WELIREG® (belzutifan) Receives First European Commission Approval for Two Indications

Rhea-AI Summary

Merck (MRK) has received European Commission conditional approval for WELIREG® (belzutifan), the first oral HIF-2α inhibitor in the EU, for two indications: treatment of adult patients with von Hippel-Lindau (VHL) disease and advanced clear cell renal cell carcinoma (RCC).

The approval is based on the LITESPARK-004 and LITESPARK-005 trials. In VHL disease-associated RCC patients, WELIREG showed a 49% objective response rate. For CNS hemangioblastomas, the response rate was 63%, and for pNET, it reached 83%. In advanced RCC patients, WELIREG reduced disease progression or death risk by 25% versus everolimus, with a 22% objective response rate compared to 4% for everolimus.

The conditional approval will be valid for one year, subject to yearly renewal pending additional clinical data. WELIREG is now approved in over 30 countries for certain advanced RCC patients and in more than 40 countries for VHL disease-associated tumors.

Positive

• First and only systemic treatment approved in EU for VHL disease-associated tumors
• High objective response rates: 49% in RCC, 63% in CNS hemangioblastomas, 83% in pNET
• 25% reduction in disease progression or death risk vs everolimus in advanced RCC
• Expanded market presence with approvals in over 30-40 countries

Negative

• Conditional approval requires yearly renewal pending additional clinical data
• Commercial availability depends on national reimbursement procedures
• Median duration of response not reached in key trials

Insights

Pharmaceutical Industry Analyst

The European Commission's approval of WELIREG represents a significant expansion of Merck's oncology footprint in the EU market. This first-in-class HIF-2α inhibitor addresses two distinct market opportunities: the rare disease space with VHL disease-associated tumors and the larger advanced RCC market. The approval is particularly noteworthy for several reasons:

In the VHL disease indication, WELIREG demonstrated remarkable efficacy with an 83% objective response rate in pancreatic neuroendocrine tumors, 63% in CNS hemangioblastomas, and 49% in RCC. These response rates, coupled with durable responses extending beyond 12 months in many patients, position WELIREG as a transformative therapy in a disease with treatment options.

For advanced RCC, while the progression-free survival benefit appears modest (25% reduction in risk), the 22% objective response rate versus 4% for everolimus is clinically meaningful in a heavily pretreated patient population. This positions WELIREG as a valuable later-line treatment option.

The conditional approval structure, requiring yearly renewal and additional clinical data, reflects the European regulatory framework's emphasis on continuous benefit-risk assessment. This approach, while creating some uncertainty, allows earlier patient access while maintaining regulatory oversight. The timing of commercial availability will vary by country due to national reimbursement procedures, which typically take 6-12 months post-approval.

With approvals now in over 40 countries for VHL disease and 30 countries for RCC, Merck is establishing WELIREG as a global oncology asset. The EU approval significantly expands the addressable patient population and strengthens Merck's competitive position in both rare diseases and oncology.

WELIREG is the first and only oral hypoxia-inducible factor-2 alpha inhibitor approved in the European Union

RAHWAY, N.J.--(BUSINESS WIRE)-- Merck (NYSE: MRK), known as MSD outside of the United States and Canada, today announced that the European Commission (EC) has conditionally approved WELIREG^® (belzutifan), Merck’s oral hypoxia-inducible factor-2 alpha (HIF-2α) inhibitor, as monotherapy for:

• The treatment of adult patients with von Hippel-Lindau (VHL) disease who require therapy for associated, localized renal cell carcinoma (RCC), central nervous system (CNS) hemangioblastomas, or pancreatic neuroendocrine tumors (pNET), and for whom localized procedures are unsuitable;
• The treatment of adult patients with advanced clear cell RCC that progressed following two or more lines of therapy that included a programmed death receptor-1 (PD-1) or programmed death-ligand 1 (PD-L1) inhibitor and at least two vascular endothelial growth factor (VEGF) targeted therapies.

The EC approval of these two indications is based on results from the LITESPARK-004 and LITESPARK-005 trials, respectively, and follows the positive recommendation from the Committee for Medicinal Products for Human Use adopted in December 2024. This marks the first approval for WELIREG in the European Union (EU). WELIREG is now approved in over 30 countries for certain adult patients with previously treated advanced RCC and in more than 40 countries for adult patients with certain eligible VHL disease-associated tumors.

“The approval of WELIREG in the EU introduces the first and only systemic treatment option for adult patients with certain VHL disease-associated tumors for whom localized procedures are unsuitable, and offers a new option for adult patients with advanced clear cell renal cell carcinoma that progressed following a PD-1 or PD-L1 inhibitor and at least two VEGF targeted therapies,” said Dr. Marjorie Green, senior vice president and head of oncology, global clinical development, Merck Research Laboratories. “This is an important moment, and we are pleased that WELIREG, a first-in-class HIF-2α inhibitor, can now potentially help these patients in need.”

