Data from CD8<sup>+</sup> T-cell Responses Are Boosted by Dual PD-1/VEGFR2 Blockade after EGFR Inhibition in <i>Egfr</i>-Mutant Lung Cancer

Abstract

<div>Abstract<p>Epidermal growth factor receptor (<i>EGFR</i>) is the most frequently mutated driver oncogene in nonsmoking-related, non–small cell lung cancer (NSCLC). <i>EGFR</i>-mutant NSCLC has a noninflamed tumor microenvironment (TME), with low infiltration by CD8<sup>+</sup> T cells and, thus, immune-checkpoint inhibitors, such as antiprogrammed cell death-1 (anti–PD-1), have weak antitumor effects. Here, we showed that CD8<sup>+</sup> T-cell responses were induced by an EGFR-tyrosine kinase inhibitor (TKI) in syngeneic <i>Egfr</i>-mutant NSCLC tumors, which was further pronounced by the sequential dual blockade of PD-1 and vascular endothelial growth factor receptor 2 (VEGFR2). However, the simultaneous triple blockade had no such effect. The PD-1/VEGFR2 dual blockade did not exert tumor-inhibitory effects without pretreatment with the EGFR-TKI, suggesting that the treatment schedule is crucial for the efficacy of the dual blockade therapy. Pretreatment with EGFR-TKI increased the CD8<sup>+</sup> T-cell/regulatory T-cell (Treg) ratio, while also increasing the expression of immunosuppressive chemokines and chemokine receptors, as well as increasing the number of M2-like macrophages, in the TME. Discontinuing EGFR-TKI treatment reversed the transient increase of immunosuppressive factors in the TME. The subsequent PD-1/VEGFR2 inhibition maintained increased numbers of infiltrating CD8<sup>+</sup> T cells and CD11c<sup>+</sup> dendritic cells. Depletion of CD8<sup>+</sup> T cells <i>in vivo</i> abolished tumor growth inhibition by EGFR-TKI alone and the sequential triple therapy, suggesting that EGFR inhibition is a prerequisite for the induction of CD8<sup>+</sup> T-cell responses. Our findings could aid in developing an alternative immunotherapy strategy in patients with cancers that have driver mutations and a noninflamed TME.</p></div>