Merck has reported that the Phase III LITESPARK-005 trial of WELIREG for the treatment of advanced renal cell carcinoma (RCC) has met its primary endpoint of progression-free survival (PFS).

The randomised, open-label study compared 120mg WELIREG, an oral hypoxia-inducible factor-2 alpha (HIF-2α) inhibitor, against 10mg everolimus.

A total of 746 patients with RCC that progressed following PD-1/L1 checkpoint inhibitor and vascular endothelial growth factor-tyrosine kinase inhibitor (VEGF-TKI) therapies were randomised to receive the oral treatment once-daily with WELIREG and everolimus.

A statistically significant and clinically meaningful improvement in PFS was observed in these patients.

This observation was based on a pre-specified interim analysis, conducted by an independent data monitoring committee.

Improvement in overall survival, a dual primary endpoint, was also observed.

The trial’s secondary endpoints of objective response rate, duration of response, safety and tolerability were also met during the study.

WELIREG's safety profile was found to be consistent in comparison to previously conducted studies.

Merck Research Laboratories global clinical development, late-stage oncology head and senior vice-president Dr Marjorie Green said: “This is the first Phase III trial to show positive results in advanced RCC following these therapies and the first new mechanism to demonstrate potential in advanced RCC in recent years.

“We look forward to discussing these results with health authorities.”

The LITESPARK-005 study is a part of the company’s development programme for WELIREG that also comprises other Phase III trials in RCC.

They include LITESPARK-011 and LITESPARK-012 evaluating WELIREG in the second-line and treatment-naive advanced disease settings, and LITESPARK-022 in the adjuvant setting.

WELIREG is currently approved in the UK, the US, Canada and several other countries to treat adult patients with von Hippel-Lindau disease.