Dynamics of resistance to immunotherapy and TKI in patients with advanced renal cell carcinoma

Immune-based combinations are the cornerstone of the first-line treatment of metastatic renal cell carcinoma patients, leading to outstanding outcomes. Nevertheless, primary resistance and disease progression is a critical clinical challenge. To properly address this issue, it is pivotal to understand the mechanisms of resistance to immunotherapy and tyrosine kinase inhibitors, that tumor eventually develop under treatment. In this review of the literature, we aim at exploring resistance mechanisms arising in patients treated with first-line immune-based combinations in order to understand the biological pattern that should be investigated to overcome them. In more detail, mechanisms of resistance to nivolumab and pembrolizumab are divided into intrinsic to cancer cells and extrinsic (stromal or immune cells). Regarding axitinib, the increased expression of Nuclear protein 1 (NUPR1) or decreased levels of insulin receptor (INSR) characterize resistant cells. The secretion of non-VEGF pro-angiogenic factors, such as PDGF-BB, IL-1β, MMP-9, Gro-α, IL-8, IL-6, and CCL-2, can lead to resistance to cabozantinib. The reactivation of pathways previously targeted by lenvatinib or the activation of alternative pathways, such as EGFR-PAK2-ERK pathway, underlie the development of resistance to lenvatinib. Exploring resistance mechanism that arise during first-line therapy can lead to the development of treatment strategy able to overcome them in order to improve duration of response and patients outcomes.