Belzutifan plus cabozantinib as first-line treatment for patients with advanced clear-cell renal cell carcinoma (LITESPARK-003): an open-label, single-arm, phase 2 study

Background: Belzutifan, a first-in-class HIF-2α inhibitor, has shown antitumour activity as monotherapy and in combination with cabozantinib in patients with previously treated advanced kidney cancer. The phase 2 LITESPARK-003 study was designed to determine the antitumour activity and safety of belzutifan in combination with cabozantinib in patients with advanced clear-cell renal cell carcinoma that was previously untreated (cohort 1) or previously treated with immunotherapy (cohort 2). Here, we report results from cohort 1 of this clinical trial.

Methods: LITESPARK-003 is an open-label, single-arm, phase 2 study at ten hospitals and cancer centres in the USA. In cohort 1, eligible patients were at least 18 years of age, had an Eastern Cooperative Oncology Group performance status of 0 or 1, and had received no previous systemic therapy for locally advanced or metastatic renal cell carcinoma. Patients received belzutifan 120 mg orally once daily and cabozantinib 60 mg orally once daily until unacceptable adverse events, disease progression, or patient withdrawal. The primary endpoint was investigator-assessed confirmed objective response according to Response Evaluation Criteria in Solid Tumors version 1.1. Antitumour activity and safety were assessed in all patients who received at least one dose of study treatment. This trial is registered with ClinicalTrials.gov, NCT03634540, and is ongoing.

Findings: Between Sept 27, 2018, and Jan 10, 2023, we screened 138 patients for eligibility, and 50 (36%) were enrolled and assigned to cohort 1. The median age was 64 years (IQR 57-72). 40 (80%) of 50 patients were male and ten (20%) were female. 48 (96%) patients were White, one (2%) patient was Black or African American, and one (2%) was of a race in the other category. As of the data cutoff (May 15, 2023), median follow-up was 24·3 months (IQR 13·9-32·0). 35 (70%, 95% CI 55-82) of 50 patients had a confirmed objective response, including four (8%) who had a complete response and 31 (62%) who had a partial response. The most frequent grade 3-4 treatment-related adverse events were hypertension (six [12%] patients), anaemia (five [10%] patients), and fatigue (four [8%] patients). Seven (14%) of 50 patients had serious treatment-related adverse events. No treatment-related deaths occurred.

Interpretation: Belzutifan plus cabozantinib has promising antitumour activity in treatment-naive patients with advanced clear-cell renal cell carcinoma and further investigation of an HIF-2α inhibitor in combination with a multitargeted tyrosine kinase inhibitor as a treatment option in this population is warranted.

Funding: Merck Sharp & Dohme LLC, a subsidiary of Merck & Co, Inc, Rahway, NJ, USA, and the National Cancer Institute.