Abstract 965: Eribulin promotes a distinct immunogenic gene expression signature as compared with paclitaxel

Abstract

Abstract Microtubule targeted agents (MTAs) are a mainstay in the treatment of breast cancer and they are often used in combination with targeted agents, including immunotherapies. Although patients with triple-negative breast cancers (TNBCs) have historically had poorer clinical outcomes due in part to a lack of targeted therapeutic options, these cancers are often more immunogenic than other types of breast cancer. Recently, the combination of the PD-L1 inhibitor atezolizumab with the taxane nab-paclitaxel was found to prolong progression-free survival in patients with metastatic TNBC. Other combinations of MTAs and immune checkpoint inhibitors are actively being evaluated in clinical trials. There is a mechanistic rationale for this combination because paclitaxel is a direct TLR4 agonist that promotes activation of the innate immune system. To date, there has not been a comprehensive comparison of the immunomodulatory effects of different MTAs on immune cells or on or TNBC cells. We hypothesized that MTAs that differentially alter interphase microtubule structure and dynamics would have distinct effects on cell-intrinsic immunogenic pathways and that these effects could impact the efficacy of these drugs in combination with immunotherapies. The effects of 5 MTAs used for the treatment of TNBC, paclitaxel, docetaxel, ixabepilone, vinorelbine, and eribulin, on the expression of antitumor cytokines and other immunomodulatory genes in myeloid and TNBC cells was evaluated. Our results show that the TLR4-mediated induction of TNFα that occurs in response to paclitaxel was not observed with either eribulin or vinorelbine. Conversely, upregulation of type 1 interferons and interferon-stimulated genes (ISGs) was observed in monocytes and in bone-marrow derived macrophages within 6 h of treatment with eribulin or vinorelbine, but not with any of the microtubule stabilizers. Eribulin-mediated induction of type 1 interferons was also observed in a subset of eribulin-treated TNBC cells and was independent of its antimitotic effects. Importantly, type I interferon signaling has been shown to enhance the efficacy of immune checkpoint inhibitors, suggesting that microtubule destabilizers could have distinct advantages as compared to microtubule stabilizers in combination with these agents. Together, these results provide evidence that MTAs have different immune modulatory properties and suggest that the specific immune signatures initiated by different MTAs need to be considered for their optimal use with targeted agents, including checkpoint inhibitors. These studies were funded by Eisai. Citation Format: Charles Fermaintt, Susan Mooberry, April L. Risinger. Eribulin promotes a distinct immunogenic gene expression signature as compared with paclitaxel [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 965.