BACKGROUND

Sitravatinib, an oral multi-kinase inhibitor targeting VEGFR, TAM, and MET, has been shown to resensitize the tumor microenvironment to immune checkpoint inhibitors (ICI) by reducing immune-suppressive myeloid cells in metastatic clear cell RCC (ccRCC). ICI is the standard first-line (1L) treatment of metastatic ccRCC, and there is unmet need for improved treatment outcomes after progression on ICI. We hypothesized that sitravatinib plus nivolumab would revert an immunosuppressive tumor microenvironment (TME) to improve clinical outcomes.

METHODS

In this investigator-initiated, phase II, multicenter trial (NCT04904302), patients with progressive metastatic ccRCC after 1-2 lines of treatment were enrolled into 3 cohorts: (1) 1L nivolumab + ipilimumab, (2) 1L pembrolizumab + axitinib, (3) prior cabozantinib or lenvatinib and ICI. Starting dose of sitravatinib was 100 mg PO daily and nivolumab was 480 mg IV every 4 weeks. The co-primary endpoints were objective response rate (ORR) and disease control rate (DCR) at 24 weeks. The study was designed to enroll 88 patients with an interim analysis for futility in each cohort using a BOP2 design, but it was terminated early due to discontinuation of sitravatinib development.

RESULTS

Fourteen patients were enrolled with 2 in cohort A, 6 in cohort B, and 6 in cohort C. Across all cohorts, the ORR was 15.4% (2/13, 1 not evaluable) and DCR at 24 weeks was 35.7% (5/14). DCR at 24 months was 63% for Cohort A + B and 0% for Cohort C. Median progression free survival was 5.5 mo [95% CI 3.8-not reached (NR)], and median overall survival was 13.3 mo (95% CI 8.77-NR). Six patients (42.9%) experienced a grade 3-4 adverse event (AE) and 2 patients (14.3%) experienced an immune-mediated AE.

CONCLUSION

In this small phase 2 trial with limited sample size due to early termination, sitravatinib plus nivolumab demonstrated a manageable safety profile and produced modest clinical benefit. The observed responses occurred in patients who did not receive prior treatment with cabozantinib or lenvatinib. (ClinicalTrials.gov Identifier: NCT04904302).