RAHWAY, NJ and TOKYO, October 28, 2025 - (JCN Newswire) - Merck & Co., Inc., Rahway, NJ, USA(known as MSD outside of the United States and Canada) and Eisai (Headquarters: Tokyo, CEO: Haruo Naito) today announced that the Phase 3 LITESPARK-011 trial evaluating the dual oral regimen of WELIREG® (belzutifan), the first-in-class oral hypoxia-inducible factor-2 alpha (HIF2α) inhibitor from Merck & Co., Inc., Rahway, NJ, USA (known as MSD outside of the United States and Canada), plus LENVIMA® (lenvatinib), an orally available multiple receptor tyrosinekinase inhibitor (TKI) discovered by Eisai, met one of its primary endpoints of progression-free survival (PFS) for the treatment of patients with advanced renal cell carcinoma (RCC) whose disease progressed on or after treatment with anti-PD-1/L1 therapy.

At a pre-specified interim analysis, WELIREG plus LENVIMA demonstrated a statistically significant and clinically meaningful improvement in PFS compared to cabozantinib in these patients. The combination also showed a statistically significant improvement in the trial’s key secondary endpoint of objective response rate (ORR) compared to cabozantinib. A trend toward improvement in overall survival (OS), the study’s other primary endpoint, was observed; however, this result did not reach statistical significance at the time of this interim analysis. OS will be tested at a subsequent analysis per the clinical protocol.

The safety profiles of WELIREG and LENVIMA in this trial were consistent with those observed in previously reported studies for the individual therapies; no new safety signals were observed. 

Merck & Co., Inc., Rahway, NJ, USA and Eisai will discuss these data with regulatory authorities worldwide and will present them at an upcoming medical meeting.

“Despite recent treatment advances, many patients with advanced RCC may still experience disease progression following treatment with a PD-1/L1 inhibitor,” said Dr. M.Catherine Pietanza, Vice President, Global Clinical Development, MSD Research Laboratories. “These positive results from LITESPARK-011 show the potential of this novel combination to reduce the risk of disease progression or death for patients who are in need of innovative options on or after treatment with immunotherapy.” 

“We are encouraged by the data observed in the LITESPARK-011 trial, which bolster our belief in the role of LENVIMA in various combinations as a treatment option for patients impacted by advanced RCC,” said Dr. Corina Dutcus, Senior Vice President, Oncology Global Clinical Development Lead at Eisai. “These results further demonstrate Eisai’s commitment to people living with advanced RCC and invigorate our mission to address the unmet needs of patients with difficult-to-treat cancers. We look forward to sharing these investigational findings with regulatory authorities worldwide, with the goal of bringing this treatment option to patients as soon as possible. We extend our heartfelt gratitude to the patients, caregivers and investigators for their participation in this study and for helping us move this important research forward.” 

LITESPARK-011 is part of a comprehensive late-stage clinical development program for WELIREG comprised of several Phase 2 and Phase 3 trials in RCC, pheochromocytoma and paraganglioma, and von Hippel-Lindau disease-associated neoplasms. The Phase 3 LITESPARK-012 trial is evaluating the addition of WELIREG to KEYTRUDA® (pembrolizumab) 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 and certain types of advanced endometrial carcinoma. 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.

For more details, please visit: https://www.eisai.com/news/2025/pdf/enews202575pdf.pdf

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