLEX™ (pembrolizumab and berahyaluronidase alfa-pmph) injection for subcutaneous use
KEYTRUDA QLEX is a fixed-combination drug product of pembrolizumab and berahyaluronidase alfa. Pembrolizumab is a programmed death receptor-1 (PD-1) blocking antibody and berahyaluronidase alfa enhances dispersion and permeability to enable subcutaneous administration of pembrolizumab. KEYTRUDA QLEX is administered as a subcutaneous injection into the thigh or abdomen, avoiding the 5 cm area around the navel, over one minute every three weeks (2.4 mL) or over two minutes every six weeks (4.8 mL).
Selected KEYTRUDA® (pembrolizumab) Indications in the U.S.
Renal Cell Carcinoma
KEYTRUDA and KEYTRUDA QLEX are each indicated, in combination with axitinib, for the first-line treatment of adult patients with advanced renal cell carcinoma (RCC).
KEYTRUDA and KEYTRUDA QLEX are each indicated for the adjuvant treatment of adult patients with renal cell carcinoma (RCC) at intermediate high or high risk of recurrence following nephrectomy, or following nephrectomy and resection of metastatic lesions.
See additional selected KEYTRUDA indications in the U.S. after the Selected Important Safety Information.
Selected Important Safety Information for KEYTRUDA and KEYTRUDA QLEX
Contraindications
KEYTRUDA QLEX is contraindicated in patients with known hypersensitivity to berahyaluronidase alfa, hyaluronidase or to any of its excipients.
Severe and Fatal Immune-Mediated Adverse Reactions
KEYTRUDA and KEYTRUDA QLEX are monoclonal antibodies that belong to a class of drugs that bind to either the programmed death receptor-1 (PD-1) or the programmed death ligand 1 (PD-L1), blocking the PD-1/PD-L1 pathway, thereby removing inhibition of the immune response, potentially breaking peripheral tolerance and inducing immune-mediated adverse reactions. Immune-mediated adverse reactions, which may be severe or fatal, can occur in any organ system or tissue, can affect more than one body system simultaneously, and can occur at any time after starting treatment or after discontinuation of treatment.
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