This approval allows marketing of WELIREG for these indications in all 27 EU member states, as well as Iceland, Liechtenstein and Norway. The conditional approval of WELIREG will be valid for one year, subject to yearly renewal, pending additional clinical data from LITESPARK-004 and another ongoing Phase 2 trial of WELIREG in patients with certain VHL disease-associated tumors. Timing for commercial availability of WELIREG in individual EU countries will depend on multiple factors, including the completion of national reimbursement procedures.

Results in Patients With Certain Eligible VHL Disease-associated Tumors (LITESPARK-004)

WELIREG is now the first and only systemic therapy for the treatment of VHL disease-associated tumors in the EU. The approval in adult patients with certain eligible VHL disease-associated tumors is based on objective response rate (ORR) and duration of response (DOR) results from the LITESPARK-004 trial.

WELIREG was approved in the U.S. in August 2021 for the treatment of adult patients with VHL disease who require therapy for associated RCC, CNS hemangioblastomas or pNET not requiring immediate surgery based on the results from LITESPARK-004. In patients with VHL disease-associated RCC (n=61), WELIREG showed an ORR of 49% (95% CI, 36-62) (n=30/61); all responses were partial responses (PR). Median DOR for these patients was not reached, with ongoing responses ranging from 2.8+ to 22+ months; among responders, 56% (n=17/30) maintained a response for at least 12 months. Among these 61 patients, the study also evaluated response rates in other common disease-associated tumors including CNS hemangioblastomas and pNET. In patients with VHL disease-associated CNS hemangioblastomas (n=24) in this trial, WELIREG showed an ORR of 63% (95% CI, 41-81) (n=15/24), with a complete response (CR) rate of 4% (n=1/24) and a PR rate of 58% (n=14/24). Median DOR for these patients was not reached, with ongoing responses ranging from 3.7+ to 22+ months; among responders, 73% (n=11/15) maintained a response for at least 12 months. In patients with VHL disease-associated pNET (n=12) in this trial, WELIREG showed an ORR of 83% (95% CI, 52-98) (n=10/12), with a CR rate of 17% (n=2/12) and a PR rate of 67% (n=8/12). Median DOR for these patients was not reached, with ongoing responses ranging from 11+ to 19+ months; among responders, 50% (n=5/10) maintained a response for at least 12 months.

Results in Certain Patients With Previously Treated Advanced RCC (LITESPARK-005)

The approval in adult patients with advanced clear cell RCC that progressed following two or more lines of therapy, including a PD-1 or PD-L1 inhibitor and at least two VEGF targeted therapies, is based on progression-free survival (PFS) and ORR results from the LITESPARK-005 trial, which was the first trial in advanced RCC to specifically evaluate patients who progressed following these treatments.

WELIREG was approved in the U.S. in December 2023 for the treatment of adult patients with advanced RCC following both a PD-1 or PD-L1 inhibitor and a VEGF-tyrosine kinase inhibitor based on the results from LITESPARK-005. In the trial, WELIREG reduced the risk of disease progression or death by 25% (HR=0.75 [95% CI, 0.63-0.90]; p=0.0008) versus everolimus. Median PFS was 5.6 months (95% CI, 3.9-7.0) for WELIREG versus 5.6 months (95% CI, 4.8-5.8) for everolimus. The ORR for WELIREG was 22% (n=82) (95% CI, 18-27), with a CR rate of 3% (n=10) and a PR rate of 19% (n=72), and the ORR for everolimus was 4% (n=13) (95% CI, 2-6), with no patients achieving a CR and a PR rate of 4% (n=13).

About LITESPARK-004

LITESPARK-004 is an open-label Phase 2 trial (ClinicalTrials.gov, NCT03401788) evaluating WELIREG for the treatment of patients with VHL disease who had at least one measurable solid tumor localized to the kidney and who did not require immediate surgery. The study enrolled 61 patients who received WELIREG (120 mg orally once daily) until disease progression or unacceptable toxicity. The primary endpoint is ORR in VHL disease-associated RCC. Secondary endpoints include, DOR, time to response, PFS, time to surgery and safety. Additionally, this study evaluated response rates in other common VHL disease-associated tumors including pNET and CNS hemangioblastomas.

About LITESPARK-005

LITESPARK-005 is an open-label, randomized, active-controlled Phase 3 trial (ClinicalTrials.gov, NCT04195750) evaluating WELIREG compared to everolimus for the treatment of patients with unresectable, locally advanced or metastatic clear cell RCC that progressed following PD-1 or PD-L1 checkpoint inhibitor and VEGF receptor targeted therapies either in sequence or in combination. The trial enrolled 746 patients who were randomized to receive WELIREG (120 mg orally once daily) or everolimus (10 mg orally once daily). The dual primary endpoints are PFS and overall survival. Secondary endpoints include ORR, DOR and safety.

