Merck and Exelixis Initiate Phase 3 Trial of Belzutifan and Zanzalintinib Combination Therapy for Recurrent Renal Cell Carcinoma
LITESPARK-033 Phase 3 Trial Initiated for Patients Who Failed Prior Adjuvant Therapy
Merck & Co. (MRK) and Exelixis (EXEL) have initiated a global Phase 3 clinical trial (LITESPARK-033 / MK-6482-033) involving 904 patients with recurrent, advanced clear cell renal cell carcinoma (ccRCC) after failing Anti-PD-1/L1 adjuvant therapy. Patients with high-risk disease who have experienced recurrence after prior adjuvant therapy have very limited subsequent treatment options, representing a significant unmet medical need. This study aims to demonstrate superior survival benefits compared to cabozantinib, the current global standard of care.
Dual Inhibition Mechanism Targeting HIF-2α and Multiple TKIs
Belzutifan (Welireg), administered in the clinical trial, is an innovative new drug that targets and inhibits hypoxia-inducible factor-2 alpha (HIF-2α), which induces angiogenesis and proliferation of cancer cells. In combination with zanzalintinib (XL092), Exelixis' next-generation oral tyrosine kinase inhibitor (TKI), the combination simultaneously blocks multiple signaling pathways, including MET, AXL, and VEGFR. This complementary mechanism is a next-generation combination designed to overcome tumor drug resistance and significantly improve anti-cancer response rates.
Direct Competition with the Global Standard of Care, Cabozantinib
This Phase 3 clinical trial is designed as a 1:1 randomized study comparing the combination therapy to cabozantinib (Cabometyx) 60mg, the current second-line standard of care. Progression-free survival (PFS) and overall survival (OS), as assessed by an independent central review committee (BICR), are designated as dual primary endpoints. Objective response rate (ORR) and duration of response (DOR) will also be evaluated as key secondary endpoints.
Restructuring the $9 Billion Renal Cell Carcinoma Market and Merck's Oncology Portfolio
The global renal cell carcinoma (RCC) treatment market is expected to grow to approximately $9.4 billion in 2026 and continue to expand through 2030. In preparation for the patent expiration of its blockbuster immune checkpoint inhibitor, Keytruda, Merck is rapidly expanding its new combination clinical ecosystem centered around Welireg. The results of this trial will be a critical turning point in determining the commercial value of Exelixis' zanzalintinib and Merck's leadership in the targeted cancer therapy market.
The LITESPARK-033 Phase 3 trial directly targets the second-line standard of care position held by Exelixis' cabozantinib (Cabometyx) in the global renal cell carcinoma (RCC) market, which is valued at over $9 billion in 2026. The combination of Merck's HIF-2α inhibitor, belzutifan (Welireg), and Exelixis' next-generation TKI, zanzalintinib (XL092), will be evaluated in 904 patients who have failed prior Anti-PD-1/L1 adjuvant therapy, with the primary endpoints of progression-free survival (PFS) and overall survival (OS). In the short term, this trial will serve as a key indicator for Exelixis (EXEL) to defend its existing cabozantinib sales and validate the commercial value of its next-generation pipeline, zanzalintinib. In the medium to long term, this trial will provide a strategic opportunity for Merck & Co. (MRK) to solidify its leadership in the renal cell carcinoma market with a new generation of targeted combination therapies based on belzutifan, in anticipation of the Keytruda patent expiration in 2028. The results will have a direct impact on the future revision of treatment guidelines (NCCN) for targeted therapies and immune checkpoint inhibitor adjuvant therapy failures, as well as the approval of new drugs (FDA).
Source: ClinicalTrials.gov (api_ct)