WELIREG® (belzutifan) Plus LENVIMA® (lenvatinib) Reduced the Risk of Disease Progression or Death by 30% Compared to Cabozantinib in Certain Previously Treated Patients With Advanced Renal Cell Carcinoma (RCC)

This is the first positive Phase 3 trial of a HIF-2 alpha inhibitor in combination with a multi-targeted tyrosine kinase inhibitor, the first for patients with RCC whose disease progressed on or after treatment with anti-PD-1/L1 therapy, and the first to improve PFS compared to a modern tyrosine kinase inhibitor

Based on these data, the U.S. FDA has accepted for review two supplemental New Drug Applications for WELIREG plus LENVIMA in certain previously treated patients with advanced RCC

RAHWAY, N.J. & NUTLEY, N.J.–(BUSINESS WIRE)–$MRK #MRK–Merck (NYSE: MRK), known as MSD outside of the United States and Canada, and Eisai today announced the first presentation of results from the Phase 3 LITESPARK-011 trial evaluating the dual oral regimen of WELIREG^® (belzutifan), Merck’s first-in-class oral hypoxia-inducible factor-2 alpha (HIF-2α) inhibitor, plus LENVIMA^® (lenvatinib), an orally available multiple receptor tyrosine kinase inhibitor (TKI) discovered by Eisai, for the treatment of patients with advanced renal cell carcinoma (RCC) whose disease progressed on or after treatment with anti-programmed death receptor-1 (PD-1)/programmed death-ligand 1 (PD-L1) therapy. These data are being presented as a late-breaking oral abstract at the 2026 American Society of Clinical Oncology (ASCO) Genitourinary (GU) Cancers Symposium (abstract #LBA417) and are included in the official ASCO GU Press Program.

At a pre-specified interim analysis with a median follow-up of 29.0 months (range, 19.3-49.2), WELIREG plus LENVIMA demonstrated a statistically significant and clinically meaningful improvement in the primary endpoint of progression-free survival (PFS), reducing the risk of disease progression or death by 30% (HR=0.70 [95% CI, 0.59-0.84]; p=0.00007) compared to cabozantinib. For WELIREG plus LENVIMA, the median PFS was 14.8 months (95% CI, 11.2-16.6) versus 10.7 months (95% CI, 9.2-11.1) for cabozantinib. A trend toward improvement in overall survival (OS), the trial’s other primary endpoint, was also observed for WELIREG plus LENVIMA (HR=0.85 [95% CI, 0.68-1.05]; p=0.06075). The median OS was 34.9 months (95% CI, 27.5-NR) for WELIREG plus LENVIMA versus 27.6 months (95% CI, 24.0-31.4) for cabozantinib. The trial is continuing, and OS will be evaluated at a subsequent analysis per the clinical trial protocol.

Based on data from the LITESPARK-011 trial, the U.S. Food and Drug Administration (FDA) has accepted two supplemental New Drug Applications (sNDA) for review seeking approval for WELIREG plus LENVIMA for the treatment of adult patients with advanced RCC with a clear cell component following a PD-1 or PD-L1 inhibitor. The FDA set a Prescription Drug User Fee Act (PDUFA), or target action date, of October 4, 2026 for both the WELIREG and LENVIMA sNDAs. Merck and Eisai will also discuss these data with regulatory authorities worldwide to support potential submissions outside the United States.

“Choosing the right treatment for patients with advanced renal cell carcinoma after immunotherapy has been an ongoing challenge, and treatment options in this setting had not previously been evaluated against a current standard of care tyrosine kinase inhibitor in a Phase 3 trial,” said Dr. Robert Motzer, Principal Investigator and Genitourinary Medical Oncologist, Memorial Sloan Kettering Cancer Center. “The LITESPARK-011 study demonstrated a 30% reduction in the risk of disease progression or death with belzutifan plus lenvatinib compared to cabozantinib, and 52.6% of patients experienced a response to treatment. These findings mark a critical step forward for these patients.”

“The LITESPARK-011 trial highlights the potential of this first-of-its-kind combination regimen to deliver a meaningful benefit for patients with advanced renal cell carcinoma whose disease progresses after PD-1/L1 therapy,” said Dr. M. Catherine Pietanza, Vice President, Global Clinical Development, Merck Research Laboratories. “These WELIREG plus LENVIMA data demonstrate important progress for patients with advanced renal cell carcinoma and reinforce our commitment to improving the lives of patients through innovative treatment strategies.”

“The LITESPARK-011 results reinforce LENVIMA’s established role in renal cell carcinoma and highlight the potential of this novel combination to address an area of significant unmet need,” said Dr. Corina Dutcus, Senior Vice President, Oncology Global Clinical Development Lead at Eisai. “The acceptance of this regulatory filing is an important milestone, and we remain committed to working toward approval to bring this option to patients as soon as possible. We are grateful to the patients, their families, and the investigators, whose dedication made this research possible.”

Additional findings

Data for objective response rate (ORR) and duration of response (DOR), two key secondary endpoints, were also reported. At the first interim analysis with a median follow-up of 19.6 months (range, 9.9-39.8), WELIREG plus LENVIMA met ORR, demonstrating a statistically significant improvement compared to cabozantinib. A confirmed ORR of 52.6% (95% CI, 47.3-57.7) was observed for WELIREG plus LENVIMA versus 39.6% (95% CI, 34.6-44.8) for cabozantinib. At the second interim analysis with a median follow-up of 29.0 months, the median DOR was 23.0 months (95% CI, 2.0-44.3+) for WELIREG plus LENVIMA versus 12.3 months (95% CI, 1.8+-35.9+) for cabozantinib.

