Biomarker analysis of zanzalintinib in clear cell renal cell carcinoma from STELLAR-001.

Abstract

4545 Background: Zanzalintinib (zanza) is a novel oral multi-targeted TKI that inhibits several receptors, including VEGFR, MET, and TAM kinases. In an expansion cohort of previously treated patients (pts) with clear cell renal cell carcinoma (ccRCC) from the phase 1b STELLAR-001 study (NCT03845166), single-agent zanza showed encouraging activity (ORR, 38%; disease control rate, 88%), with responses seen in VEGFR TKI–pretreated pts, and a manageable safety profile (Pal, IKCS NA 2023:Abs 1). Here, we investigate biomarkers associated with zanza from the STELLAR-001 ccRCC expansion cohort. Methods: Adult pts (N=32) with advanced ccRCC, ECOG ≤1, and 1–3 prior systemic anticancer therapies received zanza 100 mg once daily until unacceptable toxicity or no longer deriving clinical benefit. Circulating plasma biomarkers and immune cell populations in blood were assessed at baseline and on-study. IHC for AXL, c-Met, phosphorylated Met, and VEGFR2 was performed on archival tissue. Associations between response to zanza and biomarker levels (at baseline and treatment-related changes) were investigated by comparing zanza responders (CR/PR; n=10) and non-responders (SD/PD; n=19). The relation between baseline biomarker levels and prior exposure to VEGFR TKI was also evaluated. P values were determined using a Wilcoxon test ( P<0.05 considered significant). Results: Zanza elicited significant changes in soluble biomarkers related to angiogenesis, tumor growth and metastasis, and immune modulation, including an increase in the circulating ligands VEGF ( P<0.001) and GAS6 ( P<0.001); decreases in ANG-1 ( P<0.001) and ANG-2 ( P<0.001), and the soluble angiogenic receptors, VEGFR2 ( P<0.001) and TIE-2 ( P<0.001). A decrease in levels of the chemokine, RANTES ( P<0.001), and an increase in IFNγ ( P=0.039) and the pro-apoptotic protein, granzyme B ( P<0.001) were also observed. An analysis of immune cell subsets showed that zanza raised activated cytotoxic T cell numbers ( P=0.002). Reductions in monocytes ( P=0.001), along with immunosuppressive subsets (total MDSCs [ P=0.013] and granulocytic MDSCs [ P=0.014]) were also observed. Response to zanza was associated with lower baseline levels of plasma biomarkers including CRP ( P=0.025) and HGF ( P=0.017), but not with any tissue biomarkers or zanza-mediated changes in immune cells or plasma biomarkers tested. Lower baseline levels of VEGFR2 were observed in pts with prior VEGFR TKI exposure ( P=0.042). Conclusions: Zanza in pts with advanced ccRCC leads to modulation of plasma biomarkers associated with angiogenesis and peripheral immune cell subsets consistent with its expected mechanism of action. The reduction in immunosuppressive immune cells and activation of effector immune cells by zanza support the rationale for combining zanza with immune checkpoint inhibitors. Given the small sample sizes, further investigation in larger studies is warranted. Clinical trial information: NCT03845166 .