Exelixis and Merck Advance LITESPARK-033: A New Kidney Cancer Combo With High-Stakes Market Potential

Exelixis (EXEL) announced an update on their ongoing clinical study.

Study Overview

The LITESPARK-033 study, formally titled “A Phase 3, Randomized, Open-label Study of Belzutifan + Zanzalintinib Versus Cabozantinib in Participants With Advanced RCC Who Experienced Disease Recurrence During or After Prior Adjuvant Anti-PD-1/L1 Therapy,” is testing a new treatment option for people with advanced kidney cancer that has returned after modern immunotherapy. The main goal is to see if the drug combo belzutifan plus zanzalintinib helps patients live longer and stay free from cancer growth compared with the current standard drug cabozantinib, a result that could reshape treatment choices in this high‑need setting.

Intervention/Treatment

The study compares two oral treatment approaches. The experimental arm uses belzutifan and zanzalintinib, both taken once daily, designed to block key cancer growth pathways and limit tumor survival. The control arm uses cabozantinib, also taken once daily, a well-known targeted drug already approved in advanced kidney cancer. All medicines are pills, which makes them easier to use in routine practice if results are positive.

Study Design

This is an interventional Phase 3 trial where participants are randomly assigned to either the belzutifan plus zanzalintinib combo or cabozantinib alone. The design is “parallel,” meaning each group stays on its assigned treatment for the study’s duration. The trial is open-label, so both doctors and patients know which treatment is being given. The main purpose is treatment-focused: to measure survival and time without disease worsening, and to see if the new combo can outperform a current standard of care.

Study Timeline

The trial was first submitted in November 2025, marking the formal start of regulatory and site activation activities. The primary completion date, when the main survival and progression data should mature, has not been posted yet but will be key for any major data readout and stock-moving headlines. The estimated study completion date will follow after longer follow-up and safety tracking, setting the window for full data and potential label discussions. The most recent update was submitted on December 18, 2025, confirming that the protocol and status remain current and that recruitment is ongoing.

Market Implications

For investors, this study is important because it ties Exelixis directly to Merck’s belzutifan strategy in recurrent kidney cancer, an area with rising use of adjuvant immunotherapy and growing need for effective follow-on treatments. Positive results would strengthen Exelixis’s position in renal cell carcinoma beyond its existing cabozantinib franchise, potentially offsetting future competitive pressure if cabozantinib is outperformed in this setting. For Merck, a win would expand belzutifan’s reach and support a broader kidney cancer portfolio. On the other hand, if cabozantinib holds its own, Exelixis could defend current market share and delay displacement by newer regimens. The trial also sits within an active competitive field that includes Bristol Myers Squibb, Pfizer, and others in kidney cancer, so any strong data could quickly shift prescribing trends and investor sentiment across the group. Overall, the ongoing update signals continued investment in this combo and keeps the renal oncology pipeline a focus area for growth investors tracking Exelixis and its partners.

The LITESPARK-033 study is currently recruiting and remains active, with further details and updates available on the ClinicalTrials.gov portal.

To learn more about EXEL’s potential, visit the Exelixis drug pipeline page.