WELIREG plus LENVIMA was administered to 370 patients and cabozantinib was administered to 371 patients. Grade ≥3 treatment-related adverse events (TRAEs) occurred in 71.6% of patients receiving WELIREG plus LENVIMA versus 65.8% of patients receiving cabozantinib. Adverse events led to the discontinuation of 11.1% of patients receiving WELIREG plus LENVIMA versus 11.3% of patients receiving cabozantinib, respectively. Serious adverse events were observed in 51.6% of patients receiving WELIREG plus LENVIMA versus 43.9% of patients receiving cabozantinib, and AEs led to death in 5.4% of patients (two were treatment-related: thrombotic microangiopathy [n=1] and pneumonitis [n=1]) versus 3.2% (one was treatment-related: hemoptysis [n=1]) of patients, respectively.

LITESPARK-011 is part of a comprehensive late-stage clinical development program for WELIREG comprised of several Phase 2 and Phase 3 trials in pheochromocytoma and paraganglioma, von Hippel-Lindau disease-associated neoplasms and RCC.

The Phase 3 LITESPARK-012 trial is evaluating the addition of WELIREG to KEYTRUDA^® (pembrolizumab), Merck’s anti-PD-1 therapy, plus LENVIMA in the first-line advanced RCC disease setting.

WELIREG is approved in the U.S., European Union (EU), Japan and other countries for the treatment of adult patients with advanced clear cell RCC following a PD-1/PD-L1 inhibitor and 1-2 VEGF-TKIs based on results from the Phase 3 LITESPARK-005 trial.

KEYTRUDA plus LENVIMA is approved in the U.S., the EU, Japan and other countries for the treatment of advanced RCC. Lenvatinib is approved as KISPLYX for advanced RCC in the EU.

LENVIMA in combination with everolimus is approved in the U.S., EU and other regions for the treatment of adult patients with advanced RCC following one prior anti-angiogenic therapy.

Dr. Motzer has provided consulting and advisory services for Merck and Eisai.

About LITESPARK-011

LITESPARK-011 is a randomized, open-label Phase 3 trial (ClinicalTrials.gov, NCT04586231) evaluating WELIREG in combination with LENVIMA compared to cabozantinib for the treatment of patients with advanced clear cell RCC that has progressed on or after anti-PD-1/L1 therapy. The dual primary endpoints are PFS per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1) as assessed by blinded independent central review (BICR) and OS. Key secondary endpoints include ORR per RECIST v1.1 as assessed by BICR, DOR per RECIST v1.1 as assessed by BICR, and safety. The trial enrolled 747 patients who were randomized to receive WELIREG (120 mg orally once daily) plus LENVIMA (20 mg orally once daily) or cabozantinib (60 mg orally once daily).

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 and approximately 156,000 deaths from the disease worldwide. RCC 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 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 demonstrated antitumor activity in certain von Hippel-Lindau (VHL) disease-associated tumors, renal cell carcinoma and in pheochromocytoma or paraganglioma. As part of a broader clinical program, Merck continues to research WELIREG monotherapy and combination approaches for people with genitourinary, breast and gynecologic cancers across a range of treatment settings to further define where HIF-2α inhibition may provide clinical benefit and to better understand which patients are most likely to respond.

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 LENVIMA^® (lenvatinib); available as 10 mg and 4 mg capsules

LENVIMA, discovered and developed by Eisai, is an orally available multiple receptor tyrosine kinase inhibitor that inhibits the kinase activities of vascular endothelial growth factor (VEGF) receptors VEGFR1 (FLT1), VEGFR2 (KDR), and VEGFR3 (FLT4). LENVIMA inhibits other kinases that have been implicated in pathogenic angiogenesis, tumor growth, and cancer progression in addition to their normal cellular functions, including fibroblast growth factor (FGF) receptors FGFR1-4, the platelet derived growth factor receptor alpha (PDGFRα), KIT, and RET. In syngeneic mouse tumor models, LENVIMA decreased tumor-associated macrophages, increased activated cytotoxic T cells, and demonstrated greater antitumor activity in combination with an anti-PD-1 monoclonal antibody compared to either treatment alone. The combination of LENVIMA and everolimus showed increased antiangiogenic and antitumor activity as demonstrated by decreased human endothelial cell proliferation, tube formation, and VEGF signaling in vitro and tumor volume in mouse xenograft models of human renal cell cancer greater than each drug alone.

LENVIMA^® (lenvatinib) Indications in the U.S.

• For the treatment of adult patients with locally recurrent or metastatic, progressive, radioactive iodine-refractory differentiated thyroid cancer (DTC).
• In combination with pembrolizumab, for the first-line treatment of adult patients with advanced renal cell carcinoma (RCC).

Contacts

Media Contacts:

Merck:
Julie Cunningham
(617) 519-6264

John Infanti
(609) 500-4714

Eisai:
Marie Ronda
(551) 284-9465

Investor Contacts:

Merck:
Peter Dannenbaum
(732) 594-1579

Steven Graziano
(732) 594-1583

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