About von Hippel-Lindau disease

Von Hippel-Lindau disease is a rare genetic disease, which impacts an estimated 200,000 people worldwide and an estimated 10,000 to 15,000 people in Europe. Patients with VHL disease are at risk for recurrent, benign blood vessel tumors as well as some cancerous ones. One of the most commonly occurring tumors is RCC, a form of kidney cancer, which occurs in about 70% of patients with VHL disease.

About renal cell carcinoma

Renal cell carcinoma is by far the most common type of kidney cancer. Clear cell RCC is considered the most common form of RCC, representing about 70% of all cases. In 2020, more than 130,000 new cases of RCC were diagnosed in Europe. Renal cell carcinoma is about twice as common in men than in women. Approximately 30% of patients with kidney cancer are diagnosed at an advanced stage.

About WELIREG^® (belzutifan) 40 mg tablets, for oral use

Indications in the U.S.

Certain von Hippel-Lindau (VHL) disease-associated tumors

WELIREG (belzutifan) 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) 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).

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 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.

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 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 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).

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 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%).

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%) 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 (33%), increased creatinine (34%), decreased lymphocytes (34%), increased alanine aminotransferase (32%), decreased sodium (31%), increased potassium (29%), and increased aspartate aminotransferase (27%).

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.

Merck’s focus on cancer

Every day, we follow the science as we work to discover innovations that can help patients, no matter what stage of cancer they have. As a leading oncology company, we are pursuing research where scientific opportunity and medical need converge, underpinned by our diverse pipeline of more than 25 novel mechanisms. With one of the largest clinical development programs across more than 30 tumor types, we strive to advance breakthrough science that will shape the future of oncology. By addressing barriers to clinical trial participation, screening and treatment, we work with urgency to reduce disparities and help ensure patients have access to high-quality cancer care. Our unwavering commitment is what will bring us closer to our goal of bringing life to more patients with cancer. For more information, visit https://www.merck.com/research/oncology/.

About Merck

At Merck, known as MSD outside of the United States and Canada, we are unified around our purpose: We use the power of leading-edge science to save and improve lives around the world. For more than 130 years, we have brought hope to humanity through the development of important medicines and vaccines. We aspire to be the premier research-intensive biopharmaceutical company in the world – and today, we are at the forefront of research to deliver innovative health solutions that advance the prevention and treatment of diseases in people and animals. We foster a diverse and inclusive global workforce and operate responsibly every day to enable a safe, sustainable and healthy future for all people and communities. For more information, visit www.merck.com and connect with us X (formerly Twitter), Facebook, Instagram, YouTube and LinkedIn.

Forward-Looking Statement of Merck & Co., Inc., Rahway, N.J., USA

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Risks and uncertainties include but are not limited to, general industry conditions and competition; general economic factors, including interest rate and currency exchange rate fluctuations; the impact of pharmaceutical industry regulation and health care legislation in the United States and internationally; global trends toward health care cost containment; technological advances, new products and patents attained by competitors; challenges inherent in new product development, including obtaining regulatory approval; the company’s ability to accurately predict future market conditions; manufacturing difficulties or delays; financial instability of international economies and sovereign risk; dependence on the effectiveness of the company’s patents and other protections for innovation products; and the exposure to litigation, including patent litigation, and/or regulatory actions.

The company undertakes no obligation to publicly update any forward-looking statement, whether as a result of new information, future events or otherwise. Additional factors that could cause results to differ materially from those described in the forward-looking statements can be found in the company’s Annual Report on Form 10-K for the year ended December 31, 2023 and the company’s other filings with the Securities and Exchange Commission (SEC) available at the SEC’s Internet site (www.sec.gov).

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.

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Source: Merck & Co., Inc.

FAQ

What are the two indications approved for WELIREG (MRK) in the European Union?

WELIREG is approved for VHL disease-associated tumors and advanced clear cell RCC that progressed following two or more lines of therapy.

What is the objective response rate of WELIREG (MRK) in VHL disease-associated RCC patients?

In VHL disease-associated RCC patients, WELIREG showed an objective response rate of 49%, with all responses being partial responses.

How does WELIREG (MRK) perform compared to everolimus in advanced RCC treatment?

WELIREG reduced disease progression or death risk by 25% versus everolimus, with a 22% objective response rate compared to 4% for everolimus.

How long is WELIREG's (MRK) conditional approval valid in the EU?

The conditional approval is valid for one year and subject to yearly renewal, pending additional clinical data from ongoing trials.

What was the response rate of WELIREG (MRK) in VHL disease-associated pNET patients?

In VHL disease-associated pNET patients, WELIREG showed an 83% objective response rate, with 17% complete response and 67% partial response rates.