On April 21, 2026 Merck (NYSE: MRK), known as MSD outside of the United States and Canada, and Eisai reported results from the Phase 3 LITESPARK-012 trial evaluating combination regimens for the first-line treatment of patients with advanced clear cell renal cell carcinoma (RCC). The trial evaluated the triplet therapy of KEYTRUDA (pembrolizumab), Merck’s anti-PD-1 therapy, plus LENVIMA (lenvatinib), the orally available multiple receptor tyrosine kinase inhibitor (TKI) discovered by Eisai, plus WELIREG (belzutifan), Merck’s first-in-class, oral hypoxia-inducible factor-2 alpha (HIF-2α) inhibitor. The study also evaluated MK-1308A, the coformulation of KEYTRUDA and quavonlimab, Merck’s investigational anti-CTLA-4 antibody, plus LENVIMA. Both combination regimens were compared to KEYTRUDA plus LENVIMA for these patients.

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At a pre-specified interim analysis, the combination regimens did not meet the dual primary endpoints of progression-free survival (PFS) and overall survival (OS) for the first-line treatment of patients with RCC compared to KEYTRUDA plus LENVIMA. The safety profiles of the combination regimens were consistent with those observed in previously reported studies evaluating the individual medicines and the KEYTRUDA plus LENVIMA combination. A full evaluation of the data from this study is ongoing, and Merck and Eisai will work with investigators to share the results with the scientific community.

"With the LITESPARK-012 trial, we explored whether combining therapies with established activity could improve upon well-established standards set by KEYTRUDA-based regimens, reflecting our commitment to continuously explore ways to improve outcomes for the kidney cancer community," said Dr. M. Catherine Pietanza, Vice President, Global Clinical Development, Merck Research Laboratories. "While these regimens did not demonstrate the results we hoped, the data deepen our understanding of advanced renal cell carcinoma and will help shape the next generation of treatment approaches."

"While we are disappointed that LITESPARK-012 did not meet its primary endpoints, the findings reinforce the central role of KEYTRUDA plus LENVIMA in the first-line treatment of patients with advanced renal cell carcinoma," said Dr. Corina Dutcus, Senior Vice President, Oncology Global Clinical Development Lead at Eisai Inc. "Findings from trials such as this play an important role in shaping health care providers’ perspectives as the treatment paradigm for advanced renal cell carcinoma continues to evolve. We are committed to advancing the care of people living with this disease and we are grateful to the patients, caregivers and investigators whose participation and dedication made this research possible."

Results from the LITESPARK-012 trial do not affect other ongoing trials from the LITESPARK clinical program, including those conducted jointly with Eisai. As previously announced, the U.S. Food and Drug Administration (FDA) has accepted two supplemental New Drug Applications (sNDA) for review based on the Phase 3 LITESPARK-011 trial evaluating WELIREG in combination with LENVIMA for certain previously treated patients with advanced RCC and has set a Prescription Drug User Fee Act (PDUFA), or target action, date of Oct. 4, 2026.

KEYTRUDA is currently approved as adjuvant monotherapy and in combination regimens for appropriate patients with RCC in the U.S., European Union (EU), Japan and other countries around the world. For more information, please see the "Selected KEYTRUDA (pembrolizumab) Indications in the U.S." section below.

KEYTRUDA plus LENVIMA is approved in the U.S., EU, Japan and other countries for the first-line treatment of adult patients with 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.

WELIREG is approved in the U.S., 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.

About LITESPARK-012

LITESPARK-012 is a randomized, open-label Phase 3 trial (ClinicalTrials.gov, NCT04736706) evaluating either the triplet therapy of KEYTRUDA plus LENVIMA plus WELIREG or MK-1308A plus LENVIMA compared to KEYTRUDA plus LENVIMA for the first-line treatment of patients with advanced clear cell RCC. The primary endpoints are PFS, as assessed by blinded independent central review (BICR) according to Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1) modified to follow a maximum of 10 target lesions and a maximum of 5 target lesions per organ, and OS. Secondary endpoints are objective response rate and duration of response as assessed by BICR according to RECIST v1.1, as well as safety. The study enrolled 1,688 patients who were randomized to receive:

KEYTRUDA (400 mg intravenously [IV] every six weeks [Q6W]) plus LENVIMA (20 mg orally once daily [QD]) plus WELIREG (120 mg orally QD);
MK-1308A (coformulation of pembrolizumab [400 mg] and quavonlimab [25 mg] IV Q6W) plus LENVIMA (20 mg orally QD);
KEYTRUDA (400 mg IV Q6W) plus LENVIMA (20 mg orally QD).
All study drugs were continued until protocol-specified discontinuation criteria. KEYTRUDA and MK-1308A were administered for up to two years (approximately 18 cycles). WELIREG and LENVIMA may have been administered in combination or as a single agent until progressive disease or discontinuation.

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, and about 70% are a form called clear cell RCC, which tends to be more aggressive and faster spreading. Approximately 30% of patients with kidney cancer are diagnosed at an advanced stage.

(Press release, Eisai, APR 21, 2026, View Source [SID1234664608])