Abstract 5545: Heterodimeric interleukin 15 (hetIL-15) treatment decreases primary breast cancer 4T1 tumors and alleviates the metastatic burden

Abstract

Abstract Introduction: In this preclinical study, we tried to model the therapeutic strategies often used in the clinic to treat breast cancer patients. We analyzed the role of hetIL 15 immunotherapy alone and in combination with chemotherapy and surgery using the 4T1, a triple-negative breast cancer cell line, murine breast cancer model. Experimental Procedures: We evaluated the therapeutic potential of combining surgery, chemotherapy (doxorubicin) and immunotherapy (hetIL-15) in the murine 4T1 breast cancer model. Cancer cells were orthotopically implanted into the mammary fat pad of Balb/c mice, and the efficacy of hetIL-15 in combination with doxorubicin on the growth of primary tumors and metastatic disease was assessed. In addition, we monitored the impact of surgery alone in the development of metastatic disease, and, finally, we evaluated the effects on the metastatic burden of the three different approaches combined. Results: hetIL-15 monotherapy and combination of doxorubicin chemotherapy with hetIL-15 immunotherapy inhibited the growth of primary tumors. Interrogating the role of these treatments on lung metastatic disease, the results were unexpected. Doxorubicin alone did not affect the numbers of the metastatic lesions in the lungs. In contrast, hetIL-15 monotherapy reduced the metastatic burden. The combination strategy did not show advantage as compared to hetIL-15 monotherapy. Surgical removal of the growing tumor also decreased metastatic burden, especially when performed at an early point. Chemotherapy with doxorubicin prior to and post-surgery had no impact on the metastatic disease. In contrast, hetIL-15 treatment strongly diminished or eliminated the metastatic burden. Conclusion: Our data strongly suggest that treatment with hetIL-15 as an adjuvant therapy after surgery, or as a neoadjuvant agent before surgery, significantly impacts metastatic disease. Citation Format: Dimitris Stellas, Konstantinos Dimas, Bethany A. Nagy, Antonio Valentin, Barbara K. Felber, George N. Pavlakis. Heterodimeric interleukin 15 (hetIL-15) treatment decreases primary breast cancer 4T1 tumors and alleviates the metastatic burden [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5545.