Abstract C039: The impact of antiangiogenic therapy on blood vessels and CD8 infiltration in renal cancer metastases is space, time, site, dose, and drug dependent

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Abstract Clear cell renal cell carcinoma (ccRCC) is the most prevalent renal neoplasm, with bone as a major site for distant spread in 35% to 40% of the patients. These metastases are typically osteolytic, resistant to treatments, hence result in a variety of skeletal-related complications strongly contributing to mortality. A key feature of ccRCC is the loss of function of the von Hippel–Lindau (VHL) protein leading to extensive angiogenesis. Consequently, different anti-angiogenic tyrosine kinase inhibitors (TKIs) are used as the first or subsequent line of treatment for these patients as single agents or in combination with immune checkpoint inhibitors. However, limited data about their efficacy in bone metastasis is available, and their impact on the immune infiltrate, including effector CD8 cells, is unclear. We hypothesized that TKIs, by inhibiting angiogenesis, significantly reprogram the microenvironment and limit immune infiltration in space, time, dose, and drug dependent fashion. To test these hypotheses, we developed an immunocompetent mouse model of bone metastasis by orthotopical intratibial implantation of luciferase-GFP-positive mouse RENCA-VHL- cell line. Interestingly, intratibial injections gave rise to metastases in lungs, creating a unique opportunity to study two metastatic sites. Three different TKIs currently used in patients were tested and compared to control: axitinib (A), cabozantinib (C), and lenvantinib (L). Outcomes were monitored by macroscopic bioluminescence detection in vivo, 3D multiparametric spatial analysis of bones and lungs, in vivo, and ex vivo. Compared to control-treated mice, high doses of A, C, and L significantly reduced tumor progression in both tumor sites. Even though these TKIs are clinically considered equal, significant differences in their efficacy were noted. Spatial analysis of tumor cells and blood vessels showed a significant decrease in blood vessels formation in both an organ- and TKI-specific pattern over time. Additionally, the reduction of neo angiogenesis in treated tumors directly limited the infiltration of CD8 cells, which localized at the interface with tumor free bone/lung tissue. Interestingly, TKI dose reduction significantly improved CD8 infiltration, while controlling tumor size. TKI withdrawal, instead, led to rapid progression of tumor in both sites and significantly shortened mice survival. In conclusion, we established bone and lung metastatic models of ccRCC and characterized and compared the effects of three antiangiogenic TKIs on angiogenesis and CD8 infiltration. TKIs reduced tumor growth and progression, because of blood vessel formation inhibition. Furthermore, TKI treatment reduced the infiltration of effector T cells in tumors in a dose-dependent manner, an outcome that can have a major impact when TKIs are combined with immunotherapy, a preferential therapeutic regimen for ccRCC patients. Overall, we believe our studies provide important insights and efficacy predictions for innovative therapeutic applications in ccRCC bone metastatic patients. Citation Format: Stefan Maksimovic, Nina Costanza Boscolo, Ludovica La Posta, Matthew T. Campbell, Eleonora Dondossola. The impact of antiangiogenic therapy on blood vessels and CD8 infiltration in renal cancer metastases is space, time, site, dose, and drug dependent [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr C039.