Merck’s Combo Therapy KEYTRUDA + WELIREG Hits Primary Endpoint in Kidney Cancer Adjuvant Trial (LITESPARK-022)

Merck (known as MSD outside North America) has announced positive top-line results from its Phase 3 LITESPARK-022 trial, investigating a new combination regimen for patients with high-risk kidney cancer.

The study met its primary endpoint, showing a statistically significant and clinically meaningful improvement in disease-free survival (DFS) when KEYTRUDA combined with WELIREG was given as an adjuvant (post-surgery) treatment, compared to KEYTRUDA plus placebo.

The Trial and Combination Therapy

Trial: LITESPARK-022
Disease: Clear Cell Renal Cell Carcinoma (RCC) following nephrectomy (kidney removal surgery). This is the most common and aggressive form of kidney cancer.
Regimen Tested: KEYTRUDA (pembrolizumab, a PD-1 inhibitor) combined with WELIREG (belzutifan, an oral HIF-2α inhibitor).
Primary Endpoint Met: Disease-Free Survival (DFS), meaning the combination significantly delayed the time until the cancer returned or the patient died.
Next Steps: The trial will continue to monitor the key secondary endpoint, Overall Survival (OS).

Significance of the Finding

This combination aims to improve outcomes for a patient population that remains at high risk of recurrence even after surgery.

Current Standard: KEYTRUDA monotherapy (used alone) is already an approved and important adjuvant treatment for RCC, based on the KEYNOTE-564 trial, making it the only option proven to improve both DFS and OS in this setting.
Addressing Unmet Need: The addition of WELIREG, a first-in-class HIF-2α inhibitor, targets a different biological pathway (hypoxia-inducible factor), offering a synergistic approach to prevent cancer recurrence. Dr. M. Catherine Pietanza of Merck noted that these results “demonstrate the potential to provide additional treatment options for those most in need.”
Safety: The safety profile of the combination was reported to be consistent with previously known safety profiles for the individual drugs.

Future Plans

Merck plans to present the detailed results of the LITESPARK-022 trial at a future medical meeting and will share the data with regulatory authorities worldwide to explore potential approval for this new adjuvant regimen.